extensions: add detailed loading information

This lets you track down what exactly is happening during extension loading,
and how long various steps took.

mercurial/extensions.py

@@ -124,7 +124,7 b' def _reportimporterror(ui, err, failed, '
     # note: this ui.debug happens before --debug is processed,
     #       Use --config ui.debug=1 to see them.
     if ui.configbool('devel', 'debug.extensions'):
-        ui.debug('could not import %s (%s): trying %s\n'
+        ui.debug('debug.extensions:     - could not import %s (%s): trying %s\n'
                  % (failed, stringutil.forcebytestr(err), next))
         if ui.debugflag:
             ui.traceback()
@@ -166,7 +166,7 b' def _validatetables(ui, mod):'
             _rejectunicode(t, o._table)
     _validatecmdtable(ui, getattr(mod, 'cmdtable', {}))
 
-def load(ui, name, path):
+def load(ui, name, path, log=lambda *a: None):
     if name.startswith('hgext.') or name.startswith('hgext/'):
         shortname = name[6:]
     else:
@@ -175,8 +175,11 b' def load(ui, name, path):'
         return None
     if shortname in _extensions:
         return _extensions[shortname]
+    log('  - loading extension: %r\n', shortname)
     _extensions[shortname] = None
+    with util.timedcm() as stats:
     mod = _importext(name, path, bind(_reportimporterror, ui))
+    log('  > %r extension loaded in %s\n', shortname, stats)
 
     # Before we do anything with the extension, check against minimum stated
     # compatibility. This gives extension authors a mechanism to have their
@@ -187,12 +190,16 b' def load(ui, name, path):'
         ui.warn(_('(third party extension %s requires version %s or newer '
                   'of Mercurial; disabling)\n') % (shortname, minver))
         return
+    log('    - validating extension tables: %r\n', shortname)
     _validatetables(ui, mod)
 
     _extensions[shortname] = mod
     _order.append(shortname)
+    log('    - invoking registered callbacks: %r\n', shortname)
+    with util.timedcm() as stats:
     for fn in _aftercallbacks.get(shortname, []):
         fn(loaded=True)
+    log('    > callbacks completed in %s\n', stats)
     return mod
 
 def _runuisetup(name, ui):
@@ -225,17 +232,27 b' def _runextsetup(name, ui):'
     return True
 
 def loadall(ui, whitelist=None):
+    if ui.configbool('devel', 'debug.extensions'):
+        log = lambda msg, *values: ui.debug('debug.extensions: ',
+            msg % values, label='debug.extensions')
+    else:
+        log = lambda *a, **kw: None
     result = ui.configitems("extensions")
     if whitelist is not None:
         result = [(k, v) for (k, v) in result if k in whitelist]
     newindex = len(_order)
+    log('loading %sextensions\n', 'additional ' if newindex else '')
+    log('- processing %d entries\n', len(result))
+    with util.timedcm() as stats:
     for (name, path) in result:
         if path:
             if path[0:1] == '!':
+                    if name not in _disabledextensions:
+                        log('  - skipping disabled extension: %r\n', name)
                 _disabledextensions[name] = path[1:]
                 continue
         try:
-            load(ui, name, path)
+                load(ui, name, path, log)
         except Exception as inst:
             msg = stringutil.forcebytestr(inst)
             if path:
@@ -247,6 +264,9 b' def loadall(ui, whitelist=None):'
             if isinstance(inst, error.Hint) and inst.hint:
                 ui.warn(_("*** (%s)\n") % inst.hint)
             ui.traceback()
+
+    log('> loaded %d extensions, total time %s\n',
+        len(_order) - newindex, stats)
     # list of (objname, loadermod, loadername) tuple:
     # - objname is the name of an object in extension module,
     #   from which extra information is loaded
@@ -258,29 +278,47 b' def loadall(ui, whitelist=None):'
     earlyextraloaders = [
         ('configtable', configitems, 'loadconfigtable'),
     ]
+
+    log('- loading configtable attributes\n')
     _loadextra(ui, newindex, earlyextraloaders)
 
     broken = set()
+    log('- executing uisetup hooks\n')
     for name in _order[newindex:]:
+        log('  - running uisetup for %r\n', name)
+        with util.timedcm() as stats:
         if not _runuisetup(name, ui):
+                log('    - the %r extension uisetup failed\n', name)
             broken.add(name)
+        log('  > uisetup for %r took %s\n', name, stats)
 
+    log('- executing extsetup hooks\n')
     for name in _order[newindex:]:
         if name in broken:
             continue
+        log('  - running extsetup for %r\n', name)
+        with util.timedcm() as stats:
         if not _runextsetup(name, ui):
+                log('    - the %r extension extsetup failed\n', name)
             broken.add(name)
+        log('  > extsetup for %r took %s\n', name, stats)
 
     for name in broken:
+        log('    - disabling broken %r extension\n', name)
         _extensions[name] = None
 
     # Call aftercallbacks that were never met.
+    log('- executing remaining aftercallbacks\n')
+    with util.timedcm() as stats:
     for shortname in _aftercallbacks:
         if shortname in _extensions:
             continue
 
         for fn in _aftercallbacks[shortname]:
+                log('  - extension %r not loaded, notify callbacks\n',
+                    shortname)
             fn(loaded=False)
+    log('> remaining aftercallbacks completed in %s\n', stats)
 
