hgext/largefiles/wirestore.py

match: introduce boolean prefix() method

tl;dr: This is another step towards a (previously unstated) goal of
eliminating match.files() in conditions.

There are four types of matchers:

 * always: Matches everything, checked with always(), files() is empty

 * exact: Matches exact set of files, checked with isexact(), files()
   contains the files to match

 * patterns: Matches more complex patterns, checked with anypats(),
   files() contains roots of the matched patterns

 * prefix: Matches simple 'path:' patterns as prefixes ('foo' matches
   both 'foo' and 'foo/bar'), no single method to check, files()
   contains the prefixes to match

For completeness, it would be nice to have a method for checking for
the "prefix" type of matcher as well, so let's add that, making it
return True simply when none of the others do.

The larger goal here is to eliminate uses of match.files() in
conditions (i.e. bool(match.files())). The reason for this is that
there are scenarios when you would like to create a "prefix" matcher
that happens to match no files. One example is for 'hg files -I foo
bar'. The narrowmatcher also restricts the set of files given and it
would not surprise me if have bugs caused by that already. Note that
'if m.files() and not m.anypats()' and similar is sometimes used to
catch the "exact" and "prefix" cases above.

# Copyright 2010-2011 Fog Creek Software
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''largefile store working over Mercurial's wire protocol'''

import lfutil
import remotestore

class wirestore(remotestore.remotestore):
    def __init__(self, ui, repo, remote):
        cap = remote.capable('largefiles')
        if not cap:
            raise lfutil.storeprotonotcapable([])
        storetypes = cap.split(',')
        if 'serve' not in storetypes:
            raise lfutil.storeprotonotcapable(storetypes)
        self.remote = remote
        super(wirestore, self).__init__(ui, repo, remote.url())

    def _put(self, hash, fd):
        return self.remote.putlfile(hash, fd)

    def _get(self, hash):
        return self.remote.getlfile(hash)

    def _stat(self, hashes):
        '''For each hash, return 0 if it is available, other values if not.
        It is usually 2 if the largefile is missing, but might be 1 the server
        has a corrupted copy.'''
        batch = self.remote.batch()
        futures = {}
        for hash in hashes:
            futures[hash] = batch.statlfile(hash)
        batch.submit()
        retval = {}
        for hash in hashes:
            retval[hash] = futures[hash].value
        return retval