blackbox: adds a 'blackbox' command for viewing recent logs

Adds a 'hg blackbox' command for viewing the latest entries in the blackbox log.
By default it shows the last 10 entries, but -l allows the user to specify.

hgext/blackbox.py

@@ -1,77 +1,105 b''
 # 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.
 
 """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 = *
 
   [blackbox]
   track = command, commandfinish, commandexception, exthook, pythonhook
 
   [blackbox]
   track = incoming
 
 """
 
 from mercurial import util, cmdutil
 from mercurial.i18n import _
 import os, getpass, re, string
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
 testedwith = 'internal'
 lastblackbox = None
 
 def wrapui(ui):
     class blackboxui(ui.__class__):
         @util.propertycache
         def track(self):
             return ui.configlist('blackbox', 'track', ['*'])
 
         def log(self, event, *msg, **opts):
             global lastblackbox
             super(blackboxui, self).log(event, *msg, **opts)
 
             if not '*' in self.track and not event in self.track:
                 return
 
             if util.safehasattr(self, '_blackbox'):
                 blackbox = self._blackbox
             else:
                 # certain ui instances exist outside the context of
                 # a repo, so just default to the last blackbox that
                 # was seen.
                 blackbox = lastblackbox
 
             if blackbox:
                 date = util.datestr(None, '%Y/%m/%d %H:%M:%S')
                 user = getpass.getuser()
                 formattedmsg = msg[0] % msg[1:]
                 blackbox.write('%s %s> %s' % (date, user, formattedmsg))
                 lastblackbox = blackbox
 
         def setrepo(self, repo):
             self._blackbox = repo.opener('blackbox.log', 'a')
 
     ui.__class__ = blackboxui
 
 def uisetup(ui):
     wrapui(ui)
 
 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
 
     ui.setrepo(repo)
+
+@command('^blackbox',
+    [('l', 'limit', 10, _('the number of events to show')),
+    ],
+    _('hg blackbox [OPTION]...'))
+def blackbox(ui, repo, *revs, **opts):
+    '''view the recent repository events
+    '''
+
+    if not os.path.exists(repo.join('blackbox.log')):
+        return
+
+    limit = opts.get('limit')
+    blackbox = repo.opener('blackbox.log', 'r')
+    lines = blackbox.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)))