From patchwork Mon Sep 18 17:59:36 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Han-Wen Nienhuys X-Patchwork-Id: 13390209 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63BD5C46CA1 for ; Mon, 18 Sep 2023 17:59:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229823AbjIRR7v (ORCPT ); Mon, 18 Sep 2023 13:59:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229718AbjIRR7t (ORCPT ); Mon, 18 Sep 2023 13:59:49 -0400 Received: from mail-wm1-x334.google.com (mail-wm1-x334.google.com [IPv6:2a00:1450:4864:20::334]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C269EFA for ; Mon, 18 Sep 2023 10:59:41 -0700 (PDT) Received: by mail-wm1-x334.google.com with SMTP id 5b1f17b1804b1-402d499580dso51852175e9.1 for ; Mon, 18 Sep 2023 10:59:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1695059980; x=1695664780; darn=vger.kernel.org; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :references:in-reply-to:message-id:from:to:cc:subject:date :message-id:reply-to; bh=YQOX0wOVyb8g/uytJrbNM6EdRI3k1zLw75GkauMR7Pg=; b=PhOqVvmL5cMvF1+0I1FO9pbgI4+20gH4NoW4+nM5e1RCS243njLaUms1QM4c4YDUnE Y8k/D1VawPnLneBQ2ODonVeRM74/bTeCaOi09JumnVvOJ00tTHDbzbIBfpaf2AclrLp+ /kE6Hi6RosX1V0DpBmHWB3/gZvzlay/51iJ4+6FVpWRwJc13NgNxiQYSVYDHhl/rcxm9 74Ziz5dFyY+UXn54pc/a9z9NXUtfkTfRGdDR270VT9MSfM4HFw+g26aGWxWJ3GqZkVD3 krpNdpIkXjpWQuU6Jf6IaXHrlH4E2BZFOCHYaD43rC+u/heJ+T973Pb/YajhUWSu8cTU q+Ew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695059980; x=1695664780; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :references:in-reply-to:message-id:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=YQOX0wOVyb8g/uytJrbNM6EdRI3k1zLw75GkauMR7Pg=; b=v5iVRRDIq3JErjnwzOJfrGbgzV/OzgH33Kj2InC+ZLKCN10dmFPGAnt9Ko68OZYcKn Um3uqDwbui8odXSEt4UBE0ocwwdrWl3O5Lyw72dwUBL0nA/GP60vM3ITSF6p1Hc2evhO cGd9lZ+yXMTKj2ossT9cCtL3o+xx3di+C6qjHJtsEPV9TNpqGRGVIm4znrQwZGWLYzBx QBMBS3zpo6iAE3kJvDiNfF6xLE5LYhnNURQoVt3TxZm8Vw7tuh6MSSBDz2T0dXYNveUJ 1/woye/3OT1opiwyGbCGl+QMiFL2mCA7ij+H7wRueHhldiE1SpYctyN17w5Ehy88u7Kl V0Gg== X-Gm-Message-State: AOJu0YyQ1c54IxDRXxUXoETEBTzEsBLm9DuUle/p+CZj5N68szWlD4fU 6kZQfZw3JlPYqjDsbobsQoz2DU/n5GE= X-Google-Smtp-Source: AGHT+IHeBV6PQteeRJ5fZOmOigT77ToklKA3KJS/zwSq0QoST9hBY0XhJtz/EmFXZzdhk3enGUjq3w== X-Received: by 2002:a05:600c:11ce:b0:403:be16:baa with SMTP id b14-20020a05600c11ce00b00403be160baamr9994297wmi.29.1695059979877; Mon, 18 Sep 2023 10:59:39 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id f13-20020a5d568d000000b0031fd849e797sm13111441wrv.105.2023.09.18.10.59.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Sep 2023 10:59:39 -0700 (PDT) Message-ID: In-Reply-To: References: Date: Mon, 18 Sep 2023 17:59:36 +0000 Subject: [PATCH 1/3] refs: push lock management into packed backend Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Han-Wen Nienhuys , Han-Wen Nienhuys Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Han-Wen Nienhuys From: Han-Wen Nienhuys Introduces a ref backend method transaction_begin, which for the packed backend takes packed-refs.lock. This decouples the files backend from the packed backend, allowing the latter to be swapped out by another ref backend. Signed-off-by: Han-Wen Nienhuys --- refs.c | 8 +++++ refs/debug.c | 15 +++++++++ refs/files-backend.c | 78 +++++++++++++++---------------------------- refs/packed-backend.c | 41 ++++++++++++++--------- refs/packed-backend.h | 10 ------ refs/refs-internal.h | 5 +++ 6 files changed, 79 insertions(+), 78 deletions(-) diff --git a/refs.c b/refs.c index fcae5dddc60..a2d1012520e 100644 --- a/refs.c +++ b/refs.c @@ -1130,10 +1130,18 @@ struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs, struct strbuf *err) { struct ref_transaction *tr; + int ret = 0; assert(err); CALLOC_ARRAY(tr, 1); tr->ref_store = refs; + + if (refs->be->transaction_begin) + ret = refs->be->transaction_begin(refs, tr, err); + if (ret) { + free(tr); + return NULL; + } return tr; } diff --git a/refs/debug.c b/refs/debug.c index b7ffc4ce67e..964806e9301 100644 --- a/refs/debug.c +++ b/refs/debug.c @@ -41,6 +41,20 @@ static int debug_init_db(struct ref_store *refs, struct strbuf *err) return res; } +static int debug_transaction_begin(struct ref_store *refs, + struct ref_transaction *transaction, + struct strbuf *err) +{ + struct debug_ref_store *drefs = (struct debug_ref_store *)refs; + int res; + transaction->ref_store = drefs->refs; + res = drefs->refs->be->transaction_begin(drefs->refs, transaction, + err); + trace_printf_key(&trace_refs, "transaction_begin: %d \"%s\"\n", res, + err->buf); + return res; +} + static int debug_transaction_prepare(struct ref_store *refs, struct ref_transaction *transaction, struct strbuf *err) @@ -451,6 +465,7 @@ struct ref_storage_be refs_be_debug = { * has a function we should also have a wrapper for it here. * Test the output with "GIT_TRACE_REFS=1". */ + .transaction_begin = debug_transaction_begin, .transaction_prepare = debug_transaction_prepare, .transaction_finish = debug_transaction_finish, .transaction_abort = debug_transaction_abort, diff --git a/refs/files-backend.c b/refs/files-backend.c index 341354182bb..4a6781af783 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -1219,10 +1219,10 @@ static int files_pack_refs(struct ref_store *ref_store, struct ref_transaction *transaction; transaction = ref_store_transaction_begin(refs->packed_ref_store, &err); - if (!transaction) + if (!transaction) { + die("could not start transaction: %s", err.buf); return -1; - - packed_refs_lock(refs->packed_ref_store, LOCK_DIE_ON_ERROR, &err); + } iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, the_repository, 0); @@ -1262,8 +1262,6 @@ static int files_pack_refs(struct ref_store *ref_store, ref_transaction_free(transaction); - packed_refs_unlock(refs->packed_ref_store); - prune_refs(refs, &refs_to_prune); strbuf_release(&err); return 0; @@ -1280,16 +1278,10 @@ static int files_delete_refs(struct ref_store *ref_store, const char *msg, if (!refnames->nr) return 0; - if (packed_refs_lock(refs->packed_ref_store, 0, &err)) - goto error; - if (refs_delete_refs(refs->packed_ref_store, msg, refnames, flags)) { - packed_refs_unlock(refs->packed_ref_store); goto error; } - packed_refs_unlock(refs->packed_ref_store); - for (i = 0; i < refnames->nr; i++) { const char *refname = refnames->items[i].string; @@ -2640,7 +2632,7 @@ out: struct files_transaction_backend_data { struct ref_transaction *packed_transaction; - int packed_refs_locked; + int packed_transaction_needed; }; /* @@ -2672,10 +2664,8 @@ static void files_transaction_cleanup(struct files_ref_store *refs, strbuf_release(&err); } - if (backend_data->packed_refs_locked) - packed_refs_unlock(refs->packed_ref_store); - free(backend_data); + transaction->backend_data = NULL; } transaction->state = REF_TRANSACTION_CLOSED; @@ -2804,14 +2794,9 @@ static int files_transaction_prepare(struct ref_store *ref_store, } if (packed_transaction) { - if (packed_refs_lock(refs->packed_ref_store, 0, err)) { - ret = TRANSACTION_GENERIC_ERROR; - goto cleanup; - } - backend_data->packed_refs_locked = 1; - - if (is_packed_transaction_needed(refs->packed_ref_store, - packed_transaction)) { + backend_data->packed_transaction_needed = is_packed_transaction_needed(refs->packed_ref_store, + packed_transaction); + if (backend_data->packed_transaction_needed) { ret = ref_transaction_prepare(packed_transaction, err); /* * A failure during the prepare step will abort @@ -2823,22 +2808,6 @@ static int files_transaction_prepare(struct ref_store *ref_store, ref_transaction_free(packed_transaction); backend_data->packed_transaction = NULL; } - } else { - /* - * We can skip rewriting the `packed-refs` - * file. But we do need to leave it locked, so - * that somebody else doesn't pack a reference - * that we are trying to delete. - * - * We need to disconnect our transaction from - * backend_data, since the abort (whether successful or - * not) will free it. - */ - backend_data->packed_transaction = NULL; - if (ref_transaction_abort(packed_transaction, err)) { - ret = TRANSACTION_GENERIC_ERROR; - goto cleanup; - } } } @@ -2940,13 +2909,24 @@ static int files_transaction_finish(struct ref_store *ref_store, * First delete any packed versions of the references, while * retaining the packed-refs lock: */ - if (packed_transaction) { - ret = ref_transaction_commit(packed_transaction, err); - ref_transaction_free(packed_transaction); - packed_transaction = NULL; - backend_data->packed_transaction = NULL; - if (ret) - goto cleanup; + if (backend_data->packed_transaction) { + if (backend_data->packed_transaction_needed) { + ret = ref_transaction_commit(packed_transaction, err); + if (ret) + goto cleanup; + /* TODO: leaks on error path. */ + ref_transaction_free(packed_transaction); + packed_transaction = NULL; + backend_data->packed_transaction = NULL; + } else { + ret = ref_transaction_abort(packed_transaction, err); + if (ret) + goto cleanup; + + /* transaction_commit doesn't free the data, but transaction_abort does. Go figure. */ + packed_transaction = NULL; + backend_data->packed_transaction = NULL; + } } /* Now delete the loose versions of the references: */ @@ -3087,16 +3067,10 @@ static int files_initial_transaction_commit(struct ref_store *ref_store, NULL); } - if (packed_refs_lock(refs->packed_ref_store, 0, err)) { - ret = TRANSACTION_GENERIC_ERROR; - goto cleanup; - } - if (initial_ref_transaction_commit(packed_transaction, err)) { ret = TRANSACTION_GENERIC_ERROR; } - packed_refs_unlock(refs->packed_ref_store); cleanup: if (packed_transaction) ref_transaction_free(packed_transaction); diff --git a/refs/packed-backend.c b/refs/packed-backend.c index 59c78d7941f..5df7fa8004f 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -1552,8 +1552,6 @@ int is_packed_transaction_needed(struct ref_store *ref_store, struct