|
|
"""
|
|
|
Module provides a class allowing to wrap communication over subprocess.Popen
|
|
|
input, output, error streams into a meaningfull, non-blocking, concurrent
|
|
|
stream processor exposing the output data as an iterator fitting to be a
|
|
|
return value passed by a WSGI applicaiton to a WSGI server per PEP 3333.
|
|
|
|
|
|
Copyright (c) 2011 Daniel Dotsenko <dotsa[at]hotmail.com>
|
|
|
|
|
|
This file is part of git_http_backend.py Project.
|
|
|
|
|
|
git_http_backend.py Project is free software: you can redistribute it and/or
|
|
|
modify it under the terms of the GNU Lesser General Public License as
|
|
|
published by the Free Software Foundation, either version 2.1 of the License,
|
|
|
or (at your option) any later version.
|
|
|
|
|
|
git_http_backend.py Project is distributed in the hope that it will be useful,
|
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
|
GNU Lesser General Public License for more details.
|
|
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
|
along with git_http_backend.py Project.
|
|
|
If not, see <http://www.gnu.org/licenses/>.
|
|
|
"""
|
|
|
import os
|
|
|
import logging
|
|
|
import subprocess32 as subprocess
|
|
|
from collections import deque
|
|
|
from threading import Event, Thread
|
|
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
|
|
|
|
|
class StreamFeeder(Thread):
|
|
|
"""
|
|
|
Normal writing into pipe-like is blocking once the buffer is filled.
|
|
|
This thread allows a thread to seep data from a file-like into a pipe
|
|
|
without blocking the main thread.
|
|
|
We close inpipe once the end of the source stream is reached.
|
|
|
"""
|
|
|
|
|
|
def __init__(self, source):
|
|
|
super(StreamFeeder, self).__init__()
|
|
|
self.daemon = True
|
|
|
filelike = False
|
|
|
self.bytes = bytes()
|
|
|
if type(source) in (type(''), bytes, bytearray): # string-like
|
|
|
self.bytes = bytes(source)
|
|
|
else: # can be either file pointer or file-like
|
|
|
if type(source) in (int, long): # file pointer it is
|
|
|
# converting file descriptor (int) stdin into file-like
|
|
|
try:
|
|
|
source = os.fdopen(source, 'rb', 16384)
|
|
|
except Exception:
|
|
|
pass
|
|
|
# let's see if source is file-like by now
|
|
|
try:
|
|
|
filelike = source.read
|
|
|
except Exception:
|
|
|
pass
|
|
|
if not filelike and not self.bytes:
|
|
|
raise TypeError("StreamFeeder's source object must be a readable "
|
|
|
"file-like, a file descriptor, or a string-like.")
|
|
|
self.source = source
|
|
|
self.readiface, self.writeiface = os.pipe()
|
|
|
|
|
|
def run(self):
|
|
|
t = self.writeiface
|
|
|
if self.bytes:
|
|
|
os.write(t, self.bytes)
|
|
|
else:
|
|
|
s = self.source
|
|
|
b = s.read(4096)
|
|
|
while b:
|
|
|
os.write(t, b)
|
|
|
b = s.read(4096)
|
|
|
os.close(t)
|
|
|
|
|
|
@property
|
|
|
def output(self):
|
|
|
return self.readiface
|
|
|
|
|
|
|
|
|
class InputStreamChunker(Thread):
|
|
|
def __init__(self, source, target, buffer_size, chunk_size):
|
|
|
|
|
|
super(InputStreamChunker, self).__init__()
|
|
|
|
|
|
self.daemon = True # die die die.
