+++ /dev/null
-======================
- Using the Java agent
-======================
-
-The agent can be built in three different configurations:
-
-1) Java agent with JUL support:
-
-$ ./configure --enable-java-agent-jul
-
-2) Java agent with Log4j 1.x support (deprecated):
-
-$ export CLASSPATH=$CLASSPATH:/path/to/log4j.jar
-$ ./configure --enable-java-agent-log4j
-
-3) Java agent with Log4j 2.x support:
-
-$ export CLASSPATH=$CLASSPATH:/path/to/log4j-core.jar:/path/to/log4j-api.jar
-$ ./configure --enable-java-agent-log4j2
-
-4) Java agent with JUL + Log4j 1.x + Log4j 2.x support
-
-$ export CLASSPATH=$CLASSPATH:/path/to/log4j.jar:/path/to/log4j-core.jar:/path/to/log4j-api.jar
-$ ./configure --enable-java-agent-all
-
-To build the agent with log4j support, make sure that the log4j jar
-is in your Java classpath.
-
-The configure script will automatically detect the appropriate Java
-binaries to use in order to build the Java agent.
-
-Enabling the JUL support will build a "lttng-ust-agent-jul.jar" file. Enabling
-the log4j 1.x support will build a "lttng-ust-agent-log4j.jar" and enabling
-log4j 2.x support will build a "lttng-ust-agent-log4j2.jar". All of these jars
-depend on a third "lttng-ust-agent-common.jar", which will always be built.
-
-All these archives will be installed in the arch-agnostic "$prefix/share/java"
-path, e.g: "/usr/share/java". You need to make sure the .jar for the logging
-API you want to use (either "lttng-ust-agent-jul.jar",
-"lttng-ust-agent-log4j.jar" or "lttng-ust-agent-log4j2.jar") is on your
-application's classpath.
-
-The logging libraries require an architecture-specific shared object,
-"liblttng-ust-jul-jni.so" for JUL and "liblttng-ust-jul-log4j.so" for both
-Log4j 1.x and 2.x, which are installed by the build system when doing "make
-install". Make sure that your Java application can find this shared object, by
-using the "java.library.path" property if necessary.
-
-In order to use UST tracing in your Java application, you simply need to
-instantiate a LttngLogHandler or a LttngLogAppender (for JUL or Log4j,
-respectively), then attach it to a JUL or Log4j Logger class.
-
-Refer to the code examples in "examples/java-jul/", "examples/java-log4j/" and
-"examples/java-log4j2-*/".
-
-LTTng session daemon agents will be initialized as needed. If no session daemon
-is available, the execution will continue and the agents will retry connecting
-every 3 seconds.
-
-
-==============
- Object model
-==============
-
-The object model of the Java agent implementation is as follows:
-
----------
-Ownership
----------
-Log Handlers: LttngLogHandler, LttngLogAppender
- n handlers/appenders, managed by the application.
- Can be created programmatically, or via a configuration file,
- Each one registers to a specific agent singleton (one per logging API) that is loaded on-demand
-
-Agent singletons: LttngJulAgent, LttngLog4jAgent
- Keep track of all handlers/appenders registered to them.
- Are disposed when last handler deregisters.
- Each agent instantiates 2 TCP clients, one for the root session daemon, one for the user one.
- One type of TCP client class for now. TCP client may become a singleton in the future.
-
--------
-Control
--------
-Messages come from the session daemon through the socket connection.
-Agent passes back-reference to itself to the TCP clients.
-Clients use this reference to invoke callbacks, which modify the state of the agent (enabling/disabling events, etc.)
-
----------
-Data path
----------
-Log messages are generated by the application and sent to the Logger objects,
-which then send them to the Handlers.
-
-When a log event is received by a Handler (publish(LogRecord)), the handler
-checks with the agent if it should log it or not, via
-ILttngAgent#isEventEnabled() for example.
-
-Events that are logged call the native tracepoint through JNI, which generates
-a UST event. There is one type of tracepoint per domain (Jul or Logj4).
-
------------------------
-Filtering notifications
------------------------
-FilterChangeNotifier is the singleton notifier class.
-Applications implement an IFilterChangeListener, and register it to the notifier.
-
-Whenever new event rules are enabled or disabled, the relevant agent informs the
-notifier, which then sends notifications to all registered listeners by invoking
-their callbacks.
-
-Upon registration, a new listener will receive notifications for all currently
-active rules.
-
-The notifier keeps track of its own event rule refcounting, to handle the case
-of multiple sessions or multiple agents enabling identical event rules.
-
-The FilterChangeNotifier does not have threads of its own. The listeners's
-callbacks will be invoked by these threads:
-* In the case of a notification being received while a listener is already
- registered, the callback is executed by the TCP client's thread. This
- effectively blocks the "lttng" command line until all callbacks are processed
- (assuming no timeouts).
-* In the case of a listener registering and receiving the currently-active
- rules, the callbacks will be executed by the application's thread doing the
- registerListener() call.
-
-The notifier is entirely synchronized. This ensure that if a rule is enabled
-at the same time a listener is registered, that listener does not miss or
-receive duplicate notifications.
projects / lttng-ust.git / blobdiff