[PATCH] Thread-safe xmalloc and xrealloc needs a recursive mutex
- From
Johannes Sixt <j.sixt@viscovery.net>
- Date
- Apr 8, 2010, 07:15 UTC
- Message-ID
- <4BBD829B.8040700@viscovery.net>
- In-Reply-To
- <20100407144555.GA23911@fredrik-laptop>
From: Johannes Sixt <j6t@kdbg.org>
The mutex used to protect object access (read_mutex) may need to be acquired recursively. Introduce init_recursive_mutex() helper function in thread-utils.c that constructs a mutex with the PHREAD_MUTEX_RECURSIVE attribute.
pthread_mutex_init() emulation on Win32 is already recursive as it is implemented on top of the CRITICAL_SECTION type, which is recursive.
http://msdn.microsoft.com/en-us/library/ms682530%28VS.85%29.aspx
Add do-nothing compatibility wrappers for pthread_mutexattr* functions.
Initial-version-by: Fredrik Kuivinen <frekui@gmail.com> Signed-off-by: Johannes Sixt <j6t@kdbg.org> --- Am 4/7/2010 16:45, schrieb Fredrik Kuivinen:
> We only need something like the following (on top of Nico's previous > patch). Warning: It hasn't even been compile tested on WIN32.
Unfortunately, it doesn't build. This patch replaces the tip of nd/malloc-threading.
BTW, your uses of strerror(errno) in init_recursive_mutex() were wrong (pthread functions do not set errno), but it is better in any case to avoid die() in this function.
-- Hannes
builtin-grep.c | 2 +- builtin-pack-objects.c | 4 ++-- compat/win32/pthread.h | 8 +++++++- thread-utils.c | 16 ++++++++++++++++ thread-utils.h | 1 + 5 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/builtin-grep.c b/builtin-grep.c index 371db0a..52137f4 100644 --- a/builtin-grep.c +++ b/builtin-grep.c @@ -16,8 +16,8 @@ #include "quote.h" #ifndef NO_PTHREADS -#include "thread-utils.h" #include <pthread.h> +#include "thread-utils.h" #endif static char const * const grep_usage[] = { diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c index 0ecc198..26fc7cd 100644 --- a/builtin-pack-objects.c +++ b/builtin-pack-objects.c @@ -18,8 +18,8 @@ #include "refs.h" #ifndef NO_PTHREADS -#include "thread-utils.h" #include <pthread.h> +#include "thread-utils.h" #endif static const char pack_usage[] = @@ -1586,7 +1586,7 @@ static pthread_cond_t progress_cond; */ static void init_threaded_search(void) { - pthread_mutex_init(&read_mutex, NULL); + init_recursive_mutex(&read_mutex); pthread_mutex_init(&cache_mutex, NULL); pthread_mutex_init(&progress_mutex, NULL); pthread_cond_init(&progress_cond, NULL); diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h index c72f100..a45f8d6 100644 --- a/compat/win32/pthread.h +++ b/compat/win32/pthread.h @@ -18,11 +18,17 @@ */ #define pthread_mutex_t CRITICAL_SECTION -#define pthread_mutex_init(a,b) InitializeCriticalSection((a)) +#define pthread_mutex_init(a,b) (InitializeCriticalSection((a)), 0) #define pthread_mutex_destroy(a) DeleteCriticalSection((a)) #define pthread_mutex_lock EnterCriticalSection #define pthread_mutex_unlock LeaveCriticalSection +typedef int pthread_mutexattr_t; +#define pthread_mutexattr_init(a) (*(a) = 0) +#define pthread_mutexattr_destroy(a) do {} while (0) +#define pthread_mutexattr_settype(a, t) 0 +#define PTHREAD_MUTEX_RECURSIVE 0 + /* * Implement simple condition variable for Windows threads, based on ACE * implementation. diff --git a/thread-utils.c b/thread-utils.c index 4f9c829..589f838 100644 --- a/thread-utils.c +++ b/thread-utils.c @@ -1,4 +1,5 @@ #include "cache.h" +#include <pthread.h> #if defined(hpux) || defined(__hpux) || defined(_hpux) # include <sys/pstat.h> @@ -43,3 +44,18 @@ int online_cpus(void) return 1; } + +int init_recursive_mutex(pthread_mutex_t *m) +{ + pthread_mutexattr_t a; + int ret; + + ret = pthread_mutexattr_init(&a); + if (!ret) { + ret = pthread_mutexattr_settype(&a, PTHREAD_MUTEX_RECURSIVE); + if (!ret) + ret = pthread_mutex_init(m, &a); + pthread_mutexattr_destroy(&a); + } + return ret; +} diff --git a/thread-utils.h b/thread-utils.h index cce4b77..1727a03 100644 --- a/thread-utils.h +++ b/thread-utils.h @@ -2,5 +2,6 @@ #define THREAD_COMPAT_H extern int online_cpus(void); +extern int init_recursive_mutex(pthread_mutex_t*); #endif /* THREAD_COMPAT_H */
-- 1.7.0.3.1356.g75346