pg_connection_busy

(PHP 4 >= 4.2.0, PHP 5, PHP 7)

pg_connection_busy Get connection is busy or not

Description

pg_connection_busy ( resource $connection ) : bool

pg_connection_busy() determines whether or not a connection is busy. If it is busy, a previous query is still executing. If pg_get_result() is used on the connection, it will be blocked.

Parameters

connection

PostgreSQL database connection resource.

Return Values

Returns TRUE if the connection is busy, FALSE otherwise.

Examples

Example #1 pg_connection_busy() example

<?php
  $dbconn 
pg_connect("dbname=publisher") or die("Could not connect");
  
$bs pg_connection_busy($dbconn);
  if (
$bs) {
      echo 
'connection is busy';
  } else {
     echo 
'connection is not busy';
  }
?>

See Also

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User Contributed Notes 2 notes

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2
levi at alliancesoftware dot com dot au
9 years ago
pg_connection_busy() returning true does not necessarily mean that there are results waiting for pg_get_result(); it also stays true for some time after a query that causes any sort of postgres error. (See http://bugs.php.net/bug.php?id=36469)
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0
VLroyrenn
3 months ago
There doesn't seem to be any documented way of using this function here, and I'm sore most people trying this are going to default to using a busy loop if there is nothing else to do while waiting (in which case pg_get_result would be better, since it just blocks until a result is ready) or a sleep loop if trying to cancel the query after a certain time.

The C documentation for libPq reccomends using PQisBusy (the C equivalent of pg_connection_busy) by waiting on a socket instead, which lets you timeout if the state doesn't change after a certain period but immediately react if it changes. If you want to cancel after a timeout, you would have something like this :

<?php
class SomeKindOfTimeoutException extends Exception { }

class
SomeKindOfSQLErrorException extends Exception { }

function
query_with_timeout($conn, $query, $timeout_seconds) {
   
assert(pg_get_result($conn) === false); // Ensure that nothing is running

   
$socket = [pg_socket($conn)];
   
$null = [];

   
$dispatch_ok = pg_send_query($conn, $query);

   
$still_running = pg_connection_busy($conn);

    while(
$still_running) {
       
// https://www.postgresql.org/docs/current/libpq-async.html
        // "A typical application using these functions will have a main loop that uses select() or poll() to wait for all the conditions that it must respond to."
        // "One of the conditions will be input available from the server, which in terms of select() means readable data on the file descriptor identified by PQsocket."
        // PQisBusy is mapped to pg_connection_busy
       
stream_select($socket, $null, $null, $timeout_seconds); // Will wait on that socket until that happens or the timeout is reached
       
$still_running = pg_connection_busy($conn); // False on timeout, true if complete

        // You could keep polling like that, this just breaks and throws immediately on first loop
       
if ($still_running) {
           
$cancel_ok = pg_cancel_query($conn);
            throw new
SomeKindOfTimeoutException("TIMEOUT");
        }
    }

   
$res = pg_get_result($conn);

    try {
       
$error_msg = pg_result_error($res);
        if (
$error_msg) throw new SomeKindOfSQLErrorException($error_msg);

        return
pg_fetch_all($res);
    }
finally {
       
pg_free_result($res);
    }
}

$conn_string = "host=localhost port=5433 dbname=postgres";
$db = pg_connect($conn_string);

query_with_timeout($db, "SELECT pg_sleep(10)", 3); // Will throw
?>
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