|
|
|
|
|
|
self.source = source
|
|
|
self.target = target
|
|
|
self.chunk_count_max = int(buffer_size / chunk_size) + 1
|
|
|
self.chunk_size = chunk_size
|
|
|
|
|
|
self.data_added = Event()
|
|
|
self.data_added.clear()
|
|
|
|
|
|
self.keep_reading = Event()
|
|
|
self.keep_reading.set()
|
|
|
|
|
|
self.EOF = Event()
|
|
|
self.EOF.clear()
|
|
|
|
|
|
self.go = Event()
|
|
|
self.go.set()
|
|
|
|
|
|
def stop(self):
|
|
|
self.go.clear()
|
|
|
self.EOF.set()
|
|
|
try:
|
|
|
# this is not proper, but is done to force the reader thread let
|
|
|
# go of the input because, if successful, .close() will send EOF
|
|
|
# down the pipe.
|
|
|
self.source.close()
|
|
|
except:
|
|
|
pass
|
|
|
|
|
|
def run(self):
|
|
|
s = self.source
|
|
|
t = self.target
|
|
|
cs = self.chunk_size
|
|
|
chunk_count_max = self.chunk_count_max
|
|
|
keep_reading = self.keep_reading
|
|
|
da = self.data_added
|
|
|
go = self.go
|
|
|
|
|
|
try:
|
|
|
b = s.read(cs)
|
|
|
except ValueError:
|
|
|
b = ''
|
|
|
|
|
|
timeout_input = 20
|
|
|
while b and go.is_set():
|
|
|
if len(t) > chunk_count_max:
|
|
|
keep_reading.clear()
|
|
|
keep_reading.wait(timeout_input)
|
|
|
if len(t) > chunk_count_max + timeout_input:
|
|
|
log.error("Timed out while waiting for input from subprocess.")
|
|
|
os._exit(-1) # this will cause the worker to recycle itself
|
|
|
|
|
|
t.append(b)
|
|
|
da.set()
|
|
|
b = s.read(cs)
|
|
|
self.EOF.set()
|
|
|
da.set() # for cases when done but there was no input.
|
|
|
|
|
|
|
|
|
class BufferedGenerator(object):
|
|
|
"""
|
|
|
Class behaves as a non-blocking, buffered pipe reader.
|
|
|
Reads chunks of data (through a thread)
|
|
|
from a blocking pipe, and attaches these to an array (Deque) of chunks.
|
|
|
Reading is halted in the thread when max chunks is internally buffered.
|
|
|
The .next() may operate in blocking or non-blocking fashion by yielding
|
|
|
'' if no data is ready
|
|
|
to be sent or by not returning until there is some data to send
|
|
|
When we get EOF from underlying source pipe we raise the marker to raise
|
|
|
StopIteration after the last chunk of data is yielded.
|
|
|
"""
|
|
|
|
|
|
def __init__(self, source, buffer_size=65536, chunk_size=4096,
|
|
|
starting_values=None, bottomless=False):
|
|
|
starting_values = starting_values or []
|
|
|
|
|
|
if bottomless:
|
|
|
maxlen = int(buffer_size / chunk_size)
|
|
|
else:
|
|
|
maxlen = None
|
|
|
|
|
|
self.data = deque(starting_values, maxlen)
|
|
|
self.worker = InputStreamChunker(source, self.data, buffer_size,
|
|
|
chunk_size)
|
|
|
if starting_values:
|
|
|
self.worker.data_added.set()
|
|
|
self.worker.start()
|
|
|
|
|
|
####################
|
|
|
# Generator's methods
|
|
|
####################
|
|
|
|
|
|
def __iter__(self):
|
|
|
return self
|
|
|
|
|
|
def next(self):
|
|
|
while not len(self.data) and not self.worker.EOF.is_set():
|
|
|
self.worker.data_added.clear()
|
|
|
self.worker.data_added.wait(0.2)
|
|
|
if len(self.data):
|
|
|
self.worker.keep_reading.set()
|
|
|
return bytes(self.data.popleft())
|
|
|
elif self.worker.EOF.is_set():
|
|
|
raise StopIteration
|
|
|
|
|
|
def throw(self, exc_type, value=None, traceback=None):
|
|
|
if not self.worker.EOF.is_set():
|
|
|
raise exc_type(value)
|
|
|
|
|
|
def start(self):
|
|
|
self.worker.start()
|
|
|
|
|
|
def stop(self):
|
|
|
self.worker.stop()
|
|
|
|
|
|
def close(self):
|
|
|
try:
|
|
|
self.worker.stop()
|
|
|
self.throw(GeneratorExit)
|
|
|
except (GeneratorExit, StopIteration):
|
|
|
pass
|
|
|
|
|
|
def __del__(self):
|
|
|
self.close()
