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diff --git a/pjlib/include/pj/ioqueue.h b/pjlib/include/pj/ioqueue.h
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+/* $Id: ioqueue.h 3553 2011-05-05 06:14:19Z nanang $
+ */
+/* 
+ * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
+ * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
+ *
+ * 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 ioqueue has been fine tuned to allow multiple threads to poll the
+ * handles simultaneously, to maximize scalability when the application is
+ * running on multiprocessor systems. When more than one threads are polling
+ * the ioqueue and there are more than one handles are signaled, more than
+ * one threads will execute the callback simultaneously to serve the events.
+ * These parallel executions are completely safe when the events happen for
+ * two different handles.
+ *
+ * However, with multithreading, care must be taken when multiple events 
+ * happen on the same handle, or when event is happening on a handle (and 
+ * the callback is being executed) and application is performing 
+ * unregistration to the handle at the same time.
+ *
+ * The treatments of above scenario differ according to the concurrency
+ * setting that are applied to the handle.
+ *
+ * \subsection pj_ioq_concur_set Concurrency Settings for Handles
+ *
+ * Concurrency can be set on per handle (key) basis, by using
+ * #pj_ioqueue_set_concurrency() function. The default key concurrency value 
+ * for the handle is inherited from the key concurrency setting of the ioqueue, 
+ * and the key concurrency setting for the ioqueue can be changed by using
+ * #pj_ioqueue_set_default_concurrency(). The default key concurrency setting 
+ * for ioqueue itself is controlled by compile time setting
+ * PJ_IOQUEUE_DEFAULT_ALLOW_CONCURRENCY.
+ *
+ * Note that this key concurrency setting only controls whether multiple
+ * threads are allowed to operate <b>on the same key</b> at the same time. 
+ * The ioqueue itself always allows multiple threads to enter the ioqeuue at 
+ * the same time, and also simultaneous callback calls to <b>differrent 
+ * keys</b> is always allowed regardless to the key concurrency setting.
+ *
+ * \subsection pj_ioq_parallel Parallel Callback Executions for the Same Handle
+ *
+ * Note that when key concurrency is enabled (i.e. parallel callback calls on
+ * the same key is allowed; this is the default setting), the ioqueue will only
+ * perform simultaneous callback executions on the same key when the key has
+ * invoked multiple pending operations. This could be done for example by
+ * calling #pj_ioqueue_recvfrom() more than once on the same key, each with
+ * the same key but different operation key (pj_ioqueue_op_key_t). With this
+ * scenario, when multiple packets arrive on the key at the same time, more
+ * than one threads may execute the callback simultaneously, each with the
+ * same key but different operation key.
+ *
+ * When there is only one pending operation on the key (e.g. there is only one
+ * #pj_ioqueue_recvfrom() invoked on the key), then events occuring to the
+ * same key will be queued by the ioqueue, thus no simultaneous callback calls
+ * will be performed.
+ *
+ * \subsection pj_ioq_allow_concur Concurrency is Enabled (Default Value)
+ *
+ * The default setting for the ioqueue is to allow multiple threads to
+ * execute callbacks for the same handle/key. This setting is selected to
+ * promote good performance and scalability for application.
+ *
+ * However this setting has a major drawback with regard to synchronization,
+ * and application MUST carefully follow the following guidelines to ensure 
+ * that parallel access to the key does not cause problems:
+ *
+ *  - Always note that callback may be called simultaneously for the same
+ *    key.
+ *  - <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 the
+ *    callback <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.
+ *
+ * \subsection pj_ioq_disallow_concur Concurrency is Disabled
+ *
+ * Alternatively, application may disable key concurrency to make 
+ * synchronization easier. As noted above, there are three ways to control
+ * key concurrency setting:
+ *  - by controlling on per handle/key basis, with #pj_ioqueue_set_concurrency().
+ *  - by changing default key concurrency setting on the ioqueue, with
+ *    #pj_ioqueue_set_default_concurrency().
+ *  - by changing the default concurrency on compile time, by declaring
+ *    PJ_IOQUEUE_DEFAULT_ALLOW_CONCURRENCY macro to zero in your config_site.h
+ *
+ * \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 *activesock_data;	    /**< Active socket 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_send 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 );
+
+/**
+ * Set default concurrency policy for this ioqueue. If this function is not
+ * called, the default concurrency policy for the ioqueue is controlled by 
+ * compile time setting PJ_IOQUEUE_DEFAULT_ALLOW_CONCURRENCY.
