X-Git-Url: https://gerrit.o-ran-sc.org/r/gitweb?a=blobdiff_plain;f=src%2Frmr%2Fcommon%2Fsrc%2Fring_static.c;h=7170a9d0795caadaa191673891f8f67a699f5ffa;hb=ce1c741c01e8387cb095dac5e36a4d8ad91d006d;hp=93dfdb7e603c94a47f398fbc063ce980cdec888d;hpb=ec88d3c0563eeb6ae5f73427edb0b3c4d7acf299;p=ric-plt%2Flib%2Frmr.git

diff --git a/src/rmr/common/src/ring_static.c b/src/rmr/common/src/ring_static.c
index 93dfdb7..7170a9d 100644
--- a/src/rmr/common/src/ring_static.c
+++ b/src/rmr/common/src/ring_static.c
@@ -62,7 +62,10 @@ static int uta_ring_getpfd( void* vr ) {
 }
 
 /*
-	Make a new ring.
+	Make a new ring. The default is to NOT create a lock; if the user 
+	wants read locking then uta_config_ring() can be used to setup the
+	mutex. (We use several rings internally and the assumption is that
+	there is no locking for these.)
 */
 static void* uta_mk_ring( int size ) {
 	ring_t*	r;
@@ -72,6 +75,9 @@ static void* uta_mk_ring( int size ) {
 		return NULL;
 	}
 
+	r->flags = 0;
+	r->rgate = NULL;
+	r->wgate = NULL;
 	r->head = r->tail = 0;
 
 	max = (r->head - 1);
@@ -80,16 +86,62 @@ static void* uta_mk_ring( int size ) {
 	}
 
 	r->nelements = size;		// because we always have an empty element when full
-	if( (r->data = (void **) malloc( sizeof( void** ) * (r->nelements + 1) )) == NULL ) {
+	if( (r->data = (void **) malloc( sizeof( void* ) * (r->nelements + 1) )) == NULL ) {
 		free( r );
 		return NULL;
 	}
 
-	memset( r->data, 0, sizeof( void** ) * r->nelements );
+	memset( r->data, 0, sizeof( void* ) * r->nelements );
 	r->pfd = eventfd( 0, EFD_SEMAPHORE | EFD_NONBLOCK );		// in semaphore mode counter is maintained with each insert/extract
 	return (void *) r;
 }
 
+/*
+	Allows for configuration of a ring after it has been allocated.
+	Options are RING_* options that allow for things like setting/clearing
+	read locking. Returns 0 for failure 1 on success.
+
+	Options can be ORd together and all made effective at the same time, but
+	it will be impossible to determine a specific failure if invoked this
+	way.  Control is returned on the first error, and no provision is made
+	to "undo" previously set options if an error occurs.
+*/
+static int uta_ring_config( void* vr, int options ) {
+	ring_t*	r;
+
+	if( (r = (ring_t*) vr) == NULL ) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	if( options & RING_WLOCK ) {
+		if( r->wgate == NULL ) {		// don't realloc
+			r->wgate = (pthread_mutex_t *) malloc( sizeof( *r->wgate ) );
+			if( r->wgate == NULL ) {
+				return 0;
+			}
+	
+			pthread_mutex_init( r->wgate, NULL );
+		}
+	}
+
+	if( options & (RING_RLOCK | RING_FRLOCK) ) {				// read locking
+		if( r->rgate == NULL ) {		// don't realloc
+			r->rgate = (pthread_mutex_t *) malloc( sizeof( *r->rgate ) );
+			if( r->rgate == NULL ) {
+				return 0;
+			}
+	
+			pthread_mutex_init( r->rgate, NULL );
+		}
+		if( options & RING_FRLOCK ) {
+			r->flags |= RING_FL_FLOCK;
+		}
+	}
+
+	return 1;
+}
+
 /*
 	Ditch the ring. The caller is responsible for extracting any remaining
 	pointers and freeing them as needed.
@@ -100,7 +152,15 @@ static void uta_ring_free( void* vr ) {
 	if( (r = (ring_t*) vr) == NULL ) {
 		return;
 	}
-
+	if( r->data ){
+		free( r->data );
+	}
+	if( r->rgate ){
+		free( r->rgate );
+	}
+	if( r->wgate ){
+		free( r->wgate );
+	}
 	free( r );
 }
 
