profile: upgrade the "profile" context manager to a full class So far we have been able to use a simple decorator for this. However using the current context manager makes the scope of the profiling in dispatch constrainted and the time frame to decide to enable profiling quite limited (using "maybeprofile") This is the first step toward the ability to enable the profiling from within the profiling scope. eg:: with maybeprofiling(ui) as profiler: ... bar.foo(): ... if options['profile']: profiler.start() ... fooz() ... My target usecase is adding support for "--profile" to alias definitions with effect. These are to be used with "profiling.output=blackbox" to gather data about operation that get slow from time to time (eg: pull being minutes instead of seconds from time to time). Of course, in such case, the scope of the profiling would be smaller since profiler would be started after running extensions 'reposetup' (and other potentially costly logic), but these are not relevant for my target usecase (multiple second commits, multiple tens of seconds pull). Currently adding '--profile' to a command through alias requires to re-spin a Mercurial binary (using "!$HG" in alias), which as a significant performance impact, especially in context where startup performance is being worked on... An alternative approach would be to stop using the context manager in dispatch and move back to a try/finally setup.

# debugshell extension
"""a python shell with repo, changelog & manifest objects"""

from __future__ import absolute_import
import code
import mercurial
import sys
from mercurial import (
    demandimport,
    registrar,
)

cmdtable = {}
command = registrar.command(cmdtable)

def pdb(ui, repo, msg, **opts):
    objects = {
        'mercurial': mercurial,
        'repo': repo,
        'cl': repo.changelog,
        'mf': repo.manifestlog,
    }

    code.interact(msg, local=objects)

def ipdb(ui, repo, msg, **opts):
    import IPython

    cl = repo.changelog
    mf = repo.manifestlog
    cl, mf # use variables to appease pyflakes

    IPython.embed()

@command('debugshell|dbsh', [])
def debugshell(ui, repo, **opts):
    bannermsg = "loaded repo : %s\n" \
                "using source: %s" % (repo.root,
                                      mercurial.__path__[0])

    pdbmap = {
        'pdb'  : 'code',
        'ipdb' : 'IPython'
    }

    debugger = ui.config("ui", "debugger")
    if not debugger:
        debugger = 'pdb'

    # if IPython doesn't exist, fallback to code.interact
    try:
        with demandimport.deactivated():
            __import__(pdbmap[debugger])
    except ImportError:
        ui.warn(("%s debugger specified but %s module was not found\n")
                % (debugger, pdbmap[debugger]))
        debugger = 'pdb'

    getattr(sys.modules[__name__], debugger)(ui, repo, bannermsg, **opts)