[vlc-commits] Win32: use only one condition variable per R/W lock

[Rémi Denis-Courmont]

vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Sat Aug 20 16:39:09 2011 +0300| [6fdf44fd13f5c24efb7ac5a593e967d02449b665] | committer: Rémi Denis-Courmont

Win32: use only one condition variable per R/W lock

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=6fdf44fd13f5c24efb7ac5a593e967d02449b665
---

 configure.ac          |    2 +-
 include/vlc_threads.h |    5 ++---
 src/win32/thread.c    |   16 ++++++----------
 3 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/configure.ac b/configure.ac
index 89dce2b..bd9a073 100644
--- a/configure.ac
+++ b/configure.ac
@@ -320,7 +320,7 @@ case "${host_os}" in
   *mingw32* | *cygwin* | *wince* | *mingwce*)
     AC_CHECK_TOOL(WINDRES, windres, :)
     AC_CHECK_TOOL(OBJCOPY, objcopy, :)
-    AC_DEFINE([_WIN32_WINNT], 0x0501, [Define to '0x0501' for Windows XP APIs.])
+    AC_DEFINE([_WIN32_WINNT], 0x0600, [Define to '0x0600' for Windows Vista APIs.])
     AC_DEFINE([_WIN32_IE], 0x0501, [Define to '0x0501' for IE 5.01 (and shell) APIs.])
 
     case "${host_os}" in
diff --git a/include/vlc_threads.h b/include/vlc_threads.h
index fea79be..ddaeff1 100644
--- a/include/vlc_threads.h
+++ b/include/vlc_threads.h
@@ -151,14 +151,13 @@ typedef HANDLE  vlc_sem_t;
 typedef struct
 {
     vlc_mutex_t   mutex;
-    vlc_cond_t    read_wait;
-    vlc_cond_t    write_wait;
+    vlc_cond_t    wait;
     unsigned long readers;
     unsigned long writers;
     DWORD         writer;
 } vlc_rwlock_t;
 #define VLC_STATIC_RWLOCK \
-    { VLC_STATIC_MUTEX, VLC_STATIC_COND, VLC_STATIC_COND, 0, 0, 0 }
+    { VLC_STATIC_MUTEX, VLC_STATIC_COND, 0, 0, 0 }
 
 typedef struct vlc_threadvar *vlc_threadvar_t;
 typedef struct vlc_timer *vlc_timer_t;
diff --git a/src/win32/thread.c b/src/win32/thread.c
index 5b5753c..1dfeef6 100644
--- a/src/win32/thread.c
+++ b/src/win32/thread.c
@@ -384,8 +384,7 @@ void vlc_sem_wait (vlc_sem_t *sem)
 void vlc_rwlock_init (vlc_rwlock_t *lock)
 {
     vlc_mutex_init (&lock->mutex);
-    vlc_cond_init (&lock->read_wait);
-    vlc_cond_init (&lock->write_wait);
+    vlc_cond_init (&lock->wait);
     lock->readers = 0; /* active readers */
     lock->writers = 0; /* waiting writers */
     lock->writer = 0; /* ID of active writer */
@@ -393,8 +392,7 @@ void vlc_rwlock_init (vlc_rwlock_t *lock)
 
 void vlc_rwlock_destroy (vlc_rwlock_t *lock)
 {
-    vlc_cond_destroy (&lock->read_wait);
-    vlc_cond_destroy (&lock->write_wait);
+    vlc_cond_destroy (&lock->wait);
     vlc_mutex_destroy (&lock->mutex);
 }
 
@@ -411,7 +409,7 @@ void vlc_rwlock_rdlock (vlc_rwlock_t *lock)
     while (lock->writer != 0)
     {
         assert (lock->readers == 0);
-        vlc_cond_wait (&lock->read_wait, &lock->mutex);
+        vlc_cond_wait (&lock->wait, &lock->mutex);
     }
     if (unlikely(lock->readers == ULONG_MAX))
         abort ();
@@ -426,7 +424,7 @@ static void vlc_rwlock_rdunlock (vlc_rwlock_t *lock)
 
     /* If there are no readers left, wake up a writer. */
     if (--lock->readers == 0 && lock->writers > 0)
-        vlc_cond_signal (&lock->write_wait);
+        vlc_cond_signal (&lock->wait);
     vlc_mutex_unlock (&lock->mutex);
 }
 
@@ -438,7 +436,7 @@ void vlc_rwlock_wrlock (vlc_rwlock_t *lock)
     lock->writers++;
     /* Wait until nobody owns the lock in either way. */
     while ((lock->readers > 0) || (lock->writer != 0))
-        vlc_cond_wait (&lock->write_wait, &lock->mutex);
+        vlc_cond_wait (&lock->wait, &lock->mutex);
     lock->writers--;
     assert (lock->writer == 0);
     lock->writer = GetCurrentThreadId ();
@@ -453,9 +451,7 @@ static void vlc_rwlock_wrunlock (vlc_rwlock_t *lock)
     lock->writer = 0; /* Write unlock */
 
     /* Let reader and writer compete. Scheduler decides who wins. */
-    if (lock->writers > 0)
-        vlc_cond_signal (&lock->write_wait);
-    vlc_cond_broadcast (&lock->read_wait);
+    vlc_cond_broadcast (&lock->wait);
     vlc_mutex_unlock (&lock->mutex);
 }