+ *
+ * Note that changing the concurrency setting to the ioqueue will only affect
+ * subsequent key registrations. To modify the concurrency setting for
+ * individual key, use #pj_ioqueue_set_concurrency().
+ *
+ * @param ioqueue	The ioqueue instance.
+ * @param allow		Non-zero to allow concurrent callback calls, or
+ *			PJ_FALSE to disallow it.
+ *
+ * @return		PJ_SUCCESS on success or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_set_default_concurrency(pj_ioqueue_t *ioqueue,
+							pj_bool_t allow);
+
+/**
+ * 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.
+ *
+ * @return          PJ_SUCCESS on success or the error code.
+ *
+ * @see pj_ioqueue_is_pending
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_unregister( pj_ioqueue_key_t *key );
+
+
+/**
+ * Get user data associated with an ioqueue key.
+ *
+ * @param key	    The key that was previously obtained from registration.
+ *
+ * @return          The user data associated with the descriptor, or NULL 
+ *                  on error or if no data is associated with the key during
+ *                  registration.
+ */
+PJ_DECL(void*) pj_ioqueue_get_user_data( pj_ioqueue_key_t *key );
+
+/**
+ * Set or change the user data to be associated with the file descriptor or
+ * handle or socket descriptor.
+ *
+ * @param key	    The key that was previously obtained from registration.
+ * @param user_data User data to be associated with the descriptor.
+ * @param old_data  Optional parameter to retrieve the old user data.
+ *
+ * @return          PJ_SUCCESS on success or the error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_set_user_data( pj_ioqueue_key_t *key,
+                                               void *user_data,
+                                               void **old_data);
+
+/**
+ * Configure whether the ioqueue is allowed to call the key's callback
+ * concurrently/in parallel. The default concurrency setting for the key
+ * is controlled by ioqueue's default concurrency value, which can be
+ * changed by calling #pj_ioqueue_set_default_concurrency().
+ *
+ * If concurrency is allowed for the key, it means that if there are more
+ * than one pending operations complete simultaneously, more than one
+ * threads may call the key's  callback at the same time. This generally
+ * would promote good scalability for application, at the expense of more
+ * complexity to manage the concurrent accesses in application's code.
+ *
+ * Alternatively application may disable the concurrent access by
+ * setting the \a allow flag to false. With concurrency disabled, only
+ * one thread can call the key's callback at one time.
+ *
+ * @param key	    The key that was previously obtained from registration.
+ * @param allow	    Set this to non-zero to allow concurrent callback calls
+ *		    and zero (PJ_FALSE) to disallow it.
+ *
+ * @return	    PJ_SUCCESS on success or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_set_concurrency(pj_ioqueue_key_t *key,
+						pj_bool_t allow);
+
+/**
+ * Acquire the key's mutex. When the key's concurrency is disabled, 
+ * application may call this function to synchronize its operation
+ * with the key's callback (i.e. this function will block until the
+ * key's callback returns).
+ *
+ * @param key	    The key that was previously obtained from registration.
+ *
+ * @return	    PJ_SUCCESS on success or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_lock_key(pj_ioqueue_key_t *key);
+
+/**
+ * Release the lock previously acquired with pj_ioqueue_lock_key().
+ *
+ * @param key	    The key that was previously obtained from registration.
+ *
+ * @return	    PJ_SUCCESS on success or the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_unlock_key(pj_ioqueue_key_t *key);
+
+/**
+ * Initialize operation key.
+ *
+ * @param op_key    The operation key to be initialied.
+ * @param size	    The size of the operation key.
+ */
+PJ_DECL(void) pj_ioqueue_op_key_init( pj_ioqueue_op_key_t *op_key,
+				      pj_size_t size );
+
+/**
+ * Check if operation is pending on the specified operation key.
+ * The \c op_key must have been initialized with #pj_ioqueue_op_key_init() 
+ * or submitted as pending operation before, or otherwise the result 
+ * is undefined.
+ *
+ * @param key       The key.
+ * @param op_key    The operation key, previously submitted to any of
+ *                  the I/O functions and has returned PJ_EPENDING.
