Add a caching mechnism

pelican/cache.py

@@ -0,0 +1,37 @@
+import os.path
+import hashlib
+import pickle
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class CachedReader(object):
+
+    def __init__(self, reader, cache_path):
+        self._reader = reader
+        self._cache_path = cache_path
+
+    def process_metadata(self, *args, **kwargs):
+        return self._reader.process_metadata(*args, **kwargs)
+
+    def read(self, path):
+        mtime = os.stat(path).st_mtime
+
+        m = hashlib.md5()
+        # We want to hash path + mtime
+        m.update(path)
+        m.update(str(mtime))
+        hash_ = m.hexdigest()
+
+        cache_file = os.path.join(self._cache_path, hash_)
+        if os.path.exists(cache_file):
+            logger.debug('reading {0} from cache'.format(path))
+            with open(cache_file) as f:
+                content, metadata = pickle.load(f)
+        else:
+            content, metadata = self._reader.read(path)
+            with open(cache_file, 'w+') as f:
+                pickle.dump((content, metadata), f)
+            logger.debug('stored {0} in the cache'.format(path))
+        return content, metadata