/* * Copyright (c) Facebook, Inc. and its affiliates. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #pragma once #include #include #include namespace folly { /** * A LogWriter implementation that immediately writes to a file descriptor when * it is invoked. * * The downside of this class is that logging I/O occurs directly in your * normal program threads, so that logging I/O may block or slow down normal * processing. * * However, one benefit of this class is that log messages are written out * immediately, so if your program crashes, all log messages generated before * the crash will have already been written, and no messages will be lost. */ class ImmediateFileWriter : public LogWriter { public: /** * Construct an ImmediateFileWriter that appends to the file at the specified * path. */ explicit ImmediateFileWriter(folly::StringPiece path); /** * Construct an ImmediateFileWriter that writes to the specified File object. */ explicit ImmediateFileWriter(folly::File&& file); using LogWriter::writeMessage; void writeMessage(folly::StringPiece buffer, uint32_t flags = 0) override; void flush() override; /** * Returns true if the output steam is a tty. */ bool ttyOutput() const override { return isatty(file_.fd()); } /** * Get the output file. */ const folly::File& getFile() const { return file_; } private: ImmediateFileWriter(ImmediateFileWriter const&) = delete; ImmediateFileWriter& operator=(ImmediateFileWriter const&) = delete; folly::File file_; }; } // namespace folly