From patchwork Thu Oct 3 23:32:58 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josh Steadmon X-Patchwork-Id: 11173531 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BD418139A for ; Thu, 3 Oct 2019 23:33:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 904472133F for ; Thu, 3 Oct 2019 23:33:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="oqcIKVcI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731734AbfJCXdL (ORCPT ); Thu, 3 Oct 2019 19:33:11 -0400 Received: from mail-qk1-f201.google.com ([209.85.222.201]:37042 "EHLO mail-qk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731688AbfJCXdL (ORCPT ); Thu, 3 Oct 2019 19:33:11 -0400 Received: by mail-qk1-f201.google.com with SMTP id o133so4500834qke.4 for ; Thu, 03 Oct 2019 16:33:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=9E9hOYsrs89GMjPlB3G+AxpcVxldK5ktvSdyV9kFHvc=; b=oqcIKVcIjbFe8M4Og9t9kGrd+fuTysvBQzbcfzx1d7aB0Hr8iRFN1VZdBSdLXog7+i g3swJp9RfmlUXtKjYy+Pcjx2v4h7+htGopk4n3gK3a4aerbeEotE2Ikdt+U0t9EJMgRC PNECaO3ilLl3y2+KNA/0VGyIHG35cGy+nWeP7eqI7t8KB8vjrTHffNhiefF8zDCtzaxs jQmLjCKIxm3ijjMk4J1NeCFAYLqn2ki9zSVr88qe3DxVuyiYtR45X/5vyge/PGlyUu+d u59Ra0qSBni+n1rBtT9HNew1GWdQEeRq3T84c9Qz2xI/C/+cx+RxKoulWllpAtXCvgpk b4aQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=9E9hOYsrs89GMjPlB3G+AxpcVxldK5ktvSdyV9kFHvc=; b=LmMR32KAi13BBou7WjFjBRgOatLmaXbUpNchr46l+yb0Z0dg4QVhqN5/nZEMe9QA5x R8s+bGmzAhaweutUYSiHivMMgxb8mkbHx+Zt5tC97eyH+NZpchh6P5myKc2WJYdQpaH7 Wzl54HvKRjEbR29nWd8/ISD36g9gC0IlxtATCDORp6DrNkYKAzc/+k1GqOzeBqC/GFPE qHPHD1AOAG8GogiQjJLy0/xyZ1lOTg/Nt/HWWrXbo9nmrOO6+gfKKSeBVMCRqvgh9BcY +lcg/CIntqMtDKuzltn182GzSXszceQLMScU5s3QkUvBb3dwfrd++JWg5gZ7JDs/il73 fchQ== X-Gm-Message-State: APjAAAWCmPINFbs3waNQrva8De0Mxd8mcgRXLzZtKKkYpivVpODphg6j IbK87zPBj1vyZsi/XUC9wmrH6iPy4dE483jdnMEKguXP1gWxrZHDxWCDwLt6oRg5FC1ugh+WAWH crD+PEGKjX3gRowXRatBV9jAiyITuwLj0p69YoITS7AFDFhsqpPA0qX+ZFbXjCW4= X-Google-Smtp-Source: APXvYqwV6o061XjNaGVWMmwNI6y0rD9rs6pQ19b5XaA7DnTHel+0bi4lVgDW368PfSVWY8bBZ9lKGbPjEXuajA== X-Received: by 2002:ac8:33c3:: with SMTP id d3mr12919484qtb.41.1570145589825; Thu, 03 Oct 2019 16:33:09 -0700 (PDT) Date: Thu, 3 Oct 2019 16:32:58 -0700 In-Reply-To: Message-Id: <98a8440d3f0ef3cd3cdd0291051d976d4a659cc4.1570144820.git.steadmon@google.com> Mime-Version: 1.0 References: <99e4a0fe409a236d210d95e54cd03fce61daa291.1564438745.git.steadmon@google.com> X-Mailer: git-send-email 2.23.0.581.g78d2f28ef7-goog Subject: [PATCH v4 3/4] trace2: don't overload target directories From: Josh Steadmon To: git@vger.kernel.org, git@jeffhostetler.com Cc: stolee@gmail.com Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org trace2 can write files into a target directory. With heavy usage, this directory can fill up with files, causing difficulty for trace-processing systems. This patch adds a config option (trace2.maxFiles) to set a maximum number of files that trace2 will write to a target directory. The following behavior is enabled when the maxFiles is set to a positive integer: When trace2 would write a file to a target directory, first check whether or not the directory is overloaded. A directory is overloaded if there is a sentinel