From ec688b4723a041044226358bcd4dd6e2da39da49 Mon Sep 17 00:00:00 2001
From: Luca Muscariello <lumuscar+fdio@cisco.com>
Date: Thu, 23 Feb 2017 17:01:02 +0100
Subject: Initial commit: cframework. Longbow and Libparc

Change-Id: I90378dbd30da6033b20fb1f829b3b822cf366c59
Signed-off-by: Luca Muscariello <lumuscar+fdio@cisco.com>
---
 libparc/parc/concurrent/parc_RingBuffer_NxM.c | 167 ++++++++++++++++++++++++++
 1 file changed, 167 insertions(+)
 create mode 100755 libparc/parc/concurrent/parc_RingBuffer_NxM.c

(limited to 'libparc/parc/concurrent/parc_RingBuffer_NxM.c')

diff --git a/libparc/parc/concurrent/parc_RingBuffer_NxM.c b/libparc/parc/concurrent/parc_RingBuffer_NxM.c
new file mode 100755
index 00000000..15ec849b
--- /dev/null
+++ b/libparc/parc/concurrent/parc_RingBuffer_NxM.c
@@ -0,0 +1,167 @@
+/*
+ * 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;
+}
-- 
cgit 1.2.3-korg