mercurial/hook.py

hooks: replace if-try-finally with a "with" statement

This seems like a textbook case for the new demandimport.deactivated
context manager: check if something must be done, do it, and cleanup
at the end regardless of exceptions.

The diff isn't as bad as it seems. It's just all the whitespace
changes due to needing an extra level of indentation. It looks cleaner
with `hg diff -w`.

# hook.py - hook support for mercurial
#
# Copyright 2007 Matt Mackall <[e-mail]>
#
# 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 os, sys, time
import extensions, util, demandimport, error

def _pythonhook(ui, repo, name, hname, funcname, args, throw):
    '''call python hook. hook is callable object, looked up as
    name in python module. if callable returns "true", hook
    fails, else passes. if hook raises exception, treated as
    hook failure. exception propagates if throw is "true".

    reason for "true" meaning "hook failed" is so that
    unmodified commands (e.g. mercurial.commands.update) can
    be run as hooks without wrappers to convert return values.'''

    if callable(funcname):
        obj = funcname
        funcname = obj.__module__ + "." + obj.__name__
    else:
        d = funcname.rfind('.')
        if d == -1:
            raise util.Abort(_('%s hook is invalid ("%s" not in '
                               'a module)') % (hname, funcname))
        modname = funcname[:d]
        oldpaths = sys.path
        if util.mainfrozen():
            # binary installs require sys.path manipulation
            modpath, modfile = os.path.split(modname)
            if modpath and modfile:
                sys.path = sys.path[:] + [modpath]
                modname = modfile
        with demandimport.deactivated():
            try:
                obj = __import__(modname)
            except ImportError:
                e1 = sys.exc_type, sys.exc_value, sys.exc_traceback
                try:
                    # extensions are loaded with hgext_ prefix
                    obj = __import__("hgext_%s" % modname)
                except ImportError:
                    e2 = sys.exc_type, sys.exc_value, sys.exc_traceback
                    if ui.tracebackflag:
                        ui.warn(_('exception from first failed import '
                                  'attempt:\n'))
                    ui.traceback(e1)
                    if ui.tracebackflag:
                        ui.warn(_('exception from second failed import '
                                  'attempt:\n'))
                    ui.traceback(e2)
                    raise util.Abort(_('%s hook is invalid '
                                       '(import of "%s" failed)') %
                                     (hname, modname))
        sys.path = oldpaths
        try:
            for p in funcname.split('.')[1:]:
                obj = getattr(obj, p)
        except AttributeError:
            raise util.Abort(_('%s hook is invalid '
                               '("%s" is not defined)') %
                             (hname, funcname))
        if not callable(obj):
            raise util.Abort(_('%s hook is invalid '
                               '("%s" is not callable)') %
                             (hname, funcname))

    ui.note(_("calling hook %s: %s\n") % (hname, funcname))
    starttime = time.time()

    try:
        # redirect IO descriptors to the ui descriptors so hooks
        # that write directly to these don't mess up the command
        # protocol when running through the command server
        old = sys.stdout, sys.stderr, sys.stdin
        sys.stdout, sys.stderr, sys.stdin = ui.fout, ui.ferr, ui.fin

        r = obj(ui=ui, repo=repo, hooktype=name, **args)
    except Exception, exc:
        if isinstance(exc, util.Abort):
            ui.warn(_('error: %s hook failed: %s\n') %
                         (hname, exc.args[0]))
        else:
            ui.warn(_('error: %s hook raised an exception: '
                           '%s\n') % (hname, exc))
        if throw:
            raise
        ui.traceback()
        return True
    finally:
        sys.stdout, sys.stderr, sys.stdin = old
        duration = time.time() - starttime
        ui.log('pythonhook', 'pythonhook-%s: %s finished in %0.2f seconds\n',
               name, funcname, duration)
    if r:
        if throw:
            raise error.HookAbort(_('%s hook failed') % hname)
        ui.warn(_('warning: %s hook failed\n') % hname)
    return r

def _exthook(ui, repo, name, cmd, args, throw):
    ui.note(_("running hook %s: %s\n") % (name, cmd))

    starttime = time.time()
    env = {}
    for k, v in args.iteritems():
        if callable(v):
            v = v()
        if isinstance(v, dict):
            # make the dictionary element order stable across Python
            # implementations
            v = ('{' +
                 ', '.join('%r: %r' % i for i in sorted(v.iteritems())) +
                 '}')
        env['HG_' + k.upper()] = v

    if repo:
        cwd = repo.root
    else:
        cwd = os.getcwd()
    r = ui.system(cmd, environ=env, cwd=cwd)

    duration = time.time() - starttime
    ui.log('exthook', 'exthook-%s: %s finished in %0.2f seconds\n',
           name, cmd, duration)
    if r:
        desc, r = util.explainexit(r)
        if throw:
            raise error.HookAbort(_('%s hook %s') % (name, desc))
        ui.warn(_('warning: %s hook %s\n') % (name, desc))
    return r

def _allhooks(ui):
    hooks = []
    for name, cmd in ui.configitems('hooks'):
        if not name.startswith('priority'):
            priority = ui.configint('hooks', 'priority.%s' % name, 0)
            hooks.append((-priority, len(hooks), name, cmd))
    return [(k, v) for p, o, k, v in sorted(hooks)]

_redirect = False
def redirect(state):
    global _redirect
    _redirect = state

def hook(ui, repo, name, throw=False, **args):
    if not ui.callhooks:
        return False

    r = False
    oldstdout = -1

    try:
        for hname, cmd in _allhooks(ui):
            if hname.split('.')[0] != name or not cmd:
                continue

            if oldstdout == -1 and _redirect:
                try:
                    stdoutno = sys.__stdout__.fileno()
                    stderrno = sys.__stderr__.fileno()
                    # temporarily redirect stdout to stderr, if possible
                    if stdoutno >= 0 and stderrno >= 0:
                        sys.__stdout__.flush()
                        oldstdout = os.dup(stdoutno)
                        os.dup2(stderrno, stdoutno)
                except (OSError, AttributeError):
                    # files seem to be bogus, give up on redirecting (WSGI, etc)
                    pass

            if callable(cmd):
                r = _pythonhook(ui, repo, name, hname, cmd, args, throw) or r
            elif cmd.startswith('python:'):
                if cmd.count(':') >= 2:
                    path, cmd = cmd[7:].rsplit(':', 1)
                    path = util.expandpath(path)
                    if repo:
                        path = os.path.join(repo.root, path)
                    try:
                        mod = extensions.loadpath(path, 'hghook.%s' % hname)
                    except Exception:
                        ui.write(_("loading %s hook failed:\n") % hname)
                        raise
                    hookfn = getattr(mod, cmd)
                else:
                    hookfn = cmd[7:].strip()
                r = _pythonhook(ui, repo, name, hname, hookfn, args, throw) or r
            else:
                r = _exthook(ui, repo, hname, cmd, args, throw) or r

            # The stderr is fully buffered on Windows when connected to a pipe.
            # A forcible flush is required to make small stderr data in the
            # remote side available to the client immediately.
            sys.stderr.flush()
    finally:
        if _redirect and oldstdout >= 0:
            os.dup2(oldstdout, stdoutno)
            os.close(oldstdout)

    return r