Gerrit Inspector

NAME

Gerrit Inspector - Interactive Jython environment for Gerrit

SYNOPSIS

java -jar gerrit.war daemon
  -d <SITE_PATH>
  [--enable-httpd | --disable-httpd]
  [--enable-sshd | --disable-sshd]
  [--console-log]
  [--slave]
  -s

DESCRIPTION

Runs the Gerrit network daemon on the local system as described in the Daemon documentation, additionally starting an interactive Jython shell for inspection and troubleshooting of live data of the Gerrit instance.

Caution

Gerrit Inspector works directly on instances of Java Virtual Machine objects and it is possible to read and write instance members as well as invoke Java functions. Access is granted also to 'private' and 'protected' members. Therefore it is possible to introduce changes to the internal state of the system in an inconsistent way. Care must be taken not to break the running system and/or destroy the data.

INSTALLATION

Gerrit Inspector requires Jython library ('jython.jar') to be installed in the '$site_path/lib' directory. Jython, a Python interpreter for the Java Virtual Machine, can be obtained from the http://www.jython.org/ website. Only 'jython.jar' file is needed, installation of Jython libraries is optional. Gerrit Inspector has been tested with Jython 2.5.2 but might work an earlier version.

STARTUP

During startup Jython examines Java libraries found on the classpath. While libraries are inspected a large amount of messages is displayed on the console:

*sys-package-mgr*: processing new jar, '/home/user/.gerritcodereview/tmp/gerrit_4890671371398741854_app/sshd-core-0.5.1-r1095809.jar'

After this a system-wide embedded initialization script is started. This script is contained in the gerrit’s WAR archive. This script produces output similar to the following on the console:

"Shell" is "com.google.gerrit.pgm.shell.JythonShell@61644f2d"
"m" is "com.google.gerrit.lifecycle.LifecycleManager@6f03b248"

Welcome to the Gerrit Inspector
Enter help() to see the above again, EOF to quit and stop Gerrit

Then an optional user startup script is processed. It should be located in the gerrit user home directory as '.gerritcodereview/Startup.py'.

This script can access all variables defined in the system (such as the ones displayed by the initialization script as shown above). Variables and functions defined by the startup scripts are available for the interactive interpreter.

When interactive interpreter exits (by issuing EOF on the command line), a whole Gerrit instance is shut down gracefully.

USING THE INTERPRETER

Gerrit Inspector launches Jython interpreter in the context of the Gerrit Java Virtual Machine. All core facilities of the Jython (and Python) language are available to the user.

Additional facilities can be provided, for example a 'Lib' directory from the Jython distribution can be installed under '$site_path/lib/Lib' to provide access to many standard Python modules. Jython can also use additional Java classes and libraries and most of the Python modules and scripts.

The Inspector has by default access to classes and object instances available in the Java Virtual Machine. Objects are introspected and private and protected members are also available.

For more information on using Jython, especially with regards to its limitations in interfacing to the Java Virtual Machine, please refer to the Jython documentation.

After successful initialization it is possible to examine components of Java packages, classes and live instances.

>>> import com.google.inject
>>> dir(com.google.inject)
['AbstractModule', 'Binder', 'Binding', 'BindingAnnotation', 'ConfigurationException', 'CreationException', 'Exposed', 'Guice', 'ImplementedBy', 'Inject', 'Injector', 'Key', 'MembersInjector', 'Module', 'OutOfScopeException', 'PrivateBinder', 'PrivateModule', 'ProvidedBy', 'Provider', 'Provides', 'ProvisionException', 'Scope', 'ScopeAnnotation', 'Scopes', 'Singleton', 'Stage', 'TypeLiteral', '__name__', 'assistedinject', 'binder', 'internal', 'matcher', 'name', 'servlet', 'spi', 'util']
>>> type(com.google.inject)
<type 'javapackage'>
>>> dir(com.google.inject.Guice)
['__class__', '__copy__', '__deepcopy__', '__delattr__', '__doc__',
'__eq__', '__getattribute__', '__hash__', '__init__', '__ne__',
'__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__',
'__str__', '__unicode__', 'class', 'clone', 'createInjector',
'equals', 'finalize', 'getClass', 'hashCode', 'notify', 'notifyAll',
'registerNatives', 'toString', 'wait']

