[PATCH 1 of 6] blackbox: adds a blackbox extension

[Durham Goode]

# HG changeset patch
# User Durham Goode <durham at fb.com>
# Date 1360429429 28800
# Node ID 30544b5277d09002d6cac8c363652f71bb807516
# Parent  57b7531a5705a099637f6d6bedd4de509fb2a441
blackbox: adds a blackbox extension

Adds a blackbox extension that listens to ui.log() and writes the messages to
.hg/blackbox.log. Future commits will use ui.log() to log commands, unhandled
exceptions, incoming changes, and hooks.  The extension defaults to logging
everything, but can be configured via blackbox.trackedevents to only log
certain events. Log lines are of the format:  "date time user> message"

Example log line:
2013/02/09 08:35:19 durham> 1 incoming changes - new heads: d84ced58aaa

diff --git a/hgext/blackbox.py b/hgext/blackbox.py
new file mode 100644
--- /dev/null
+++ b/hgext/blackbox.py
@@ -0,0 +1,68 @@
+"""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.trackedevents
+config key. Examples:
+
+  [blackbox]
+  trackedevents=*
+
+  [blackbox]
+  trackedevents=command,commandfinished,commandexception,exthook,pythonhook
+
+  [blackbox]
+  trackedevents=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 trackedevents(self):
+            events = ui.config('blackbox', 'trackedevents', '*')
+            return string.split(events, ',')
+
+        def log(self, command, msg):
+            global lastblackbox
+            super(blackboxui, self).log(command, msg)
+
+            if not '*' in self.trackedevents and \
+               not command in self.trackedevents:
+                return
+
+            if '_blackbox' in self.__dict__:
+                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()
+                blackbox.write('%s %s> %s\n' % (date, user, msg))
+                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):
+    if not repo.local():
+        return
+
+    ui.setrepo(repo)