MongoCursor::awaitData

(PECL mongo >=1.2.11)

MongoCursor::awaitData — Sets whether this cursor will wait for a while for a tailable cursor to return more data

说明

public MongoCursor::awaitData ([ bool $wait = TRUE ] ) : MongoCursor

This method is to be used with tailable cursors. If we are at the end of the data, block for a while rather than returning no data. After a timeout period, we do return as normal.

参数

wait

If the cursor should wait for more data to become available.

返回值

Returns this cursor.

错误／异常

Throws MongoCursorException if this cursor has started iterating.

范例

Example #1 MongoCursor::awaitData() example

In this example we tail the "oplog" and instead of sleeping during every iteration, we set the MongoCursor::awaitData() option. MongoCursor::hasNext() will now block until there is more data available.

<?php
$m = new MongoClient( 'mongodb://localhost:13000', array( 'replSet' => 'seta' ) );
$c = $m->local->selectCollection( 'oplog.rs' );
$cursor = $c->find( array( 'ns' => 'demo.article', 'op' => 'i' ) );
$cursor->tailable( true );
$cursor->awaitData( true );

while (true) {
    if (!$cursor->hasNext()) {
        // we've read all the results, exit
        if ($cursor->dead()) {
            break;
        }
    } else {
        var_dump( $cursor->getNext() );
    }
}
?>

参见

MongoDB core docs on » tailable cursors.