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gluon/cfs.py

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+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+This file is part of the web2py Web Framework
+Copyrighted by Massimo Di Pierro <mdipierro@cs.depaul.edu>
+License: LGPLv3 (http://www.gnu.org/licenses/lgpl.html)
+
+Functions required to execute app components
+============================================
+
+FOR INTERNAL USE ONLY
+"""
+
+import os
+import stat
+import thread
+from fileutils import read_file
+
+cfs = {}  # for speed-up
+cfs_lock = thread.allocate_lock()  # and thread safety
+
+
+def getcfs(key, filename, filter=None):
+    """
+    Caches the *filtered* file `filename` with `key` until the file is
+    modified.
+
+    :param key: the cache key
+    :param filename: the file to cache
+    :param filter: is the function used for filtering. Normally `filename` is a
+        .py file and `filter` is a function that bytecode compiles the file.
+        In this way the bytecode compiled file is cached. (Default = None)
+
+    This is used on Google App Engine since pyc files cannot be saved.
+    """
+    t = os.stat(filename)[stat.ST_MTIME]
+    cfs_lock.acquire()
+    item = cfs.get(key, None)
+    cfs_lock.release()
+    if item and item[0] == t:
+        return item[1]
+    if not filter:
+        data = read_file(filename)
+    else:
+        data = filter()
+    cfs_lock.acquire()
+    cfs[key] = (t, data)
+    cfs_lock.release()
+    return data
+
+
+