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ortools-clone/ortools/math_opt/solvers/message_callback_data.h
Corentin Le Molgat b4b226801b update include guards
2025-11-05 11:54:02 +01:00

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// Copyright 2010-2025 Google LLC
// 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.
#ifndef ORTOOLS_MATH_OPT_SOLVERS_MESSAGE_CALLBACK_DATA_H_
#define ORTOOLS_MATH_OPT_SOLVERS_MESSAGE_CALLBACK_DATA_H_
#include <optional>
#include <string>
#include <vector>
#include "absl/strings/string_view.h"
#include "absl/synchronization/mutex.h"
#include "ortools/math_opt/core/solver_interface.h"
namespace operations_research::math_opt {
// Buffer for solvers messages that enforces the contract of MessageCallback.
//
// This contract mandates that each message is a full finished line. As a
// consequence, if the solver calls the callback with a partial last line, this
// one must not be passed immediately to MessageCallback but kept until the end
// of the line is reached (or the solve is done).
//
// To implement that this class has two methods:
//
// - Parse() that is to be called for each received message from the solver.
//
// - Flush() that must be called at the end of the solve to generate the data
// corresponding the last message sent by the solver if it was an unfinished -
// line.
class MessageCallbackData {
public:
MessageCallbackData() = default;
MessageCallbackData(const MessageCallbackData&) = delete;
MessageCallbackData& operator=(const MessageCallbackData&) = delete;
// Parses the input message, returning a vector with all finished
// lines. Returns an empty vector if the input message did not contain any
// '\n'.
//
// It updates this object with the last unfinished line to use it to complete
// the next message.
std::vector<std::string> Parse(absl::string_view message);
// Returns a vector with the last unfinished line if it exists, else an empty
// vector.
std::vector<std::string> Flush();
private:
// The last message line not ending with '\n'.
std::string unfinished_line_;
};
// Buffers callback data into lines using MessageCallbackData and invokes the
// callback as new lines are ready.
//
// In MathOpt, typically used for solvers that provide a callback with the
// solver logs where the logs contain `\n` characters and messages may be both
// less than a complete line or multiple lines. Recommended use:
// * Register a callback with the underlying solver to get its logs. In the
// callback, when given a log string, call OnMessage() on it.
// * Run the solver's Solve() function.
// * Unregister the callback with the underlying solver.
// * Call Flush() to ensure any final incomplete lines are sent.
//
// If initialized with a nullptr for the user callback, all functions on this
// class have no effect.
//
// This class is threadsafe if the input callback is also threadsafe.
class BufferedMessageCallback {
public:
explicit BufferedMessageCallback(
SolverInterface::MessageCallback user_message_callback);
// If false, incoming messages are ignored and OnMessage() and Flush() have no
// effect.
bool has_user_message_callback() const {
return user_message_callback_ != nullptr;
}
// Appends `message` to the buffer, then invokes the callback once on all
// newly complete lines and removes those lines from the buffer. In
// particular, the callback is not invoked if message does not contain any
// `\n`.
void OnMessage(absl::string_view message);
// If the buffer has any pending message, sends it to the callback. This
// function has no effect if called when the buffer is empty. Calling this
// function when the buffer is non-empty before the stream of logs is complete
// will result in the user getting extra line breaks.
void Flush();
private:
SolverInterface::MessageCallback user_message_callback_;
absl::Mutex mutex_;
MessageCallbackData message_callback_data_ ABSL_GUARDED_BY(mutex_);
};
} // namespace operations_research::math_opt
#endif // ORTOOLS_MATH_OPT_SOLVERS_MESSAGE_CALLBACK_DATA_H_