MongoDB::Monitoring(3pm) User Contributed Perl Documentation MongoDB::Monitoring(3pm)

MongoDB::Monitoring - Internal event monitoring API for instrumentation

version v2.2.2

The MongoDB::MongoClient takes an optional "monitoring_callback" attribute, which can be used to monitor events that occur during the operation of the driver.

The API is very simple: given a code reference, a hashref for each event is passed to the code reference. Here is a simple example that just accumulates events in an array:

    our @events;
    my $cb = sub { push @events, $_[0] };
    MongoDB->connect( $uri, { monitoring_callback => $cb } );

Every event is a hash reference, with a "type" field indicating the type, e.g. "command_started". Each type is described below.

These events are fired for commands directly to the wire and the response.

command_started

This event is sent just before a command is put one the wire. It will be followed by either a "command_succeeded" or "command_failed" event.

Fields:

  • type: "command_started"
  • databaseName: the name of the database to which the command applies
  • commandName: the name of the command being executed; for legacy operations that don't use commands, the driver will convert them to appear as if they are in command form.
  • command: a hash reference representing the full command to be sent
  • requestId: the request identifier sent to the server
  • connectionId: address and port of the destination server

command_succeeded

This event is sent just after a command reply is received, but only if the database reply document contains a non-false "ok" field. NOTE: write errors will have "ok:1" even though they have write errors; for writes, success indicates that the write attempt was valid, not that the write succeeded.

Fields:

  • type: "command_succeeded"
  • commandName: the name of the command being executed
  • durationSecs: the elapsed time in seconds since the "command_started" event.
  • reply: a hash reference representing the full database reply
  • requestId: the request identifier sent to the server
  • connectionId: address and port of the destination server

command_failed

This event is sent just after a command reply is received, but only if the database reply document contains a false "ok" field or if an exception occurred during send or receive operations.

Fields:

  • type: "command_failed"
  • commandName: the name of the command being executed
  • durationSecs: the elapsed time in seconds since the "command_started" event.
  • failure: a string with a error message about the failure
  • eval_error: if an exception occurs, this contains the value of $@ when the exception was caught
  • reply: a hash reference representing the full database reply or an empty hashref if the failure is due to an exception
  • requestId: the request identifier sent to the server
  • connectionId: address and port of the destination server

These events are fired when servers and topology are amended.

server_opening_event

This event is sent when a new server is added to the topology.

Fields:

  • type: "server_opening_event"
  • topologyId: The topology refaddr
  • address: address of the server

server_closed_event

This event is sent when a server is removed from the topology.

Fields:

  • type: "server_closed_event"
  • topologyId: The topology refaddr
  • address: address of the server

server_description_changed_event

This event is sent when the server description changes, but does not include changes to the RTT.

Fields:

  • type: "server_description_changed_event"
  • address: address of the server
  • topologyId: The topology refaddr
  • previousDescription: Server Description before the change
  • newDescription: Server Description after the change

topology_opening_event

This event is sent when the topology is created.

Fields:

  • type: "topology_opening_event"
  • topologyId: The topology refaddr

topology_closed_event

This event is sent when the topology is closed.

Fields:

  • type: "topology_closed_event"
  • topologyId: The topology refaddr

topology_description_changed_event

This event is sent when the topology description changes.

Fields:

  • type: "topology_description_changed_event"
  • topologyId: The topology refaddr
  • previousDescription: Topology Description before the change
  • newDescription: Topology Description after the change

server_heartbeat_started_event

This event is sent before the ismaster command is sent to the server.

Fields:

  • type: "server_heartbeat_started_event"
  • connectionId: address of the link to connect to

server_heartbeat_succeeded_event

This event is sent after the reply from the ismaster command arrives from a successful reply.

Fields:

  • type: "server_heartbeat_succeeded_event"
  • duration: time it took to send and receive a reply
  • reply: the ismaster command reply
  • connectionId: address of the server

server_heartbeat_failed_event

This event is sent if there is a failure from the ismaster command, which returns an error string of some sort.

Fields:

  • type: "server_heartbeat_failed_event"
  • duration: time it took to send and receive a reply
  • failure: Returns an error string of the failure
  • connectionId: address of the server

Certain commands are considered sensitive. When any of the following commands are seen in monitoring, the command body and database reply body are replaced with an empty document:

This software is Copyright (c) 2020 by MongoDB, Inc.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004
2022-06-30 perl v5.34.0