80 lines
2.4 KiB
C++
80 lines
2.4 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 <ostream>
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#include <folly/logging/LogCategory.h>
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#include <folly/logging/LogMessage.h>
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namespace folly {
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/**
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* A std::streambuf implementation for use by LogStream
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*/
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class LogStreamBuffer : public std::streambuf {
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public:
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LogStreamBuffer() {
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// We intentionally do not reserve any string buffer space initially,
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// since this will not be needed for XLOG() and XLOGF() statements
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// that do not use the streaming API. (e.g., XLOG(INFO, "test ", 1234) )
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}
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bool empty() const { return str_.empty(); }
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std::string extractString() {
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str_.resize(pptr() - (&str_.front()));
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return std::move(str_);
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}
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int_type overflow(int_type ch) override;
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private:
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enum : size_t { kInitialCapacity = 256 };
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std::string str_;
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};
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class LogStreamProcessor;
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/**
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* A std::ostream implementation for use by the logging macros.
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*
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* All-in-all this is pretty similar to std::stringstream, but lets us
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* destructively extract an rvalue-reference to the underlying string.
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*/
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class LogStream : public std::ostream {
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public:
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// Explicitly declare the default constructor and destructor, but only
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// define them in the .cpp file. This prevents them from being inlined at
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// each FB_LOG() or XLOG() statement. Inlining them just causes extra code
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// bloat, with minimal benefit--for debug log statements these never even get
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// called in the common case where the log statement is disabled.
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explicit LogStream(LogStreamProcessor* processor);
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~LogStream() override;
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bool empty() const { return buffer_.empty(); }
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std::string extractString() { return buffer_.extractString(); }
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LogStreamProcessor* getProcessor() const { return processor_; }
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private:
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LogStreamBuffer buffer_;
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LogStreamProcessor* const processor_;
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};
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} // namespace folly
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