From patchwork Fri Nov 11 09:23:38 2016
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Subject: [6,of,8] exchange: obtain compression engines from the registrar
From: Gregory Szorc <gregory.szorc@gmail.com>
X-Patchwork-Id: 17473
Message-Id: <45801e65f33949e6663e.1478856218@ubuntu-vm-main>
To: mercurial-devel@mercurial-scm.org
Date: Fri, 11 Nov 2016 01:23:38 -0800

# HG changeset patch
# User Gregory Szorc <gregory.szorc@gmail.com>
# Date 1478849655 28800
#      Thu Nov 10 23:34:15 2016 -0800
# Node ID 45801e65f33949e6663ebfff651cb78d01afcc3e
# Parent  0239a4e94147ce85aecb71bfb0dbf227410a7b67
exchange: obtain compression engines from the registrar

util.compengines has knowledge of all registered compression engines
and the metadata that associates them with various bundle types.

This patch removes the now redundant declaration of this metadata from
exchange.py and obtains it from the new source.

The effect of this patch is that once a new compression engine is
registered with util.compengines, `hg bundle -t <engine>` will just
work.

diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -37,12 +37,6 @@ from . import (
 urlerr = util.urlerr
 urlreq = util.urlreq
 
-# Maps bundle compression human names to internal representation.
-_bundlespeccompressions = {'none': None,
-                           'bzip2': 'BZ',
-                           'gzip': 'GZ',
-                          }
-
 # Maps bundle version human names to changegroup versions.
 _bundlespeccgversions = {'v1': '01',
                          'v2': '02',
@@ -114,7 +108,7 @@ def parsebundlespec(repo, spec, strict=T
     if '-' in spec:
         compression, version = spec.split('-', 1)
 
-        if compression not in _bundlespeccompressions:
+        if compression not in util.compengines.supportedbundlenames:
             raise error.UnsupportedBundleSpecification(
                     _('%s compression is not supported') % compression)
 
@@ -130,7 +124,7 @@ def parsebundlespec(repo, spec, strict=T
 
         spec, params = parseparams(spec)
 
-        if spec in _bundlespeccompressions:
+        if spec in util.compengines.supportedbundlenames:
             compression = spec
             version = 'v1'
             if 'generaldelta' in repo.requirements:
@@ -157,7 +151,8 @@ def parsebundlespec(repo, spec, strict=T
                       ', '.join(sorted(missingreqs)))
 
     if not externalnames:
-        compression = _bundlespeccompressions[compression]
+        engine = util.compengines.forbundlename(compression)
+        compression = engine.bundletype()[1]
         version = _bundlespeccgversions[version]
     return compression, version, params
 
@@ -196,10 +191,10 @@ def getbundlespec(ui, fh):
     restored.
     """
     def speccompression(alg):
-        for k, v in _bundlespeccompressions.items():
-            if v == alg:
-                return k
-        return None
+        try:
+            return util.compengines.forbundletype(alg).bundletype()[0]
+        except KeyError:
+            return None
 
     b = readbundle(ui, fh, None)
     if isinstance(b, changegroup.cg1unpacker):