|
|
|
|
|
|
####################
|
|
|
# Threaded reader's infrastructure.
|
|
|
####################
|
|
|
@property
|
|
|
def input(self):
|
|
|
return self.worker.w
|
|
|
|
|
|
@property
|
|
|
def data_added_event(self):
|
|
|
return self.worker.data_added
|
|
|
|
|
|
@property
|
|
|
def data_added(self):
|
|
|
return self.worker.data_added.is_set()
|
|
|
|
|
|
@property
|
|
|
def reading_paused(self):
|
|
|
return not self.worker.keep_reading.is_set()
|
|
|
|
|
|
@property
|
|
|
def done_reading_event(self):
|
|
|
"""
|
|
|
Done_reding does not mean that the iterator's buffer is empty.
|
|
|
Iterator might have done reading from underlying source, but the read
|
|
|
chunks might still be available for serving through .next() method.
|
|
|
|
|
|
:returns: An Event class instance.
|
|
|
"""
|
|
|
return self.worker.EOF
|
|
|
|
|
|
@property
|
|
|
def done_reading(self):
|
|
|
"""
|
|
|
Done_reding does not mean that the iterator's buffer is empty.
|
|
|
Iterator might have done reading from underlying source, but the read
|
|
|
chunks might still be available for serving through .next() method.
|
|
|
|
|
|
:returns: An Bool value.
|
|
|
"""
|
|
|
return self.worker.EOF.is_set()
|
|
|
|
|
|
@property
|
|
|
def length(self):
|
|
|
"""
|
|
|
returns int.
|
|
|
|
|
|
This is the lenght of the que of chunks, not the length of
|
|
|
the combined contents in those chunks.
|
|
|
|
|
|
__len__() cannot be meaningfully implemented because this
|
|
|
reader is just flying throuh a bottomless pit content and
|
|
|
can only know the lenght of what it already saw.
|
|
|
|
|
|
If __len__() on WSGI server per PEP 3333 returns a value,
|
|
|
the responce's length will be set to that. In order not to
|
|
|
confuse WSGI PEP3333 servers, we will not implement __len__
|
|
|
at all.
|
|
|
"""
|
|
|
return len(self.data)
|
|
|
|
|
|
def prepend(self, x):
|
|
|
self.data.appendleft(x)
|
|
|
|
|
|
def append(self, x):
|
|
|
self.data.append(x)
|
|
|
|
|
|
def extend(self, o):
|
|
|
self.data.extend(o)
|
|
|
|
|
|
def __getitem__(self, i):
|
|
|
return self.data[i]
|
|
|
|
|
|
|
|
|
class SubprocessIOChunker(object):
|
|
|
"""
|
|
|
Processor class wrapping handling of subprocess IO.
|
|
|
|
|
|
.. important::
|
|
|
|
|
|
Watch out for the method `__del__` on this class. If this object
|
|
|
is deleted, it will kill the subprocess, so avoid to
|
|
|
return the `output` attribute or usage of it like in the following
|
|
|
example::
|
|
|
|
|
|
# `args` expected to run a program that produces a lot of output
|
|
|
output = ''.join(SubprocessIOChunker(
|
|
|
args, shell=False, inputstream=inputstream, env=environ).output)
|
|
|
|
|
|
# `output` will not contain all the data, because the __del__ method
|
|
|
# has already killed the subprocess in this case before all output
|
|
|
# has been consumed.
|
|
|
|
|
|
|
|
|
|
|
|
In a way, this is a "communicate()" replacement with a twist.