A built-in help() function provides values of global variables defined in the interpreter:

>>> help()
"m" is "com.google.gerrit.lifecycle.LifecycleManager@6f03b248"
"Shell" is "com.google.gerrit.pgm.shell.JythonShell@61644f2d"
"d" is "com.google.gerrit.pgm.Daemon@28a3f689"

Welcome to the Gerrit Inspector
Enter help() to see the above again, EOF to quit and stop Gerrit

Java and Python exceptions are intercepted by the Inspector:

>>> import java.lang.RuntimeException
>>> raise java.lang.RuntimeException("Exiting")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
        at org.python.core.PyReflectedConstructor.constructProxy(PyReflectedConstructor.java:210)

java.lang.RuntimeException: java.lang.RuntimeException: Exiting
>>>

To exit the interpreter, use EOF character (Ctrl-D on Unix systems, Ctrl-Z on Windows).

It is also possible to shut down the JVM by using System.exit()

>>> import java.lang.System
>>> java.lang.System.exit(1)

And Gerrit should shut down all its subsystems and exit:

[2012-04-17 15:31:08,458] INFO  com.google.gerrit.pgm.Daemon : caught shutdown, cleaning up

TROUBLESHOOTING

Gerrit Inspector is logging to the Gerrit error log.

A successful startup is indicated in the logfile:

  [2012-04-17 13:43:44,888] INFO  com.google.gerrit.pgm.shell.JythonShell : Jython shell instance created.

If 'jython.jar' library is not available, Gerrit refuses to start when given -s option:

[2012-04-17 13:57:29,611] ERROR com.google.gerrit.pgm.Daemon : Unable to start daemon
com.google.inject.ProvisionException: Guice provision errors:

1) Error injecting constructor, java.lang.UnsupportedOperationException: Cannot create Jython shell: Class org.python.util.InteractiveConsole not found
     (You might need to install jython.jar in the lib directory)
  at com.google.gerrit.pgm.shell.JythonShell.<init>(JythonShell.java:47)
  while locating com.google.gerrit.pgm.shell.JythonShell
  while locating com.google.gerrit.pgm.shell.InteractiveShell

Errors during processing of the startup script, 'Startup.py', are logged to the error log:

[2012-04-17 14:20:30,558] INFO  com.google.gerrit.pgm.shell.JythonShell : Jython shell instance created.
[2012-04-17 14:20:38,005] ERROR com.google.gerrit.pgm.shell.JythonShell : Exception occurred while loading file Startup.py :
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:616)
        at com.google.gerrit.pgm.shell.JythonShell.runMethod0(JythonShell.java:112)
        at com.google.gerrit.pgm.shell.JythonShell.execFile(JythonShell.java:194)
        at com.google.gerrit.pgm.shell.JythonShell.reload(JythonShell.java:178)
        at com.google.gerrit.pgm.shell.JythonShell.run(JythonShell.java:152)
        at com.google.gerrit.pgm.Daemon.run(Daemon.java:190)
        at com.google.gerrit.pgm.util.AbstractProgram.main(AbstractProgram.java:67)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:616)
        at com.google.gerrit.launcher.GerritLauncher.invokeProgram(GerritLauncher.java:167)
        at com.google.gerrit.launcher.GerritLauncher.mainImpl(GerritLauncher.java:91)
        at com.google.gerrit.launcher.GerritLauncher.main(GerritLauncher.java:49)
        at Main.main(Main.java:25)
Caused by: Traceback (most recent call last):
  File "/home/user/.gerritcodereview/Startup.py", line 1, in <module>
    Test
NameError: name 'Test' is not defined

Those errors are non-fatal. System and user scripts can be loaded again by issuing the following command in the Gerrit Inspector console:

Shell.reload()

LOGGING

Error and warning messages from the server are automatically written to the log file under '$site_path/logs/error_log'.

Output and error messages (including Java and Python exceptions) resulting from interactive work are logged to the console.

KNOWN ISSUES

The Inspector does not yet recognize Google Guice bindings.

Important

Using the Inspector may void your warranty.

Part of Gerrit Code Review