diff options
author | Nguyễn Thái Ngọc Duy <pclouds@gmail.com> | 2014-03-25 17:41:41 +0400 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2014-04-16 20:29:41 +0400 |
commit | 39539495acb24abfb4dee551e3e9f2e696be7abf (patch) | |
tree | fbf97b4f412312b0788e290fc4008e616bdc28eb /builtin | |
parent | 5f95c9f850b19b368c43ae399cc831b17a26a5ac (diff) |
index-pack: work around thread-unsafe pread()
Multi-threaing of index-pack was disabled with c0f8654
(index-pack: Disable threading on cygwin - 2012-06-26), because
pread() implementations for Cygwin and MSYS were not thread
safe. Recent Cygwin does offer usable pread() and we enabled
multi-threading with 103d530f (Cygwin 1.7 has thread-safe pread,
2013-07-19).
Work around this problem on platforms with a thread-unsafe
pread() emulation by opening one file handle per thread; it
would prevent parallel pread() on different file handles from
stepping on each other.
Also remove NO_THREAD_SAFE_PREAD that was introduced in c0f8654
because it's no longer used anywhere.
This workaround is unconditional, even for platforms with
thread-safe pread() because the overhead is small (a couple file
handles more) and not worth fragmenting the code.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Tested-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin')
-rw-r--r-- | builtin/index-pack.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/builtin/index-pack.c b/builtin/index-pack.c index 2f37a38fbc..ed489bbe9a 100644 --- a/builtin/index-pack.c +++ b/builtin/index-pack.c @@ -40,17 +40,13 @@ struct base_data { int ofs_first, ofs_last; }; -#if !defined(NO_PTHREADS) && defined(NO_THREAD_SAFE_PREAD) -/* pread() emulation is not thread-safe. Disable threading. */ -#define NO_PTHREADS -#endif - struct thread_local { #ifndef NO_PTHREADS pthread_t thread; #endif struct base_data *base_cache; size_t base_cache_used; + int pack_fd; }; /* @@ -91,7 +87,8 @@ static off_t consumed_bytes; static unsigned deepest_delta; static git_SHA_CTX input_ctx; static uint32_t input_crc32; -static int input_fd, output_fd, pack_fd; +static int input_fd, output_fd; +static const char *curr_pack; #ifndef NO_PTHREADS @@ -134,6 +131,7 @@ static inline void unlock_mutex(pthread_mutex_t *mutex) */ static void init_thread(void) { + int i; init_recursive_mutex(&read_mutex); pthread_mutex_init(&counter_mutex, NULL); pthread_mutex_init(&work_mutex, NULL); @@ -141,11 +139,18 @@ static void init_thread(void) pthread_mutex_init(&deepest_delta_mutex, NULL); pthread_key_create(&key, NULL); thread_data = xcalloc(nr_threads, sizeof(*thread_data)); + for (i = 0; i < nr_threads; i++) { + thread_data[i].pack_fd = open(curr_pack, O_RDONLY); + if (thread_data[i].pack_fd == -1) + die_errno(_("unable to open %s"), curr_pack); + } + threads_active = 1; } static void cleanup_thread(void) { + int i; if (!threads_active) return; threads_active = 0; @@ -154,6 +159,8 @@ static void cleanup_thread(void) pthread_mutex_destroy(&work_mutex); if (show_stat) pthread_mutex_destroy(&deepest_delta_mutex); + for (i = 0; i < nr_threads; i++) + close(thread_data[i].pack_fd); pthread_key_delete(key); free(thread_data); } @@ -288,13 +295,13 @@ static const char *open_pack_file(const char *pack_name) output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600); if (output_fd < 0) die_errno(_("unable to create '%s'"), pack_name); - pack_fd = output_fd; + nothread_data.pack_fd = output_fd; } else { input_fd = open(pack_name, O_RDONLY); if (input_fd < 0) die_errno(_("cannot open packfile '%s'"), pack_name); output_fd = -1; - pack_fd = input_fd; + nothread_data.pack_fd = input_fd; } git_SHA1_Init(&input_ctx); return pack_name; @@ -542,7 +549,7 @@ static void *unpack_data(struct object_entry *obj, do { ssize_t n = (len < 64*1024) ? len : 64*1024; - n = pread(pack_fd, inbuf, n, from); + n = pread(get_thread_data()->pack_fd, inbuf, n, from); if (n < 0) die_errno(_("cannot pread pack file")); if (!n) @@ -1490,7 +1497,7 @@ static void show_pack_info(int stat_only) int cmd_index_pack(int argc, const char **argv, const char *prefix) { int i, fix_thin_pack = 0, verify = 0, stat_only = 0; - const char *curr_pack, *curr_index; + const char *curr_index; const char *index_name = NULL, *pack_name = NULL; const char *keep_name = NULL, *keep_msg = NULL; char *index_name_buf = NULL, *keep_name_buf = NULL; |