Github user NicoK commented on a diff in the pull request: https://github.com/apache/flink/pull/3143#discussion_r97065423 --- Diff: flink-contrib/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/AbstractRocksDBState.java --- @@ -132,55 +132,91 @@ public void setCurrentNamespace(N namespace) { namespaceSerializer); int keyGroup = KeyGroupRangeAssignment.assignToKeyGroup(des.f0, backend.getNumberOfKeyGroups()); - writeKeyWithGroupAndNamespace(keyGroup, des.f0, des.f1); - return backend.db.get(columnFamily, keySerializationStream.toByteArray()); + + // we cannot reuse the keySerializationStream member since this method + // is called concurrently to the other ones and it may thus contain garbage + ByteArrayOutputStreamWithPos tmpKeySerializationStream = + new ByteArrayOutputStreamWithPos(128); + DataOutputViewStreamWrapper tmpKeySerializationDateDataOutputView = + new DataOutputViewStreamWrapper(tmpKeySerializationStream); + + writeKeyWithGroupAndNamespace(keyGroup, des.f0, des.f1, + tmpKeySerializationStream, tmpKeySerializationDateDataOutputView); + + return backend.db.get(columnFamily, tmpKeySerializationStream.toByteArray()); } protected void writeCurrentKeyWithGroupAndNamespace() throws IOException { - writeKeyWithGroupAndNamespace(backend.getCurrentKeyGroupIndex(), backend.getCurrentKey(), currentNamespace); + writeKeyWithGroupAndNamespace( + backend.getCurrentKeyGroupIndex(), + backend.getCurrentKey(), + currentNamespace, + this.keySerializationStream, + this.keySerializationDateDataOutputView); } - protected void writeKeyWithGroupAndNamespace(int keyGroup, K key, N namespace) throws IOException { + protected void writeKeyWithGroupAndNamespace( + int keyGroup, K key, N namespace, + final ByteArrayOutputStreamWithPos keySerializationStream, + final DataOutputView keySerializationDateDataOutputView) throws IOException { + keySerializationStream.reset(); - writeKeyGroup(keyGroup); - writeKey(key); - writeNameSpace(namespace); + writeKeyGroup(keyGroup, keySerializationDateDataOutputView); + writeKey(key, keySerializationStream, keySerializationDateDataOutputView); + writeNameSpace(namespace, keySerializationStream, keySerializationDateDataOutputView); } - private void writeKeyGroup(int keyGroup) throws IOException { + private void writeKeyGroup( + int keyGroup, final DataOutputView keySerializationDateDataOutputView) + throws IOException { + for (int i = backend.getKeyGroupPrefixBytes(); --i >= 0;) { keySerializationDateDataOutputView.writeByte(keyGroup >>> (i << 3)); } } - private void writeKey(K key) throws IOException { + private void writeKey( + K key, final ByteArrayOutputStreamWithPos keySerializationStream, + final DataOutputView keySerializationDateDataOutputView) throws IOException { + //write key int beforeWrite = keySerializationStream.getPosition(); backend.getKeySerializer().serialize(key, keySerializationDateDataOutputView); if (ambiguousKeyPossible) { //write size of key - writeLengthFrom(beforeWrite); + writeLengthFrom(beforeWrite, keySerializationStream, + keySerializationDateDataOutputView); } } - private void writeNameSpace(N namespace) throws IOException { + private void writeNameSpace( + N namespace, final ByteArrayOutputStreamWithPos keySerializationStream, + final DataOutputView keySerializationDateDataOutputView) throws IOException { + int beforeWrite = keySerializationStream.getPosition(); namespaceSerializer.serialize(namespace, keySerializationDateDataOutputView); if (ambiguousKeyPossible) { //write length of namespace - writeLengthFrom(beforeWrite); + writeLengthFrom(beforeWrite, keySerializationStream, + keySerializationDateDataOutputView); } } - private void writeLengthFrom(int fromPosition) throws IOException { + private static void writeLengthFrom( + int fromPosition, final ByteArrayOutputStreamWithPos keySerializationStream, + final DataOutputView keySerializationDateDataOutputView) throws IOException { + int length = keySerializationStream.getPosition() - fromPosition; - writeVariableIntBytes(length); + writeVariableIntBytes(length, keySerializationDateDataOutputView); } - private void writeVariableIntBytes(int value) throws IOException { + private static void writeVariableIntBytes( + int value, final DataOutputView keySerializationDateDataOutputView) --- End diff -- Just a habit of mine so that I don't accidentally change a variable that is not supposed to in the current implementation of the method. I agree, however, that it is not very consistent among the parameters of each method, e.g. the `value` parameter in your example. I'll remove them.
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