注: The following applies to 3.0.7 and later.
Internally in PHP a connection status is maintained.
There are 3 possible states:
When a PHP script is running normally the NORMAL state,
is active. If the remote client disconnects the ABORTED state
flag is turned on. A remote client disconnect is usually
caused by the user hitting his STOP button. If the
PHP-imposed time limit (see
set_time_limit()) is hit, the TIMEOUT state flag is
turned on.
You can decide whether or not you want a client
disconnect to cause your script to be aborted. Sometimes it
is handy to always have your scripts run to completion even
if there is no remote browser receiving the output. The
default behaviour is however for your script to be aborted
when the remote client disconnects. This behaviour can be set
via the ignore_user_abort php.ini
directive as well as through the corresponding "php_value
ignore_user_abort" Apache .conf directive or with the
ignore_user_abort() function. If you do not tell PHP
to ignore a user abort and the user aborts, your script will
terminate. The one exception is if you have registered a
shutdown function using register_shutdown_function(). With a
shutdown function, when the remote user hits his STOP button,
the next time your script tries to output something PHP will
detect that the connection has been aborted and the shutdown
function is called. This shutdown function will also get
called at the end of your script terminating normally, so to
do something different in case of a client disconnect you can
use the connection_aborted() function. This
function will return TRUE if
the connection was aborted.
Your script can also be terminated by the built-in
script timer. The default timeout is 30 seconds. It can be
changed using the max_execution_time
php.ini directive or the corresponding "php_value
max_execution_time" Apache .conf directive as well as with
the set_time_limit() function. When the timer
expires the script will be aborted and as with the above
client disconnect case, if a shutdown function has been
registered it will be called. Within this shutdown function
you can check to see if a timeout caused the shutdown
function to be called by calling the
connection_timeout() function. This function will
return TRUE if a timeout
caused the shutdown function to be called.
One thing to note is that both the ABORTED and the
TIMEOUT states can be active at the same time. This is
possible if you tell PHP to ignore user aborts. PHP will
still note the fact that a user may have broken the
connection, but the script will keep running. If it then hits
the time limit it will be aborted and your shutdown function,
if any, will be called. At this point you will find that
connection_timeout() and
connection_aborted() return
TRUE. You can also check both states in a single
call by using the
connection_status(). This
function returns a bitfield of the active states. So, if both
states are active it would return 3, for example.