ioqueue.h

一个开源的sip源代码

/* $Id: ioqueue.h 974 2007-02-19 01:13:53Z bennylp $
 */
/* 
 * Copyright (C)2003-2007 Benny Prijono <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#ifndef __PJ_IOQUEUE_H__
#define __PJ_IOQUEUE_H__

/**
 * @file ioqueue.h
 * @brief I/O Dispatching Mechanism
 */

#include <pj/types.h>

PJ_BEGIN_DECL

/**
 * @defgroup PJ_IO Input/Output
 * @brief Input/Output
 * @ingroup PJ_OS
 *
 * This section contains API building blocks to perform network I/O and 
 * communications. If provides:
 *  - @ref PJ_SOCK
 *\n
 *    A highly portable socket abstraction, runs on all kind of
 *    network APIs such as standard BSD socket, Windows socket, Linux
 *    \b kernel socket, PalmOS networking API, etc.
 *
 *  - @ref pj_addr_resolve
 *\n
 *    Portable address resolution, which implements #pj_gethostbyname().
 *
 *  - @ref PJ_SOCK_SELECT
 *\n
 *    A portable \a select() like API (#pj_sock_select()) which can be
 *    implemented with various back-ends.
 *
 *  - @ref PJ_IOQUEUE
 *\n
 *    Framework for dispatching network events.
 *
 * For more information see the modules below.
 */

/**
 * @defgroup PJ_IOQUEUE IOQueue: I/O Event Dispatching with Proactor Pattern
 * @ingroup PJ_IO
 * @{
 *
 * I/O Queue provides API for performing asynchronous I/O operations. It
 * conforms to proactor pattern, which allows application to submit an
 * asynchronous operation and to be notified later when the operation has
 * completed.
 *
 * The I/O Queue can work on both socket and file descriptors. For 
 * asynchronous file operations however, one must make sure that the correct
 * file I/O back-end is used, because not all file I/O back-end can be
 * used with the ioqueue. Please see \ref PJ_FILE_IO for more details.
 *
 * The framework works natively in platforms where asynchronous operation API
 * exists, such as in Windows NT with IoCompletionPort/IOCP. In other 
 * platforms, the I/O queue abstracts the operating system's event poll API
 * to provide semantics similar to IoCompletionPort with minimal penalties
 * (i.e. per ioqueue and per handle mutex protection).
 *
 * The I/O queue provides more than just unified abstraction. It also:
 *  - makes sure that the operation uses the most effective way to utilize
 *    the underlying mechanism, to achieve the maximum theoritical
 *    throughput possible on a given platform.
 *  - choose the most efficient mechanism for event polling on a given
 *    platform.
 *
 * Currently, the I/O Queue is implemented using:
 *  - <tt><b>select()</b></tt>, as the common denominator, but the least 
 *    efficient. Also the number of descriptor is limited to 
 *    \c PJ_IOQUEUE_MAX_HANDLES (which by default is 64).
 *  - <tt><b>/dev/epoll</b></tt> on Linux (user mode and kernel mode), 
 *    a much faster replacement for select() on Linux (and more importantly
 *    doesn't have limitation on number of descriptors).
 *  - <b>I/O Completion ports</b> on Windows NT/2000/XP, which is the most 
 *    efficient way to dispatch events in Windows NT based OSes, and most 
 *    importantly, it doesn't have the limit on how many handles to monitor.
 *    And it works with files (not only sockets) as well.
 *
 *
 * \section pj_ioqueue_concurrency_sec Concurrency Rules
 *
 * The items below describe rules that must be obeyed when using the I/O 
 * queue, with regard to concurrency:
 *  - simultaneous operations (by different threads) to different key is safe.
 *  - simultaneous operations to the same key is also safe, except
 *    <b>unregistration</b>, which is described below.
 *  - <b>care must be taken when unregistering a key</b> from the
 *    ioqueue. Application must take care that when one thread is issuing
 *    an unregistration, other thread is not simultaneously invoking an
 *    operation <b>to the same key</b>.
 *\n
 *    This happens because the ioqueue functions are working with a pointer
 *    to the key, and there is a possible race condition where the pointer
 *    has been rendered invalid by other threads before the ioqueue has a
 *    chance to acquire mutex on it.
 *
 * \section pj_ioqeuue_examples_sec Examples
 *
 * For some examples on how to use the I/O Queue, please see:
 *
 *  - \ref page_pjlib_ioqueue_tcp_test
 *  - \ref page_pjlib_ioqueue_udp_test
 *  - \ref page_pjlib_ioqueue_perf_test
 */


