PHP function stream_select()

Availability in versions: PHP 4.3.0

Runs the equivalent of the select() system call on the given arrays of streams with a timeout specified by tv_sec and tv_usec

Parameters

Parameter	Data type	Default value	Note
$read	array	not	The streams listed in the read array will be watched to see if characters become available for reading (more precisely, to see if a read will not block - in particular, a stream resource is also ready on end-of-file, in which case an fread will return a zero length string).
$write	array	not	The streams listed in the write array will be watched to see if a write will not block.
$except	array	not	The streams listed in the except array will be watched for high priority exceptional ("out-of-band") data arriving.
$tv_sec	int	not	The tv_sec and tv_usec together form the timeout parameter, tv_sec specifies the number of seconds while tv_usec the number of microseconds. The timeout is an upper bound on the amount of time that stream_select will wait before it returns. If tv_sec and tv_usec are both set to 0, stream_select will not wait for data - instead it will return immediately, indicating the current status of the streams.
$tv_usec	int	null	See tv_sec description.

Return values

int

On success stream_select returns the number of stream resources contained in the modified arrays, which may be zero if the timeout expires before anything interesting happens. On error false is returned and a warning raised (this can happen if the system call is interrupted by an incoming signal).

Other resources

Official stream-select documentation