packed_transaction_backend_data { /* True iff the transaction owns the packed-refs lock. */ - int own_lock; - struct string_list updates; }; @@ -1568,9 +1566,8 @@ static void packed_transaction_cleanup(struct packed_ref_store *refs, if (is_tempfile_active(refs->tempfile)) delete_tempfile(&refs->tempfile); - if (data->own_lock && is_lock_file_locked(&refs->lock)) { + if (is_lock_file_locked(&refs->lock)) { packed_refs_unlock(&refs->base); - data->own_lock = 0; } free(data); @@ -1580,6 +1577,28 @@ static void packed_transaction_cleanup(struct packed_ref_store *refs, transaction->state = REF_TRANSACTION_CLOSED; } +static int packed_transaction_begin(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *err) +{ + struct packed_ref_store *refs = packed_downcast( + ref_store, + REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB, + "ref_transaction_begin"); + struct packed_transaction_backend_data *data; + + CALLOC_ARRAY(data, 1); + string_list_init_nodup(&data->updates); + + if (!is_lock_file_locked(&refs->lock)) { + if (packed_refs_lock(ref_store, 0, err)) + /* todo: leaking data */ + return -1; + } + transaction->backend_data = data; + return 0; +} + static int packed_transaction_prepare(struct ref_store *ref_store, struct ref_transaction *transaction, struct strbuf *err) @@ -1588,7 +1607,7 @@ static int packed_transaction_prepare(struct ref_store *ref_store, ref_store, REF_STORE_READ | REF_STORE_WRITE | REF_STORE_ODB, "ref_transaction_prepare"); - struct packed_transaction_backend_data *data; + struct packed_transaction_backend_data *data = transaction->backend_data; size_t i; int ret = TRANSACTION_GENERIC_ERROR; @@ -1601,11 +1620,6 @@ static int packed_transaction_prepare(struct ref_store *ref_store, * do so itself. */ - CALLOC_ARRAY(data, 1); - string_list_init_nodup(&data->updates); - - transaction->backend_data = data; - /* * Stick the updates in a string list by refname so that we * can sort them: @@ -1623,12 +1637,6 @@ static int packed_transaction_prepare(struct ref_store *ref_store, if (ref_update_reject_duplicates(&data->updates, err)) goto failure; - if (!is_lock_file_locked(&refs->lock)) { - if (packed_refs_lock(ref_store, 0, err)) - goto failure; - data->own_lock = 1; - } - if (write_with_updates(refs, &data->updates, err)) goto failure; @@ -1758,6 +1766,7 @@ struct ref_storage_be refs_be_packed = { .name = "packed", .init = packed_ref_store_create, .init_db = packed_init_db, + .transaction_begin = packed_transaction_begin, .transaction_prepare = packed_transaction_prepare, .transaction_finish = packed_transaction_finish, .transaction_abort = packed_transaction_abort, diff --git a/refs/packed-backend.h b/refs/packed-backend.h index 9dd8a344c34..ade3c8a5ac4 100644 --- a/refs/packed-backend.h +++ b/refs/packed-backend.h @@ -17,16 +17,6 @@ struct ref_store *packed_ref_store_create(struct repository *repo, const char *gitdir, unsigned int store_flags); -/* - * Lock the packed-refs file for writing. Flags is passed to - * hold_lock_file_for_update(). Return 0 on success. On errors, write - * an error message to `err` and return a nonzero value. - */ -int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err); - -void packed_refs_unlock(struct ref_store *ref_store); -int packed_refs_is_locked(struct ref_store *ref_store); - /* * Return true if `transaction` really needs to be carried out against * the specified packed_ref_store, or false if it can be skipped diff --git a/refs/refs-internal.h b/refs/refs-internal.h index 9db8aec4da8..87f8e8b51d6 100644 --- a/refs/refs-internal.h +++ b/refs/refs-internal.h @@ -531,6 +531,10 @@ typedef struct ref_store *ref_store_init_fn(struct repository *repo, typedef int ref_init_db_fn(struct ref_store *refs, struct strbuf *err); +typedef int ref_transaction_begin_fn(struct ref_store *refs, + struct ref_transaction *transaction, + struct strbuf *err); + typedef int ref_transaction_prepare_fn(struct ref_store *refs, struct ref_transaction *transaction, struct strbuf *err); @@ -670,6 +674,7 @@ struct ref_storage_be { ref_store_init_fn *init; ref_init_db_fn *init_db; + ref_transaction_begin_fn *transaction_begin; ref_transaction_prepare_fn *transaction_prepare; ref_transaction_finish_fn *transaction_finish; ref_transaction_abort_fn *transaction_abort; From patchwork Mon Sep 18 17:59:37 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Han-Wen Nienhuys X-Patchwork-Id: 13390210 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88BCFCD37B0 for ; Mon, 18 Sep 2023 17:59:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229981AbjIRR75 (ORCPT ); Mon, 18 Sep 2023 13:59:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229776AbjIRR7u (ORCPT ); Mon, 18 Sep 2023 13:59:50 -0400 Received: from mail-wm1-x332.google.com (mail-wm1-x332.google.com [IPv6:2a00:1450:4864:20::332]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4CDB0121 for ; Mon, 18 Sep 2023 10:59:43 -0700 (PDT) Received: by mail-wm1-x332.google.com with SMTP id 5b1f17b1804b1-404c023ef5eso30535335e9.2 for ; Mon, 18 Sep 2023 10:59:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1695059981; x=1695664781; darn=vger.kernel.org; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :references:in-reply-to:message-id:from:to:cc:subject:date :message-id:reply-to; bh=ubMxsbUvW5XykwgiLxu8nvh4K8in8d8MnELnnIs2AaY=; b=V0Ma3NNYnanW3Cnmx510cIbUPEEL3iGgZbqSObUgsEk76+RoGTCIiP/p84mO+V1WQ8 Zly/fJ398dG6je2HmASXJpgEzczb0MBwuUQyVfLBr8UXK78m+5jptuaY3Z6BUWUSleVr Qigr5Rn3UFZ6xnjjniBFEtLqlVEEF7Qrmgq9br6DquBCDjwx2WfaetIETMZ8Zc9EgDXO IhumlvQzcddGGnCjinWC8yE4hGH3BuYqAhpwhdBgDTJt4str08zUEHZKZT2Kjvu6hkpo CKqmFKVmKvkw8nJRkQ3FAzun17fEEYudMkXundJmlP5maquTNcdEqb4qnoE49nYwbnVW 5YXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695059981; x=1695664781; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :references:in-reply-to:message-id:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ubMxsbUvW5XykwgiLxu8nvh4K8in8d8MnELnnIs2AaY=; b=o18WsmrKY5oH+7pqtvH8eA0ZRXb6Y1Fx37XAPzXcAl6yWc9YfOPwE6s7wVLgk8H+sJ 2HaNaYYVFBLCX0fPUavOJZJk1UJ9MYg5NBnfYMVPKPVkz3j6RU4ijBcSeun/QBEovxkM PXPjGWiJey0aDmJe5RvJa9LqtOKg2oTtwRsl4NkkaN8DJb6xjkZ+6Hmg6hC5pYJBlQwa gfWr8gDFXaZFxHMBh7NnXViiPrFUMdGYsfKwZ54UUw6KzsmQu/KZCf6lREy5rPL7SUPx fsvUtUE2nnd1/5N1FNSG4jJKElASPM8mz3bcT/Ehj9zvn0k4RmUTY16RaUifu/bWZ7GM h2LA== X-Gm-Message-State: AOJu0Yz9wncA1mLat14foL6XnDwYW/luECgFqOWaOl1rEmvBjez+4rbM j/891hKCW1Fh/OeEJhrJFYnCIpYH9Zc= X-Google-Smtp-Source: AGHT+IFDot9zJbxUjuZ7drxPiu00atDCMnoSEobASPzxAI0+8HFr4+H4ZNn4pk3FHKjgkh2tfGZMZw== X-Received: by 2002:a05:600c:21d7:b0:3fe:d1e9:e6b8 with SMTP id x23-20020a05600c21d700b003fed1e9e6b8mr8222371wmj.12.1695059980876; Mon, 18 Sep 2023 10:59:40 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id r4-20020adfdc84000000b0031753073abcsm13183737wrj.36.2023.09.18.10.59.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Sep 2023 10:59:40 -0700 (PDT) Message-ID: In-Reply-To: References: Date: Mon, 18 Sep 2023 17:59:37 +0000 Subject: [PATCH 2/3] refs: move is_packed_transaction_needed out of packed-backend.c Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Han-Wen Nienhuys , Han-Wen Nienhuys Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Han-Wen Nienhuys From: Han-Wen Nienhuys It is no longer specific to the packed backend. Signed-off-by: Han-Wen Nienhuys --- refs/files-backend.c | 96 +++++++++++++++++++++++++++++++++++++++++++ refs/packed-backend.c | 95 ------------------------------------------ refs/packed-backend.h | 9 ---- 3 files changed, 96 insertions(+), 104 deletions(-) diff --git a/refs/files-backend.c b/refs/files-backend.c index 4a6781af783..c0a7e3d375b 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -2630,6 +2630,101 @@ out: return ret; } + +/* + * Return true if `transaction` really needs to be carried out against + * the specified packed_ref_store, or false if it can be skipped + * (i.e., because it is an obvious NOOP). `ref_store` must be locked + * before calling this function. + */ +static int is_packed_transaction_needed(struct ref_store *ref_store, + struct ref_transaction *transaction) +{ + struct strbuf referent = STRBUF_INIT; + size_t i; + int ret; + + /* + * We're only going to bother returning false for the common, + * trivial case that references are only being deleted, their + * old values are not being checked, and the old `packed-refs` + * file doesn't contain any of those reference(s). This gives + * false positives for some other cases that could + * theoretically be optimized away: + * + * 1. It could be that the old value is being verified without + * setting a new value. In this case, we could verify the + * old value here and skip the update if it agrees. If it + * disagrees, we could either let the update go through + * (the actual commit would re-detect and report the + * problem), or come up with a way of reporting such an + * error to *our* caller. + * + * 2. It could be that a new value is being set, but that it + * is identical to the current packed value of the + * reference. + * + * Neither of these cases will come up in the current code, + * because the only caller of this function passes to it a + * transaction that only includes `delete` updates with no + * `old_id`. Even if that ever changes, false positives only + * cause an optimization to be missed; they do not affect + * correctness. + */ + + /* + * Start with the cheap checks that don't require old + * reference values to be read: + */ + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + + if (update->flags & REF_HAVE_OLD) + /* Have to check the old value -> needed. */ + return 1; + + if ((update->flags & REF_HAVE_NEW) && !is_null_oid(&update->new_oid)) + /* Have to set a new value -> needed. */ + return 1; + } + + /* + * The transaction isn't checking any old values nor is it + * setting any nonzero new values, so it still might be able + * to be skipped. Now do the more expensive check: the update + * is needed if any of the updates is a delete, and the old + * `packed-refs` file contains a value for that reference. + */ + ret = 0; + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + int failure_errno; + unsigned int type; + struct object_id oid; + + if (!