|
|
|
|
|
|
- We are multithreaded. Writing in and reading out, err are all sep threads.
|
|
|
- We support concurrent (in and out) stream processing.
|
|
|
- The output is not a stream. It's a queue of read string (bytes, not unicode)
|
|
|
chunks. The object behaves as an iterable. You can "for chunk in obj:" us.
|
|
|
- We are non-blocking in more respects than communicate()
|
|
|
(reading from subprocess out pauses when internal buffer is full, but
|
|
|
does not block the parent calling code. On the flip side, reading from
|
|
|
slow-yielding subprocess may block the iteration until data shows up. This
|
|
|
does not block the parallel inpipe reading occurring parallel thread.)
|
|
|
|
|
|
The purpose of the object is to allow us to wrap subprocess interactions into
|
|
|
and interable that can be passed to a WSGI server as the application's return
|
|
|
value. Because of stream-processing-ability, WSGI does not have to read ALL
|
|
|
of the subprocess's output and buffer it, before handing it to WSGI server for
|
|
|
HTTP response. Instead, the class initializer reads just a bit of the stream
|
|
|
to figure out if error ocurred or likely to occur and if not, just hands the
|
|
|
further iteration over subprocess output to the server for completion of HTTP
|
|
|
response.
|
|
|
|
|
|
The real or perceived subprocess error is trapped and raised as one of
|
|
|
EnvironmentError family of exceptions
|
|
|
|
|
|
Example usage:
|
|
|
# try:
|
|
|
# answer = SubprocessIOChunker(
|
|
|
# cmd,
|
|
|
# input,
|
|
|
# buffer_size = 65536,
|
|
|
# chunk_size = 4096
|
|
|
# )
|
|
|
# except (EnvironmentError) as e:
|
|
|
# print str(e)
|
|
|
# raise e
|
|
|
#
|
|
|
# return answer
|
|
|
|
|
|
|
|
|
"""
|
|
|
|
|
|
# TODO: johbo: This is used to make sure that the open end of the PIPE
|
|
|
# is closed in the end. It would be way better to wrap this into an
|
|
|
# object, so that it is closed automatically once it is consumed or
|
|
|
# something similar.
|
|
|
_close_input_fd = None
|
|
|
|
|
|
_closed = False
|
|
|
|
|
|
def __init__(self, cmd, inputstream=None, buffer_size=65536,
|
|
|
chunk_size=4096, starting_values=None, fail_on_stderr=True,
|
|
|
fail_on_return_code=True, **kwargs):
|
|
|
"""
|
|
|
Initializes SubprocessIOChunker
|
|
|
|
|
|
:param cmd: A Subprocess.Popen style "cmd". Can be string or array of strings
|
|
|
:param inputstream: (Default: None) A file-like, string, or file pointer.
|
|
|
:param buffer_size: (Default: 65536) A size of total buffer per stream in bytes.
|
|
|
:param chunk_size: (Default: 4096) A max size of a chunk. Actual chunk may be smaller.
|
|
|
:param starting_values: (Default: []) An array of strings to put in front of output que.
|
|
|
:param fail_on_stderr: (Default: True) Whether to raise an exception in
|
|
|
case something is written to stderr.
|
|
|
:param fail_on_return_code: (Default: True) Whether to raise an
|
|
|
exception if the return code is not 0.
|
|
|
"""
|
|
|
|
|
|
starting_values = starting_values or []
|
|
|
if inputstream:
|
|
|
input_streamer = StreamFeeder(inputstream)
|
|
|
input_streamer.start()
|
|
|
inputstream = input_streamer.output
|
|
|
self._close_input_fd = inputstream
|
|
|
|
|
|
self._fail_on_stderr = fail_on_stderr
|
|
|
self._fail_on_return_code = fail_on_return_code
|
|
|
|
|
|
_shell = kwargs.get('shell', True)
|
|
|
kwargs['shell'] = _shell
|
|
|
|
|
|
_p = subprocess.Popen(cmd, bufsize=-1,
|
|
|
stdin=inputstream,
|
|
|
stdout=subprocess.PIPE,
|
|
|
stderr=subprocess.PIPE,
|
|
|
**kwargs)
|
|
|
|
|
|
bg_out = BufferedGenerator(_p.stdout, buffer_size, chunk_size,
|
|
|
starting_values)
|
|
|
bg_err = BufferedGenerator(_p.stderr, 16000, 1, bottomless=True)
|
|
|
|
|
|
while not bg_out.done_reading and not bg_out.reading_paused and not bg_err.length:
