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diff --git a/testing/mozbase/docs/mozprocess.rst b/testing/mozbase/docs/mozprocess.rst new file mode 100644 index 0000000000..ef90e5aa0c --- /dev/null +++ b/testing/mozbase/docs/mozprocess.rst @@ -0,0 +1,324 @@ +:mod:`mozprocess` --- Launch and manage processes +================================================= + +Mozprocess is a process-handling module that provides some additional +features beyond those available with python's subprocess: + +* better handling of child processes, especially on Windows +* the ability to timeout the process after some absolute period, or some + period without any data written to stdout/stderr +* the ability to specify output handlers that will be called + for each line of output produced by the process +* the ability to specify handlers that will be called on process timeout + and normal process termination + +Running a process +----------------- + +mozprocess consists of two classes: ProcessHandler inherits from ProcessHandlerMixin. + +Let's see how to run a process. +First, the class should be instantiated with at least one argument which is a command (or a list formed by the command followed by its arguments). +Then the process can be launched using the *run()* method. +Finally the *wait()* method will wait until end of execution. + +.. code-block:: python + + from mozprocess import processhandler + + # under Windows replace by command = ['dir', '/a'] + command = ['ls', '-l'] + p = processhandler.ProcessHandler(command) + print("execute command: %s" % p.commandline) + p.run() + p.wait() + +Note that using *ProcessHandler* instead of *ProcessHandlerMixin* will print the output of executed command. The attribute *commandline* provides the launched command. + +Collecting process output +------------------------- + +Let's now consider a basic shell script that will print numbers from 1 to 5 waiting 1 second between each. +This script will be used as a command to launch in further examples. + +**proc_sleep_echo.sh**: + +.. code-block:: sh + + #!/bin/sh + + for i in 1 2 3 4 5 + do + echo $i + sleep 1 + done + +If you are running under Windows, you won't be able to use the previous script (unless using Cygwin). +So you'll use the following script: + +**proc_sleep_echo.bat**: + +.. code-block:: bat + + @echo off + FOR %%A IN (1 2 3 4 5) DO ( + ECHO %%A + REM if you have TIMEOUT then use it instead of PING + REM TIMEOUT /T 1 /NOBREAK + PING -n 2 127.0.0.1 > NUL + ) + +Mozprocess allows the specification of custom output handlers to gather process output while running. +ProcessHandler will by default write all outputs on stdout. You can also provide (to ProcessHandler or ProcessHandlerMixin) a function or a list of functions that will be used as callbacks on each output line generated by the process. + +In the following example the command's output will be stored in a file *output.log* and printed in stdout: + +.. code-block:: python + + import sys + from mozprocess import processhandler + + fd = open('output.log', 'w') + + def tostdout(line): + sys.stdout.write("<%s>\n" % line) + + def tofile(line): + fd.write("<%s>\n" % line) + + # under Windows you'll replace by 'proc_sleep_echo.bat' + command = './proc_sleep_echo.sh' + outputs = [tostdout, tofile] + + p = processhandler.ProcessHandlerMixin(command, processOutputLine=outputs) + p.run() + p.wait() + + fd.close() + +The process output can be saved (*obj = ProcessHandler(..., storeOutput=True)*) so as it is possible to request it (*obj.output*) at any time. Note that the default value for *stroreOutput* is *True*, so it is not necessary to provide it in the parameters. + +.. code-block:: python + + import time + import sys + from mozprocess import processhandler + + command = './proc_sleep_echo.sh' # Windows: 'proc_sleep_echo.bat' + + p = processhandler.ProcessHandler(command, storeOutput=True) + p.run() + for i in xrange(10): + print(p.output) + time.sleep(0.5) + p.wait() + +In previous example, you will see the *p.output* list growing. + +Execution +--------- + +Status +`````` + +It is possible to query the status of the process via *poll()* that will return None if the process is still running, 0 if it ended without failures and a negative value if it was killed by a signal (Unix-only). + +.. code-block:: python + + import time + import signal + from mozprocess import processhandler + + command = './proc_sleep_echo.sh' + p = processhandler.ProcessHandler(command) + p.run() + time.sleep(2) + print("poll status: %s" % p.poll()) + time.sleep(1) + p.kill(signal.SIGKILL) + print("poll status: %s" % p.poll()) + +Timeout +``````` + +A timeout can be provided to the *run()* method. If the process last more than timeout seconds, it will be stopped. + +After execution, the property *timedOut* will be set to True if a timeout was reached. + +It is also possible to provide functions (*obj = ProcessHandler[Mixin](..., onTimeout=functions)*) that will be called if the timeout was reached. + +.. code-block:: python + + from mozprocess import processhandler + + def ontimeout(): + print("REACHED TIMEOUT") + + command = './proc_sleep_echo.sh' # Windows: 'proc_sleep_echo.bat' + functions = [ontimeout] + p = processhandler.ProcessHandler(command, onTimeout=functions) + p.run(timeout=2) + p.wait() + print("timedOut = %s" % p.timedOut) + +By default the process will be killed on timeout but it is possible to prevent this by setting *kill_on_timeout* to *False*. + +.. code-block:: python + + p = processhandler.ProcessHandler(command, onTimeout=functions, kill_on_timeout=False) + p.run(timeout=2) + p.wait() + print("timedOut = %s" % p.timedOut) + +In this case, no output will be available after the timeout, but the process will still be running. + +Waiting +``````` + +It is possible to wait until the process exits as already seen with the method *wait()*, or until the end of a timeout if given. Note that in last case the process is still alive after the timeout. + +.. code-block:: python + + command = './proc_sleep_echo.sh' # Windows: 'proc_sleep_echo.bat' + p = processhandler.ProcessHandler(command) + p.run() + p.wait(timeout=2) + print("timedOut = %s" % p.timedOut) + p.wait() + +Killing +``````` + +You can request to kill the process with the method *kill*. f the parameter "ignore_children" is set to False when the process handler class is initialized, all the process's children will be killed as well. + +Except on Windows, you can specify the signal with which to kill method the process (e.g.: *kill(signal.SIGKILL)*). + +.. code-block:: python + + import time + from mozprocess import processhandler + + command = './proc_sleep_echo.sh' # Windows: 'proc_sleep_echo.bat' + p = processhandler.ProcessHandler(command) + p.run() + time.sleep(2) + p.kill() + +End of execution +```````````````` + +You can provide a function or a list of functions to call at the end of the process using the initialization parameter *onFinish*. + +.. code-block:: python + + from mozprocess import processhandler + + def finish(): + print("Finished!!") + + command = './proc_sleep_echo.sh' # Windows: 'proc_sleep_echo.bat' + + p = processhandler.ProcessHandler(command, onFinish=finish) + p.run() + p.wait() + +Child management +---------------- + +Consider the following scripts: + +**proc_child.sh**: + +.. code-block:: sh + + #!/bin/sh + for i in a b c d e + do + echo $i + sleep 1 + done + +**proc_parent.sh**: + +.. code-block:: sh + + #!/bin/sh + ./proc_child.sh + for i in 1 2 3 4 5 + do + echo $i + sleep 1 + done + +For windows users consider: + +**proc_child.bat**: + +.. code-block:: bat + + @echo off + FOR %%A IN (a b c d e) DO ( + ECHO %%A + REM TIMEOUT /T 1 /NOBREAK + PING -n 2 127.0.0.1 > NUL + ) + +**proc_parent.bat**: + +.. code-block:: bat + + @echo off + call proc_child.bat + FOR %%A IN (1 2 3 4 5) DO ( + ECHO %%A + REM TIMEOUT /T 1 /NOBREAK + PING -n 2 127.0.0.1 > NUL + ) + +For processes that launch other processes, mozprocess allows you to get child running status, wait for child termination, and kill children. + +Ignoring children +````````````````` + +By default the *ignore_children* option is False. In that case, killing the main process will kill all its children at the same time. + +.. code-block:: python + + import time + from mozprocess import processhandler + + def finish(): + print("Finished") + + command = './proc_parent.sh' + p = processhandler.ProcessHandler(command, ignore_children=False, onFinish=finish) + p.run() + time.sleep(2) + print("kill") + p.kill() + +If *ignore_children* is set to *True*, killing will apply only to the main process that will wait children end of execution before stopping (join). + +.. code-block:: python + + import time + from mozprocess import processhandler + + def finish(): + print("Finished") + + command = './proc_parent.sh' + p = processhandler.ProcessHandler(command, ignore_children=True, onFinish=finish) + p.run() + time.sleep(2) + print("kill") + p.kill() + +API Documentation +----------------- + +.. module:: mozprocess +.. autoclass:: ProcessHandlerMixin + :members: __init__, timedOut, commandline, run, kill, processOutputLine, onTimeout, onFinish, wait +.. autoclass:: ProcessHandler + :members: |