blackbox: extract global last logger to proxylogger class

So the blackboxlogger can be instantiated with a repo.

hgext/blackbox.py

@@ -1,242 +1,245 b''
 # blackbox.py - log repository events to a file for post-mortem debugging
 #
 # Copyright 2010 Nicolas Dumazet
 # 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.
 
 """log repository events to a blackbox for debugging
 
 Logs event information to .hg/blackbox.log to help debug and diagnose problems.
 The events that get logged can be configured via the blackbox.track config key.
 
 Examples::
 
   [blackbox]
   track = *
   # dirty is *EXPENSIVE* (slow);
   # each log entry indicates `+` if the repository is dirty, like :hg:`id`.
   dirty = True
   # record the source of log messages
   logsource = True
 
   [blackbox]
   track = command, commandfinish, commandexception, exthook, pythonhook
 
   [blackbox]
   track = incoming
 
   [blackbox]
   # limit the size of a log file
   maxsize = 1.5 MB
   # rotate up to N log files when the current one gets too big
   maxfiles = 3
 
   [blackbox]
   # Include nanoseconds in log entries with %f (see Python function
   # datetime.datetime.strftime)
   date-format = '%Y-%m-%d @ %H:%M:%S.%f'
 
 """
 
 from __future__ import absolute_import
 
 import errno
 import re
 
 from mercurial.i18n import _
 from mercurial.node import hex
 
 from mercurial import (
     encoding,
     pycompat,
     registrar,
 )
 from mercurial.utils import (
     dateutil,
     procutil,
 )
 
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
 # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
 # be specifying the version(s) of Mercurial they are tested with, or
 # leave the attribute unspecified.
 testedwith = 'ships-with-hg-core'
 
 cmdtable = {}
 command = registrar.command(cmdtable)
 
 configtable = {}
 configitem = registrar.configitem(configtable)
 
 configitem('blackbox', 'dirty',
     default=False,
 )
 configitem('blackbox', 'maxsize',
     default='1 MB',
 )
 configitem('blackbox', 'logsource',
     default=False,
 )
 configitem('blackbox', 'maxfiles',
     default=7,
 )
 configitem('blackbox', 'track',
     default=lambda: ['*'],
 )
 configitem('blackbox', 'date-format',
     default='%Y/%m/%d %H:%M:%S',
 )
 
-_lastlogger = None
-
 def _openlogfile(ui, vfs):
     def rotate(oldpath, newpath):
         try:
             vfs.unlink(newpath)
         except OSError as err:
             if err.errno != errno.ENOENT:
                 ui.debug("warning: cannot remove '%s': %s\n" %
                          (newpath, err.strerror))
         try:
             if newpath:
                 vfs.rename(oldpath, newpath)
         except OSError as err:
             if err.errno != errno.ENOENT:
                 ui.debug("warning: cannot rename '%s' to '%s': %s\n" %
                          (newpath, oldpath, err.strerror))
 
     maxsize = ui.configbytes('blackbox', 'maxsize')
     name = 'blackbox.log'
     if maxsize > 0:
         try:
             st = vfs.stat(name)
         except OSError:
             pass
         else:
             if st.st_size >= maxsize:
                 path = vfs.join(name)
                 maxfiles = ui.configint('blackbox', 'maxfiles')
                 for i in pycompat.xrange(maxfiles - 1, 1, -1):
                     rotate(oldpath='%s.%d' % (path, i - 1),
                            newpath='%s.%d' % (path, i))
                 rotate(oldpath=path,
                        newpath=maxfiles > 0 and path + '.1')
     return vfs(name, 'a')
 
+class proxylogger(object):
+    """Forward log events to another logger to be set later"""
+
+    def __init__(self):
+        self.logger = None
+
+    def tracked(self, event):
+        return self.logger is not None and self.logger.tracked(event)
+
+    def log(self, ui, event, msg, opts):
+        assert self.logger is not None
+        self.logger.log(ui, event, msg, opts)
+
+_lastlogger = proxylogger()
+
 class blackboxlogger(object):
     def __init__(self, ui):
         self._repo = None
         self._trackedevents = set(ui.configlist('blackbox', 'track'))
 
