From patchwork Thu Oct 7 20:25:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Han-Wen Nienhuys X-Patchwork-Id: 12543007 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E6A7C433F5 for ; Thu, 7 Oct 2021 20:25:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3806261175 for ; Thu, 7 Oct 2021 20:25:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242100AbhJGU1Y (ORCPT ); Thu, 7 Oct 2021 16:27:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241979AbhJGU1R (ORCPT ); Thu, 7 Oct 2021 16:27:17 -0400 Received: from mail-wr1-x430.google.com (mail-wr1-x430.google.com [IPv6:2a00:1450:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA9A5C061762 for ; Thu, 7 Oct 2021 13:25:22 -0700 (PDT) Received: by mail-wr1-x430.google.com with SMTP id i12so10137466wrb.7 for ; Thu, 07 Oct 2021 13:25:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:in-reply-to:references:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=7xlN60GC0R7hvPRvPSqKS5geQsLs0YGurdc/9/8+Gbs=; b=k2vZ6ZQz2/cC8oRbfcgeJhTcOzaVCbXrNEm5b8BF52+hknY4idJgVLVRsSAqWvGhkA tzNpmn0yWm//fuJLMo2eiQcYuokyuUFgJ2LdjfwMuzr7xHfZOuhNa9Ult4vjN4s1HD84 Zq0KFMQLof5zEtLIIjPa3/8h/Lq014zV8PW44a6kLX3xDYPKimPiusNy/X6nhGrE7Xwq Ltu7mWWnqFtae0FagODYlgL4FlC5N4EPtIe5PSaPkUdpafdth8h47BlzFLlGzmwFfNhK NoQLIAPvnbzqIGQqA7Sko/EoaSiGnAoqKZNG5ut4fv19FtPN0GMO1YXjcy092qK8bYkI KjXg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:in-reply-to:references:from:date :subject:fcc:content-transfer-encoding:mime-version:to:cc; bh=7xlN60GC0R7hvPRvPSqKS5geQsLs0YGurdc/9/8+Gbs=; b=ZqwHcWSYA+0TM+rKq+2DJstZllRnlhtGSmnC+Fl3iHIUCW7wqZW0NuTiqpiW7fGLdX LjOwey0RkKD21e+YfC/DnYU0zA33JXjZoC3Q4nzVkcDEQCEThVLQxzdWQqoKqOVL1Ap2 sv7RTaAM08eAINNGyyQmw2XmRCGnjvikkLPa6XfmcwRuBHnSGFN7OJKHJU4Rxl2uTOcj 74yTnHjDuQhwnzxHxZRTw3Q5cNpDUH53lRMPZ8jpkRxSYyzEFgeuPGwS+pkCuNPYNboZ zxrwqRCxplaqiXDRH4PE4YDWhmkgoxkqgraT2FSeRIoC2lh4ZZphRa4c6g0kIrSnVBZl AyNw== X-Gm-Message-State: AOAM5301qTUCNKS0oyJm+vdRtT70LD9E59gAUXyDjHp/VcidfkKKWnpc 2ulirx0zxpb8xoXVcJJhP4eP99/8oBs= X-Google-Smtp-Source: ABdhPJx0tw6bRysCaphxTSsXWxl1WevGyo5XR9zNVsqtqdV7sF6FpqnZ+ijWmLop02JWEZeBWAxDgg== X-Received: by 2002:a7b:cc0d:: with SMTP id f13mr6445078wmh.85.1633638321405; Thu, 07 Oct 2021 13:25:21 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id n7sm360894wra.37.2021.10.07.13.25.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Oct 2021 13:25:21 -0700 (PDT) Message-Id: <80036f93e2e9b7823e49ee2764344f2db55ed768.1633638316.git.gitgitgadget@gmail.com> In-Reply-To: References: Date: Thu, 07 Oct 2021 20:25:01 +0000 Subject: [PATCH v4 05/19] reftable: add blocksource, an abstraction for random access reads Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Han-Wen Nienhuys , Carlo Marcelo Arenas =?utf-8?b?QmVsw7Nu?= , =?utf-8?b?w4Z2YXIgQXJuZmrDtnI=?= =?utf-8?b?w7A=?= Bjarmason , 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 The reftable format is usually used with files for storage. However, we abstract away this using the blocksource data structure. This has two advantages: * log blocks are zlib compressed, and handling them is simplified if we can discard byte segments from within the block layer. * for unittests, it is useful to read and write in-memory. The blocksource allows us to abstract the data away from on-disk files. Signed-off-by: Han-Wen Nienhuys --- Makefile | 1 + reftable/blocksource.c | 148 ++++++++++++++++++++++++++++++++ reftable/blocksource.h | 22 +++++ reftable/reftable-blocksource.h | 49 +++++++++++ 4 files changed, 220 insertions(+) create mode 100644 reftable/blocksource.c create mode 100644 reftable/blocksource.h create mode 100644 reftable/reftable-blocksource.h diff --git a/Makefile b/Makefile index aa5ac56cde6..bfdac1e04c4 100644 --- a/Makefile +++ b/Makefile @@ -2431,6 +2431,7 @@ xdiff-objs: $(XDIFF_OBJS) REFTABLE_OBJS += reftable/basics.o REFTABLE_OBJS += reftable/error.o +REFTABLE_OBJS += reftable/blocksource.o REFTABLE_OBJS += reftable/publicbasics.o REFTABLE_TEST_OBJS += reftable/test_framework.o diff --git a/reftable/blocksource.c b/reftable/blocksource.c new file mode 100644 index 00000000000..0044eecd9aa --- /dev/null +++ b/reftable/blocksource.c @@ -0,0 +1,148 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#include "system.h" + +#include "basics.h" +#include "blocksource.h" +#include "reftable-blocksource.h" +#include "reftable-error.h" + +static void strbuf_return_block(void *b, struct reftable_block *dest) +{ + memset(dest->data, 0xff, dest->len); + reftable_free(dest->data); +} + +static void strbuf_close(void *b) +{ +} + +static int strbuf_read_block(void *v, struct reftable_block *dest, uint64_t off, + uint32_t size) +{ + struct strbuf *b = v; + assert(off + size <= b->len); + dest->data = reftable_calloc(size); + memcpy(dest->data, b->buf + off, size); + dest->len = size; + return size; +} + +static uint64_t strbuf_size(void *b) +{ + return ((struct strbuf *)b)->len; +} + +static struct reftable_block_source_vtable strbuf_vtable = { + .size = &strbuf_size, + .read_block = &strbuf_read_block, + .return_block = &strbuf_return_block, + .close = &strbuf_close, +}; + +void block_source_from_strbuf(struct reftable_block_source *bs, + struct strbuf *buf) +{ + assert(!bs->ops); + bs->ops = &strbuf_vtable; + bs->arg = buf; +} + +static void malloc_return_block(void *b, struct reftable_block *dest) +{ + memset(dest->data, 0xff, dest->len); + reftable_free(dest->data); +} + +static struct reftable_block_source_vtable malloc_vtable = { + .return_block = &malloc_return_block, +}; + +static struct reftable_block_source malloc_block_source_instance = { + .ops = &malloc_vtable, +}; + +struct reftable_block_source malloc_block_source(void) +{ + return malloc_block_source_instance; +} + +struct file_block_source { + int fd; + uint64_t size; +}; + +static uint64_t file_size(void *b) +{ + return ((struct file_block_source *)b)->size; +} + +static void file_return_block(void *b, struct reftable_block *dest) +{ + memset(dest->data, 0xff, dest->len); + reftable_free(dest->data); +} + +static void file_close(void *b) +{ + int fd = ((struct file_block_source *)b)->fd; + if (fd > 0) { + close(fd); + ((struct file_block_source *)b)->fd = 0; + } + + reftable_free(b); +} + +static int file_read_block(void *v, struct reftable_block *dest, uint64_t off, + uint32_t size) +{ + struct file_block_source *b = v; + assert(off + size <= b->size); + dest->data = reftable_malloc(size); + if (pread(b->fd, dest->data, size, off) != size) + return -1; + dest->len = size; + return size; +} + +static struct reftable_block_source_vtable file_vtable = { + .size = &file_size, + .read_block = &file_read_block, + .return_block = &file_return_block, + .close = &file_close, +}; + +int reftable_block_source_from_file(struct reftable_block_source *bs, + const char *name) +{ + struct stat st = { 0 }; + int err = 0; + int fd = open(name, O_RDONLY); + struct file_block_source *p = NULL; + if (fd < 0) { + if (errno == ENOENT) { + return REFTABLE_NOT_EXIST_ERROR; + } + return -1; + } + + err = fstat(fd, &st); + if (err < 0) + return -1; + + p = reftable_calloc(sizeof(struct file_block_source)); + p->size = st.st_size; + p->fd = fd; + + assert(!bs->ops); + bs->ops = &file_vtable; + bs->arg = p; + return 0; +} diff --git a/reftable/blocksource.h b/reftable/blocksource.h new file mode 100644 index 00000000000..072e2727ad2 --- /dev/null +++ b/reftable/blocksource.h @@ -0,0 +1,22 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#ifndef BLOCKSOURCE_H +#define BLOCKSOURCE_H + +#include "system.h" + +struct reftable_block_source; + +/* Create an in-memory block source for reading reftables */ +void block_source_from_strbuf(struct reftable_block_source *bs, + struct strbuf *buf); + +struct reftable_block_source malloc_block_source(void); + +#endif diff --git a/reftable/reftable-blocksource.h b/reftable/reftable-blocksource.h new file mode 100644 index 00000000000..5aa3990a573 --- /dev/null +++ b/reftable/reftable-blocksource.h @@ -0,0 +1,49 @@ +/* +Copyright 2020 Google LLC + +Use of this source code is governed by a BSD-style +license that can be found in the LICENSE file or at +https://developers.google.com/open-source/licenses/bsd +*/ + +#ifndef REFTABLE_BLOCKSOURCE_H +#define REFTABLE_BLOCKSOURCE_H + +#include + +/* block_source is a generic wrapper for a seekable readable file. + */ +struct reftable_block_source { + struct reftable_block_source_vtable *ops; + void *arg; +}; + +/* a contiguous segment of bytes. It keeps track of its generating block_source + * so it can return itself into the pool. */ +struct reftable_block { + uint8_t *data; + int len; + struct reftable_block_source source; +}; + +/* block_source_vtable are the operations that make up block_source */ +struct reftable_block_source_vtable { + /* returns the size of a block source */ + uint64_t (*size)(void *source); + + /* reads a segment from the block source. It is an error to read + beyond the end of the block */ + int (*read_block)(void *source, struct reftable_block *dest, + uint64_t off, uint32_t size); + /* mark the block as read; may return the data back to malloc */ + void (*return_block)(void *source, struct reftable_block *blockp); + + /* release all resources associated with the block source */ + void (*close)(void *source); +}; + +/* opens a file on the file system as a block_source */ +int reftable_block_source_from_file(struct reftable_block_source *block_src, + const char *name); + +#endif