msg_receive
Receive a message from a message queue
Description
bool 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
)
Parameters
-
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.
Return Values
Returns true
on success or false
on failure.
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.
See Also
- msg_remove_queue
- msg_send
- msg_stat_queue
- msg_set_queue