Add mboxes

src/mbox.c

@@ -0,0 +1,77 @@
+#include "mbox.h"
+#include "util.h"
+
+#include <pthread.h>
+
+struct mbox * mbox_create( void )
+{
+	struct mbox * mbox = xmalloc( sizeof( struct mbox ) );
+	FATAL_UNLESS( 0 == pthread_cond_init( &mbox->filled_cond, NULL ),
+			"Failed to initialise a condition variable" );
+	FATAL_UNLESS( 0 == pthread_cond_init( &mbox->emptied_cond, NULL ),
+			"Failed to initialise a condition variable" );
+	FATAL_UNLESS( 0 == pthread_mutex_init( &mbox->mutex, NULL ),
+			"Failed to initialise a mutex" );
+	return mbox;
+}
+
+void mbox_post( struct mbox * mbox, void * contents )
+{
+	pthread_mutex_lock( &mbox->mutex );
+	{
+		if (mbox->full){
+			pthread_cond_wait( &mbox->emptied_cond, &mbox->mutex );
+		}
+		mbox->contents = contents;
+		mbox->full = 1;
+		while( 0 != pthread_cond_signal( &mbox->filled_cond ) );
+	}
+	pthread_mutex_unlock( &mbox->mutex );
+}
+
+
+void * mbox_contents( struct mbox * mbox )
+{
+	return mbox->contents;
+}
+
+
+int mbox_is_full( struct mbox * mbox )
+{
+	return mbox->full;
+}
+
+
+void * mbox_receive( struct mbox * mbox )
+{
+	NULLCHECK( mbox );
+	void * result;
+
+	pthread_mutex_lock( &mbox->mutex );
+	{
+		if ( !mbox->full ) {
+			pthread_cond_wait( &mbox->filled_cond, &mbox->mutex );
+		}
+		mbox->full = 0;
+		result = mbox->contents;
+		mbox->contents = NULL;
+		while( 0 != pthread_cond_signal( &mbox->emptied_cond));
+	}
+	pthread_mutex_unlock( &mbox->mutex );
+
+
+	return result;
+}
+
+
+void mbox_destroy( struct mbox * mbox )
+{
+	NULLCHECK( mbox );
+
+	while( 0 != pthread_cond_destroy( &mbox->emptied_cond ) );
+	while( 0 != pthread_cond_destroy( &mbox->filled_cond ) );
+
+	while( 0 != pthread_mutex_destroy( &mbox->mutex ) );
+
+	free( mbox );
+}