(update->flags & REF_HAVE_NEW)) + /* + * This reference isn't being deleted -> not + * needed. + */ + continue; + + if (!refs_read_raw_ref(ref_store, update->refname, &oid, + &referent, &type, &failure_errno) || + failure_errno != ENOENT) { + /* + * We have to actually delete that reference + * -> this transaction is needed. + */ + ret = 1; + break; + } + } + + strbuf_release(&referent); + return ret; +} + struct files_transaction_backend_data { struct ref_transaction *packed_transaction; int packed_transaction_needed; @@ -3294,3 +3389,4 @@ struct ref_storage_be refs_be_files = { .delete_reflog = files_delete_reflog, .reflog_expire = files_reflog_expire }; + diff --git a/refs/packed-backend.c b/refs/packed-backend.c index 5df7fa8004f..ba895c845c0 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -1455,101 +1455,6 @@ error: return -1; } -int is_packed_transaction_needed(struct ref_store *ref_store, - struct ref_transaction *transaction) -{ - struct packed_ref_store *refs = packed_downcast( - ref_store, - REF_STORE_READ, - "is_packed_transaction_needed"); - struct strbuf referent = STRBUF_INIT; - size_t i; - int ret; - - if (!is_lock_file_locked(&refs->lock)) - BUG("is_packed_transaction_needed() called while unlocked"); - - /* - * We're only going to bother returning false for the common, - * trivial case that references are only being deleted, their - * old values are not being checked, and the old `packed-refs` - * file doesn't contain any of those reference(s). This gives - * false positives for some other cases that could - * theoretically be optimized away: - * - * 1. It could be that the old value is being verified without - * setting a new value. In this case, we could verify the - * old value here and skip the update if it agrees. If it - * disagrees, we could either let the update go through - * (the actual commit would re-detect and report the - * problem), or come up with a way of reporting such an - * error to *our* caller. - * - * 2. It could be that a new value is being set, but that it - * is identical to the current packed value of the - * reference. - * - * Neither of these cases will come up in the current code, - * because the only caller of this function passes to it a - * transaction that only includes `delete` updates with no - * `old_id`. Even if that ever changes, false positives only - * cause an optimization to be missed; they do not affect - * correctness. - */ - - /* - * Start with the cheap checks that don't require old - * reference values to be read: - */ - for (i = 0; i < transaction->nr; i++) { - struct ref_update *update = transaction->updates[i]; - - if (update->flags & REF_HAVE_OLD) - /* Have to check the old value -> needed. */ - return 1; - - if ((update->flags & REF_HAVE_NEW) && !is_null_oid(&update->new_oid)) - /* Have to set a new value -> needed. */ - return 1; - } - - /* - * The transaction isn't checking any old values nor is it - * setting any nonzero new values, so it still might be able - * to be skipped. Now do the more expensive check: the update - * is needed if any of the updates is a delete, and the old - * `packed-refs` file contains a value for that reference. - */ - ret = 0; - for (i = 0; i < transaction->nr; i++) { - struct ref_update *update = transaction->updates[i]; - int failure_errno; - unsigned int type; - struct object_id oid; - - if (!(update->flags & REF_HAVE_NEW)) - /* - * This reference isn't being deleted -> not - * needed. - */ - continue; - - if (!refs_read_raw_ref(ref_store, update->refname, &oid, - &referent, &type, &failure_errno) || - failure_errno != ENOENT) { - /* - * We have to actually delete that reference - * -> this transaction is needed. - */ - ret = 1; - break; - } - } - - strbuf_release(&referent); - return ret; -} - struct packed_transaction_backend_data { /* True iff the transaction owns the packed-refs lock. */ struct string_list updates; diff --git a/refs/packed-backend.h b/refs/packed-backend.h index ade3c8a5ac4..51a3b6a332a 100644 --- a/refs/packed-backend.h +++ b/refs/packed-backend.h @@ -17,13 +17,4 @@ struct ref_store *packed_ref_store_create(struct repository *repo, const char *gitdir, unsigned int store_flags); -/* - * Return true if `transaction` really needs to be carried out against - * the specified packed_ref_store, or false if it can be skipped - * (i.e., because it is an obvious NOOP). `ref_store` must be locked - * before calling this function. - */ -int is_packed_transaction_needed(struct ref_store *ref_store, - struct ref_transaction *transaction); - #endif /* REFS_PACKED_BACKEND_H */ From patchwork Mon Sep 18 17:59:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Han-Wen Nienhuys X-Patchwork-Id: 13390211 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82714CD13D2 for ; Mon, 18 Sep 2023 17:59:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229718AbjIRR76 (ORCPT ); Mon, 18 Sep 2023 13:59:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229692AbjIRR74 (ORCPT ); Mon, 18 Sep 2023 13:59:56 -0400 Received: from mail-wr1-x42d.google.com (mail-wr1-x42d.google.com [IPv6:2a00:1450:4864:20::42d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2C11C115 for ; Mon, 18 Sep 2023 10:59:44 -0700 (PDT) Received: by mail-wr1-x42d.google.com with SMTP id ffacd0b85a97d-31f7638be6eso4577187f8f.3 for ; Mon, 18 Sep 2023 10:59:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1695059982; x=1695664782; darn=vger.kernel.org; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :references:in-reply-to:message-id:from:to:cc:subject:date :message-id:reply-to; bh=ENjkO0NRwHoOCTlrqUjumzmfdKK+k69aubAoOwOuMx0=; b=HV2kMLDANxuZNzbFDuddLu7x2pRaP8n/gZQnQB2pbcE3X92YFxzyQ54Ef5bs5J14Fb uL5iwV/3pHnyJNmLvWrjmYaDmNh5rz+DbssCKRc4wJvHPqg2S6qqXYoT0xzpMQjT1Nie uEq4Edd9xuWlwyJM52fluYQRTgFeP0KXTeplAiU60N4OT+KyDyJRo86XjQExV8psdXGD K09F1XeOUBBtliBlMHp3/yqZhol98BuRhoVNXdJSaqOuBlu7zBj/3Bn7ZTMIy37/c9D3 JyOetDatR8yxKy9H8Gv1H1LG0/c/C4ti8Yph8YD3hLiY+shCKhakw/YvaurgZCKxSAOJ ybAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695059982; x=1695664782; h=cc:to:mime-version:content-transfer-encoding:fcc:subject:date:from :references:in-reply-to:message-id:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ENjkO0NRwHoOCTlrqUjumzmfdKK+k69aubAoOwOuMx0=; b=l4w1dOYVVeD8slINxrdNwkuAYeX3sTZonohS7ETZjPYfML36q4BwDCy+PCQXTy9j6y FwGGSQDJ/fn32kCdGNJDr8LZ7S7bEX77fPo928ZxjgEX+L6UGCHRF+mK1tky+ox/0oIJ LYjm0IqQq59mJiaExgIx1e7YN8XKTA1pzOwnHXfUgMWA1sxGVmWb4Fq99GY9RGtCdDqp 0YmFEKG7BtzJ60eEPBiQHZwor4B6s0Lz3TLoXXSMOs/tydJn8XxUk3B2Xk4oG7lRYNrV lGVH9uG2QxRLGTsJDIUMGU6JbVv65Sb3QSe2z54zDcKPIMxt9SKXj+qR07zPnd39BIyE 6+Gg== X-Gm-Message-State: AOJu0YyEzef3RhYMGcw3XXDbIQii9rmFBJnqAn6yjcUTDM+uz+5+XYeH QfotaipcBAQDFDL/KhgMmWssyn3dTJw= X-Google-Smtp-Source: AGHT+IExzsCQSZMaywDj8l2Hg22S9dIAevn+VVj28Y/4OdtYECIeXmGdH08YOY9IJ04ymzpP3ZFh6g== X-Received: by 2002:a05:6000:1f14:b0:320:93a:6273 with SMTP id bv20-20020a0560001f1400b00320093a6273mr5414813wrb.49.1695059981786; Mon, 18 Sep 2023 10:59:41 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id z11-20020a5d440b000000b0031423a8f4f7sm13136654wrq.56.2023.09.18.10.59.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Sep 2023 10:59:41 -0700 (PDT) Message-ID: <559c04cee998ed05c7b49bcac092df8a05cd709c.1695059978.git.gitgitgadget@gmail.com> In-Reply-To: References: Date: Mon, 18 Sep 2023 17:59:38 +0000 Subject: [PATCH 3/3] refs: alternate reftable ref backend implementation Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Han-Wen Nienhuys , Han-Wen Nienhuys Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org From: Han-Wen Nienhuys From: Han-Wen Nienhuys This introduces the reftable backend as an alternative to the packed backend. This simplifies the code, because we now longer have to worry about: - pseudorefs and the HEAD ref - worktrees - commands that blur together files and references (cherry-pick, rebase) This deviates from the spec that in Documentation/technical/reftable.txt. It might be possible to update the code such that all writes by default go to reftable directly. Then the result would be compatible with an implementation that writes only reftable (the reftable lock would still prevent races) relative to an implementation that disregards loose refs. Or, JGit could be adapted to follow this implementation. For this incremental path, the reftable format is arguably more complex than necessary, as - packed-refs doesn't support symrefs - reflogs aren't moved into reftable/ on the other hand, the code is already there, and it's well-structured and well-tested. This implementation is a prototype. To test, you need to do `export GIT_TEST_REFTABLE=1`. Doing so creates a handful of errors in the test-suite, most seemingly related to the new behavior of pack-refs (which creates a reftable/ dir and not a packed-refs file.), but it seems overseeable. Signed-off-by: Han-Wen Nienhuys --- Makefile | 1 + config.mak.uname | 2 +- contrib/workdir/git-new-workdir | 2 +- refs/files-backend.c | 8 +- refs/packed-backend.c | 14 +- refs/refs-internal.h | 1 + refs/reftable-backend.c | 1745 +++++++++++++++++++++++++++++++ refs/reftable-backend.h | 8 + 8 files changed, 1766 insertions(+), 15 deletions(-) create mode 100644 refs/reftable-backend.c create mode 100644 refs/reftable-backend.h diff --git a/Makefile b/Makefile index 57763093653..272d3f7f1e9 100644 --- a/Makefile +++ b/Makefile @@ -1118,6 +1118,7 @@ LIB_OBJS += reflog.o LIB_OBJS += refs.o LIB_OBJS += refs/debug.o LIB_OBJS += refs/files-backend.o +LIB_OBJS += refs/reftable-backend.o LIB_OBJS += refs/iterator.o LIB_OBJS += refs/packed-backend.o LIB_OBJS += refs/ref-cache.o diff --git a/config.mak.uname b/config.mak.uname index 3bb03f423a0..843829c02fd 100644 --- a/config.mak.uname +++ b/config.mak.uname @@ -743,7 +743,7 @@ vcxproj: # Make .vcxproj files and add them perl contrib/buildsystems/generate -g Vcxproj - git add -f git.sln {*,*/lib,t/helper/*}/*.vcxproj + git add -f git.sln {*,*/lib,*/libreftable,t/helper/*}/*.vcxproj # Generate the LinkOrCopyBuiltins.targets and LinkOrCopyRemoteHttp.targets file (echo '' && \ diff --git a/contrib/workdir/git-new-workdir b/contrib/workdir/git-new-workdir index 888c34a5215..989197aace0 100755 --- a/contrib/workdir/git-new-workdir +++ b/contrib/workdir/git-new-workdir @@ -79,7 +79,7 @@ trap cleanup $siglist # create the links to the original repo. explicitly exclude index, HEAD and # logs/HEAD from the list since they are purely related to the current working # directory, and should not be shared. -for x in config refs logs/refs objects info hooks packed-refs remotes rr-cache svn +for x in config refs logs/refs objects info hooks packed-refs remotes rr-cache svn reftable do # create a containing directory if needed case $x in diff --git a/refs/files-backend.c b/refs/files-backend.c index c0a7e3d375b..725321a229e 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -9,6 +9,7 @@ #include "refs-internal.h" #include "ref-cache.h" #include "packed-backend.h" +#include "reftable-backend.h" #include "../ident.h" #include "../iterator.h" #include "../dir-iterator.h" @@ -103,8 +104,13 @@ static struct ref_store *files_ref_store_create(struct repository *repo, refs->store_flags = flags; get_common_dir_noenv(&sb, gitdir); refs->gitcommondir = strbuf_detach(&sb, NULL); + + /* TODO: should look at the repo to decide whether to use packed-refs or + * reftable. */ refs->packed_ref_store = - packed_ref_store_create(repo, refs->gitcommondir, flags); + git_env_bool("GIT_TEST_REFTABLE", 0) + ? git_reftable_ref_store_create(repo, refs->gitcommondir, flags) + : packed_ref_store_create(repo, refs->gitcommondir, flags); chdir_notify_reparent("files-backend $GIT_DIR", &refs->base.gitdir); chdir_notify_reparent("files-backend $GIT_COMMONDIR", diff --git a/refs/packed-backend.c b/refs/packed-backend.c index ba895c845c0..ad72cad8024 100644 --- a/refs/packed-backend.c +++ b/refs/packed-backend.c @@ -1153,7 +1153,7 @@ static int write_packed_entry(FILE *fh, const char *refname, return 0; } -int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err) +static int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err) { struct packed_ref_store *refs = packed_downcast(ref_store, REF_STORE_WRITE | REF_STORE_MAIN, @@ -1212,7 +1212,7 @@ int packed_refs_lock(struct ref_store *ref_store, int flags, struct strbuf *err) return 0; } -void packed_refs_unlock(struct ref_store *ref_store) +static void packed_refs_unlock(struct ref_store *ref_store) { struct packed_ref_store *refs = packed_downcast( ref_store, @@ -1224,16 +1224,6 @@ void packed_refs_unlock(struct ref_store *ref_store) rollback_lock_file(&refs->lock); } -int packed_refs_is_locked(struct ref_store *ref_store) -{ - struct packed_ref_store *refs = packed_downcast( - ref_store, - REF_STORE_READ | REF_STORE_WRITE, - "packed_refs_is_locked"); - - return is_lock_file_locked(&refs->lock); -} - /* * The packed-refs header line that we write out. Perhaps other traits * will be added later. diff --git a/refs/refs-internal.h b/refs/refs-internal.h index 87f8e8b51d6..172ae23534b 100644 --- a/refs/refs-internal.h +++ b/refs/refs-internal.h @@ -700,6 +700,7 @@ struct ref_storage_be { }; extern struct ref_storage_be refs_be_files; +extern struct ref_storage_be refs_be_reftable; extern struct ref_storage_be refs_be_packed; /* diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c new file mode 100644 index 00000000000..367bcae2857 --- /dev/null +++ b/refs/reftable-backend.c @@ -0,0 +1,1745 @@ +#include "../git-compat-util.h" +#include "../abspath.h" +#include "../chdir-notify.h" +#include "../config.h" +#include "../environment.h" +#include "../hash.h" +#include "../hex.h" +#include "../iterator.h" +#include "../ident.h" +#include "../lockfile.h" +#include "../object.h" +#include "../path.h" +#include "../refs.h" +#include "../reftable/reftable-stack.h" +#include "../reftable/reftable-record.h" +#include "../reftable/reftable-error.h" +#include "../reftable/reftable-blocksource.h" +#include "../reftable/reftable-reader.h" +#include "../reftable/reftable-iterator.h" +#include "../reftable/reftable-merged.h" +#include "../reftable/reftable-generic.h" +#include "../worktree.h" +#include "refs-internal.h" +#include "reftable-backend.h" + +extern struct ref_storage_be refs_be_reftable; + +struct git_reftable_ref_store { + struct ref_store base; + unsigned int store_flags; + + int err; + char *repo_dir; + char *reftable_dir; + + struct reftable_stack *main_stack; + + struct reftable_write_options write_options; +}; + +static struct reftable_stack *stack_for(struct git_reftable_ref_store *store, + const char *refname) +{ + return store->main_stack; +} + +static int should_log(const char *refname) +{ + return log_all_ref_updates != LOG_REFS_NONE && + (log_all_ref_updates == LOG_REFS_ALWAYS || + log_all_ref_updates == LOG_REFS_UNSET || + should_autocreate_reflog(refname)); +} + +static const char *bare_ref_name(const char *ref) +{ + const char *stripped; + parse_worktree_ref(ref, NULL, NULL, &stripped); + return stripped; +} + +static int git_reftable_read_raw_ref(struct ref_store *ref_store, + const char *refname, struct object_id *oid, + struct strbuf *referent, + unsigned int *type, int *failure_errno); + +static void clear_reftable_log_record(struct reftable_log_record *log) +{ + switch (log->value_type) { + case REFTABLE_LOG_UPDATE: + /* when we write log records, the hashes are owned by a struct + * oid */ + log->value.update.old_hash = NULL; + log->value.update.new_hash = NULL; + break; + case REFTABLE_LOG_DELETION: + break; + } + reftable_log_record_release(log); +} + +static void fill_reftable_log_record(struct reftable_log_record *log) +{ + const char *info = git_committer_info(0); + struct ident_split split = { NULL }; + int result = split_ident_line(&split, info, strlen(info)); + int sign = 1; + assert(0 == result); + + reftable_log_record_release(log); + log->value_type = REFTABLE_LOG_UPDATE; + log->value.update.name = + xstrndup(split.name_begin, split.name_end - split.name_begin); + log->value.update.email = + xstrndup(split.mail_begin, split.mail_end - split.mail_begin); + log->value.update.time = atol(split.date_begin); + if (*split.tz_begin == '-') { + sign = -1; + split.tz_begin++; + } + if (*split.tz_begin == '+') { + sign = 1; + split.tz_begin++; + } + + log->value.update.tz_offset = sign * atoi(split.tz_begin); +} + +struct ref_store *git_reftable_ref_store_create(struct repository *repo, + const char *gitdir, + unsigned int store_flags) +{ + struct git_reftable_ref_store *refs = xcalloc(1, sizeof(*refs)); + struct ref_store *ref_store = (struct ref_store *)refs; + struct strbuf sb = STRBUF_INIT; + int shared = get_shared_repository(); + if (shared < 0) + shared = -shared; + + refs->write_options.block_size = 4096; + refs->write_options.hash_id = the_hash_algo->format_id; + if (shared && (shared & 0600)) + refs->write_options.default_permissions = shared; + + /* XXX should this use `path` or `gitdir.buf` ? */ + base_ref_store_init(ref_store, repo, gitdir, &refs_be_reftable); + refs->store_flags = store_flags; + strbuf_addf(&sb, "%s/reftable", gitdir); + refs->reftable_dir = xstrdup(sb.buf); + safe_create_dir(refs->reftable_dir, 1); + + refs->base.repo = repo; + strbuf_reset(&sb); + + refs->err = reftable_new_stack(&refs->main_stack, refs->reftable_dir, + refs->write_options); + assert(refs->err != REFTABLE_API_ERROR); + + strbuf_release(&sb); + + /* TODO something with chdir_notify_reparent() ? */ + + return ref_store; +} + +static int git_reftable_init_db(struct ref_store *ref_store, struct strbuf *err) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + safe_create_dir(refs->reftable_dir, 1); + return 0; +} + +struct git_reftable_iterator { + struct ref_iterator base; + struct reftable_iterator iter; + struct reftable_ref_record ref; + struct object_id oid; + struct ref_store *ref_store; + + unsigned int flags; + int err; + const char *prefix; +}; + +static int reftable_ref_iterator_advance(struct ref_iterator *ref_iterator) +{ + struct git_reftable_iterator *ri = + (struct git_reftable_iterator *)ref_iterator; + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ri->ref_store; + + while (ri->err == 0) { + int signed_flags = 0; + ri->err = reftable_iterator_next_ref(&ri->iter, &ri->ref); + if (ri->err) { + break; + } + + ri->base.flags = 0; + + if (!strcmp(ri->ref.refname, "HEAD")) { + /* + HEAD should not be produced by default.Other + pseudorefs (FETCH_HEAD etc.) shouldn't be + stored in reftables at all. + */ + continue; + } + ri->base.refname = ri->ref.refname; + if (ri->prefix && + strncmp(ri->prefix, ri->ref.refname, strlen(ri->prefix))) { + ri->err = 1; + break; + } + if (ri->flags & DO_FOR_EACH_PER_WORKTREE_ONLY && + parse_worktree_ref(ri->base.refname, NULL, NULL, NULL) != + REF_WORKTREE_CURRENT) + continue; + + if (ri->flags & DO_FOR_EACH_INCLUDE_BROKEN && + check_refname_format(ri->base.refname, + REFNAME_ALLOW_ONELEVEL)) { + /* This is odd, as REF_BAD_NAME and REF_ISBROKEN are + orthogonal, but it's what the spec says and the + files-backend does. */ + ri->base.flags |= REF_BAD_NAME | REF_ISBROKEN; + break; + } + + switch (ri->ref.value_type) { + case REFTABLE_REF_VAL1: + oidread(&ri->oid, ri->ref.value.val1); + break; + case REFTABLE_REF_VAL2: + oidread(&ri->oid, ri->ref.value.val2.value); + break; + case REFTABLE_REF_SYMREF: + ri->base.flags = REF_ISSYMREF; + break; + default: + abort(); + } + + ri->base.oid = &ri->oid; + if (!