# The MongoDB\Driver\Monitoring\LogSubscriber interface

(mongodb >=1.17.0)

## Introduction

Classes implementing this interface may be registered as a subscriber and receive log messages from the extension. This is similar to stream-based debug logging (i.e. mongodb.debug) except that trace-level log messages are not received.

As with stream-based logging, it is only possible to register a logger globally using MongoDB\Driver\Monitoring\addSubscriber(). The extension is not able to distinguish log messages for individual MongoDB\Driver\Manager objects.

## Interface synopsis

class MongoDB\Driver\Monitoring\LogSubscriber implements MongoDB\Driver\Monitoring\Subscriber {
/* Constants */
const int LEVEL_ERROR = 0;
const int LEVEL_CRITICAL = 1;
const int LEVEL_WARNING = 2;
const int LEVEL_MESSAGE = 3;
const int LEVEL_INFO = 4;
const int LEVEL_DEBUG = 5;
/* Methods */
abstract public log(int `$level`, string `$domain`, string `$message`): void
}

## Predefined Constants

`MongoDB\Driver\Monitoring\LogSubscriber::LEVEL_ERROR`

  Error log level. An error condition that the extension is unable to report through its API. This is the most severe log level in the extension.

`MongoDB\Driver\Monitoring\LogSubscriber::LEVEL_CRITICAL`

  Critical log level. An error condition with slightly less severity. This constant exists for consistency with libmongoc; however, the extension is unlikely to use it in practice.

`MongoDB\Driver\Monitoring\LogSubscriber::LEVEL_WARNING`

  Warning log level. Indicates a situation where undesirable application behavior may occur.

`MongoDB\Driver\Monitoring\LogSubscriber::LEVEL_MESSAGE`

  Message or notice log level. Indicates an event that is unusual but not problematic.

`MongoDB\Driver\Monitoring\LogSubscriber::LEVEL_INFO`

  Info log level. High-level information about normal driver behavior.

`MongoDB\Driver\Monitoring\LogSubscriber::LEVEL_DEBUG`

  Debug log level. Detailed information that may be helpful when debugging an application.

## Table of Contents

- MongoDB\Driver\Monitoring\LogSubscriber::log — Notification method for a log message

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