From 4b3384620213b6b0a42f3275a48bd4a71cc1b3b7 Mon Sep 17 00:00:00 2001 From: Karsten Blees Date: Sun, 8 Sep 2013 14:23:27 +0200 Subject: [PATCH] mingw: add infrastructure for read-only file system level caches Add a macro to mark code sections that only read from the file system, along with a config option and documentation. This facilitates implementation of relatively simple file system level caches without the need to synchronize with the file system. Enable read-only sections for 'git status' and preload_index. Signed-off-by: Karsten Blees --- Documentation/config/core.txt | 6 ++++++ builtin/commit.c | 1 + compat/mingw.c | 6 ++++++ compat/mingw.h | 2 ++ git-compat-util.h | 15 +++++++++++++++ preload-index.c | 3 +++ 6 files changed, 33 insertions(+) diff --git a/Documentation/config/core.txt b/Documentation/config/core.txt index 8f6d8e77541261..58153413c5aae6 100644 --- a/Documentation/config/core.txt +++ b/Documentation/config/core.txt @@ -685,6 +685,12 @@ relatively high IO latencies. When enabled, Git will do the index comparison to the filesystem data in parallel, allowing overlapping IO's. Defaults to true. +core.fscache:: + Enable additional caching of file system data for some operations. ++ +Git for Windows uses this to bulk-read and cache lstat data of entire +directories (instead of doing lstat file by file). + core.unsetenvvars:: Windows-only: comma-separated list of environment variables' names that need to be unset before spawning any other process. diff --git a/builtin/commit.c b/builtin/commit.c index ef5e622c07746f..ef4b87615ba910 100644 --- a/builtin/commit.c +++ b/builtin/commit.c @@ -1583,6 +1583,7 @@ struct repository *repo UNUSED) PATHSPEC_PREFER_FULL, prefix, argv); + enable_fscache(1); if (status_format != STATUS_FORMAT_PORCELAIN && status_format != STATUS_FORMAT_PORCELAIN_V2) progress_flag = REFRESH_PROGRESS; diff --git a/compat/mingw.c b/compat/mingw.c index a26aa951413364..5f8ee834959f89 100644 --- a/compat/mingw.c +++ b/compat/mingw.c @@ -246,6 +246,7 @@ enum hide_dotfiles_type { static int core_restrict_inherited_handles = -1; static enum hide_dotfiles_type hide_dotfiles = HIDE_DOTFILES_DOTGITONLY; static char *unset_environment_variables; +int core_fscache; int mingw_core_config(const char *var, const char *value, const struct config_context *ctx UNUSED, @@ -259,6 +260,11 @@ int mingw_core_config(const char *var, const char *value, return 0; } + if (!strcmp(var, "core.fscache")) { + core_fscache = git_config_bool(var, value); + return 0; + } + if (!strcmp(var, "core.unsetenvvars")) { if (!value) return config_error_nonbool(var); diff --git a/compat/mingw.h b/compat/mingw.h index 8c86693fdb6cfd..d8852df7bba146 100644 --- a/compat/mingw.h +++ b/compat/mingw.h @@ -11,6 +11,8 @@ typedef _sigset_t sigset_t; #undef _POSIX_THREAD_SAFE_FUNCTIONS #endif +extern int core_fscache; + struct config_context; int mingw_core_config(const char *var, const char *value, const struct config_context *ctx, void *cb); diff --git a/git-compat-util.h b/git-compat-util.h index e42c61193f582a..9411305fe099b0 100644 --- a/git-compat-util.h +++ b/git-compat-util.h @@ -1555,6 +1555,21 @@ static inline int is_missing_file_error(int errno_) return (errno_ == ENOENT || errno_ == ENOTDIR); } +/* + * Enable/disable a read-only cache for file system data on platforms that + * support it. + * + * Implementing a live-cache is complicated and requires special platform + * support (inotify, ReadDirectoryChangesW...). enable_fscache shall be used + * to mark sections of git code that extensively read from the file system + * without modifying anything. Implementations can use this to cache e.g. stat + * data or even file content without the need to synchronize with the file + * system. + */ +#ifndef enable_fscache +#define enable_fscache(x) /* noop */ +#endif + int cmd_main(int, const char **); /* diff --git a/preload-index.c b/preload-index.c index ab94d6f39967ea..5a48636886d918 100644 --- a/preload-index.c +++ b/preload-index.c @@ -136,6 +136,7 @@ void preload_index(struct index_state *index, pthread_mutex_init(&pd.mutex, NULL); } + enable_fscache(1); for (i = 0; i < threads; i++) { struct thread_data *p = data+i; int err; @@ -171,6 +172,8 @@ void preload_index(struct index_state *index, trace2_data_intmax("index", NULL, "preload/sum_lstat", t2_sum_lstat); trace2_region_leave("index", "preload", NULL); + + enable_fscache(0); } int repo_read_index_preload(struct repository *repo,