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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* A thread-safe fixed size ring buffer.
*
* The multiple producer, multiple consumer version uses a pthread mutex around a NxM ring buffer.
*
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <errno.h>
#include <string.h>
#include <parc/algol/parc_Memory.h>
#include <parc/algol/parc_Object.h>
#include <LongBow/runtime.h>
#include <parc/concurrent/parc_RingBuffer_1x1.h>
#include <parc/concurrent/parc_RingBuffer_NxM.h>
struct parc_ringbuffer_NxM {
PARCRingBuffer1x1 *onebyone;
// This protectes the overall data structure for Acquire and Release
pthread_mutex_t allocation_mutex;
pthread_mutex_t writer_mutex;
pthread_mutex_t reader_mutex;
RingBufferEntryDestroyer *destroyer;
};
/*
* Attemps a lock and returns false if we cannot get it.
*
* @endcode
*/
static bool
_lock(pthread_mutex_t *mutex)
{
int failure = pthread_mutex_lock(mutex);
assertFalse(failure, "Error locking mutex: (%d) %s\n", errno, strerror(errno));
return true;
}
static bool
_unlock(pthread_mutex_t *mutex)
{
int failure = pthread_mutex_unlock(mutex);
assertFalse(failure, "Error unlocking mutex: (%d) %s\n", errno, strerror(errno));
return true;
}
static void
_destroy(PARCRingBufferNxM **ringptr)
{
PARCRingBufferNxM *ring = *ringptr;
if (ring->destroyer) {
void *ptr = NULL;
while (parcRingBufferNxM_Get(ring, &ptr)) {
ring->destroyer(&ptr);
}
}
parcRingBuffer1x1_Release(&ring->onebyone);
}
parcObject_ExtendPARCObject(PARCRingBufferNxM, _destroy, NULL, NULL, NULL, NULL, NULL, NULL);
static PARCRingBufferNxM *
_create(uint32_t elements, RingBufferEntryDestroyer *destroyer)
{
PARCRingBufferNxM *ring = parcObject_CreateInstance(PARCRingBufferNxM);
assertNotNull(ring, "parcObject_Create returned NULL");
ring->onebyone = parcRingBuffer1x1_Create(elements, destroyer);
ring->destroyer = destroyer;
pthread_mutex_init(&ring->allocation_mutex, NULL);
pthread_mutex_init(&ring->writer_mutex, NULL);
pthread_mutex_init(&ring->reader_mutex, NULL);
return ring;
}
PARCRingBufferNxM *
parcRingBufferNxM_Create(uint32_t elements, RingBufferEntryDestroyer *destroyer)
{
return _create(elements, destroyer);
}
PARCRingBufferNxM *
parcRingBufferNxM_Acquire(PARCRingBufferNxM *ring)
{
PARCRingBufferNxM *acquired;
_lock(&ring->allocation_mutex);
acquired = parcObject_Acquire(ring);
_unlock(&ring->allocation_mutex);
return acquired;
}
void
parcRingBufferNxM_Release(PARCRingBufferNxM **ringPtr)
{
PARCRingBufferNxM *ring = *ringPtr;
_lock(&ring->allocation_mutex);
parcObject_Release((void **) ringPtr);
_unlock(&ring->allocation_mutex);
}
/**
* Put is protected by the writer mutex. This means that the tail mutex could
* actually increase while this is happening. That's ok. Increasing the tail
* just means there is _more_ room in the ring. We only modify writer_head.
*/
bool
parcRingBufferNxM_Put(PARCRingBufferNxM *ring, void *data)
{
// **** LOCK
_lock(&ring->writer_mutex);
bool success = parcRingBuffer1x1_Put(ring->onebyone, data);
// **** UNLOCK
_unlock(&ring->writer_mutex);
return success;
}
bool
parcRingBufferNxM_Get(PARCRingBufferNxM *ring, void **outputDataPtr)
{
// **** LOCK
_lock(&ring->reader_mutex);
bool success = parcRingBuffer1x1_Get(ring->onebyone, outputDataPtr);
// **** UNLOCK
_unlock(&ring->reader_mutex);
return success;
}
uint32_t
parcRingBufferNxM_Remaining(PARCRingBufferNxM *ring)
{
_lock(&ring->writer_mutex);
_lock(&ring->reader_mutex);
uint32_t remaining = parcRingBuffer1x1_Remaining(ring->onebyone);
_unlock(&ring->reader_mutex);
_unlock(&ring->writer_mutex);
return remaining;
}
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