On Thu, Apr 19, 2012 at 08:45:52AM +0200, Johannes Sixt wrote:
> I don't see any mutual exclusion happening in this chain. Perhaps it is
> not needed, provided that the pread() call in get_data_from_pack is
> atomic. But our git_pread() from compat/pread.c, which we use on Windows,
> is not atomic.
OK assume it's Windows' pread thread-safe problem (it does look like
so given how pread.c implements it), maybe this patch will help:
-- 8< --
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 847dbb3..5d539cd 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -102,6 +102,10 @@ static pthread_mutex_t work_mutex;
#define work_lock() lock_mutex(&work_mutex)
#define work_unlock() unlock_mutex(&work_mutex)
+#ifdef WIN32
+static pthread_mutex_t pread_mutex;
+#endif
+
static pthread_key_t key;
static inline void lock_mutex(pthread_mutex_t *mutex)
@@ -124,6 +128,9 @@ static void init_thread(void)
init_recursive_mutex(&read_mutex);
pthread_mutex_init(&counter_mutex, NULL);
pthread_mutex_init(&work_mutex, NULL);
+#ifdef WIN32
+ pthread_mutex_init(&pread_mutex, NULL);
+#endif
pthread_key_create(&key, NULL);
thread_data = xcalloc(nr_threads, sizeof(*thread_data));
threads_active = 1;
@@ -137,6 +144,9 @@ static void cleanup_thread(void)
pthread_mutex_destroy(&read_mutex);
pthread_mutex_destroy(&counter_mutex);
pthread_mutex_destroy(&work_mutex);
+#ifdef WIN32
+ pthread_mutex_destroy(&pread_mutex);
+#endif
pthread_key_delete(key);
free(thread_data);
}
@@ -456,6 +466,20 @@ static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_
return data;
}
+#ifdef WIN32
+/* pread is reimplemented in compat/pread.c and is not thread-safe */
+static ssize_t pread_threadsafe(int fd, void *buf, size_t count, off_t from)
+{
+ ssize_t n;
+ lock_mutex(&pread_mutex);
+ n = pread(fd, buf, count, from);
+ unlock_mutex(&pread_mutex);
+ return n;
+}
+#else
+#define pread_threadsafe(fd,buf,count,from) pread(fd, buf, count, from)
+#endif
+
static void *get_data_from_pack(struct object_entry *obj)
{
off_t from = obj[0].idx.offset + obj[0].hdr_size;
@@ -474,7 +498,7 @@ static void *get_data_from_pack(struct object_entry *obj)
do {
ssize_t n = (len < 64*1024) ? len : 64*1024;
- n = pread(pack_fd, inbuf, n, from);
+ n = pread_threadsafe(pack_fd, inbuf, n, from);
if (n < 0)
die_errno("cannot pread pack file");
if (!n)
-- 8< --
--
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