comparison mercurial/dispatch.py @ 34306:bd50aa1aa035

alias: make alias command lazily resolved

With many aliases, resolving them could have some visible overhead. Below is
part of traceprof [1] output of `hg bookmark --hidden`:

  (time unit: ms)
  37  \ addaliases                             dispatch.py:526
  37   | __init__ (60 times)                   dispatch.py:402
  33   | findcmd (108 times)                   cmdutil.py:721
  16   | findpossible (49 times)               cmdutil.py:683

It may get better by optimizing `findcmd` to do a bisect, but we don't
really need to resolve an alias if it's not used, so let's make those
command entries lazy.

After this patch, `addalias` takes less than 1ms.

.. perf:: improved performance when many aliases are defined

[1]: https://bitbucket.org/facebook/hg-experimental/src/9aca0dbdbdfc48457e5d2581ca2d6e662fced2e6/hgext3rd/traceprof.pyx

Differential Revision: https://phab.mercurial-scm.org/D805

34305:0e48813cc106

            except error.SignatureError:
                args = ' '.join([self.cmdname] + self.args)
                ui.debug("alias '%s' expands to '%s'\n" % (self.name, args))
                raise

def addaliases(ui, cmdtable):
    # aliases are processed after extensions have been loaded, so they
    # may use extension commands. Aliases can also use other alias definitions,
    # but only if they have been defined prior to the current definition.
    for alias, definition in ui.configitems('alias'):
        try:
            if cmdtable[alias][0].definition == definition:
                continue
        except (KeyError, AttributeError):
            # definition might not exist or it might not be a cmdalias
            pass

        source = ui.configsource('alias', alias)
        aliasdef = cmdalias(alias, definition, cmdtable, source)
        cmdtable[aliasdef.name] = (aliasdef, aliasdef.opts, aliasdef.help)

def _parse(ui, args):
    options = {}
    cmdoptions = {}

34306:bd50aa1aa035

            except error.SignatureError:
                args = ' '.join([self.cmdname] + self.args)
                ui.debug("alias '%s' expands to '%s'\n" % (self.name, args))
                raise

class lazyaliasentry(object):
    """like a typical command entry (func, opts, help), but is lazy"""

    def __init__(self, name, definition, cmdtable, source):
        self.name = name
        self.definition = definition
        self.cmdtable = cmdtable.copy()
        self.source = source

    @util.propertycache
    def _aliasdef(self):
        return cmdalias(self.name, self.definition, self.cmdtable, self.source)

    def __getitem__(self, n):
        aliasdef = self._aliasdef
        if n == 0:
            return aliasdef
        elif n == 1:
            return aliasdef.opts
        elif n == 2:
            return aliasdef.help
        else:
            raise IndexError

    def __iter__(self):
        for i in range(3):
            yield self[i]

    def __len__(self):
        return 3

def addaliases(ui, cmdtable):
    # aliases are processed after extensions have been loaded, so they
    # may use extension commands. Aliases can also use other alias definitions,
    # but only if they have been defined prior to the current definition.
    for alias, definition in ui.configitems('alias'):
        try:
            if cmdtable[alias].definition == definition:
                continue
        except (KeyError, AttributeError):
            # definition might not exist or it might not be a cmdalias
            pass

        source = ui.configsource('alias', alias)
        entry = lazyaliasentry(alias, definition, cmdtable, source)
        cmdtable[alias] = entry

def _parse(ui, args):
    options = {}
    cmdoptions = {}