From 08f4d259b7d9068982e15a0e99deba49654fb70d Mon Sep 17 00:00:00 2001
From: Valentin Samir <valentin.samir@crans.org>
Date: Tue, 2 Dec 2014 15:20:50 +0100
Subject: [PATCH] [ldapcertfs] fallback sur un cache local si des erreurs ldap
 surviennent

---
 utils/ldapcertfs.py | 89 ++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 83 insertions(+), 6 deletions(-)

diff --git a/utils/ldapcertfs.py b/utils/ldapcertfs.py
index dc218fae..ceeade11 100755
--- a/utils/ldapcertfs.py
+++ b/utils/ldapcertfs.py
@@ -48,6 +48,8 @@ import ldap
 import time
 import fuse
 import errno
+import pickle
+import hashlib
 import getpass
 
 from OpenSSL import crypto
@@ -59,12 +61,61 @@ import gestion.secrets_new as secrets
 fuse.fuse_python_api = (0, 2)
 
 import logging
-LOG_FILENAME = 'ldapcertfs.log'
-logging.basicConfig(filename=LOG_FILENAME,level=logging.WARNING)
+import logging.handlers
+logger = logging.getLogger('ldapcertfs')
+logger.setLevel(logging.DEBUG)
+formatter = logging.Formatter('%(name)s: [%(levelname)s] %(message)s')
+handler = logging.handlers.SysLogHandler(address = '/dev/log')
+try:
+    handler.addFormatter(formatter)
+except AttributeError:
+    handler.formatter = formatter
+logger.addHandler(handler)
 
 
 CACHE = {}
 CACHE_TIMEOUT = 60
+CACHE_DIR = "/var/lib/ldapcertfs/"
+CACHE_STATIC_UPDATE = 3600
+CACHE_STATIC_EXPIRE = 3600 * 24 * 30
+LAST_CLEAN = 0
+
+try:
+    os.mkdir(CACHE_DIR, 0700)
+except OSError as e:
+    if e.errno != 17: # File exists
+        raise
+    os.chmod(CACHE_DIR, 0700)
+
+def clean_static_cache(storage={}):
+    global LAST_CLEAN
+    if time.time() - LAST_CLEAN > CACHE_STATIC_UPDATE:
+        LAST_CLEAN = time.time()
+        for file in os.listdir(CACHE_DIR):
+            path = os.path.join(CACHE_DIR, file)
+            if time.time() - os.path.getmtime(path) > CACHE_STATIC_EXPIRE and not path in storage:
+                os.remove(path)
+
+clean_static_cache()
+
+def get_from_static_cache(key):
+    path = os.path.join(CACHE_DIR, hashlib.md5(key).hexdigest())
+    if os.path.isfile(path):
+        with open(path) as f:
+            return (os.path.getmtime(path), pickle.load(f))
+    else:
+        raise ValueError("Not Found")
+
+def set_to_static_cache(key, value):
+    try:
+        (mtime, old_value) = get_from_static_cache(key)
+    except ValueError:
+        old_value = None
+    if old_value != value:
+        path = os.path.join(CACHE_DIR, hashlib.md5(key).hexdigest())
+        with open(path, 'w+') as f:
+            pickle.dump(value, f)
+        os.chmod(path, 0600)
 
 def set_to_cache(keys, value, now=None, null=False):
     global CACHE
@@ -116,6 +167,21 @@ class Item(object):
         else:
             self.data = ''
 
+    def __eq__(self, obj):
+        if isinstance(obj, Item):
+            return self.dev == obj.dev and \
+            self.mode == obj.mode and \
+            self.uid == obj.uid and \
+            self.gid == obj.gid and \
+            self.xattr == obj.xattr and \
+            self.data == obj.data and \
+            abs(self.mtime - obj.mtime) < CACHE_STATIC_UPDATE
+        else:
+            return False
+
+    def __ne__(self, obj):
+        return not self == obj
+
     def read(self, offset, length):
         return self.data[offset:offset+length]
 
@@ -189,16 +255,16 @@ class LdapCertFS(fuse.Fuse):
                 try:
                     self.conn = lc_ldap.shortcuts.lc_ldap_readonly()
                     if not rec:
-                        logger.warning("[ldapcertfs] ldap down, retrying")
+                        logger.warning("ldap down, retrying")
                         kwargs['rec'] = True
                         self.func_cache(func, *args, **kwargs)
                 except Exception as e:
-                    logger.error("[ldapcertfs] uncaught exception %r" % e)
+                    logger.error("uncaught exception %r" % e)
                 # Si le serveur est down on essaye de fournir un ancienne valeur du cache
                 try:
                     return get_from_cache(serial, expire=-1)
                 except ValueError:
-                    logger.critical("[ldapcertfs] fail to return a valid result, I will probably crash next to this")
+                    logger.critical("fail to return a valid result, I will probably crash next to this")
                     return []
 
     def search_cache(self, filter, **kwargs):
@@ -358,9 +424,20 @@ class LdapCertFS(fuse.Fuse):
                 elif machine_host and xid and file:
                     self.make_file(xid, file)
             set_to_cache(path, True)
+            set_to_static_cache(path, self._storage[path])
     # --- Metadata -----------------------------------------------------------
     def getattr(self, path):
-        self.build_path(path)
+        try:
+            self.build_path(path)
+            clean_static_cache(self._storage)
+        except Exception as e:
+            logger.warning("Erreur : %s\n%s" % (e, traceback.format_exc()))
+            if not path in self._storage:
+                try:
+                    (ts, v) = get_from_static_cache(path)
+                    self._storage[path] = v
+                except ValueError:
+                    pass
         if not path in self._storage:
             return -errno.ENOENT