(ri->flags & DO_FOR_EACH_INCLUDE_BROKEN) && + !ref_resolves_to_object(ri->base.refname, refs->base.repo, + ri->base.oid, ri->base.flags)) { + continue; + } + + /* Arguably, resolving recursively following symlinks should be + * lifted to refs.c because it is shared between reftable and + * the files backend, but it's here now. + */ + if (!refs_resolve_ref_unsafe(ri->ref_store, ri->ref.refname, + RESOLVE_REF_READING, &ri->oid, + &signed_flags)) { + ri->base.flags = signed_flags; + if (ri->ref.value_type == REFTABLE_REF_SYMREF && + ri->flags & DO_FOR_EACH_OMIT_DANGLING_SYMREFS) + continue; + + if (ri->ref.value_type == REFTABLE_REF_SYMREF && + !(ri->flags & DO_FOR_EACH_INCLUDE_BROKEN) && + (ri->base.flags & REF_ISBROKEN)) { + continue; + } + + if (is_null_oid(&ri->oid)) { + oidclr(&ri->oid); + ri->base.flags |= REF_ISBROKEN; + } + } + break; + } + + if (ri->err > 0) { + return ITER_DONE; + } + if (ri->err < 0) { + return ITER_ERROR; + } + + return ITER_OK; +} + +static int reftable_ref_iterator_peel(struct ref_iterator *ref_iterator, + struct object_id *peeled) +{ + struct git_reftable_iterator *ri = + (struct git_reftable_iterator *)ref_iterator; + if (ri->ref.value_type == REFTABLE_REF_VAL2) { + oidread(peeled, ri->ref.value.val2.target_value); + return 0; + } + + return -1; +} + +static int reftable_ref_iterator_abort(struct ref_iterator *ref_iterator) +{ + struct git_reftable_iterator *ri = + (struct git_reftable_iterator *)ref_iterator; + reftable_ref_record_release(&ri->ref); + reftable_iterator_destroy(&ri->iter); + return 0; +} + +static struct ref_iterator_vtable reftable_ref_iterator_vtable = { + reftable_ref_iterator_advance, reftable_ref_iterator_peel, + reftable_ref_iterator_abort +}; + +static struct ref_iterator * +git_reftable_ref_iterator_begin(struct ref_store *ref_store, const char *prefix, + const char **exclude_patterns_TODO, + unsigned int flags) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct git_reftable_iterator *ri = xcalloc(1, sizeof(*ri)); + + if (refs->err < 0) { + ri->err = refs->err; + } else { + struct reftable_merged_table *mt = + reftable_stack_merged_table(refs->main_stack); + ri->err = reftable_merged_table_seek_ref(mt, &ri->iter, prefix); + } + + base_ref_iterator_init(&ri->base, &reftable_ref_iterator_vtable, 1); + ri->prefix = prefix; + ri->base.oid = &ri->oid; + ri->flags = flags; + ri->ref_store = ref_store; + return &ri->base; +} + +static int fixup_symrefs(struct ref_store *ref_store, + struct ref_transaction *transaction) +{ + struct strbuf referent = STRBUF_INIT; + int i = 0; + int err = 0; + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *update = transaction->updates[i]; + struct object_id old_oid; + int failure_errno; + + err = git_reftable_read_raw_ref(ref_store, update->refname, + &old_oid, &referent, + /* mutate input, like + files-backend.c */ + &update->type, &failure_errno); + if (err < 0 && failure_errno == ENOENT && + is_null_oid(&update->old_oid)) { + err = 0; + } + if (err < 0) + goto done; + + if (!(update->type & REF_ISSYMREF)) + continue; + + if (update->flags & REF_NO_DEREF) { + /* what should happen here? See files-backend.c + * lock_ref_for_update. */ + } else { + /* + If we are updating a symref (eg. HEAD), we should also + update the branch that the symref points to. + + This is generic functionality, and would be better + done in refs.c, but the current implementation is + intertwined with the locking in files-backend.c. + */ + int new_flags = update->flags; + struct ref_update *new_update = NULL; + + /* if this is an update for HEAD, should also record a + log entry for HEAD? See files-backend.c, + split_head_update() + */ + new_update = ref_transaction_add_update( + transaction, referent.buf, new_flags, + &update->new_oid, &update->old_oid, + update->msg); + new_update->parent_update = update; + + /* files-backend sets REF_LOG_ONLY here. */ + update->flags |= REF_NO_DEREF | REF_LOG_ONLY; + update->flags &= ~REF_HAVE_OLD; + } + } + +done: + assert(err != REFTABLE_API_ERROR); + strbuf_release(&referent); + return err; +} + +static int git_reftable_transaction_prepare(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *errbuf) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_addition *add = NULL; + struct reftable_stack *stack = stack_for( + refs, + transaction->nr ? transaction->updates[0]->refname : NULL); + int i; + + int err = refs->err; + if (err < 0) { + goto done; + } + + err = reftable_stack_reload(stack); + if (err) { + goto done; + } + + err = reftable_stack_new_addition(&add, stack); + if (err) { + goto done; + } + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *u = transaction->updates[i]; + if ((u->flags & REF_HAVE_NEW) && !is_null_oid(&u->new_oid) && + !(u->flags & REF_SKIP_OID_VERIFICATION) && + !(u->flags & REF_LOG_ONLY)) { + struct object *o = + parse_object(refs->base.repo, &u->new_oid); + if (!o) { + strbuf_addf( + errbuf, + "trying to write ref '%s' with nonexistent object %s", + u->refname, oid_to_hex(&u->new_oid)); + err = -1; + goto done; + } + } + } + + err = fixup_symrefs(ref_store, transaction); + if (err) { + goto done; + } + + transaction->backend_data = add; + transaction->state = REF_TRANSACTION_PREPARED; + +done: + assert(err != REFTABLE_API_ERROR); + if (err < 0) { + if (add) { + reftable_addition_destroy(add); + add = NULL; + } + transaction->state = REF_TRANSACTION_CLOSED; + if (!errbuf->len) + strbuf_addf(errbuf, "reftable: transaction prepare: %s", + reftable_error_str(err)); + } + + return err; +} + +static int git_reftable_transaction_abort(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *err) +{ + struct reftable_addition *add = + (struct reftable_addition *)transaction->backend_data; + reftable_addition_destroy(add); + transaction->backend_data = NULL; + + /* XXX. Shouldn't this be handled generically in refs.c? */ + transaction->state = REF_TRANSACTION_CLOSED; + return 0; +} + +static int reftable_check_old_oid(struct ref_store *refs, const char *refname, + struct object_id *want_oid) +{ + struct object_id out_oid; + int out_flags = 0; + const char *resolved = refs_resolve_ref_unsafe( + refs, refname, RESOLVE_REF_READING, &out_oid, &out_flags); + if (is_null_oid(want_oid) != !resolved) { + return REFTABLE_LOCK_ERROR; + } + + if (resolved && !oideq(&out_oid, want_oid)) { + return REFTABLE_LOCK_ERROR; + } + + return 0; +} + +static int ref_update_cmp(const void *a, const void *b) +{ + return strcmp((*(struct ref_update **)a)->refname, + (*(struct ref_update **)b)->refname); +} + +static int write_transaction_table(struct reftable_writer *writer, void *arg) +{ + struct ref_transaction *transaction = (struct ref_transaction *)arg; + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)transaction->ref_store; + struct reftable_stack *stack = + stack_for(refs, transaction->updates[0]->refname); + uint64_t ts = reftable_stack_next_update_index(stack); + int err = 0; + int i = 0; + int log_count = 0; + struct reftable_log_record *logs = + calloc(transaction->nr, sizeof(*logs)); + struct ref_update **sorted = + malloc(transaction->nr * sizeof(struct ref_update *)); + struct reftable_merged_table *mt = reftable_stack_merged_table(stack); + struct reftable_table tab = { NULL }; + struct reftable_ref_record ref = { NULL }; + reftable_table_from_merged_table(&tab, mt); + COPY_ARRAY(sorted, transaction->updates, transaction->nr); + QSORT(sorted, transaction->nr, ref_update_cmp); + reftable_writer_set_limits(writer, ts, ts); + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *u = sorted[i]; + struct reftable_log_record *log = &logs[log_count]; + struct object_id old_id = *null_oid(); + + log->value.update.new_hash = NULL; + log->value.update.old_hash = NULL; + if ((u->flags & REF_FORCE_CREATE_REFLOG) || + should_log(u->refname)) + log_count++; + fill_reftable_log_record(log); + + log->update_index = ts; + log->value_type = REFTABLE_LOG_UPDATE; + log->refname = xstrdup(u->refname); + log->value.update.new_hash = u->new_oid.hash; + log->value.update.message = + xstrndup(u->msg, refs->write_options.block_size / 2); + + err = reftable_table_read_ref(&tab, u->refname, &ref); + if (err < 0) + goto done; + else if (err > 0) { + err = 0; + } + + /* XXX if this is a symref (say, HEAD), should we deref the + * symref and check the update.old_hash against the referent? */ + if (ref.value_type == REFTABLE_REF_VAL2 || + ref.value_type == REFTABLE_REF_VAL1) + oidread(&old_id, ref.value.val1); + + /* XXX fold together with the old_id check below? */ + log->value.update.old_hash = old_id.hash; + if (u->flags & REF_LOG_ONLY) { + continue; + } + + if (u->flags & REF_HAVE_NEW) { + struct reftable_ref_record ref = { NULL }; + struct object_id peeled; + + int peel_error = peel_object(&u->new_oid, &peeled); + ref.refname = (char *)u->refname; + ref.update_index = ts; + + if (!peel_error) { + ref.value_type = REFTABLE_REF_VAL2; + ref.value.val2.target_value = peeled.hash; + ref.value.val2.value = u->new_oid.hash; + } else if (!is_null_oid(&u->new_oid)) { + ref.value_type = REFTABLE_REF_VAL1; + ref.value.val1 = u->new_oid.hash; + } + + err = reftable_writer_add_ref(writer, &ref); + if (err < 0) { + goto done; + } + } + } + + for (i = 0; i < log_count; i++) { + err = reftable_writer_add_log(writer, &logs[i]); + logs[i].value.update.new_hash = NULL; + logs[i].value.update.old_hash = NULL; + clear_reftable_log_record(&logs[i]); + if (err < 0) { + goto done; + } + } + +done: + assert(err != REFTABLE_API_ERROR); + reftable_ref_record_release(&ref); + free(logs); + free(sorted); + return