selfcare init

proxy_c/utils_queue.c

@@ -0,0 +1,138 @@
+/*
+ *          File: queue.c
+ *        Author: Robert I. Pitts <rip@cs.bu.edu>
+ * Last Modified: March 9, 2000
+ *         Topic: Queue - Array Implementation
+ * ----------------------------------------------------------------
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include<pthread.h>
+
+#include "utils_queue.h"
+
+
+/*
+ * struct queueCDT gives the implementation of a queue.
+ * It holds the information that we need for each queue.
+ */
+typedef struct queueCDT {
+	queueElementT *contents;
+	int front;
+	int count;
+
+	int	elem_size;
+	pthread_rwlock_t queueRWLock;
+}queueCDT;
+
+queueADT QueueCreate(const int elem_size)
+{
+	queueADT queue;
+
+	queue = (queueADT)malloc(sizeof(queueCDT));
+
+	if(queue == NULL) {
+		fprintf(stderr, "Insufficient Memory for new Queue.\n");
+		return NULL;  /* Exit program, returning error code. */
+	}
+
+	queue->contents = (queueElementT*)malloc(elem_size * sizeof(queueElementT));
+
+	if(queue == NULL) {
+		fprintf(stderr, "Insufficient Memory for QueueElems.\n");
+		return NULL;  /* Exit program, returning error code. */
+	}
+
+	queue->front = 0;
+	queue->count = 0;
+
+	queue->elem_size = elem_size;
+	pthread_rwlock_init(&(queue->queueRWLock), NULL);
+
+	return queue;
+}
+
+void QueueDestroy(queueADT queue)
+{
+	free(queue->contents);
+	free(queue);
+}
+
+int QueueEnter(queueADT queue, queueElementT element)
+{
+	int newElementIndex;
+
+	pthread_rwlock_wrlock(&queue->queueRWLock);
+
+	if (queue->count >= queue->elem_size) {
+		fprintf(stderr, "QueueEnter on Full Queue.\n");
+		pthread_rwlock_unlock(&queue->queueRWLock);	
+		return ERROR_QUEUE;  /* Exit program, returning error code. */
+	}
+
+	/*
+	* Calculate index at which to put
+	* next element.
+	*/
+	newElementIndex = (queue->front + queue->count) % queue->elem_size;
+	queue->contents[newElementIndex] = element;
+
+	queue->count++;
+
+	pthread_rwlock_unlock(&queue->queueRWLock);
+	return SUCCESS_QUEUE;
+}
+
+queueElementT QueueDelete(queueADT queue)
+{
+	queueElementT oldElement;
+
+	pthread_rwlock_wrlock(&queue->queueRWLock);
+	if (queue->count <= 0) {
+		fprintf(stderr, "QueueDelete on Empty Queue.\n");
+		pthread_rwlock_unlock(&queue->queueRWLock);
+		return NULL;  /* Exit program, returning error code. */
+	}
+
+	/* Save the element so we can return it. */
+	oldElement = queue->contents[queue->front];
+
+	/*
+	* Advance the index of the front,
+	* making sure it wraps around the
+	* array properly.
+	*/
+	queue->front++;
+	queue->front %= queue->elem_size;
+
+	queue->count--;
+	pthread_rwlock_unlock(&queue->queueRWLock);
+	return oldElement;
+}
+
+int QueueIsEmpty(queueADT queue)
+{
+	int rc;
+
+	pthread_rwlock_rdlock(&queue->queueRWLock);
+
+	rc = queue->count <= 0;
+
+	pthread_rwlock_unlock(&queue->queueRWLock);
+	return rc;
+}
+
+int QueueIsFull(queueADT queue)
+{
+	int rc;
+
+	pthread_rwlock_rdlock(&queue->queueRWLock);
+
+	rc = queue->count >= queue->elem_size;
+
+	pthread_rwlock_unlock(&queue->queueRWLock);
+	
+	return rc;
+}
+