1 files changed, 46 insertions, 2 deletions
diff --git a/lib/spack/spack/fetch_strategy.py b/lib/spack/spack/fetch_strategy.py
index 1953d7c1b3..6f28ec34b2 100644
--- a/lib/spack/spack/fetch_strategy.py
+++ b/lib/spack/spack/fetch_strategy.py
@@ -310,7 +310,7 @@ class URLFetchStrategy(FetchStrategy):
         if not extension(destination) == extension(self.archive_file):
             raise ValueError("Cannot archive without matching extensions.")
 
-        shutil.move(self.archive_file, destination)
+        shutil.copy(self.archive_file, destination)
 
     @_needs_stage
     def check(self):
@@ -348,7 +348,7 @@ class URLFetchStrategy(FetchStrategy):
 
     def __repr__(self):
         url = self.url if self.url else "no url"
-        return "URLFetchStrategy<%s>" % url
+        return "%s<%s>" % (self.__class__.__name__, url)
 
     def __str__(self):
         if self.url:
@@ -357,6 +357,24 @@ class URLFetchStrategy(FetchStrategy):
             return "[no url]"
 
 
+class CacheURLFetchStrategy(URLFetchStrategy):
+    """The resource associated with a cache URL may be out of date."""
+    def __init__(self, *args, **kwargs):
+        super(CacheURLFetchStrategy, self).__init__(*args, **kwargs)
+    
+    @_needs_stage
+    def fetch(self):
+        super(CacheURLFetchStrategy, self).fetch()
+        if self.digest:
+            try:
+                self.check()
+            except ChecksumError:
+                # Future fetchers will assume they don't need to download if the
+                # file remains
+                os.remove(self.archive_file)
+                raise
+
+
 class VCSFetchStrategy(FetchStrategy):
 
     def __init__(self, name, *rev_types, **kwargs):
@@ -815,6 +833,32 @@ def for_package_version(pkg, version):
     raise InvalidArgsError(pkg, version)
 
 
+class FsCache(object):
+    def __init__(self, root):
+        self.root = os.path.abspath(root)
+
+    def store(self, fetcher, relativeDst):
+        unique = False
+        uidGroups = [['tag', 'commit'], ['digest'], ['revision']]
+        for grp in uidGroups:
+            try:
+                unique |= any(getattr(fetcher, x) for x in grp)
+            except AttributeError:
+                pass
+            if unique:
+                break
+        if not unique:
+            return
+
+        dst = join_path(self.root, relativeDst)
+        mkdirp(os.path.dirname(dst))
+        fetcher.archive(dst)
+        
+    def fetcher(self, targetPath, digest):
+        url = "file://" + join_path(self.root, targetPath)
+        return CacheURLFetchStrategy(url, digest)
+
+
 class FetchError(spack.error.SpackError):
 
     def __init__(self, msg, long_msg=None):