2 * Copyright 2004-present Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include <folly/Range.h>
23 * LogWriter defines the interface for processing a serialized log message.
28 * Bit flag values for use with writeMessage()
30 enum Flags : uint32_t {
33 * Ensure that this log message never gets discarded.
35 * Some LogWriter implementations may discard messages when messages are
36 * being received faster than they can be written. This flag ensures that
37 * this message will never be discarded.
39 * This flag is used to ensure that LOG(FATAL) messages never get
40 * discarded, so we always report the reason for a crash.
45 virtual ~LogWriter() {}
48 * Write a serialized log message.
50 * The flags parameter is a bitwise-ORed set of Flag values defined above.
52 virtual void writeMessage(folly::StringPiece buffer, uint32_t flags = 0) = 0;
55 * Write a serialized message.
57 * This version of writeMessage() accepts a std::string&&.
58 * The default implementation calls the StringPiece version of
59 * writeMessage(), but subclasses may override this implementation if
62 virtual void writeMessage(std::string&& buffer, uint32_t flags = 0) {
63 writeMessage(folly::StringPiece{buffer}, flags);
67 * Block until all messages that have already been sent to this LogWriter
70 * Other threads may still call writeMessage() while flush() is running.
71 * writeMessage() calls that did not complete before the flush() call started
72 * will not necessarily be processed by the flush call.
74 virtual void flush() = 0;