queue.h

/*
 *  Aerospike Foundation
 *  include/queue.h - queue primitives
 *
 * Copyright (c) 2008-2012 Aerospike, Inc. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#pragma once
#include <stdint.h>
#include <stdbool.h>

/* SYNOPSIS
 * Queue
 */


/* cf_queue
 * A queue */
#define CF_QUEUE_ALLOCSZ (64 * 1024)
typedef struct cf_queue_s {
	bool threadsafe;  // sometimes it's good to live dangerously
	unsigned int allocsz;      // number of queue elements currently allocated
	unsigned int write_offset; // 0 offset is first queue element.
						   		// write is always greater than or equal to read
	unsigned int read_offset; // 
	size_t elementsz;     // number of bytes in an element
	pthread_mutex_t LOCK;  // the mutex lock
	pthread_cond_t CV;    // hte condvar
	uint8_t *queue;         // the actual bytes that make up the queue
} cf_queue;

#define CF_Q_SZ(__q) (__q->write_offset - __q->read_offset)

#define CF_Q_EMPTY(__q) (__q->write_offset == __q->read_offset)

// todo: maybe it's faster to keep the read and write offsets in bytes,
// to avoid the extra multiply?
#define CF_Q_ELEM_PTR(__q, __i) (&q->queue[ (__i % __q->allocsz) * q->elementsz ] )


/* External functions */
extern cf_queue *cf_queue_create(size_t elementsz, bool threadsafe);

extern void cf_queue_destroy(cf_queue *q);

// Always pushes to the end of the queue
extern int cf_queue_push(cf_queue *q, void *ptr);

// Pushes to the head of the queue
extern int cf_queue_push_head(cf_queue *q, void *ptr);

// Get the number of elements currently in the queue
extern int cf_queue_sz(cf_queue *q);




// POP pops from the end of the queue, which is the most efficient
// But understand this makes it LIFO, the least fair of queues
// Elements added at the very beginning might not make it out

#define CF_QUEUE_EMPTY -2
#define CF_QUEUE_ERR -1
#define CF_QUEUE_OK 0

// uswait < 0 wait forever
// uswait == 0 wait not at all
// uswait > 0 wait that number of us
#define CF_QUEUE_FOREVER -1
#define CF_QUEUE_NOWAIT 0
extern int cf_queue_pop(cf_queue *q, void *buf, int uswait);

// Queue Reduce
// Run the entire queue, calling the callback, with the lock held
// You can return values in the callback to cause deletes
// Great for purging dying stuff out of a queue synchronously
//
// Return -2 from the callback to trigger a delete
// return -1 stop iterating the queue
// return 0 for success
typedef int (*cf_queue_reduce_fn) (void *buf, void *udata);

extern int cf_queue_reduce(cf_queue *q, cf_queue_reduce_fn cb, void *udata);

//
// The most common reason to want to 'reduce' is delete - so provide
// a simple delete function
extern int cf_queue_delete(cf_queue *q, void *buf, bool only_one);


//
// A simple priority queue implementation, which is simply a set of queues
// underneath
// This currently doesn't support 'delete' and 'reduce' functionality
//

typedef struct cf_queue_priority_s {
	bool threadsafe;
	cf_queue	*low_q;
	cf_queue	*medium_q;
	cf_queue	*high_q;
	
	pthread_mutex_t		LOCK;
	pthread_cond_t	 	CV;
} cf_queue_priority;

#define CF_QUEUE_PRIORITY_HIGH 1
#define CF_QUEUE_PRIORITY_MEDIUM 2
#define CF_QUEUE_PRIORITY_LOW 3

#define CF_Q_PRI_EMPTY(__q) (CF_Q_EMPTY(__q->low_q) && CF_Q_EMPTY(__q->medium_q) && CF_Q_EMPTY(__q->high_q))

extern cf_queue_priority *cf_queue_priority_create(size_t elementsz, bool threadsafe);
extern void cf_queue_priority_destroy(cf_queue_priority *q);
extern int cf_queue_priority_push(cf_queue_priority *q, void *ptr, int pri);
extern int cf_queue_priority_pop(cf_queue_priority *q, void *buf, int uswait);
extern int cf_queue_priority_sz(cf_queue_priority *q);



//
// Call this function to do a set of internal validation unit tests
// 0 means success, and it blocks until complete

extern int cf_queue_test();