|
|
|
# doing this until we reach either end of file, or end of buffer.
|
|
|
bg_out.data_added_event.wait(1)
|
|
|
bg_out.data_added_event.clear()
|
|
|
|
|
|
# at this point it's still ambiguous if we are done reading or just full buffer.
|
|
|
# Either way, if error (returned by ended process, or implied based on
|
|
|
# presence of stuff in stderr output) we error out.
|
|
|
# Else, we are happy.
|
|
|
_returncode = _p.poll()
|
|
|
|
|
|
if ((_returncode and fail_on_return_code) or
|
|
|
(fail_on_stderr and _returncode is None and bg_err.length)):
|
|
|
try:
|
|
|
_p.terminate()
|
|
|
except Exception:
|
|
|
pass
|
|
|
bg_out.stop()
|
|
|
bg_err.stop()
|
|
|
if fail_on_stderr:
|
|
|
err = ''.join(bg_err)
|
|
|
raise EnvironmentError(
|
|
|
"Subprocess exited due to an error:\n" + err)
|
|
|
if _returncode and fail_on_return_code:
|
|
|
err = ''.join(bg_err)
|
|
|
if not err:
|
|
|
# maybe get empty stderr, try stdout instead
|
|
|
# in many cases git reports the errors on stdout too
|
|
|
err = ''.join(bg_out)
|
|
|
raise EnvironmentError(
|
|
|
"Subprocess exited with non 0 ret code:%s: stderr:%s" % (
|
|
|
_returncode, err))
|
|
|
|
|
|
self.process = _p
|
|
|
self.output = bg_out
|
|
|
self.error = bg_err
|
|
|
|
|
|
def __iter__(self):
|
|
|
return self
|
|
|
|
|
|
def next(self):
|
|
|
# Note: mikhail: We need to be sure that we are checking the return
|
|
|
# code after the stdout stream is closed. Some processes, e.g. git
|
|
|
# are doing some magic in between closing stdout and terminating the
|
|
|
# process and, as a result, we are not getting return code on "slow"
|
|
|
# systems.
|
|
|
result = None
|
|
|
stop_iteration = None
|
|
|
try:
|
|
|
result = self.output.next()
|
|
|
except StopIteration as e:
|
|
|
stop_iteration = e
|
|
|
|
|
|
if self.process.poll() and self._fail_on_return_code:
|
|
|
err = '%s' % ''.join(self.error)
|
|
|
raise EnvironmentError(
|
|
|
"Subprocess exited due to an error:\n" + err)
|
|
|
|
|
|
if stop_iteration:
|
|
|
raise stop_iteration
|
|
|
return result
|
|
|
|
|
|
def throw(self, type, value=None, traceback=None):
|
|
|
if self.output.length or not self.output.done_reading:
|
|
|
raise type(value)
|
|
|
|
|
|
def close(self):
|
|
|
if self._closed:
|
|
|
return
|
|
|
self._closed = True
|
|
|
try:
|
|
|
self.process.terminate()
|
|
|
except:
|
|
|
pass
|
|
|
if self._close_input_fd:
|
|
|
os.close(self._close_input_fd)
|
|
|
try:
|
|
|
self.output.close()
|
|
|
except:
|
|
|
pass
|
|
|
try:
|
|
|
self.error.close()
|
|
|
except:
|
|
|
pass
|
|
|
|
|
|
def __del__(self):
|
|
|
self.close()
|
|
|
|