@@ -108,11 +168,17 @@ static void uta_ring_free( void* vr ) {
 /*
 	Pull the next data pointer from the ring; null if there isn't
 	anything to be pulled.
+
+	If the read lock exists for the ring, then this will BLOCK until
+	it gets the lock.  There is always a chance that once the lock
+	is obtained that the ring is empty, so the caller MUST handle
+	a nil pointer as the return.
 */
 static inline void* uta_ring_extract( void* vr ) {
 	ring_t*		r;
 	uint16_t	ti;		// real index in data
 	int64_t	ctr;		// pfd counter
+	void*		data;
 
 	if( !RING_FAST ) {								// compiler should drop the conditional when always false
 		if( (r = (ring_t*) vr) == NULL ) {
@@ -122,10 +188,26 @@ static inline void* uta_ring_extract( void* vr ) {
 		r = (ring_t*) vr;
 	}
 
-	if( r->tail == r->head ) {			// empty ring
+	if( r->tail == r->head ) {						// empty ring we can bail out quickly
 		return NULL;
 	}
 
+	if( r->rgate != NULL ) {							// if lock exists we must honour it
+		if( r->flags & RING_FL_FLOCK ) {				// fast read locking try once and return nil if we cant lock
+			if( pthread_mutex_trylock( r->rgate ) != 0 ) {	// quick fail if not able to get a lock
+				return NULL;
+			}
+		} else {
+			if( pthread_mutex_lock( r->rgate ) != 0 ) {
+				return NULL;
+			}
+		}
+		if( r->tail == r->head ) {					// ensure ring didn't go empty while waiting
+			pthread_mutex_unlock( r->rgate );
+			return NULL;
+		}
+	}
+
 	ti = r->tail;
 	r->tail++;
 	if( r->tail >= r->nelements ) {
@@ -138,12 +220,24 @@ future -- investigate if it's possible only to set/clear when empty or going to
 	if( r->tail == r->head ) {								// if this emptied the ring, turn off ready
 	}
 */
-	return r->data[ti];
+
+	data = r->data[ti];						// secure data and clear before letting go of the lock
+	r->data[ti] = NULL;
+
+	if( r->rgate != NULL ) {							// if locked above...
+		pthread_mutex_unlock( r->rgate );
+	}
+
+	return data;
 }
 
+
 /*
 	Insert the pointer at the next open space in the ring.
-	Returns 1 if the inert was ok, and 0 if the ring is full.
+	Returns 1 if the inert was ok, and 0 if there is an error;
+	errno will be set to EXFULL if  the ring is full, if the attempt
+	fails with anyt other error that indicates the inability to obtain
+	a lock on the ring.
 */
 static inline int uta_ring_insert( void* vr, void* new_data ) {
 	ring_t*		r;
@@ -157,10 +251,26 @@ static inline int uta_ring_insert( void* vr, void* new_data ) {
 		r = (ring_t*) vr;
 	}
 
+	if( r->wgate != NULL ) {						// if lock exists we must honour it
+		if( pthread_mutex_lock( r->wgate ) != 0 ) {
+			return 0;								// leave mutex reason in place
+		}
+	}
+
 	if( r->head+1 == r->tail || (r->head+1 >= r->nelements && !r->tail) ) {		// ring is full
+		if( r->wgate != NULL ) {												// ensure released if needed
+			pthread_mutex_unlock( r->wgate );
+		}
+		errno = EXFULL;
 		return 0;
 	}
 
+	r->data[r->head] = new_data;
+	r->head++;
+	if( r->head >= r->nelements ) {
+		r->head = 0;
+	}
+
 	write( r->pfd, &inc, sizeof( inc ) );
 /*
 future -- investigate if it's possible only to set/clear when empty or going to empty
@@ -168,12 +278,9 @@ future -- investigate if it's possible only to set/clear when empty or going to
 	}
 */
 
-	r->data[r->head] = new_data;
-	r->head++;
-	if( r->head >= r->nelements ) {
-		r->head = 0;
+	if( r->wgate != NULL ) {						// if lock exists we must unlock before going
+		pthread_mutex_unlock( r->wgate );
 	}
-
 	return 1;
 }