medfall

commit 2a895e681beb2b2cba66c6a69953867b8cf16a5b
parent 2bc43ba669eab4e630ef645fe1228c1c9c9689cb
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Sat Apr  1 19:38:23 +0300

Add optimised Semaphore and semaphore_destroy

Diffstat:
darwin_semaphore.h
 | 
16
++++++++++++----
platform_semaphore.h
 | 
31
+++++++++++++++++++++++++++++++
unix_semaphore.h
 | 
34
+++++++++++++++++++++++++---------
win32_semaphore.h
 | 
20
+++++++++++++-------
4 files changed, 81 insertions(+), 20 deletions(-)
diff --git a/darwin_semaphore.h b/darwin_semaphore.h
@@ -2,18 +2,26 @@
 
 #include <dispatch/dispatch.h>
 
-struct Semaphore {
+struct PlatformSemaphore {
 	dispatch_semaphore_t sem;
 };
 
-inline void semaphore_init( Semaphore * sem ) {
+inline void platform_semaphore_init( PlatformSemaphore * sem ) {
 	sem->sem = dispatch_semaphore_create( 0 );
+	if( sem->sem == NULL ) {
+		FATAL( "dispatch_semaphore_create" );
+	}
 }
 
-inline void semaphore_signal( Semaphore * sem ) {
+inline void platform_semaphore_signal( PlatformSemaphore * sem ) {
 	dispatch_semaphore_signal( sem->sem );
 }
 
-inline void semaphore_wait( Semaphore * sem ) {
+inline void platform_semaphore_wait( PlatformSemaphore * sem ) {
 	dispatch_semaphore_wait( sem->sem, DISPATCH_TIME_FOREVER );
 }
+
+inline void platform_semaphore_destroy( PlatformSemaphore * sem ) {
+	// TODO: might need a cast to dispatch_object_t
+	dispatch_release( sem->sem );
+}
diff --git a/platform_semaphore.h b/platform_semaphore.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "platform.h"
+#include "platform_atomic.h"
 
 #if PLATFORM_WINDOWS
 #include "win32_semaphore.h"
@@ -11,3 +12,33 @@
 #else
 #error new platform
 #endif
+
+struct Semaphore {
+	PlatformSemaphore sem;
+	// when n < 0, n = - number of waiting threads
+	// when n >= 0, n = number of tasks remaining
+	atomic_s32 n;
+};
+
+inline void semaphore_init( Semaphore * sem ) {
+	platform_semaphore_init( &sem->sem );
+	store_release( &sem->n, 0 );
+}
+
+inline void semaphore_signal( Semaphore * sem ) {
+	// if n was < 0, wake up a waiting thread
+	if( fetch_add_acqrel( &sem->n, 1 ) < 0 ) {
+		platform_semaphore_signal( &sem->sem );
+	}
+}
+
+inline void semaphore_wait( Semaphore * sem ) {
+	// if n is now < 0, put this thread to sleep
+	if( fetch_add_acqrel( &sem->n, -1 ) <= 0 ) {
+		platform_semaphore_wait( &sem->sem );
+	}
+}
+
+inline void semaphore_destroy( Semaphore * sem ) {
+	platform_semaphore_destroy( &sem->sem );
+}
diff --git a/unix_semaphore.h b/unix_semaphore.h
@@ -1,23 +1,39 @@
 #pragma once
 
-#include <err.h>
 #include <semaphore.h>
 
-struct Semaphore {
+#include "log.h"
+
+struct PlatformSemaphore {
 	sem_t sem;
 };
 
-inline void semaphore_init( Semaphore * sem ) {
+inline void platform_semaphore_init( PlatformSemaphore * sem ) {
 	int ok = sem_init( &sem->sem, 0, 0 );
-	if( ok == -1 ) {
-		err( 1, "sem_init failed" );
+	if( ok != 0 ) {
+		FATAL( "sem_init" );
+	}
+}
+
+inline void platform_semaphore_signal( PlatformSemaphore * sem ) {
+	int ok = sem_post( &sem->sem );
+	if( ok != 0 && errno != EOVERFLOW ) {
+		FATAL( "sem_post" );
 	}
 }
 
-inline void semaphore_signal( Semaphore * sem ) {
-	sem_post( &sem->sem );
+inline void platform_semaphore_wait( PlatformSemaphore * sem ) {
+	while( true ) {
+		int ok = sem_wait( &sem->sem );
+		if( ok == 0 ) break;
+		if( errno == EINTR ) continue;
+		FATAL( "sem_wait" );
+	}
 }
 
-inline void semaphore_wait( Semaphore * sem ) {
-	sem_wait( &sem->sem );
+inline void platform_semaphore_destroy( PlatformSemaphore * sem ) {
+	int ok = sem_destroy( &sem->sem );
+	if( ok != 0 ) {
+		FATAL( "sem_destroy" );
+	}
 }
diff --git a/win32_semaphore.h b/win32_semaphore.h
@@ -4,31 +4,37 @@
 
 #include "log.h"
 
-struct Semaphore {
+struct PlatformSemaphore {
 	HANDLE sem;
 };
 
-inline void semaphore_init( Semaphore * sem ) {
+inline void platform_semaphore_init( PlatformSemaphore * sem ) {
 	LONG max = 1024; // TODO
 	sem->sem = CreateSemaphore( NULL, 0, max, NULL );
 	if( sem->sem == NULL ) {
-		FATAL( "CreateSemaphore failed" );
+		FATAL( "CreateSemaphore" );
 	}
 }
 
-inline void semaphore_signal( Semaphore * sem ) {
+inline void platform_semaphore_signal( PlatformSemaphore * sem ) {
 	if( ReleaseSemaphore( sem->sem, 1, NULL ) == 0 ) {
 		DWORD error = GetLastError();
 		if( error == ERROR_TOO_MANY_POSTS ) {
 			return;
 		}
 
-		FATAL( "ReleaseSemaphore failed" );
+		FATAL( "ReleaseSemaphore" );
 	}
 }
 
-inline void semaphore_wait( Semaphore * sem ) {
+inline void platform_semaphore_wait( PlatformSemaphore * sem ) {
 	if( WaitForSingleObject( sem->sem, INFINITE ) == WAIT_FAILED ) {
-		FATAL( "WaitForSingleObject failed" );
+		FATAL( "WaitForSingleObject" );
+	}
+}
+
+inline void platform_semaphore_destroy( PlatformSemaphore * sem ) {
+	if( CloseHandle( sem->sem ) == NULL ) {
+		FATAL( "CloseHandle" );
 	}
 }