+ *
+ * @return          Non-zero if operation is still pending.
+ */
+PJ_DECL(pj_bool_t) pj_ioqueue_is_pending( pj_ioqueue_key_t *key,
+                                          pj_ioqueue_op_key_t *op_key );
+
+
+/**
+ * Post completion status to the specified operation key and call the
+ * appropriate callback. When the callback is called, the number of bytes 
+ * received in read/write callback or the status in accept/connect callback
+ * will be set from the \c bytes_status parameter.
+ *
+ * @param key           The key.
+ * @param op_key        Pending operation key.
+ * @param bytes_status  Number of bytes or status to be set. A good value
+ *                      to put here is -PJ_ECANCELLED.
+ *
+ * @return              PJ_SUCCESS if completion status has been successfully
+ *                      sent.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_post_completion( pj_ioqueue_key_t *key,
+                                                 pj_ioqueue_op_key_t *op_key,
+                                                 pj_ssize_t bytes_status );
+
+
+
+#if defined(PJ_HAS_TCP) && PJ_HAS_TCP != 0
+/**
+ * Instruct I/O Queue to accept incoming connection on the specified 
+ * listening socket. This function will return immediately (i.e. non-blocking)
+ * regardless whether a connection is immediately available. If the function
+ * can't complete immediately, the caller will be notified about the incoming
+ * connection when it calls pj_ioqueue_poll(). If a new connection is
+ * immediately available, the function returns PJ_SUCCESS with the new
+ * connection; in this case, the callback WILL NOT be called.
+ *
+ * @param key	    The key which registered to the server socket.
+ * @param op_key    An operation specific key to be associated with the
+ *                  pending operation, so that application can keep track of
+ *                  which operation has been completed when the callback is
+ *                  called.
+ * @param new_sock  Argument which contain pointer to receive the new socket
+ *                  for the incoming connection.
+ * @param local	    Optional argument which contain pointer to variable to 
+ *                  receive local address.
+ * @param remote    Optional argument which contain pointer to variable to 
+ *                  receive the remote address.
+ * @param addrlen   On input, contains the length of the buffer for the
+ *		    address, and on output, contains the actual length of the
+ *		    address. This argument is optional.
+ * @return
+ *  - PJ_SUCCESS    When connection is available immediately, and the 
+ *                  parameters will be updated to contain information about 
+ *                  the new connection. In this case, a completion callback
+ *                  WILL NOT be called.
+ *  - PJ_EPENDING   If no connection is available immediately. When a new
+ *                  connection arrives, the callback will be called.
+ *  - non-zero      which indicates the appropriate error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_accept( pj_ioqueue_key_t *key,
+                                        pj_ioqueue_op_key_t *op_key,
+					pj_sock_t *new_sock,
+					pj_sockaddr_t *local,
+					pj_sockaddr_t *remote,
+					int *addrlen );
+
+/**
+ * Initiate non-blocking socket connect. If the socket can NOT be connected
+ * immediately, asynchronous connect() will be scheduled and caller will be
+ * notified via completion callback when it calls pj_ioqueue_poll(). If
+ * socket is connected immediately, the function returns PJ_SUCCESS and
+ * completion callback WILL NOT be called.
+ *
+ * @param key	    The key associated with TCP socket
+ * @param addr	    The remote address.
+ * @param addrlen   The remote address length.
+ *
+ * @return
+ *  - PJ_SUCCESS    If socket is connected immediately. In this case, the
+ *                  completion callback WILL NOT be called.
+ *  - PJ_EPENDING   If operation is queued, or 
+ *  - non-zero      Indicates the error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_connect( pj_ioqueue_key_t *key,
+					 const pj_sockaddr_t *addr,
+					 int addrlen );
+
+#endif	/* PJ_HAS_TCP */
+
+/**
+ * Poll the I/O Queue for completed events.
+ *
+ * Note: polling the ioqueue is not necessary in Symbian. Please see
+ * @ref PJ_SYMBIAN_OS for more info.
+ *
+ * @param ioque		the I/O Queue.
+ * @param timeout	polling timeout, or NULL if the thread wishes to wait
+ *			indefinetely for the event.
+ *
+ * @return 
+ *  - zero if timed out (no event).