     @property
     def _bbvfs(self):
         vfs = None
         if self._repo:
             vfs = self._repo.vfs
             if not vfs.isdir('.'):
                 vfs = None
         return vfs
 
     def tracked(self, event):
         return b'*' in self._trackedevents or event in self._trackedevents
 
     def log(self, ui, event, msg, opts):
-        global _lastlogger
         if self._bbvfs:
-            _lastlogger = self
-        elif _lastlogger and _lastlogger._bbvfs:
-            # certain logger instances exist outside the context of
-            # a repo, so just default to the last blackbox logger that
-            # was seen.
-            pass
+            _lastlogger.logger = self
         else:
             return
-        _lastlogger._log(ui, event, msg, opts)
 
-    def _log(self, ui, event, msg, opts):
         default = ui.configdate('devel', 'default-date')
         date = dateutil.datestr(default, ui.config('blackbox', 'date-format'))
         user = procutil.getuser()
         pid = '%d' % procutil.getpid()
         rev = '(unknown)'
         changed = ''
         ctx = self._repo[None]
         parents = ctx.parents()
         rev = ('+'.join([hex(p.node()) for p in parents]))
         if (ui.configbool('blackbox', 'dirty') and
             ctx.dirty(missing=True, merge=False, branch=False)):
             changed = '+'
         if ui.configbool('blackbox', 'logsource'):
             src = ' [%s]' % event
         else:
             src = ''
         try:
             fmt = '%s %s @%s%s (%s)%s> %s'
             args = (date, user, rev, changed, pid, src, msg)
             with _openlogfile(ui, self._bbvfs) as fp:
                 fp.write(fmt % args)
         except (IOError, OSError) as err:
             # deactivate this to avoid failed logging again
             self._repo = None
             ui.debug('warning: cannot write to blackbox.log: %s\n' %
                      encoding.strtolocal(err.strerror))
 
     def setrepo(self, repo):
         self._repo = repo
 
 def uipopulate(ui):
-    ui.setlogger(b'blackbox', blackboxlogger(ui))
+    ui.setlogger(b'blackbox', _lastlogger)
 
 def reposetup(ui, repo):
     # During 'hg pull' a httppeer repo is created to represent the remote repo.
     # It doesn't have a .hg directory to put a blackbox in, so we don't do
     # the blackbox setup for it.
     if not repo.local():
         return
 
     # Since blackbox.log is stored in the repo directory, the logger should be
     # instantiated per repository.
     logger = blackboxlogger(ui)
     ui.setlogger(b'blackbox', logger)
-    if logger:
-        logger.setrepo(repo)
+    logger.setrepo(repo)
 
-        # Set _lastlogger even if ui.log is not called. This gives blackbox a
-        # fallback place to log.
-        global _lastlogger
-        if _lastlogger is None:
-            _lastlogger = logger
+    # Set _lastlogger even if ui.log is not called. This gives blackbox a
+    # fallback place to log
+    if _lastlogger.logger is None:
+        _lastlogger.logger = logger
 
     repo._wlockfreeprefix.add('blackbox.log')
 
 @command('blackbox',
     [('l', 'limit', 10, _('the number of events to show')),
     ],
     _('hg blackbox [OPTION]...'),
     helpcategory=command.CATEGORY_MAINTENANCE,
     helpbasic=True)
 def blackbox(ui, repo, *revs, **opts):
     '''view the recent repository events
     '''
 
     if not repo.vfs.exists('blackbox.log'):
         return
 
     limit = opts.get(r'limit')
     fp = repo.vfs('blackbox.log', 'r')
     lines = fp.read().split('\n')
 
     count = 0
     output = []
     for line in reversed(lines):
         if count >= limit:
             break
 
         # count the commands by matching lines like: 2013/01/23 19:13:36 root>
         if re.match('^\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2} .*> .*', line):
             count += 1
         output.append(line)
 
     ui.status('\n'.join(reversed(output)))