err; +} + +static int git_reftable_transaction_finish(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *errmsg) +{ + struct reftable_addition *add = + (struct reftable_addition *)transaction->backend_data; + int err = 0; + int i; + + for (i = 0; i < transaction->nr; i++) { + struct ref_update *u = transaction->updates[i]; + if (u->flags & REF_HAVE_OLD) { + err = reftable_check_old_oid(transaction->ref_store, + u->refname, &u->old_oid); + if (err < 0) { + goto done; + } + } + } + if (transaction->nr) { + err = reftable_addition_add(add, &write_transaction_table, + transaction); + if (err < 0) { + goto done; + } + } + + err = reftable_addition_commit(add); + +done: + assert(err != REFTABLE_API_ERROR); + reftable_addition_destroy(add); + transaction->state = REF_TRANSACTION_CLOSED; + transaction->backend_data = NULL; + if (err) { + strbuf_addf(errmsg, "reftable: transaction failure: %s", + reftable_error_str(err)); + return -1; + } + return err; +} + +static int +git_reftable_transaction_initial_commit(struct ref_store *ref_store, + struct ref_transaction *transaction, + struct strbuf *errmsg) +{ + int err = git_reftable_transaction_prepare(ref_store, transaction, + errmsg); + if (err) + return err; + + return git_reftable_transaction_finish(ref_store, transaction, errmsg); +} + +struct write_delete_refs_arg { + struct git_reftable_ref_store *refs; + struct reftable_stack *stack; + struct string_list *refnames; + const char *logmsg; + unsigned int flags; +}; + +static int write_delete_refs_table(struct reftable_writer *writer, void *argv) +{ + struct write_delete_refs_arg *arg = + (struct write_delete_refs_arg *)argv; + uint64_t ts = reftable_stack_next_update_index(arg->stack); + int err = 0; + int i = 0; + + reftable_writer_set_limits(writer, ts, ts); + for (i = 0; i < arg->refnames->nr; i++) { + struct reftable_ref_record ref = { + .refname = (char *)arg->refnames->items[i].string, + .value_type = REFTABLE_REF_DELETION, + .update_index = ts, + }; + err = reftable_writer_add_ref(writer, &ref); + if (err < 0) { + return err; + } + } + + for (i = 0; i < arg->refnames->nr; i++) { + struct reftable_log_record log = { + .update_index = ts, + }; + struct reftable_ref_record current = { NULL }; + fill_reftable_log_record(&log); + log.update_index = ts; + log.refname = xstrdup(arg->refnames->items[i].string); + if (!should_log(log.refname)) { + continue; + } + log.value.update.message = xstrndup( + arg->logmsg, arg->refs->write_options.block_size / 2); + log.value.update.new_hash = NULL; + log.value.update.old_hash = NULL; + if (reftable_stack_read_ref(arg->stack, log.refname, + ¤t) == 0) { + log.value.update.old_hash = + reftable_ref_record_val1(¤t); + } + err = reftable_writer_add_log(writer, &log); + log.value.update.old_hash = NULL; + reftable_ref_record_release(¤t); + + clear_reftable_log_record(&log); + if (err < 0) { + return err; + } + } + return 0; +} + +static int git_reftable_delete_refs(struct ref_store *ref_store, + const char *msg, + struct string_list *refnames, + unsigned int flags) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for( + refs, refnames->nr ? refnames->items[0].string : NULL); + struct write_delete_refs_arg arg = { + .refs = refs, + .stack = stack, + .refnames = refnames, + .logmsg = msg, + .flags = flags, + }; + int err = refs->err; + if (err < 0) { + goto done; + } + + string_list_sort(refnames); + err = reftable_stack_reload(stack); + if (err) { + goto done; + } + err = reftable_stack_add(stack, &write_delete_refs_table, &arg); +done: + assert(err != REFTABLE_API_ERROR); + return err; +} + +static int git_reftable_pack_refs(struct ref_store *ref_store, + struct pack_refs_opts *opts) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + + int err = refs->err; + if (err < 0) { + return err; + } + err = reftable_stack_compact_all(refs->main_stack, NULL); + if (err == 0) + err = reftable_stack_clean(refs->main_stack); + + return err; +} + +struct write_create_symref_arg { + struct git_reftable_ref_store *refs; + struct reftable_stack *stack; + const char *refname; + const char *target; + const char *logmsg; +}; + +static int write_create_symref_table(struct reftable_writer *writer, void *arg) +{ + struct write_create_symref_arg *create = + (struct write_create_symref_arg *)arg; + uint64_t ts = reftable_stack_next_update_index(create->stack); + int err = 0; + + struct reftable_ref_record ref = { + .refname = (char *)create->refname, + .value_type = REFTABLE_REF_SYMREF, + .value.symref = (char *)create->target, + .update_index = ts, + }; + reftable_writer_set_limits(writer, ts, ts); + err = reftable_writer_add_ref(writer, &ref); + if (err == 0) { + struct reftable_log_record log = { NULL }; + struct object_id new_oid; + struct object_id old_oid; + + fill_reftable_log_record(&log); + log.refname = xstrdup(create->refname); + if (!should_log(log.refname)) { + return err; + } + log.update_index = ts; + log.value.update.message = + xstrndup(create->logmsg, + create->refs->write_options.block_size / 2); + if (refs_resolve_ref_unsafe( + (struct ref_store *)create->refs, create->refname, + RESOLVE_REF_READING, &old_oid, NULL)) { + log.value.update.old_hash = old_oid.hash; + } + + if (refs_resolve_ref_unsafe((struct ref_store *)create->refs, + create->target, RESOLVE_REF_READING, + &new_oid, NULL)) { + log.value.update.new_hash = new_oid.hash; + } + + if (log.value.update.old_hash || + log.value.update.new_hash) { + err = reftable_writer_add_log(writer, &log); + } + log.refname = NULL; + log.value.update.message = NULL; + log.value.update.old_hash = NULL; + log.value.update.new_hash = NULL; + clear_reftable_log_record(&log); + } + return err; +} + +static int git_reftable_create_symref(struct ref_store *ref_store, + const char *refname, const char *target, + const char *logmsg) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct write_create_symref_arg arg = { .refs = refs, + .stack = stack, + .refname = refname, + .target = target, + .logmsg = logmsg }; + int err = refs->err; + if (err < 0) { + goto done; + } + err = reftable_stack_reload(stack); + if (err) { + goto done; + } + err = reftable_stack_add(stack, &write_create_symref_table, &arg); +done: + assert(err != REFTABLE_API_ERROR); + return err; +} + +struct write_rename_arg { + struct git_reftable_ref_store *refs; + struct reftable_stack *stack; + const char *oldname; + const char *newname; + const char *logmsg; +}; + +static int write_rename_table(struct reftable_writer *writer, void *argv) +{ + struct write_rename_arg *arg = (struct write_rename_arg *)argv; + uint64_t ts = reftable_stack_next_update_index(arg->stack); + struct reftable_ref_record old_ref = { NULL }; + struct reftable_ref_record new_ref = { NULL }; + int err = reftable_stack_read_ref(arg->stack, arg->oldname, &old_ref); + struct reftable_ref_record todo[2] = { + { + .refname = (char *)arg->oldname, + .update_index = ts, + .value_type = REFTABLE_REF_DELETION, + }, + old_ref, + }; + + if (err) { + goto done; + } + + /* git-branch supports a --force, but the check is not atomic. */ + if (!reftable_stack_read_ref(arg->stack, arg->newname, &new_ref)) { + goto done; + } + + reftable_writer_set_limits(writer, ts, ts); + + todo[1].update_index = ts; + todo[1].refname = (char *)arg->newname; + + err = reftable_writer_add_refs(writer, todo, 2); + if (err < 0) { + goto done; + } + + if (reftable_ref_record_val1(&old_ref)) { + uint8_t *val1 = reftable_ref_record_val1(&old_ref); + struct reftable_log_record todo[2] = { { NULL } }; + int firstlog = 0; + int lastlog = 2; + char *msg = xstrndup(arg->logmsg, + arg->refs->write_options.block_size / 2); + fill_reftable_log_record(&todo[0]); + fill_reftable_log_record(&todo[1]); + + todo[0].refname = xstrdup(arg->oldname); + todo[0].update_index = ts; + todo[0].value.update.message = msg; + todo[0].value.update.old_hash = val1; + todo[0].value.update.new_hash = NULL; + + todo[1].refname = xstrdup(arg->newname); + todo[1].update_index = ts; + todo[1].value.update.old_hash = NULL; + todo[1].value.update.new_hash = val1; + todo[1].value.update.message = xstrdup(msg); + + if (!should_log(todo[1].refname)) { + lastlog--; + } + if (!should_log(todo[0].refname)) { + firstlog++; + } + err = reftable_writer_add_logs(writer, &todo[firstlog], + lastlog - firstlog); + + clear_reftable_log_record(&todo[0]); + clear_reftable_log_record(&todo[1]); + if (err < 0) { + goto done; + } + + } else { + /* XXX what should we write into the reflog if we rename a + * symref? */ + } + +done: + assert(err != REFTABLE_API_ERROR); + reftable_ref_record_release(&new_ref); + reftable_ref_record_release(&old_ref); + return err; +} + +static int write_copy_table(struct reftable_writer *writer, void *argv) +{ + struct write_rename_arg *arg = (struct write_rename_arg *)argv; + uint64_t ts = reftable_stack_next_update_index(arg->stack); + struct reftable_ref_record old_ref = { NULL }; + struct reftable_ref_record new_ref = { NULL }; + struct reftable_log_record log = { NULL }; + struct reftable_iterator it = { NULL }; + int err = reftable_stack_read_ref(arg->stack, arg->oldname, &old_ref); + if (err) { + goto done; + } + + /* git-branch supports a --force, but the check is not atomic. */ + if (reftable_stack_read_ref(arg->stack, arg->newname, &new_ref) == 0) { + goto done; + } + + reftable_writer_set_limits(writer, ts, ts); + + FREE_AND_NULL(old_ref.refname); + old_ref.refname = xstrdup(arg->newname); + old_ref.update_index = ts; + err = reftable_writer_add_ref(writer, &old_ref); + if (err < 0) { + goto done; + } + + /* XXX this copies the entire reflog history. Is this the right + * semantics? should clear out existing reflog entries for oldname? */ + if (!should_log(arg->newname)) + goto done; + + err = reftable_merged_table_seek_log( + reftable_stack_merged_table(arg->stack), &it, arg->oldname); + if (err < 0) { + goto done; + } + while (1) { + int err = reftable_iterator_next_log(&it, &log); + if (err < 0) { + goto done; + } + + if (err > 0 || strcmp(log.refname, arg->oldname)) { + break; + } + FREE_AND_NULL(log.refname); + log.refname = xstrdup(arg->newname); + reftable_writer_add_log(writer, &log); + reftable_log_record_release(&log); + } + +done: + assert(err != REFTABLE_API_ERROR); + reftable_ref_record_release(&new_ref); + reftable_ref_record_release(&old_ref); + reftable_log_record_release(&log); + reftable_iterator_destroy(&it); + return err; +} + +static int git_reftable_rename_ref(struct ref_store *ref_store, + const char *oldrefname, + const char *newrefname, const char *logmsg) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, newrefname); + struct write_rename_arg arg = { + .refs = refs, + .stack = stack, + .oldname = oldrefname, + .newname = newrefname, + .logmsg = logmsg, + }; + int err = refs->err; + if (err < 0) { + goto done; + } + err = reftable_stack_reload(stack); + if (err) { + goto done; + } + + err = reftable_stack_add(stack, &write_rename_table, &arg); +done: + assert(err != REFTABLE_API_ERROR); + return err; +} + +static int git_reftable_copy_ref(struct ref_store *ref_store, + const char *oldrefname, const char *newrefname, + const char *logmsg) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, newrefname); + struct write_rename_arg arg = { + .refs = refs, + .stack = stack, + .oldname = oldrefname, + .newname = newrefname, + .logmsg = logmsg, + }; + int err = refs->err; + if (err < 0) { + goto done; + } + err = reftable_stack_reload(stack); + if (err) { + goto done; + } + + err = reftable_stack_add(stack, &write_copy_table, &arg); +done: + assert(err != REFTABLE_API_ERROR); + return err; +} + +struct git_reftable_reflog_ref_iterator { + struct ref_iterator base; + struct reftable_iterator iter; + struct reftable_log_record log; + struct object_id oid; + struct git_reftable_ref_store *refs; + + /* Used when iterating over worktree & main */ + struct reftable_merged_table *merged; + char *last_name; +}; + +static int +git_reftable_reflog_ref_iterator_advance(struct ref_iterator *ref_iterator) +{ + struct git_reftable_reflog_ref_iterator *ri = + (struct git_reftable_reflog_ref_iterator *)ref_iterator; + + while (1) { + int flags = 0; + int err = reftable_iterator_next_log(&ri->iter, &ri->log); + + if (err > 0) { + return ITER_DONE; + } + if (err < 0) { + return ITER_ERROR; + } + + ri->base.refname = ri->log.refname; + if (ri->last_name && + !strcmp(ri->log.refname, ri->last_name)) { + /* we want the refnames that we have reflogs for, so we + * skip if we've already produced this name. This could + * be faster by seeking directly to + * reflog@update_index==0. + */ + continue; + } + + if (!refs_resolve_ref_unsafe(&ri->refs->base, ri->log.refname, + 0, &ri->oid, &flags)) { + error("bad ref for %s", ri->log.refname); + continue; + } + + free(ri->last_name); + ri->last_name = xstrdup(ri->log.refname); + ri->base.oid = &ri->oid; + ri->base.flags = flags; + return ITER_OK; + } +} + +static int +git_reftable_reflog_ref_iterator_peel(struct ref_iterator *ref_iterator, + struct object_id *peeled) +{ + BUG("not supported."); + return -1; +} + +static int +git_reftable_reflog_ref_iterator_abort(struct ref_iterator *ref_iterator) +{ + struct git_reftable_reflog_ref_iterator *ri = + (struct git_reftable_reflog_ref_iterator *)ref_iterator; + reftable_log_record_release(&ri->log); + reftable_iterator_destroy(&ri->iter); + if (ri->merged) + reftable_merged_table_free(ri->merged); + return 0; +} + +static struct ref_iterator_vtable git_reftable_reflog_ref_iterator_vtable = { + git_reftable_reflog_ref_iterator_advance, + git_reftable_reflog_ref_iterator_peel, + git_reftable_reflog_ref_iterator_abort +}; + +static struct ref_iterator * +git_reftable_reflog_iterator_begin(struct ref_store *ref_store) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct git_reftable_reflog_ref_iterator *ri = xcalloc(1, sizeof(*ri)); + struct reftable_stack *stack = refs->main_stack; + struct reftable_merged_table *mt = + reftable_stack_merged_table(stack); + int err = reftable_merged_table_seek_log(mt, &ri->iter, ""); + + ri->refs = refs; + if (err < 0) { + free(ri); + /* XXX how to handle errors in iterator_begin()? */ + return NULL; + } + base_ref_iterator_init(&ri->base, + &git_reftable_reflog_ref_iterator_vtable, 1); + ri->base.oid = &ri->oid; + + return (struct ref_iterator *)ri; +} + +static int git_reftable_for_each_reflog_ent_newest_first( + struct ref_store *ref_store, const char *refname, each_reflog_ent_fn fn, + void *cb_data) +{ + struct reftable_iterator it = { NULL }; + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct reftable_merged_table *mt = NULL; + int err = 0; + struct reftable_log_record log = { NULL }; + + if (refs->err < 0) { + return refs->err; + } + refname = bare_ref_name(refname); + + mt = reftable_stack_merged_table(stack); + err = reftable_merged_table_seek_log(mt, &it, refname); + while (err == 0) { + struct object_id old_oid; + struct object_id new_oid; + const char *full_committer = ""; + + err = reftable_iterator_next_log(&it, &log); + if (err > 0) { + err = 0; + break; + } + if (err < 0) { + break; + } + + if (strcmp(log.refname, refname)) { + break; + } + + oidread(&old_oid, log.value.update.old_hash); + oidread(&new_oid, log.value.update.new_hash); + + if (is_null_oid(&old_oid) && is_null_oid(&new_oid)) { + /* placeholder for existence. */ + continue; + } + + full_committer = fmt_ident(log.value.update.name, + log.value.update.email, + WANT_COMMITTER_IDENT, + /*date*/ NULL, IDENT_NO_DATE); + err = fn(&old_oid, &new_oid, full_committer, + log.value.update.time, log.value.update.tz_offset, + log.value.update.message, cb_data); + if (err) + break; + } + + reftable_log_record_release(&log); + reftable_iterator_destroy(&it); + return err; +} + +static int git_reftable_for_each_reflog_ent_oldest_first( + struct ref_store *ref_store, const char *refname, each_reflog_ent_fn fn, + void *cb_data) +{ + struct reftable_iterator it = { NULL }; + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct reftable_merged_table *mt = NULL; + struct reftable_log_record *logs = NULL; + int cap = 0; + int len = 0; + int err = 0; + int i = 0; + + if (refs->err < 0) { + return refs->err; + } + refname = bare_ref_name(refname); + mt = reftable_stack_merged_table(stack); + err = reftable_merged_table_seek_log(mt, &it, refname); + + while (err == 0) { + struct reftable_log_record log = { NULL }; + err = reftable_iterator_next_log(&it, &log); + if (err > 0) { + err = 0; + break; + } + if (err < 0) { + break; + } + + if (strcmp(log.refname, refname)) { + break; + } + + if (len == cap) { + cap = 2 * cap + 1; + logs = realloc(logs, cap * sizeof(*logs)); + } + + logs[len++] = log; + } + + for (i = len; i--;) { + struct reftable_log_record *log = &logs[i]; + struct object_id old_oid; + struct object_id new_oid; + const char *full_committer = ""; + + oidread(&old_oid, log->value.update.old_hash); + oidread(&new_oid, log->value.update.new_hash); + + if (is_null_oid(&old_oid) && is_null_oid(&new_oid)) { + /* placeholder for existence. */ + continue; + } + + full_committer = fmt_ident(log->value.update.name, + log->value.update.email, + WANT_COMMITTER_IDENT, NULL, + IDENT_NO_DATE); + err = fn(&old_oid, &new_oid, full_committer, + log->value.update.time, log->value.update.tz_offset, + log->value.update.message, cb_data); + if (err) { + break; + } + } + + for (i = 0; i < len; i++) { + reftable_log_record_release(&logs[i]); + } + free(logs); + + reftable_iterator_destroy(&it); + return err; +} + +static int git_reftable_reflog_exists(struct ref_store *ref_store, + const char *refname) +{ + struct reftable_iterator it = { NULL }; + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct reftable_merged_table *mt = reftable_stack_merged_table(stack); + struct reftable_log_record log = { NULL }; + int err = refs->err; + + if (err < 0) { + goto done; + } + + refname = bare_ref_name(refname); + err = reftable_merged_table_seek_log(mt, &it, refname); + if (err) { + goto done; + } + err = reftable_iterator_next_log(&it, &log); + if (err) { + goto done; + } + + if (strcmp(log.refname, refname)) { + err = 1; + } + +done: + reftable_iterator_destroy(&it); + reftable_log_record_release(&log); + return !err; +} + +struct write_reflog_existence_arg { + struct git_reftable_ref_store *refs; + const char *refname; + struct reftable_stack *stack; +}; + +static int write_reflog_existence_table(struct reftable_writer *writer, + void *argv) +{ + struct write_reflog_existence_arg *arg = + (struct write_reflog_existence_arg *)argv; + uint64_t ts = reftable_stack_next_update_index(arg->stack); + struct reftable_log_record log = { NULL }; + + int err = reftable_stack_read_log(arg->stack, arg->refname, &log); + if (err <= 0) { + goto done; + } + + reftable_writer_set_limits(writer, ts, ts); + + log.refname = (char *)arg->refname; + log.update_index = ts; + log.value_type = REFTABLE_LOG_UPDATE; + err = reftable_writer_add_log(writer, &log); + + /* field is not malloced */ + log.refname = NULL; + +done: + assert(err != REFTABLE_API_ERROR); + reftable_log_record_release(&log); + return err; +} + +static int git_reftable_create_reflog(struct ref_store *ref_store, + const char *refname, + struct strbuf *errmsg) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct write_reflog_existence_arg arg = { + .refs = refs, + .stack = stack, + .refname = refname, + }; + int err = refs->err; + if (err < 0) { + goto done; + } + + err = reftable_stack_reload(stack); + if (err) { + goto done; + } + + err = reftable_stack_add(stack, &write_reflog_existence_table, &arg); + +done: + return err; +} + +struct write_reflog_delete_arg { + struct reftable_stack *stack; + const char *refname; +}; + +static int write_reflog_delete_table(struct reftable_writer *writer, void *argv) +{ + struct write_reflog_delete_arg *arg = argv; + struct reftable_merged_table *mt = + reftable_stack_merged_table(arg->stack); + struct reftable_log_record log = { NULL }; + struct reftable_iterator it = { NULL }; + uint64_t ts = reftable_stack_next_update_index(arg->stack); + int err = reftable_merged_table_seek_log(mt, &it, arg->refname); + + reftable_writer_set_limits(writer, ts, ts); + while (err == 0) { + struct reftable_log_record tombstone = { + .refname = (char *)arg->refname, + .update_index = REFTABLE_LOG_DELETION, + }; + err = reftable_iterator_next_log(&it, &log); + if (err > 0) { + err = 0; + break; + } + + if (err < 0 || strcmp(log.refname, arg->refname)) { + break; + } + if (log.value_type == REFTABLE_LOG_DELETION) + continue; + + tombstone.update_index = log.update_index; + err = reftable_writer_add_log(writer, &tombstone); + } + + reftable_log_record_release(&log); + return err; +} + +static int git_reftable_delete_reflog(struct ref_store *ref_store, + const char *refname) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct write_reflog_delete_arg arg = { + .stack = stack, + .refname = refname, + }; + int err = reftable_stack_add(stack, &write_reflog_delete_table, &arg); + assert(err != REFTABLE_API_ERROR); + return err; +} + +struct reflog_expiry_arg { + struct reftable_stack *stack; + struct reftable_log_record *records; + int len; + const char *refname; +}; + +static int write_reflog_expiry_table(struct reftable_writer *writer, void *argv) +{ + struct reflog_expiry_arg *arg = (struct reflog_expiry_arg *)argv; + uint64_t ts = reftable_stack_next_update_index(arg->stack); + int i = 0; + int live_records = 0; + uint64_t max_ts = 0; + for (i = 0; i < arg->len; i++) { + if (arg->records[i].value_type == REFTABLE_LOG_UPDATE) + live_records++; + + if (max_ts < arg->records[i].update_index) + max_ts = arg->records[i].update_index; + } + + reftable_writer_set_limits(writer, ts, ts); + if (live_records == 0) { + struct reftable_log_record log = { + .refname = (char *)arg->refname, + .update_index = max_ts + 1, + .value_type = REFTABLE_LOG_UPDATE, + /* existence dummy has null new/old oid */ + }; + int err; + if (log.update_index < ts) + log.update_index = ts; + + err = reftable_writer_add_log(writer, &log); + if (err) { + return err; + } + } + + for (i = 0; i < arg->len; i++) { + int err = reftable_writer_add_log(writer, &arg->records[i]); + if (err) { + return err; + } + } + return 0; +} + +static int git_reftable_reflog_expire( + struct ref_store *ref_store, const char *refname, unsigned int flags, + reflog_expiry_prepare_fn prepare_fn, + reflog_expiry_should_prune_fn should_prune_fn, + reflog_expiry_cleanup_fn cleanup_fn, void *policy_cb_data) +{ + /* + For log expiry, we write tombstones in place of the expired entries, + This means that the entries are still retrievable by delving into the + stack, and expiring entries paradoxically takes extra memory. + + This memory is only reclaimed when some operation issues a + git_reftable_pack_refs(), which will compact the entire stack and get + rid of deletion entries. + + It would be better if the refs backend supported an API that sets a + criterion for all refs, passing the criterion to pack_refs(). + + On the plus side, because we do the expiration per ref, we can easily + insert the reflog existence dummies. + */ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct reftable_merged_table *mt = NULL; + struct reflog_expiry_arg arg = { + .stack = stack, + .refname = refname, + }; + struct reftable_log_record *logs = NULL; + struct reftable_log_record *rewritten = NULL; + struct reftable_ref_record ref_record = { NULL }; + int logs_len = 0; + int logs_cap = 0; + int i = 0; + uint8_t *last_hash = NULL; + struct reftable_iterator it = { NULL }; + struct reftable_addition *add = NULL; + int err = 0; + struct object_id oid = { 0 }; + if (refs->err < 0) { + return refs->err; + } + err = reftable_stack_reload(stack); + if (err) { + goto done; + } + + mt = reftable_stack_merged_table(stack); + err = reftable_merged_table_seek_log(mt, &it, refname); + if (err < 0) { + goto done; + } + + err = reftable_stack_new_addition(&add, stack); + if (err) { + goto done; + } + if (!reftable_stack_read_ref(stack, refname, &ref_record)) { + uint8_t *hash = reftable_ref_record_val1(&ref_record); + if (hash) + oidread(&oid, hash); + } + + prepare_fn(refname, &oid, policy_cb_data); + while (1) { + struct reftable_log_record log = { NULL }; + int err = reftable_iterator_next_log(&it, &log); + if (err < 0) { + goto done; + } + + if (err > 0 || strcmp(log.refname, refname)) { + break; + } + + if (logs_len >= logs_cap) { + int new_cap = logs_cap * 2 + 1; + logs = realloc(logs, new_cap * sizeof(*logs)); + logs_cap = new_cap; + } + logs[logs_len++] = log; + } + + rewritten = calloc(logs_len, sizeof(*rewritten)); + for (i = logs_len - 1; i >= 0; i--) { + struct object_id ooid; + struct object_id noid; + struct reftable_log_record *dest = &rewritten[i]; + + *dest = logs[i]; + oidread(&ooid, logs[i].value.update.old_hash); + oidread(&noid, logs[i].value.update.new_hash); + + if (should_prune_fn(&ooid, &noid, logs[i].value.update.email, + (timestamp_t)logs[i].value.update.time, + logs[i].value.update.tz_offset, + logs[i].value.update.message, + policy_cb_data)) { + dest->value_type = REFTABLE_LOG_DELETION; + } else { + if ((flags & EXPIRE_REFLOGS_REWRITE) && + last_hash) { + dest->value.update.old_hash = last_hash; + } + last_hash = logs[i].value.update.new_hash; + } + } + + arg.records = rewritten; + arg.len = logs_len; + err = reftable_addition_add(add, &write_reflog_expiry_table, &arg); + if (err < 0) { + goto done; + } + + if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) { + /* future improvement: we could skip writing records that were + * not changed. */ + err = reftable_addition_commit(add); + } + +done: + if (add) { + cleanup_fn(policy_cb_data); + } + assert(err != REFTABLE_API_ERROR); + reftable_addition_destroy(add); + for (i = 0; i < logs_len; i++) + reftable_log_record_release(&logs[i]); + free(logs); + free(rewritten); + reftable_iterator_destroy(&it); + return err; +} + +static int git_reftable_read_raw_ref(struct ref_store *ref_store, + const char *refname, struct object_id *oid, + struct strbuf *referent, + unsigned int *type, int *failure_errno) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct reftable_ref_record ref = { NULL }; + int err = 0; + + refname = bare_ref_name(refname); /* XXX - in which other cases should + we do this? */ + if (refs->err < 0) { + return refs->err; + } + + /* This is usually not needed, but Git doesn't signal to ref backend if + a subprocess updated the ref DB. So we always check. + */ + err = reftable_stack_reload(stack); + if (err) { + goto done; + } + + err = reftable_stack_read_ref(stack, refname, &ref); + if (err > 0) { + *failure_errno = ENOENT; + err = -1; + goto done; + } + if (err < 0) { + goto done; + } + + if (ref.value_type == REFTABLE_REF_SYMREF) { + strbuf_reset(referent); + strbuf_addstr(referent, ref.value.symref); + *type |= REF_ISSYMREF; + } else if (reftable_ref_record_val1(&ref)) { + oidread(oid, reftable_ref_record_val1(&ref)); + } else { + /* We got a tombstone, which should not happen. */ + BUG("Got reftable_ref_record with value type %d", + ref.value_type); + } + +done: + assert(err != REFTABLE_API_ERROR); + reftable_ref_record_release(&ref); + return err; +} + +static int git_reftable_read_symbolic_ref(struct ref_store *ref_store, + const char *refname, + struct strbuf *referent) +{ + struct git_reftable_ref_store *refs = + (struct git_reftable_ref_store *)ref_store; + struct reftable_stack *stack = stack_for(refs, refname); + struct reftable_ref_record ref = { NULL }; + int err = 0; + + err = reftable_stack_read_ref(stack, refname, &ref); + if (err == 0 && ref.value_type == REFTABLE_REF_SYMREF) { + strbuf_addstr(referent, ref.value.symref); + } else { + err = -1; + } + + reftable_ref_record_release(&ref); + return err; +} + +struct ref_storage_be refs_be_reftable = { + .next = &refs_be_files, + .name = "reftable", + .init = git_reftable_ref_store_create, + .init_db = git_reftable_init_db, + .transaction_prepare = git_reftable_transaction_prepare, + .transaction_finish = git_reftable_transaction_finish, + .transaction_abort = git_reftable_transaction_abort, + .initial_transaction_commit = git_reftable_transaction_initial_commit, + + .pack_refs = git_reftable_pack_refs, + .create_symref = git_reftable_create_symref, + .delete_refs = git_reftable_delete_refs, + .rename_ref = git_reftable_rename_ref, + .copy_ref = git_reftable_copy_ref, + + .iterator_begin = git_reftable_ref_iterator_begin, + .read_raw_ref = git_reftable_read_raw_ref, + .read_symbolic_ref = git_reftable_read_symbolic_ref, + + .reflog_iterator_begin = git_reftable_reflog_iterator_begin, + .for_each_reflog_ent = git_reftable_for_each_reflog_ent_oldest_first, + .for_each_reflog_ent_reverse = + git_reftable_for_each_reflog_ent_newest_first, + .reflog_exists = git_reftable_reflog_exists, + .create_reflog = git_reftable_create_reflog, + .delete_reflog = git_reftable_delete_reflog, + .reflog_expire = git_reftable_reflog_expire, +}; diff --git a/refs/reftable-backend.h b/refs/reftable-backend.h new file mode 100644 index 00000000000..bf5fd42229a --- /dev/null +++ b/refs/reftable-backend.h @@ -0,0 +1,8 @@ +#ifndef REFS_REFTABLE_BACKEND_H +#define REFS_REFTABLE_BACKEND_H + +struct ref_store *git_reftable_ref_store_create(struct repository *repo, + const char *gitdir, + unsigned int store_flags); + +#endif /* REFS_REFTABLE_BACKEND_H */