1 files changed, 63 insertions, 0 deletions
diff --git a/patchtracker/CacheObject.py b/patchtracker/CacheObject.py
new file mode 100644
index 0000000..c37c3b5
--- /dev/null
+++ b/patchtracker/CacheObject.py
@@ -0,0 +1,63 @@
+import errno
+import gzip
+import md5
+import os
+
+import Conf
+
+class CacheMissException (Exception):
+  pass
+ 
+class CacheObject:
+  """ A CacheObject is a compressed on-disk version of a serialized object.
+  """
+  def __init__ (self, key=None, keys=None):
+    self.obj = None
+    #print "CacheObject: key=%s keys=%s"%(key, keys)
+    if not key and not keys:
+      raise "CacheObject needs at least one of key, keys"
+    checksum = md5.md5()
+    if key:
+      checksum.update(key)
+    if keys:
+      for k in keys:
+        checksum.update(str(k))
+    self.path = os.path.sep.join([Conf.cachedir, checksum.hexdigest()])
+
+  def get(self):
+    if not self.obj:
+      try:
+        if Conf.cachecompress:
+          self.obj = gzip.GzipFile(self.path).read()
+        else:
+          self.obj = file(self.path).read()
+      except IOError, e:
+        if e.errno != errno.ENOENT:
+          raise e
+        else:
+          #print "CacheObject: cache miss"
+          raise CacheMissException("Object not present in cache")
+    #print "CacheObject: cache hit"
+    return self.obj
+
+  def put(self, obj):
+    self.obj = obj
+    #print "CacheObject: cache put"
+    try:
+      if Conf.cachecompress:
+        gzip.GzipFile(self.path, "wb").write(str(self.obj))
+      else:
+        file(self.path, "wb").write(str(self.obj))
+    except Exception, e:
+      os.unlink(self.path)
+      raise e
+
+if __name__ == '__main__':
+  co = CacheObject( key="magic" )
+  try:
+    print "going to try to read an object before it exists"
+    print "first line:", co.get().split()[0]
+  except CacheMissException:
+    print "file was missing as expected.  now let's try to put it and fetch it"
+    co.put(file("/etc/passwd").read())
+    print "first line:", co.get().split()[0]