/**
 * This structure describes operation specific key to be submitted to
 * I/O Queue when performing the asynchronous operation. This key will
 * be returned to the application when completion callback is called.
 *
 * Application normally wants to attach it's specific data in the
 * \c user_data field so that it can keep track of which operation has
 * completed when the callback is called. Alternatively, application can
 * also extend this struct to include its data, because the pointer that
 * is returned in the completion callback will be exactly the same as
 * the pointer supplied when the asynchronous function is called.
 */
typedef struct pj_ioqueue_op_key_t
{ 
    void *internal__[32];           /**< Internal I/O Queue data.   */
    void *user_data;                /**< Application data.          */
} pj_ioqueue_op_key_t;

/**
 * This structure describes the callbacks to be called when I/O operation
 * completes.
 */
typedef struct pj_ioqueue_callback
{
    /**
     * This callback is called when #pj_ioqueue_recv or #pj_ioqueue_recvfrom
     * completes.
     *
     * @param key	    The key.
     * @param op_key        Operation key.
     * @param bytes_read    >= 0 to indicate the amount of data read, 
     *                      otherwise negative value containing the error
     *                      code. To obtain the pj_status_t error code, use
     *                      (pj_status_t code = -bytes_read).
     */
    void (*on_read_complete)(pj_ioqueue_key_t *key, 
                             pj_ioqueue_op_key_t *op_key, 
                             pj_ssize_t bytes_read);

    /**
     * This callback is called when #pj_ioqueue_write or #pj_ioqueue_sendto
     * completes.
     *
     * @param key	    The key.
     * @param op_key        Operation key.
     * @param bytes_sent    >= 0 to indicate the amount of data written, 
     *                      otherwise negative value containing the error
     *                      code. To obtain the pj_status_t error code, use
     *                      (pj_status_t code = -bytes_sent).
     */
    void (*on_write_complete)(pj_ioqueue_key_t *key, 
                              pj_ioqueue_op_key_t *op_key, 
                              pj_ssize_t bytes_sent);

    /**
     * This callback is called when #pj_ioqueue_accept completes.
     *
     * @param key	    The key.
     * @param op_key        Operation key.
     * @param sock          Newly connected socket.
     * @param status	    Zero if the operation completes successfully.
     */
    void (*on_accept_complete)(pj_ioqueue_key_t *key, 
                               pj_ioqueue_op_key_t *op_key, 
                               pj_sock_t sock, 
                               pj_status_t status);

    /**
     * This callback is called when #pj_ioqueue_connect completes.
     *
     * @param key	    The key.
     * @param status	    PJ_SUCCESS if the operation completes successfully.
     */
    void (*on_connect_complete)(pj_ioqueue_key_t *key, 
                                pj_status_t status);
} pj_ioqueue_callback;


/**
 * Types of pending I/O Queue operation. This enumeration is only used
 * internally within the ioqueue.
 */
typedef enum pj_ioqueue_operation_e
{
    PJ_IOQUEUE_OP_NONE		= 0,	/**< No operation.          */
    PJ_IOQUEUE_OP_READ		= 1,	/**< read() operation.      */
    PJ_IOQUEUE_OP_RECV          = 2,    /**< recv() operation.      */
    PJ_IOQUEUE_OP_RECV_FROM	= 4,	/**< recvfrom() operation.  */
    PJ_IOQUEUE_OP_WRITE		= 8,	/**< write() operation.     */
    PJ_IOQUEUE_OP_SEND          = 16,   /**< send() operation.      */
    PJ_IOQUEUE_OP_SEND_TO	= 32,	/**< sendto() operation.    */
#if defined(PJ_HAS_TCP) && PJ_HAS_TCP != 0
    PJ_IOQUEUE_OP_ACCEPT	= 64,	/**< accept() operation.    */
    PJ_IOQUEUE_OP_CONNECT	= 128	/**< connect() operation.   */
#endif	/* PJ_HAS_TCP */
} pj_ioqueue_operation_e;


