com.google.common.flogger.backend.system

Class BackendFactory

java.lang.Object

com.google.common.flogger.backend.system.BackendFactory

Direct Known Subclasses:

SimpleBackendFactory

public abstract class BackendFactory
extends java.lang.Object

An API to create logger backends for a given class name. This is implemented as an abstract class (rather than an interface) to reduce to risk of breaking existing implementations if the API changes.

Essential Implementation Restrictions

Any implementation of this API MUST follow the rules listed below to avoid any risk of re-entrant code calling during logger initialization. Failure to do so risks creating complex, hard to debug, issues with Flogger configuration.

1. Implementations MUST NOT attempt any logging in static methods or constructors.
2. Implementations MUST NOT statically depend on any unknown code.
3. Implementations MUST NOT depend on any unknown code in constructors.

Note that logging and calling arbitrary unknown code (which might log) are permitted inside the instance methods of this API, since they are not called during platform initialization. The easiest way to achieve this is to simply avoid having any non-trivial static fields or any instance fields at all in the implementation.

While this sounds onerous it's not difficult to achieve because this API is a singleton, and can delay any actual work until its methods are called. For example if any additional state is required in the implementation, it can be held via a "lazy holder" to defer initialization.

Constructor Summary

Constructors

Constructor and Description
BackendFactory()

Method Summary

Modifier and Type	Method and Description
abstract com.google.common.flogger.backend.LoggerBackend	create(java.lang.String loggingClassName) Creates a logger backend of the given class name for use by a Fluent Logger.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BackendFactory

public BackendFactory()

Method Detail

create

public abstract com.google.common.flogger.backend.LoggerBackend create(java.lang.String loggingClassName)

Creates a logger backend of the given class name for use by a Fluent Logger. Note that the returned backend need not be unique; one backend could be used by multiple loggers. The given class name must be in the normal dot-separated form (e.g., "com.example.Foo$Bar") rather than the internal binary format "com/example/Foo$Bar").

Parameters:

loggingClassName - the fully-qualified name of the Java class to which the logger is associated. The logger name is derived from this string in a backend specific way.