store: introduce _matchtrackedpath() and use it to filter store files This patch introduces a function to filter store files on the basis of the path which they are tracking. The function assumes that the entries can be of two types, 'meta/*' and 'data/*' which means it will just work on revlog based storage and not with another storage ways. For the 'data/*' entries, we remove the 'data/' part and '.i/.d' part from the beginning and the end then pass that to matcher. For the 'meta/*' entries, we remove the 'meta/' and '/00manifest.(i/d)' part from beginning and end then call matcher.visitdir() with it to make sure all the parent directories are also downloaded. Since the storage filtering for narrow stream clones is implemented with this patch, we remove the un-implemented error message, add some more tests and add the treemanifest case to tests too. The tests demonstrate that it works correctly. After this patch, we have now narrow stream clones working. Narrow stream clones are a very important feature for large repositories who have good internet connection because they use streamclones for cloning and if they do normal narrow clone, that takes more time then a full streamclone. Also narrow-stream clone will drastically speed up clone timings. Differential Revision: https://phab.mercurial-scm.org/D5139

--- a/mercurial/store.py	Wed Oct 17 17:24:55 2018 +0300
+++ b/mercurial/store.py	Wed Oct 17 17:42:32 2018 +0300
@@ -24,6 +24,20 @@
 
 parsers = policy.importmod(r'parsers')
 
+def _matchtrackedpath(path, matcher):
+    """parses a fncache entry and returns whether the entry is tracking a path
+    matched by matcher or not.
+
+    If matcher is None, returns True"""
+
+    if matcher is None:
+        return True
+    path = decodedir(path)
+    if path.startswith('data/'):
+        return matcher(path[len('data/'):-len('.i')])
+    elif path.startswith('meta/'):
+        return matcher.visitdir(path[len('meta/'):-len('/00manifest.i')] or '.')
+
 # This avoids a collision between a file named foo and a dir named
 # foo.i or foo.d
 def _encodedir(path):
@@ -413,6 +427,8 @@
 
     def datafiles(self, matcher=None):
         for a, b, size in super(encodedstore, self).datafiles():
+            if not _matchtrackedpath(a, matcher):
+                continue
             try:
                 a = decodefilename(a)
             except KeyError:
@@ -542,6 +558,8 @@
 
     def datafiles(self, matcher=None):
         for f in sorted(self.fncache):
+            if not _matchtrackedpath(f, matcher):
+                continue
             ef = self.encode(f)
             try:
                 yield f, ef, self.getsize(ef)