log_sink.h (2345B)
1 // Copyright 2022 The Abseil Authors. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 // ----------------------------------------------------------------------------- 16 // File: log/log_sink.h 17 // ----------------------------------------------------------------------------- 18 // 19 // This header declares the interface class `absl::LogSink`. 20 21 #ifndef ABSL_LOG_LOG_SINK_H_ 22 #define ABSL_LOG_LOG_SINK_H_ 23 24 #include "absl/base/config.h" 25 #include "absl/log/log_entry.h" 26 27 namespace absl { 28 ABSL_NAMESPACE_BEGIN 29 30 // absl::LogSink 31 // 32 // `absl::LogSink` is an interface which can be extended to intercept and 33 // process particular messages (with `LOG.ToSinkOnly()` or 34 // `LOG.ToSinkAlso()`) or all messages (if registered with 35 // `absl::AddLogSink`). Implementations must not take any locks that might be 36 // held by the `LOG` caller. 37 class LogSink { 38 public: 39 virtual ~LogSink() = default; 40 41 // LogSink::Send() 42 // 43 // `Send` is called synchronously during the log statement. `Send` must be 44 // thread-safe. 45 // 46 // It is safe to use `LOG` within an implementation of `Send`. `ToSinkOnly` 47 // and `ToSinkAlso` are safe in general but can be used to create an infinite 48 // loop if you try. 49 virtual void Send(const absl::LogEntry& entry) = 0; 50 51 // LogSink::Flush() 52 // 53 // Sinks that buffer messages should override this method to flush the buffer 54 // and return. `Flush` must be thread-safe. 55 virtual void Flush() {} 56 57 protected: 58 LogSink() = default; 59 // Implementations may be copyable and/or movable. 60 LogSink(const LogSink&) = default; 61 LogSink& operator=(const LogSink&) = default; 62 63 private: 64 // https://lld.llvm.org/missingkeyfunction.html#missing-key-function 65 virtual void KeyFunction() const final; // NOLINT(readability/inheritance) 66 }; 67 68 ABSL_NAMESPACE_END 69 } // namespace absl 70 71 #endif // ABSL_LOG_LOG_SINK_H_