annotate mercurial/worker.py @ 20964:a939eeb94833

http: reuse authentication info after the first failed request (issue3567)

[This was applied in 181108726ea5 but backed out again in af02783dea65 because
of Python 2.4 issues. This edition and test-http.t works with Python 2.4.]

Context: mercurial access to repository server with http access, and this
server is protected by basic auth.

Before patch:

* mercurial try an anonymous access to server, server return 401 response and
  mercurial resend request with login / password information

After patch:

* mercurial try an anonymous access to server, server return
  401 response. For all next requests, mercurial keep in memory this
  information (this server need basic auth information).

This patch reduce the number of http access against mercurial server.

Example, before patch:

10.10.168.170 - - [25/Oct/2013:15:44:51 +0200] "GET /hg/testagt?cmd=capabilities
HTTP/1.1" 401 260 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:44:52 +0200] "GET /hg/testagt?cmd=capabilities
HTTP/1.1" 200 147 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:00 +0200] "GET /hg/testagt?cmd=capabilities
HTTP/1.1" 401 260 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:01 +0200] "GET /hg/testagt?cmd=capabilities
HTTP/1.1" 200 147 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:03 +0200] "GET /hg/testagt?cmd=batch
HTTP/1.1" 401 260 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:04 +0200] "GET /hg/testagt?cmd=batch
HTTP/1.1" 200 42 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:06 +0200] "GET /hg/testagt?cmd=getbundle
HTTP/1.1" 401 260 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:07 +0200] "GET /hg/testagt?cmd=getbundle
HTTP/1.1" 200 61184 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:09 +0200] "GET /hg/testagt?cmd=listkeys
HTTP/1.1" 401 260 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:10 +0200] "GET /hg/testagt?cmd=listkeys
HTTP/1.1" 200 15 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:12 +0200] "GET /hg/testagt?cmd=listkeys
HTTP/1.1" 401 260 "-" "mercurial/proto-1.0"
10.10.168.170 - - [25/Oct/2013:15:45:12 +0200] "GET /hg/testagt?cmd=listkeys
HTTP/1.1" 200 - "-" "mercurial/proto-1.0"

Example after patch:

10.10.168.170 - - [28/Oct/2013:11:49:14 +0100] "GET /hg/testagt?cmd=capabilities
HTTP/1.1" 401 260 "-" "mercurial/proto-1.0"
10.10.168.170 - - [28/Oct/2013:11:49:15 +0100] "GET /hg/testagt?cmd=capabilities
HTTP/1.1" 200 147 "-" "mercurial/proto-1.0"
10.10.168.170 - - [28/Oct/2013:11:49:17 +0100] "GET /hg/testagt?cmd=batch
HTTP/1.1" 200 42 "-" "mercurial/proto-1.0"
10.10.168.170 - - [28/Oct/2013:11:49:19 +0100] "GET /hg/testagt?cmd=getbundle
HTTP/1.1" 200 61184 "-" "mercurial/proto-1.0"
10.10.168.170 - - [28/Oct/2013:11:49:22 +0100] "GET /hg/testagt?cmd=listkeys
HTTP/1.1" 200 15 "-" "mercurial/proto-1.0"
10.10.168.170 - - [28/Oct/2013:11:49:24 +0100] "GET /hg/testagt?cmd=listkeys
HTTP/1.1" 200 - "-" "mercurial/proto-1.0"

In this last example, you can see only one 401 response.

# worker.py - master-slave parallelism support
#
# Copyright 2013 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from i18n import _
import errno, os, signal, sys, threading
import util

def countcpus():
    '''try to count the number of CPUs on the system'''

    # posix
    try:
        n = int(os.sysconf('SC_NPROCESSORS_ONLN'))
        if n > 0:
            return n
    except (AttributeError, ValueError):
        pass

    # windows
    try:
        n = int(os.environ['NUMBER_OF_PROCESSORS'])
        if n > 0:
            return n
    except (KeyError, ValueError):
        pass

    return 1

def _numworkers(ui):
    s = ui.config('worker', 'numcpus')
    if s:
        try:
            n = int(s)
            if n >= 1:
                return n
        except ValueError:
            raise util.Abort(_('number of cpus must be an integer'))
    return min(max(countcpus(), 4), 32)

if os.name == 'posix':
    _startupcost = 0.01
else:
    _startupcost = 1e30

def worthwhile(ui, costperop, nops):
    '''try to determine whether the benefit of multiple processes can
    outweigh the cost of starting them'''
    linear = costperop * nops
    workers = _numworkers(ui)
    benefit = linear - (_startupcost * workers + linear / workers)
    return benefit >= 0.15

def worker(ui, costperarg, func, staticargs, args):
    '''run a function, possibly in parallel in multiple worker
    processes.

    returns a progress iterator

    costperarg - cost of a single task

    func - function to run

    staticargs - arguments to pass to every invocation of the function

    args - arguments to split into chunks, to pass to individual
    workers
    '''
    if worthwhile(ui, costperarg, len(args)):
        return _platformworker(ui, func, staticargs, args)
    return func(*staticargs + (args,))

def _posixworker(ui, func, staticargs, args):
    rfd, wfd = os.pipe()
    workers = _numworkers(ui)
    oldhandler = signal.getsignal(signal.SIGINT)
    signal.signal(signal.SIGINT, signal.SIG_IGN)
    pids, problem = [], [0]
    for pargs in partition(args, workers):
        pid = os.fork()
        if pid == 0:
            signal.signal(signal.SIGINT, oldhandler)
            try:
                os.close(rfd)
                for i, item in func(*(staticargs + (pargs,))):
                    os.write(wfd, '%d %s\n' % (i, item))
                os._exit(0)
            except KeyboardInterrupt:
                os._exit(255)
                # other exceptions are allowed to propagate, we rely
                # on lock.py's pid checks to avoid release callbacks
        pids.append(pid)
    pids.reverse()
    os.close(wfd)
    fp = os.fdopen(rfd, 'rb', 0)
    def killworkers():
        # if one worker bails, there's no good reason to wait for the rest
        for p in pids:
            try:
                os.kill(p, signal.SIGTERM)
            except OSError, err:
                if err.errno != errno.ESRCH:
                    raise
    def waitforworkers():
        for _ in pids:
            st = _exitstatus(os.wait()[1])
            if st and not problem[0]:
                problem[0] = st
                killworkers()
    t = threading.Thread(target=waitforworkers)
    t.start()
    def cleanup():
        signal.signal(signal.SIGINT, oldhandler)
        t.join()
        status = problem[0]
        if status:
            if status < 0:
                os.kill(os.getpid(), -status)
            sys.exit(status)
    try:
        for line in fp:
            l = line.split(' ', 1)
            yield int(l[0]), l[1][:-1]
    except: # re-raises
        killworkers()
        cleanup()
        raise
    cleanup()

def _posixexitstatus(code):
    '''convert a posix exit status into the same form returned by
    os.spawnv

    returns None if the process was stopped instead of exiting'''
    if os.WIFEXITED(code):
        return os.WEXITSTATUS(code)
    elif os.WIFSIGNALED(code):
        return -os.WTERMSIG(code)

if os.name != 'nt':
    _platformworker = _posixworker
    _exitstatus = _posixexitstatus

def partition(lst, nslices):
    '''partition a list into N slices of equal size'''
    n = len(lst)
    chunk, slop = n / nslices, n % nslices
    end = 0
    for i in xrange(nslices):
        start = end
        end = start + chunk
        if slop:
            end += 1
            slop -= 1
        yield lst[start:end]