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-rw-r--r--pymemcache/serde.py63
1 files changed, 59 insertions, 4 deletions
diff --git a/pymemcache/serde.py b/pymemcache/serde.py
index f92aeb7..2926403 100644
--- a/pymemcache/serde.py
+++ b/pymemcache/serde.py
@@ -16,12 +16,13 @@ from functools import partial
import logging
from io import BytesIO
import pickle
+import zlib
FLAG_BYTES = 0
FLAG_PICKLE = 1 << 0
FLAG_INTEGER = 1 << 1
FLAG_LONG = 1 << 2
-FLAG_COMPRESSED = 1 << 3 # unused, to main compatibility with python-memcached
+FLAG_COMPRESSED = 1 << 3
FLAG_TEXT = 1 << 4
# Pickle protocol version (highest available to runtime)
@@ -121,6 +122,63 @@ class PickleSerde:
return python_memcache_deserializer(key, value, flags)
+pickle_serde = PickleSerde()
+
+
+class CompressedSerde:
+ """
+ An object which implements the serialization/deserialization protocol for
+ :py:class:`pymemcache.client.base.Client` and its descendants with
+ configurable compression.
+ """
+
+ def __init__(
+ self,
+ compress=zlib.compress,
+ decompress=zlib.decompress,
+ serde=pickle_serde,
+ # Discovered scientifically by testing at what point the serialization
+ # begins to improve, with a little padded on since compression adds
+ # CPU overhead
+ # >>> foo = 'foo'*4
+ # >>> len(zlib.compress(foo.encode('utf-8'))), len(foo)
+ # (13, 12)
+ # >>> foo = 'foo'*5
+ # >>> len(zlib.compress(foo.encode('utf-8'))), len(foo)
+ # (13, 15)
+ min_compress_len=30,
+ ):
+ self._serde = serde
+ self._compress = compress
+ self._decompress = decompress
+ self._min_compress_len = min_compress_len
+
+ def serialize(self, key, value):
+ value, flags = self._serde.serialize(key, value)
+
+ if len(value) > self._min_compress_len > 0:
+ old_value = value
+ value = self._compress(value)
+ # Don't use the compressed value if our end result is actually
+ # larger uncompressed.
+ if len(old_value) < len(value):
+ value = old_value
+ else:
+ flags |= FLAG_COMPRESSED
+
+ return value, flags
+
+ def deserialize(self, key, value, flags):
+ if flags & FLAG_COMPRESSED:
+ value = self._decompress(value)
+
+ value = self._serde.deserialize(key, value, flags)
+ return value
+
+
+compressed_serde = CompressedSerde()
+
+
class LegacyWrappingSerde:
"""
This class defines how to wrap legacy de/serialization functions into a
@@ -141,6 +199,3 @@ class LegacyWrappingSerde:
def _default_deserialize(self, key, value, flags):
return value
-
-
-pickle_serde = PickleSerde()