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Thread-safe xmalloc and xrealloc needs a recursive mutex

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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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Johannes Sixt 2010-04-08 09:15:39 +02:00 committed by Junio C Hamano
parent a9a746364b
commit 9374919442
5 changed files with 27 additions and 4 deletions
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2
builtin-grep.c
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@ -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[] = {

4
builtin-pack-objects.c
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@ -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);

8
compat/win32/pthread.h
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@ -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.

16
thread-utils.c
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@ -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;
}

1
thread-utils.h
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@ -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 */