/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the Server Side Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#pragma once

/**
 * DiagStr concurrency helper
 */

#include "spin_lock.h"

namespace mongo {

// todo: rename this to ThreadSafeString or something
/** there is now one mutex per DiagStr.  If you have hundreds or millions of
    DiagStrs you'll need to do something different.
*/
class DiagStr {
    mutable SpinLock m;
    std::string _s;

public:
    DiagStr(const DiagStr& r) : _s(r.get()) {}
    DiagStr(const std::string& r) : _s(r) {}
    DiagStr() {}
    bool empty() const {
        scoped_spinlock lk(m);
        return _s.empty();
    }
    std::string get() const {
        scoped_spinlock lk(m);
        return _s;
    }
    void set(const char* s) {
        scoped_spinlock lk(m);
        _s = s;
    }
    void set(const std::string& s) {
        scoped_spinlock lk(m);
        _s = s;
    }
    operator std::string() const {
        return get();
    }
    void operator=(const std::string& s) {
        set(s);
    }
    void operator=(const DiagStr& rhs) {
        set(rhs.get());
    }

    // == is not defined.  use get() == ... instead.  done this way so one thinks about if composing
    // multiple operations
    bool operator==(const std::string& s) const;
};
}  // namespace mongo