caching the zip manifests Fixes #154

--HG--
extra : rebase_source : 0f32792e01b6a1b746a1e07ffa4d7a85eeda1595

pkg_resources.py

@@ -1530,7 +1530,21 @@ class EmptyProvider(NullProvider):
 empty_provider = EmptyProvider()
 
 
-def build_zipmanifest(path):
+class ZipManifests(object):
+
+    def __init__(self):
+        self.known = dict()
+
+    def __call__(self, path):
+        path = os.path.normpath(path)
+        stat = os.stat(path)
+
+        if path not in self.known or self.known[path][0] != stat.st_mtime:
+            self.known[path] = (stat.st_mtime, self.build_manifest(path))
+
+        return self.known[path][1]
+
+    def build_manifest(self, path):
         """
         This builds a similar dictionary to the zipimport directory
         caches.  However instead of tuples, ZipInfo objects are stored.
@@ -1557,6 +1571,7 @@ def build_zipmanifest(path):
                 zipinfo[zpath] = zfile.getinfo(zitem)
                 assert zipinfo[zpath] is not None
         return zipinfo
+build_zipmanifest = ZipManifests()
 
 
 class ContextualZipFile(zipfile.ZipFile):
@@ -1586,7 +1601,6 @@ class ZipProvider(EggProvider):
 
     def __init__(self, module):
         EggProvider.__init__(self, module)
-        self.zipinfo = build_zipmanifest(self.loader.archive)
         self.zip_pre = self.loader.archive+os.sep
 
     def _zipinfo_name(self, fspath):
@@ -1802,7 +1816,6 @@ class EggMetadata(ZipProvider):
     def __init__(self, importer):
         """Create a metadata provider from a zipimporter"""
 
-        self.zipinfo = build_zipmanifest(importer.archive)
         self.zip_pre = importer.archive+os.sep
         self.loader = importer
         if importer.prefix: