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    pg_connection_busy

    (PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

    pg_connection_busy — 接続がビジーかどうか調べる

    説明

    pg_connection_busy(PgSql\Connection $connection): bool

    pg_connection_busy() は、接続がビジーかどうかを調べます。 接続がビジーである場合、以前のクエリがまだ実行中です。 もしこの接続に pg_get_result() がコールされた場合、 それはブロックされます。

    パラメータ

    connection

    PgSql\Connection クラスのインスタンス。

    戻り値

    接続がビジーの場合に true 、そうでない場合に false を返します。

    変更履歴

    バージョン 説明
    8.1.0 connection は、PgSql\Connection クラスのインスタンスを期待するようになりました。 これより前のバージョンでは、リソース を期待していました。

    例

    例1 pg_connection_busy() の例

    <?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';
    }
    ?>

    参考

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    User Contributed Notes 2 notes

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    2
    levi at alliancesoftware dot com dot au
    15 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)
    up
    1
    VLroyrenn
    5 years 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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