From db39ffdbcc8c616b7010aa93f06637d87ee7ae02 Mon Sep 17 00:00:00 2001
From: Loo Rong Jie <loorongjie@gmail.com>
Date: Thu, 22 Jun 2017 09:03:29 +0800
Subject: [PATCH] Implement pthread_cond_t with Win32 CONDITION_VARIABLE

Win32 CONDITION_VARIABLE has better performance and is easier to
maintain.

Since CONDITION_VARIABLE is not available in Windows XP and below,
old implementation of pthread_cond_t is kept under define guard
'GIT_WIN_XP_SUPPORT'. To enable old implementation, build with
make CFLAGS="-DGIT_WIN_XP_SUPPORT".

Signed-off-by: Loo Rong Jie <loorongjie@gmail.com>

fast-forwarded.
---
 compat/win32/pthread.c | 40 ++++++++++++++++++++++++++++++++++++++++
 compat/win32/pthread.h |  4 ++++
 2 files changed, 44 insertions(+)

diff --git a/compat/win32/pthread.c b/compat/win32/pthread.c
index e18f5c6e2e55a4..80243b67cb8dc1 100644
--- a/compat/win32/pthread.c
+++ b/compat/win32/pthread.c
@@ -57,6 +57,8 @@ pthread_t pthread_self(void)
 	return t;
 }
 
+#ifdef GIT_WIN_XP_SUPPORT
+
 int pthread_cond_init(pthread_cond_t *cond, const void *unused)
 {
 	cond->waiters = 0;
@@ -194,3 +196,41 @@ int pthread_cond_broadcast(pthread_cond_t *cond)
 	}
 	return 0;
 }
+
+#else // GIT_WIN_XP_SUPPORT
+
+WINBASEAPI VOID WINAPI InitializeConditionVariable (PCONDITION_VARIABLE ConditionVariable);
+WINBASEAPI VOID WINAPI WakeConditionVariable (PCONDITION_VARIABLE ConditionVariable);
+WINBASEAPI VOID WINAPI WakeAllConditionVariable (PCONDITION_VARIABLE ConditionVariable);
+WINBASEAPI WINBOOL WINAPI SleepConditionVariableCS (PCONDITION_VARIABLE ConditionVariable, PCRITICAL_SECTION CriticalSection, DWORD dwMilliseconds);
+
+int pthread_cond_init(pthread_cond_t *cond, const void *unused)
+{
+	InitializeConditionVariable(cond);
+	return 0;
+}
+
+int pthread_cond_destroy(pthread_cond_t *cond)
+{
+	return 0;
+}
+
+int pthread_cond_wait(pthread_cond_t *cond, CRITICAL_SECTION *mutex)
+{
+	SleepConditionVariableCS(cond, mutex, INFINITE);
+	return 0;
+}
+
+int pthread_cond_signal(pthread_cond_t *cond)
+{
+	WakeConditionVariable(cond);
+	return 0;
+}
+
+int pthread_cond_broadcast(pthread_cond_t *cond)
+{
+	WakeAllConditionVariable(cond);
+	return 0;
+}
+
+#endif // GIT_WIN_XP_SUPPORT
diff --git a/compat/win32/pthread.h b/compat/win32/pthread.h
index 1c164088fbb64d..10a9d45f07eadd 100644
--- a/compat/win32/pthread.h
+++ b/compat/win32/pthread.h
@@ -32,6 +32,7 @@ typedef int pthread_mutexattr_t;
 #define pthread_mutexattr_settype(a, t) 0
 #define PTHREAD_MUTEX_RECURSIVE 0
 
+#ifdef GIT_WIN_XP_SUPPORT
 /*
  * Implement simple condition variable for Windows threads, based on ACE
  * implementation.
@@ -47,6 +48,9 @@ typedef struct {
 	HANDLE sema;
 	HANDLE continue_broadcast;
 } pthread_cond_t;
+#else
+typedef CONDITION_VARIABLE pthread_cond_t;
+#endif
 
 extern int pthread_cond_init(pthread_cond_t *cond, const void *unused);
 extern int pthread_cond_destroy(pthread_cond_t *cond);