1 files changed, 107 insertions, 0 deletions
diff --git a/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.c b/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.c
new file mode 100644
index 00000000..fbd71b6e
--- /dev/null
+++ b/libparc/examples/How To Create an Object Pool/parc_SimpleBufferPool.c
@@ -0,0 +1,107 @@
+/*
+ * 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.
+ */
+
+#include <stdio.h>
+
+#include <parc/algol/parc_Object.h>
+#include <parc/algol/parc_DisplayIndented.h>
+#include <parc/algol/parc_Memory.h>
+
+#include <parc/algol/parc_LinkedList.h>
+
+#include "parc_SimpleBufferPool.h"
+
+struct PARCSimpleBufferPool {
+    size_t bufferSize;
+    size_t limit;
+    PARCLinkedList *freeList;
+    PARCObjectDescriptor *descriptor;
+};
+
+static bool
+_parcSimpleBufferPool_Destructor(PARCSimpleBufferPool **instancePtr)
+{
+    assertNotNull(instancePtr, "Parameter must be a non-null pointer to a PARCSimpleBufferPool pointer.");
+
+    PARCSimpleBufferPool *pool = *instancePtr;
+
+    parcLinkedList_Apply(pool->freeList, (void (*))parcObject_SetDescriptor, (const void *) &PARCBuffer_Descriptor);
+
+    parcLinkedList_Release(&pool->freeList);
+
+    return true;
+}
+
+static bool
+_parcSimpleBufferPool_BufferDestructor(PARCBuffer **bufferPtr)
+{
+    PARCBuffer *buffer = *bufferPtr;
+    *bufferPtr = 0;
+
+    PARCSimpleBufferPool *bufferPool = parcObjectDescriptor_GetTypeState(parcObject_GetDescriptor(buffer));
+
+    if (bufferPool->limit > parcLinkedList_Size(bufferPool->freeList)) {
+        parcLinkedList_Append(bufferPool->freeList, buffer);
+    } else {
+        parcBuffer_Acquire(buffer);
+        parcObject_SetDescriptor(buffer, &parcObject_DescriptorName(PARCBuffer));
+        parcBuffer_Release(&buffer);
+    }
+
+    return false;
+}
+
+parcObject_ImplementAcquire(parcSimpleBufferPool, PARCSimpleBufferPool);
+
+parcObject_ImplementRelease(parcSimpleBufferPool, PARCSimpleBufferPool);
+
+parcObject_Override(PARCSimpleBufferPool, PARCObject,
+                    .destructor = (PARCObjectDestructor *) _parcSimpleBufferPool_Destructor);
+
+PARCSimpleBufferPool *
+parcSimpleBufferPool_Create(size_t limit, size_t bufferSize)
+{
+    PARCSimpleBufferPool *result = parcObject_CreateInstance(PARCSimpleBufferPool);
+
+    if (result != NULL) {
+        result->limit = limit;
+        result->bufferSize = bufferSize;
+        result->freeList = parcLinkedList_Create();
+
+        char *string;
+        asprintf(&string, "PARCSimpleBufferPool=%zu", bufferSize);
+        result->descriptor = parcObjectDescriptor_CreateExtension(&parcObject_DescriptorName(PARCBuffer), string);
+        free(string);
+        result->descriptor->destructor = (PARCObjectDestructor *) _parcSimpleBufferPool_BufferDestructor;
+        result->descriptor->typeState = (PARCObjectTypeState *) result;
+    }
+
+    return result;
+}
+
+PARCBuffer *
+parcSimpleBufferPool_GetInstance(PARCSimpleBufferPool *bufferPool)
+{
+    PARCBuffer *result;
+
+    if (parcLinkedList_Size(bufferPool->freeList) > 0) {
+        result = parcLinkedList_RemoveFirst(bufferPool->freeList);
+    } else {
+        result = parcBuffer_Allocate(bufferPool->bufferSize);
+        parcObject_SetDescriptor(result, bufferPool->descriptor);
+    }
+
+    return result;
+}