The MongoDB Profiling example, using the PHP Stream Notification API For more info, see: http://bjori.blogspot.com/2013/09/query-logging-and-profiling-in-mongodb.html

profile.example.php

<?php
class MongoNotifications {
    public $reqs = array();


    /* Our callback function
     * The prototype is define by the PHP Stream Notification system: http://php.net/stream_notification_callback
     */
    function update($notification_code, $severity, $message, $message_code, $bytes_transferred, $bytes_max) {
        switch($notification_code) {
            /* For now, lets focus on the TYPE_LOG, and ignore the others */
            case MONGO_STREAM_NOTIFY_TYPE_LOG:
                /* This notification only uses two arguments, so we can ignore the rest */
                return $this->logMessage($message_code, $message);

            default:
        }
    }

    /* Our logging function
     * The $code describes the operation being executed,
     * and $message is a json serialized array, packed with information
     * Note: If ext/json is not available, $message with be PHP serialize()d instead
     */
    function logMessage($code, $message) {
        $data = json_decode($message, true);

        switch($code) {
            /* Write operations are a one way street in MongoDB, so these don't end with a
             * MONGO_STREAM_NOTIFY_LOG_RESPONSE_HEADER.
             * When using WriteConcern (defaults to 1), and additional query (command) is
             * sent to check for errors, called getLastError*/
            case MONGO_STREAM_NOTIFY_LOG_INSERT:
            case MONGO_STREAM_NOTIFY_LOG_UPDATE:
            case MONGO_STREAM_NOTIFY_LOG_DELETE:
            case MONGO_STREAM_NOTIFY_LOG_GETMORE:
            case MONGO_STREAM_NOTIFY_LOG_KILLCURSOR:
            case MONGO_STREAM_NOTIFY_LOG_BATCHINSERT:
                /* We only care about the query and response headers, for now */
                break;

            /* We´ve got a query */
            case MONGO_STREAM_NOTIFY_LOG_QUERY:
                /* Retrieve the Wire protocol Request ID, so we can match it with the
                 * Response headers once the query as executed */
                $reqid = $data["server"]["request_id"];

                /* Log all the metadata we have about the query, and add the start time */
                $this->reqs[$reqid] = $data;
                $this->reqs[$reqid]["start"] = microtime(true);
            break;

            /* The query has executed on the server, and now we are reading the
             * response headers */
            case MONGO_STREAM_NOTIFY_LOG_RESPONSE_HEADER:
                // Get the Request ID this respose is for
                $id = $data["server"]["request_id"];

                /* The driver runs some commands internally, such as isMaster() to
                 * sanitycheck the connection to the server, these commands currently
                 * don't trigger the notification system - that may/will change in the
                 * future though */
                if (!isset($this->reqs[$id])) {
                    return;
                }

                // Fetch the request info
                $req = $this->reqs[$id];
                // End the timer
                $end = microtime(true);

                // Add the ending time, and how long it took
                $req["ended"] = $end;
                $req["total"] = $end - $req["start"];

                $this->reqs[$id] = $req;
            break;

            default:
                // Unknown log message code, ignore
        }
    }

    function getRequests() {
        return $this->reqs;
    }
}

/* Some Helper Functions */

/* Split a Server Hash to extract the server name from it */
function getServerName($hash) {
    list($server, $replicaset, $dbname, $pid) = explode(";", $hash);

    return $server;
}

/* Resolve the server type to a readable string */
function getServerType($type) {
    switch($type) {
        // FIXME: Do we not export these as constants?
        case 0x01: return "STANDALONE";
        case 0x02: return "PRIMARY";
        case 0x04: return "SECONDARY";
        case 0x10: return "MONGOS";
    }
}

/* Resolve Cursor (Query) Options to something meaningful */
function getCursorOptions($opts) {
    // FIXME: Do we not export these as constants?
    if (($opts & 0x04) == 0x04) {
        return "slaveOkay";
    }
    return "Primary Only";
}


/* Boilerplate stuff to setup a ReplicaSet connection */
// My replicaset seed list
$seeds = "toddler.local:30200,toddler.local:30201";

// MongoDB Connection options
$moptions = array(
    // Don't wait to long on servers that are down
    "connectTimeoutMS" => 300,
    // Read from secondaries, if available
    "readPreference" => MongoClient::RP_SECONDARY_PREFERRED,
    // My local ReplicaSet name
    "replicaSet" => "REPLICASET",
    // Don't wait more then a second to confirm Replication
    "wTimeoutMS" => 1000,
);


/* Registering a stream context! This is the fun part! */

// Create an instance of our callback object
$mn = new MongoNotifications;

// No Stream Context Options, for now
$coptions = array();
// Configure the Notification Stream Context Parameter to call MongoNotification->update()
$cparams  = array("notification" => array($mn, "update"));

// Create the Stream Context
$ctx = stream_context_create($coptions, $cparams);

$doptions = array("context" => $ctx);


// Instanciate a MongoClient with all our options
$mc = new MongoClient($seeds, $moptions, $doptions);

// Query the example collection in the test database
// you should probably change this to something meaningful
$collection = $mc->selectCollection("test", "example");


// Random search criteria, you should change this to something meaningful
$criteria = array("search" => "criteria");
// Add some sorting & limit for the fun of it
$cursor = $collection->find($criteria)->skip(13)->limit(5)->sort(array("_id" => 1));

// Count on a secondary (we constructed the MongoClient with SECONDARY_PREFERRED)
$count = $cursor->count();
echo "We have $count results in total\n";

// Fetch the data from a primary
$cursor->setReadPreference(MongoClient::RP_PRIMARY);

/* The query isn't execute until we start iterating over it.. */
foreach($cursor as $doc) {
}



// Fetch our requests from our logger
$reqs = $mn->getRequests();
foreach($reqs as $request) {
    printf("Hit %s (which is a %s, I asked for %s) with:\n%s\n",
        getServerName($request["server"]["hash"]),
        getServerType($request["server"]["type"]),
        getCursorOptions($request["info"]["options"]),
        json_encode($request["query"], JSON_PRETTY_PRINT)
    );
    printf("Skipping the first %d matches, limiting the results to %d documents..\n",
        $request["info"]["skip"],
        $request["info"]["limit"]
    );
    printf("Server execution time+network latency: %.8f sec\n\n", $request["total"]);
}