+ *  - (<0) if error occured during polling. Callback will NOT be called.
+ *  - (>1) to indicate numbers of events. Callbacks have been called.
+ */
+PJ_DECL(int) pj_ioqueue_poll( pj_ioqueue_t *ioque,
+			      const pj_time_val *timeout);
+
+
+/**
+ * Instruct the I/O Queue to read from the specified handle. This function
+ * returns immediately (i.e. non-blocking) regardless whether some data has 
+ * been transfered. If the operation can't complete immediately, caller will 
+ * be notified about the completion when it calls pj_ioqueue_poll(). If data
+ * is immediately available, the function will return PJ_SUCCESS and the
+ * callback WILL NOT be called.
+ *
+ * @param key	    The key that uniquely identifies the handle.
+ * @param op_key    An operation specific key to be associated with the
+ *                  pending operation, so that application can keep track of
+ *                  which operation has been completed when the callback is
+ *                  called. Caller must make sure that this key remains 
+ *                  valid until the function completes.
+ * @param buffer    The buffer to hold the read data. The caller MUST make sure
+ *		    that this buffer remain valid until the framework completes
+ *		    reading the handle.
+ * @param length    On input, it specifies the size of the buffer. If data is
+ *                  available to be read immediately, the function returns
+ *                  PJ_SUCCESS and this argument will be filled with the
+ *                  amount of data read. If the function is pending, caller
+ *                  will be notified about the amount of data read in the
+ *                  callback. This parameter can point to local variable in
+ *                  caller's stack and doesn't have to remain valid for the
+ *                  duration of pending operation.
+ * @param flags     Recv flag. If flags has PJ_IOQUEUE_ALWAYS_ASYNC then
+ *		    the function will never return PJ_SUCCESS.
+ *
+ * @return
+ *  - PJ_SUCCESS    If immediate data has been received in the buffer. In this
+ *                  case, the callback WILL NOT be called.
+ *  - PJ_EPENDING   If the operation has been queued, and the callback will be
+ *                  called when data has been received.
+ *  - non-zero      The return value indicates the error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_recv( pj_ioqueue_key_t *key,
+                                      pj_ioqueue_op_key_t *op_key,
+				      void *buffer,
+				      pj_ssize_t *length,
+				      pj_uint32_t flags );
+
+/**
+ * This function behaves similarly as #pj_ioqueue_recv(), except that it is
+ * normally called for socket, and the remote address will also be returned
+ * along with the data. Caller MUST make sure that both buffer and addr
+ * remain valid until the framework completes reading the data.
+ *
+ * @param key	    The key that uniquely identifies the handle.
+ * @param op_key    An operation specific key to be associated with the
+ *                  pending operation, so that application can keep track of
+ *                  which operation has been completed when the callback is
+ *                  called.
+ * @param buffer    The buffer to hold the read data. The caller MUST make sure
+ *		    that this buffer remain valid until the framework completes
+ *		    reading the handle.
+ * @param length    On input, it specifies the size of the buffer. If data is
+ *                  available to be read immediately, the function returns
+ *                  PJ_SUCCESS and this argument will be filled with the
+ *                  amount of data read. If the function is pending, caller
+ *                  will be notified about the amount of data read in the
+ *                  callback. This parameter can point to local variable in
+ *                  caller's stack and doesn't have to remain valid for the
+ *                  duration of pending operation.
+ * @param flags     Recv flag. If flags has PJ_IOQUEUE_ALWAYS_ASYNC then
+ *		    the function will never return PJ_SUCCESS.
+ * @param addr      Optional Pointer to buffer to receive the address.
+ * @param addrlen   On input, specifies the length of the address buffer.
+ *                  On output, it will be filled with the actual length of
+ *                  the address. This argument can be NULL if \c addr is not
+ *                  specified.
+ *
+ * @return
+ *  - PJ_SUCCESS    If immediate data has been received. In this case, the 
+ *		    callback must have been called before this function 
+ *		    returns, and no pending operation is scheduled.
+ *  - PJ_EPENDING   If the operation has been queued.