file declaring an overload, or if the number of files exceeds trace2.maxFiles. If the latter, create a sentinel file to speed up later overload checks. The assumption is that a separate trace-processing system is dealing with the generated traces; once it processes and removes the sentinel file, it should be safe to generate new trace files again. The default value for trace2.maxFiles is zero, which disables the overload check. The config can also be overridden with a new environment variable: GIT_TRACE2_MAX_FILES. Signed-off-by: Josh Steadmon --- Documentation/config/trace2.txt | 6 +++ t/t0212-trace2-event.sh | 17 +++++++ trace2/tr2_dst.c | 86 +++++++++++++++++++++++++++++++++ trace2/tr2_sysenv.c | 3 ++ trace2/tr2_sysenv.h | 2 + 5 files changed, 114 insertions(+) diff --git a/Documentation/config/trace2.txt b/Documentation/config/trace2.txt index 2edbfb02fe..4ce0b9a6d1 100644 --- a/Documentation/config/trace2.txt +++ b/Documentation/config/trace2.txt @@ -54,3 +54,9 @@ trace2.destinationDebug:: By default, these errors are suppressed and tracing is silently disabled. May be overridden by the `GIT_TRACE2_DST_DEBUG` environment variable. + +trace2.maxFiles:: + Integer. When writing trace files to a target directory, do not + write additional traces if we would exceed this many files. Instead, + write a sentinel file that will block further tracing to this + directory. Defaults to 0, which disables this check. diff --git a/t/t0212-trace2-event.sh b/t/t0212-trace2-event.sh index ff5b9cc729..2ff97e72da 100755 --- a/t/t0212-trace2-event.sh +++ b/t/t0212-trace2-event.sh @@ -265,4 +265,21 @@ test_expect_success JSON_PP 'using global config, event stream, error event' ' test_cmp expect actual ' +test_expect_success "don't overload target directory" ' + mkdir trace_target_dir && + test_when_finished "rm -r trace_target_dir" && + ( + GIT_TRACE2_MAX_FILES=5 && + export GIT_TRACE2_MAX_FILES && + cd trace_target_dir && + test_seq $GIT_TRACE2_MAX_FILES >../expected_filenames.txt && + xargs touch <../expected_filenames.txt && + cd .. && + GIT_TRACE2_EVENT="$(pwd)/trace_target_dir" test-tool trace2 001return 0 + ) && + echo git-trace2-overload >>expected_filenames.txt && + ls trace_target_dir >ls_output.txt && + test_cmp expected_filenames.txt ls_output.txt +' + test_done diff --git a/trace2/tr2_dst.c b/trace2/tr2_dst.c index 5dda0ca1cd..af3405f179 100644 --- a/trace2/tr2_dst.c +++ b/trace2/tr2_dst.c @@ -1,3 +1,5 @@ +#include + #include "cache.h" #include "trace2/tr2_dst.h" #include "trace2/tr2_sid.h" @@ -8,6 +10,19 @@ */ #define MAX_AUTO_ATTEMPTS 10 +/* + * Sentinel file used to detect when we're overloading a directory with too many + * trace files. + */ +#define OVERLOAD_SENTINEL_NAME "git-trace2-overload" + +/* + * When set to zero, disables directory overload checking. Otherwise, controls + * how many files we can write to a directory before entering overload mode. + * This can be overridden via the TR2_SYSENV_MAX_FILES setting. + */ +static int tr2env_max_files = 0; + static int tr2_dst_want_warning(void) { static int tr2env_dst_debug = -1; @@ -32,6 +47,67 @@ void tr2_dst_trace_disable(struct tr2_dst *dst) dst->need_close = 0; } +/* + * Check to make sure we're not overloading the target directory with too many + * files. First get the threshold (if present) from the config or envvar. If + * it's zero or unset, disable this check. Next check for the presence of a + * sentinel file, then check file count. If we are overloaded, create the + * sentinel file if it doesn't already exist. + * + * We expect that some trace processing system is gradually collecting files + * from the target directory; after it removes the sentinel file we'll start + * writing traces again. + */ +static int tr2_dst_overloaded(const char *tgt_prefix) +{ + int file_count = 0, max_files = 0, ret = 0; + const char *max_files_var; + DIR *dirp; + struct strbuf path = STRBUF_INIT, sentinel_path = STRBUF_INIT; + struct stat statbuf; + + /* Get the config or envvar and decide if we should continue this check */ + max_files_var = tr2_sysenv_get(TR2_SYSENV_MAX_FILES); + if (max_files_var && *max_files_var && ((max_files = atoi(max_files_var)) >= 0)) + tr2env_max_files = max_files; + + if (!tr2env_max_files) { + ret = 0; + goto cleanup; + } + + strbuf_addstr(&path, tgt_prefix); + if (!is_dir_sep(path.buf[path.len - 1])) { + strbuf_addch(&path, '/'); + } + + /* check sentinel */ + strbuf_addbuf(&sentinel_path, &path); + strbuf_addstr(&sentinel_path, OVERLOAD_SENTINEL_NAME); + if (!stat(sentinel_path.buf, &statbuf)) { + ret = 1; + goto cleanup; + } + + /* check file count */ + dirp = opendir(path.buf); + while (file_count < tr2env_max_files && dirp && readdir(dirp)) + file_count++; + if (dirp) + closedir(dirp); + + if (file_count >= tr2env_max_files) { + creat(sentinel_path.buf, 0666); + ret = 1; + goto cleanup; + } + +cleanup: + strbuf_release(&path); + strbuf_release(&sentinel_path); + return ret; +} + static int tr2_dst_try_auto_path(struct tr2_dst *dst, const char *tgt_prefix) { int fd; @@ -50,6 +126,16 @@ static int tr2_dst_try_auto_path(struct tr2_dst *dst, const char *tgt_prefix) strbuf_addstr(&path, sid); base_path_len = path.len; + if (tr2_dst_overloaded(tgt_prefix)) { + strbuf_release(&path); + if (tr2_dst_want_warning()) + warning("trace2: not opening %s trace file due to too " + "many files in target directory %s", + tr2_sysenv_display_name(dst->sysenv_var), + tgt_prefix); + return 0; + } + for (attempt_count = 0; attempt_count < MAX_AUTO_ATTEMPTS; attempt_count++) { if (attempt_count > 0) { strbuf_setlen(&path, base_path_len); diff --git a/trace2/tr2_sysenv.c b/trace2/tr2_sysenv.c index 5958cfc424..3c3792eca2 100644 --- a/trace2/tr2_sysenv.c +++ b/trace2/tr2_sysenv.c @@ -49,6 +49,9 @@ static struct tr2_sysenv_entry tr2_sysenv_settings[] = { "trace2.perftarget" }, [TR2_SYSENV_PERF_BRIEF] = { "GIT_TRACE2_PERF_BRIEF", "trace2.perfbrief" }, + + [TR2_SYSENV_MAX_FILES] = { "GIT_TRACE2_MAX_FILES", + "trace2.maxfiles" }, }; /* clang-format on */ diff --git a/trace2/tr2_sysenv.h b/trace2/tr2_sysenv.h index 8dd82a7a56..d4364a7b85 100644 --- a/trace2/tr2_sysenv.h +++ b/trace2/tr2_sysenv.h @@ -24,6 +24,8 @@ enum tr2_sysenv_variable { TR2_SYSENV_PERF, TR2_SYSENV_PERF_BRIEF, + TR2_SYSENV_MAX_FILES, + TR2_SYSENV_MUST_BE_LAST };