/**
 * This macro specifies the maximum number of events that can be
 * processed by the ioqueue on a single poll cycle, on implementation
 * that supports it. The value is only meaningfull when specified
 * during PJLIB build.
 */
#ifndef PJ_IOQUEUE_MAX_EVENTS_IN_SINGLE_POLL
#   define PJ_IOQUEUE_MAX_EVENTS_IN_SINGLE_POLL     (16)
#endif

/**
 * When this flag is specified in ioqueue's recv() or send() operations,
 * the ioqueue will always mark the operation as asynchronous.
 */
#define PJ_IOQUEUE_ALWAYS_ASYNC	    ((pj_uint32_t)1 << (pj_uint32_t)31)

/**
 * Return the name of the ioqueue implementation.
 *
 * @return		Implementation name.
 */
PJ_DECL(const char*) pj_ioqueue_name(void);


/**
 * Create a new I/O Queue framework.
 *
 * @param pool		The pool to allocate the I/O queue structure. 
 * @param max_fd	The maximum number of handles to be supported, which 
 *			should not exceed PJ_IOQUEUE_MAX_HANDLES.
 * @param ioqueue	Pointer to hold the newly created I/O Queue.
 *
 * @return		PJ_SUCCESS on success.
 */
PJ_DECL(pj_status_t) pj_ioqueue_create( pj_pool_t *pool, 
					pj_size_t max_fd,
					pj_ioqueue_t **ioqueue);

/**
 * Destroy the I/O queue.
 *
 * @param ioque	        The I/O Queue to be destroyed.
 *
 * @return              PJ_SUCCESS if success.
 */
PJ_DECL(pj_status_t) pj_ioqueue_destroy( pj_ioqueue_t *ioque );

/**
 * Set the lock object to be used by the I/O Queue. This function can only
 * be called right after the I/O queue is created, before any handle is
 * registered to the I/O queue.
 *
 * Initially the I/O queue is created with non-recursive mutex protection. 
 * Applications can supply alternative lock to be used by calling this 
 * function.
 *
 * @param ioque         The ioqueue instance.
 * @param lock          The lock to be used by the ioqueue.
 * @param auto_delete   In non-zero, the lock will be deleted by the ioqueue.
 *
 * @return              PJ_SUCCESS or the appropriate error code.
 */
PJ_DECL(pj_status_t) pj_ioqueue_set_lock( pj_ioqueue_t *ioque, 
					  pj_lock_t *lock,
					  pj_bool_t auto_delete );

/**
 * Register a socket to the I/O queue framework. 
 * When a socket is registered to the IOQueue, it may be modified to use
 * non-blocking IO. If it is modified, there is no guarantee that this 
 * modification will be restored after the socket is unregistered.
 *
 * @param pool	    To allocate the resource for the specified handle, 
 *		    which must be valid until the handle/key is unregistered 
 *		    from I/O Queue.
 * @param ioque	    The I/O Queue.
 * @param sock	    The socket.
 * @param user_data User data to be associated with the key, which can be
 *		    retrieved later.
 * @param cb	    Callback to be called when I/O operation completes. 
 * @param key       Pointer to receive the key to be associated with this
 *                  socket. Subsequent I/O queue operation will need this
 *                  key.
 *
 * @return	    PJ_SUCCESS on success, or the error code.
 */
PJ_DECL(pj_status_t) pj_ioqueue_register_sock( pj_pool_t *pool,
					       pj_ioqueue_t *ioque,
					       pj_sock_t sock,
					       void *user_data,
					       const pj_ioqueue_callback *cb,
                                               pj_ioqueue_key_t **key );

/**
 * Unregister from the I/O Queue framework. Caller must make sure that
 * the key doesn't have any pending operations before calling this function,
 * by calling #pj_ioqueue_is_pending() for all previously submitted
 * operations except asynchronous connect, and if necessary call
 * #pj_ioqueue_post_completion() to cancel the pending operations.
 *
 * Note that asynchronous connect operation will automatically be 
 * cancelled during the unregistration.
 *
 * Also note that when I/O Completion Port backend is used, application
 * MUST close the handle immediately after unregistering the key. This is
 * because there is no unregistering API for IOCP. The only way to
 * unregister the handle from IOCP is to close the handle.
 *
 * @param key	    The key that was previously obtained from registration.
 *