// Copyright 2022 The Abseil Authors.

//

// 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

//

//      https://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.

//

// -----------------------------------------------------------------------------

// File: log/log_sink.h

// -----------------------------------------------------------------------------

//

// This header declares the interface class `absl::LogSink`.

#ifndef ABSL_LOG_LOG_SINK_H_

#define ABSL_LOG_LOG_SINK_H_

#include "absl/base/config.h"

#include "absl/log/log_entry.h"

namespace absl {

ABSL_NAMESPACE_BEGIN

// absl::LogSink

//

// `absl::LogSink` is an interface which can be extended to intercept and

// process particular messages (with `LOG.ToSinkOnly()` or

// `LOG.ToSinkAlso()`) or all messages (if registered with

// `absl::AddLogSink`).  Implementations must be thread-safe, and should take

// care not to take any locks that might be held by the `LOG` caller.

class LogSink {

 public:

  virtual ~LogSink() = default;

  // LogSink::Send()

  //

  // `Send` is called synchronously during the log statement.

  //

  // It is safe to use `LOG` within an implementation of `Send`.  `ToSinkOnly`

  // and `ToSinkAlso` are safe in general but can be used to create an infinite

  // loop if you try.

  virtual void Send(const absl::LogEntry& entry) = 0;

  // LogSink::Flush()

  //

  // Sinks that buffer messages should override this method to flush the buffer

  // and return.

  virtual void Flush() {}

 private:

  // https://lld.llvm.org/missingkeyfunction.html#missing-key-function

  virtual void KeyFunction() const final;  // NOLINT(readability/inheritance)

};

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_LOG_LOG_SINK_H_