Php/docs/function.msg-receive

• PHP Manual
• Semaphore 函数
• Receive a message from a message queue

msg_receive

(PHP 4 >= 4.3.0, PHP 5, PHP 7)

msg_receive — Receive a message from a message queue

说明

msg_receive ( SysvMessageQueue $queue , int $desired_message_type , int &$received_message_type , int $max_message_size , mixed &$message [, bool $unserialize = true [, int $flags = 0 [, int &$error_code = null ]]] ) : bool

msg_receive() will receive the first message from the specified queue of the type specified by desired_message_type.

参数

queue

The message queue.

desired_message_type

If desired_message_type is 0, the message from the front of the queue is returned. If desired_message_type is greater than 0, then the first message of that type is returned. If desired_message_type is less than 0, the first message on the queue with a type less than or equal to the absolute value of desired_message_type will be read. If no messages match the criteria, your script will wait until a suitable message arrives on the queue. You can prevent the script from blocking by specifying MSG_IPC_NOWAIT in the flags parameter.

received_message_type

The type of the message that was received will be stored in this parameter.

max_message_size

The maximum size of message to be accepted is specified by the max_message_size; if the message in the queue is larger than this size the function will fail (unless you set flags as described below).

message

The received message will be stored in message, unless there were errors receiving the message.

unserialize

If set to true, the message is treated as though it was serialized using the same mechanism as the session module. The message will be unserialized and then returned to your script. This allows you to easily receive arrays or complex object structures from other PHP scripts, or if you are using the WDDX serializer, from any WDDX compatible source.

If unserialize is false, the message will be returned as a binary-safe string.

flags

The optional flags allows you to pass flags to the low-level msgrcv system call. It defaults to 0, but you may specify one or more of the following values (by adding or ORing them together).

Flag values for msg_receive

MSG_IPC_NOWAIT	If there are no messages of the desired_message_type, return immediately and do not wait. The function will fail and return an integer value corresponding to MSG_ENOMSG.
MSG_EXCEPT	Using this flag in combination with a desired_message_type greater than 0 will cause the function to receive the first message that is not equal to desired_message_type.
MSG_NOERROR	If the message is longer than max_message_size, setting this flag will truncate the message to max_message_size and will not signal an error.

error_code

If the function fails, the optional error_code will be set to the value of the system errno variable.

返回值

成功时返回 true， 或者在失败时返回 false。

Upon successful completion the message queue data structure is updated as follows: msg_lrpid is set to the process-ID of the calling process, msg_qnum is decremented by 1 and msg_rtime is set to the current time.

更新日志

版本	说明
8.0.0	queue expects a SysvMessageQueue instance now; previously, a resource was expected.

参见

• msg_remove_queue() - Destroy a message queue
• msg_send() - Send a message to a message queue
• msg_stat_queue() - Returns information from the message queue data structure
• msg_set_queue() - Set information in the message queue data structure