a cache plugin that stores facts persistently in local json dumps

lib/ansible/cache/jsonfile.py

+# (c) 2014, Brian Coca, Josh Drake, et al
+#
+# This file is part of Ansible
+#
+# Ansible is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Ansible is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import time
+import json
+import errno
+
+from ansible import constants as C
+from ansible import utils
+from ansible.cache.base import BaseCacheModule
+
+
+class CacheModule(BaseCacheModule):
+    """
+    A caching module backed by json files.
+    """
+    def __init__(self, *args, **kwargs):
+
+        self._timeout = float(C.CACHE_PLUGIN_TIMEOUT)
+        self._cache = {}
+        self._cache_dir = C.CACHE_PLUGIN_CONNECTION # expects a dir path
+
+        if not os.path.exists(self._cache_dir):
+            try:
+                os.makedirs(self._cache_dir)
+            except (OSError,IOError), e:
+                utils.warning("error while trying to create cache dir %s : %s" % (self._cache_dir, str(e)))
+                return None
+
+    def get(self, key):
+
+        if key in self._cache:
+            return self._cache.get(key)
+
+        if self.has_expired(key):
+           raise KeyError
+
+        cachefile = "%s/%s" % (self._cache_dir, key)
+        try:
+            f = open( cachefile, 'r')
+        except (OSError,IOError), e:
+            utils.warning("error while trying to write to %s : %s" % (cachefile, str(e)))
+        else:
+            value = json.load(f)
+            self._cache[key] = value
+            return value
+        finally:
+            f.close()
+
+    def set(self, key, value):
+
+        self._cache[key] = value
+
+        cachefile = "%s/%s" % (self._cache_dir, key)
+        try:
+            #TODO: check if valid keys can have invalid FS chars, base32?
+            f = open(cachefile, 'w')
+        except (OSError,IOError), e:
+            utils.warning("error while trying to read %s : %s" % (cachefile, str(e)))
+        else:
+            json.dump(value, f, ensure_ascii=False)
+        finally:
+            f.close()
+
+    def has_expired(self, key):
+
+        cachefile = "%s/%s" % (self._cache_dir, key)
+        try:
+            st = os.stat(cachefile)
+        except (OSError,IOError), e:
+            if e.errno == errno.ENOENT:
+                return False
+            else:
+                utils.warning("error while trying to stat %s : %s" % (cachefile, str(e)))
+
+        if time.time() - st.st_mtime <= self._timeout:
+            return False
+
+        if key in self._cache:
+            del self._cache[key]
+        return True
+
+    def keys(self):
+        keys = []
+        for k in os.listdir(self._cache_dir):
+            if not self.has_expired(k):
+                keys.append(k)
+        return keys
+
+    def contains(self, key):
+
+        if key in self._cache:
+            return True
+
+        if self.has_expired(key):
+            return False
+        try:
+            st = os.stat("%s/%s" % (self._cache_dir, key))
+            return True
+        except (OSError,IOError), e:
+            if e.errno == errno.ENOENT:
+                return False
+            else:
+                utils.warning("error while trying to stat %s : %s" % (cachefile, str(e)))
+
+    def delete(self, key):
+        del self._cache[key]
+        try:
+            os.remove("%s/%s" % (self._cache_dir, key))
+        except (OSError,IOError), e:
+            pass #TODO: only pass on non existing?
+
+    def flush(self):
+        self._cache = {}
+        for key in self.keys():
+            self.delete(key)
+
+    def copy(self):
+        ret = dict()
+        for key in self.keys():
+            ret[key] = self.get(key)
+        return ret