     # loadall() is called multiple times and lingering _aftercallbacks
     # entries could result in double execution. See issue4646.
@@ -304,6 +342,7 b' def loadall(ui, whitelist=None):'
     # - loadermod is the module where loader is placed
     # - loadername is the name of the function,
     #   which takes (ui, extensionname, extraobj) arguments
+    log('- loading extension registration objects\n')
     extraloaders = [
         ('cmdtable', commands, 'loadcmdtable'),
         ('colortable', color, 'loadcolortable'),
@@ -314,7 +353,10 b' def loadall(ui, whitelist=None):'
         ('templatefunc', templatefuncs, 'loadfunction'),
         ('templatekeyword', templatekw, 'loadkeyword'),
     ]
+    with util.timedcm() as stats:
     _loadextra(ui, newindex, extraloaders)
+    log('> extension registration object loading took %s\n', stats)
+    log('extension loading complete\n')
 
 def _loadextra(ui, newindex, extraloaders):
     for name in _order[newindex:]:

mercurial/hg.py

@@ -9,6 +9,7 b''
 from __future__ import absolute_import
 
 import errno
+import functools
 import hashlib
 import os
 import shutil
@@ -162,9 +163,16 b' def _peerorrepo(ui, path, create=False, '
     """return a repository object for the specified path"""
     obj = _peerlookup(path).instance(ui, path, create, intents=intents)
     ui = getattr(obj, "ui", ui)
+    if ui.configbool('devel', 'debug.extensions'):
+        log = functools.partial(
+            ui.debug, 'debug.extensions: ', label='debug.extensions')
+    else:
+        log = lambda *a, **kw: None
     for f in presetupfuncs or []:
         f(ui, obj)
+    log('- executing reposetup hooks\n')
     for name, module in extensions.extensions(ui):
+        log('  - running reposetup for %s\n' % (name,))
         hook = getattr(module, 'reposetup', None)
         if hook:
             hook(ui, obj)

tests/test-bad-extension.t

@@ -77,18 +77,49 b' show traceback for ImportError of hgext.'
   $ (hg help help --traceback --debug --config devel.debug.extensions=yes 2>&1) \
   > | grep -v '^ ' \
   > | egrep 'extension..[^p]|^Exception|Traceback|ImportError|not import'
+  debug.extensions: loading extensions
+  debug.extensions: - processing 5 entries
+  debug.extensions:   - loading extension: 'gpg'
+  debug.extensions:   > 'gpg' extension loaded in * (glob)
+  debug.extensions:     - validating extension tables: 'gpg'
+  debug.extensions:     - invoking registered callbacks: 'gpg'
+  debug.extensions:     > callbacks completed in * (glob)
+  debug.extensions:   - loading extension: 'badext'
   *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
   Traceback (most recent call last):
   Exception: bit bucket overflow
-  could not import hgext.badext2 (No module named *badext2): trying hgext3rd.badext2 (glob)
+  debug.extensions:   - loading extension: 'baddocext'
+  debug.extensions:   > 'baddocext' extension loaded in * (glob)
+  debug.extensions:     - validating extension tables: 'baddocext'
+  debug.extensions:     - invoking registered callbacks: 'baddocext'
+  debug.extensions:     > callbacks completed in * (glob)
+  debug.extensions:   - loading extension: 'badext2'
+  debug.extensions:     - could not import hgext.badext2 (No module named badext2): trying hgext3rd.badext2
   Traceback (most recent call last):
   ImportError: No module named *badext2 (glob)
-  could not import hgext3rd.badext2 (No module named *badext2): trying badext2 (glob)
+  debug.extensions:     - could not import hgext3rd.badext2 (No module named badext2): trying badext2
   Traceback (most recent call last):
   ImportError: No module named *badext2 (glob)
   *** failed to import extension badext2: No module named badext2
   Traceback (most recent call last):
   ImportError: No module named badext2
+  debug.extensions: > loaded 2 extensions, total time * (glob)
+  debug.extensions: - loading configtable attributes
+  debug.extensions: - executing uisetup hooks
+  debug.extensions:   - running uisetup for 'gpg'
+  debug.extensions:   > uisetup for 'gpg' took * (glob)
+  debug.extensions:   - running uisetup for 'baddocext'
+  debug.extensions:   > uisetup for 'baddocext' took * (glob)
+  debug.extensions: - executing extsetup hooks
+  debug.extensions:   - running extsetup for 'gpg'
+  debug.extensions:   > extsetup for 'gpg' took * (glob)
+  debug.extensions:   - running extsetup for 'baddocext'
+  debug.extensions:   > extsetup for 'baddocext' took * (glob)
+  debug.extensions: - executing remaining aftercallbacks
+  debug.extensions: > remaining aftercallbacks completed in * (glob)
+  debug.extensions: - loading extension registration objects
+  debug.extensions: > extension registration object loading took * (glob)
+  debug.extensions: extension loading complete
 
 confirm that there's no crash when an extension's documentation is bad