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