+ *  - non-zero      The return value indicates the error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_recvfrom( pj_ioqueue_key_t *key,
+                                          pj_ioqueue_op_key_t *op_key,
+					  void *buffer,
+					  pj_ssize_t *length,
+                                          pj_uint32_t flags,
+					  pj_sockaddr_t *addr,
+					  int *addrlen);
+
+/**
+ * Instruct the I/O Queue to write to the handle. This function will return
+ * immediately (i.e. non-blocking) regardless whether some data has been 
+ * transfered. If the function can't complete immediately, the caller will
+ * be notified about the completion when it calls pj_ioqueue_poll(). If 
+ * operation completes immediately and data has been transfered, the function
+ * returns PJ_SUCCESS and the callback will NOT be called.
+ *
+ * @param key	    The key that identifies the handle.
+ * @param op_key    An operation specific key to be associated with the
+ *                  pending operation, so that application can keep track of
+ *                  which operation has been completed when the callback is
+ *                  called.
+ * @param data	    The data to send. Caller MUST make sure that this buffer 
+ *		    remains valid until the write operation completes.
+ * @param length    On input, it specifies the length of data to send. When
+ *                  data was sent immediately, this function returns PJ_SUCCESS
+ *                  and this parameter contains the length of data sent. If
+ *                  data can not be sent immediately, an asynchronous operation
+ *                  is scheduled and caller will be notified via callback the
+ *                  number of bytes sent. This parameter can point to local 
+ *                  variable on caller's stack and doesn't have to remain 
+ *                  valid until the operation has completed.
+ * @param flags     Send flags. If flags has PJ_IOQUEUE_ALWAYS_ASYNC then
+ *		    the function will never return PJ_SUCCESS.
+ *
+ * @return
+ *  - PJ_SUCCESS    If data was immediately transfered. In this case, no
+ *                  pending operation has been scheduled and the callback
+ *                  WILL NOT be called.
+ *  - PJ_EPENDING   If the operation has been queued. Once data base been
+ *                  transfered, the callback will be called.
+ *  - non-zero      The return value indicates the error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_send( pj_ioqueue_key_t *key,
+                                      pj_ioqueue_op_key_t *op_key,
+				      const void *data,
+				      pj_ssize_t *length,
+				      pj_uint32_t flags );
+
+
+/**
+ * Instruct the I/O Queue to write to the handle. This function will return
+ * immediately (i.e. non-blocking) regardless whether some data has been 
+ * transfered. If the function can't complete immediately, the caller will
+ * be notified about the completion when it calls pj_ioqueue_poll(). If 
+ * operation completes immediately and data has been transfered, the function
+ * returns PJ_SUCCESS and the callback will NOT be called.
+ *
+ * @param key	    the key that identifies the handle.
+ * @param op_key    An operation specific key to be associated with the
+ *                  pending operation, so that application can keep track of
+ *                  which operation has been completed when the callback is
+ *                  called.
+ * @param data	    the data to send. Caller MUST make sure that this buffer 
+ *		    remains valid until the write operation completes.
+ * @param length    On input, it specifies the length of data to send. When
+ *                  data was sent immediately, this function returns PJ_SUCCESS
+ *                  and this parameter contains the length of data sent. If
+ *                  data can not be sent immediately, an asynchronous operation
+ *                  is scheduled and caller will be notified via callback the
+ *                  number of bytes sent. This parameter can point to local 
+ *                  variable on caller's stack and doesn't have to remain 
+ *                  valid until the operation has completed.
+ * @param flags     send flags. If flags has PJ_IOQUEUE_ALWAYS_ASYNC then
+ *		    the function will never return PJ_SUCCESS.
+ * @param addr      Optional remote address.
+ * @param addrlen   Remote address length, \c addr is specified.
+ *
+ * @return
+ *  - PJ_SUCCESS    If data was immediately written.
+ *  - PJ_EPENDING   If the operation has been queued.
+ *  - non-zero      The return value indicates the error code.
+ */
+PJ_DECL(pj_status_t) pj_ioqueue_sendto( pj_ioqueue_key_t *key,
+                                        pj_ioqueue_op_key_t *op_key,
+					const void *data,
+					pj_ssize_t *length,
+                                        pj_uint32_t flags,
+					const pj_sockaddr_t *addr,
+					int addrlen);
+
+
+/**
+ * !}
+ */
+
+PJ_END_DECL
+
+#endif	/* __PJ_IOQUEUE_H__ */
+