# The MongoLog class

(PECL mongo >=1.2.3)

## Introduction

Logging can be used to get detailed information about what the driver is doing. Logging is disabled by default, but this class allows you to activate specific levels of logging for various parts of the driver. Some examples:

`<?php
// print every log message possible
MongoLog::setLevel(MongoLog::ALL); // all log levels
MongoLog::setModule(MongoLog::ALL); // all parts of the driver
// print significant events about replica set failover
MongoLog::setLevel(MongoLog::INFO);
MongoLog::setModule(MongoLog::RS);
// print info- and diagnostic-level events for replica sets and connections
MongoLog::setLevel(MongoLog::INFO|MongoLog::FINE);
MongoLog::setModule(MongoLog::RS|MongoLog::CON);
?>`

> Note:

> By default, MongoLog emits all log messages as PHP notices. Depending on the SAPI you use, messages may be sent to `stderr` (for CLI) or the web server's error log. If, after configuring MongoLog, log messages are not appearing as expected, ensure that the `E_NOTICE` bit is included in error_reporting and that display_errors is on.

## Class synopsis

MongoLog {
/* Constants */
const int NONE = 0 ;
const int ALL = 31 ;
level constants {
const int WARNING = 1 ;
const int INFO = 2 ;
const int FINE = 4 ;
module constants {
const int RS = 1 ;
const int POOL = 1 ;
const int CON = 2 ;
const int IO = 4 ;
const int SERVER = 8 ;
const int PARSE = 16 ;
/* Fields */
private static int $callback ;
private static int $level ;
private static int $module ;
/* Methods */
public static getCallback ( ) : callable
public static getLevel ( ) : int
public static getModule ( ) : int
public static setCallback ( callable `$log_function` ) : void
public static setLevel ( int `$level` ) : void
public static setModule ( int `$module` ) : void
}

## Predefined Constants

## MongoLog Constants

These constants can be used by both MongoLog::setLevel() and MongoLog::setModule().

`MongoLog::NONE`
  Log nothing.
`MongoLog::ALL`
  Log everything.

## MongoLog Level Constants

These constants can be used by MongoLog::setLevel().

`MongoLog::WARNING`
  Log events that are somewhat exceptional, but not quite worthy of an actual exception (e.g. recoverable connection errors).
`MongoLog::INFO`
  Log events that may be of interest to administrators, but are not particularly noteworthy (e.g. option parsing, authentication steps).
`MongoLog::FINE`
  Log most events that the driver performs (e.g. server selection, socket communication). Depending on the module being logged, this can be extremely noisy and is primarily useful for debugging.

## MongoLog Module Constants

These constants can be used by MongoLog::setModule().

`MongoLog::CON`
  Log connection activity. Creating new connections, authentication, pinging, timeouts, etc.
`MongoLog::IO`
  Log traffic to/from the database. Unless your program is trivial, this will create an enormous number of log messages.
`MongoLog::PARSE`
  Log parsing of the connection string and options when constructing MongoClient.
`MongoLog::POOL`
  Previously used to log connection pool activity. This option is now a deprecated alias of `MongoLog::RS`.
`MongoLog::RS`
  Log replica set activity. Failovers, read preference selection, etc.
`MongoLog::SERVER`
  Previously used to log server status changes. This option is deprecated in favor of `MongoLog::RS`.

## Changelog

Version | Description
--- | ---
PECL mongo 1.3.0 | Added `MongoLog::CON` and deprecated `MongoLog::POOL` and `MongoLog::SERVER`.

## Table of Contents

- MongoLog::getCallback — Gets the previously set callback function
- MongoLog::getLevel — Gets the level(s) currently being logged
- MongoLog::getModule — Gets the module(s) currently being logged
- MongoLog::setCallback — Sets a callback function to be invoked for events
- MongoLog::setLevel — Sets the level(s) to be logged
- MongoLog::setModule — Sets the module(s) to be logged