pursuing a strategy using fetch.archive and treating var/spack/cache as a mirror. this should support both URLFetchStrategy as well as VCSFetchStrategy (the previous strategy supported only the former). this won't work until URLFetchStrategy.archive is updated

lib/spack/spack/fetch_strategy.py

@@ -156,11 +156,6 @@ def fetch(self):
         if self.archive_file:
             tty.msg("Already downloaded %s" % self.archive_file)
             return
-        cached = self.search_cache()
-        if cached:
-            tty.msg("Cached %s." % cached)
-            shutil.copy(cached, "./")
-            return
 
         tty.msg("Trying to fetch from %s" % self.url)
 
@@ -216,8 +211,6 @@ def fetch(self):
 
         if not self.archive_file:
             raise FailedDownloadError(self.url)
-        elif self.digest:
-            shutil.copy(self.archive_file, spack.cache_path)
 
 
     @property
@@ -292,16 +285,6 @@ def check(self):
                     "Expected %s but got %s" % (self.digest, checker.sum))
 
 
-    def search_cache(self):
-        if not self.digest:
-            return
-        checker = crypto.Checker(self.digest)
-        paths = (join_path(spack.cache_path, f) for f in os.listdir(spack.cache_path))
-        for p in paths:
-            if checker.check(p):
-                return p
-
-
     @_needs_stage
     def reset(self):
         """Removes the source path if it exists, then re-expands the archive."""

lib/spack/spack/package.py

@@ -715,6 +715,8 @@ def do_fetch(self, mirror_only=False):
         if spack.do_checksum and self.version in self.versions:
             self.stage.check()
 
+        self.stage.cache_local()
+        
 
     def do_stage(self, mirror_only=False):
         """Unpacks the fetched tarball, then changes into the expanded tarball

lib/spack/spack/stage.py

@@ -273,6 +273,7 @@ def fetch(self, mirror_only=False):
             # the root, so we add a '/' if it is not present.
             mirror_roots = [root if root.endswith('/') else root + '/'
                             for root in mirrors.values()]
+            mirror_roots.append("file://" + os.path.abspath(spack.cache_path) + os.sep)
             urls = [urljoin(root, self.mirror_path) for root in mirror_roots]
 
             # If this archive is normally fetched from a tarball URL,
@@ -305,6 +306,7 @@ def fetch(self, mirror_only=False):
             self.fetcher = self.default_fetcher
             raise fs.FetchError(errMessage, None)
 
+
     def check(self):
         """Check the downloaded archive against a checksum digest.
            No-op if this stage checks code out of a repository."""
@@ -318,6 +320,15 @@ def check(self):
         else:
             self.fetcher.check()
 
+
+    def cache_local(self):
+        archiveDst = join_path(os.path.abspath(spack.cache_path), self.mirror_path)
+        mkdirp(os.path.dirname(archiveDst))
+        # TODO: this moves the archive for URLFetchStrategy vs. a copy - edit
+        # to do a move?
+        self.fetcher.archive(archiveDst)
+
+
     def expand_archive(self):
         """Changes to the stage directory and attempt to expand the downloaded
            archive.  Fail if the stage is not set up or if the archive is not yet
@@ -421,7 +432,7 @@ def expand_archive(self):
                 shutil.move(source_path, destination_path)
 
 
-@pattern.composite(method_list=['fetch', 'create', 'check', 'expand_archive',  'restage', 'destroy'])
+@pattern.composite(method_list=['fetch', 'create', 'check', 'expand_archive',  'restage', 'destroy', 'cache_local'])
 class StageComposite:
     """
     Composite for Stage type objects. The first item in this composite is considered to be the root package, and