/**
*    Copyright (C) 2008 10gen Inc.
*
*    This program is free software: you can redistribute it and/or  modify
*    it under the terms of the GNU Affero General Public License, version 3,
*    as published by the Free Software Foundation.
*
*    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
*    GNU Affero General Public License for more details.
*
*    You should have received a copy of the GNU Affero General Public License
*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#pragma once

namespace mongo {

    /* object-orienty background thread dispatching.

       subclass and define run()

       It is ok to call go() more than once -- if the previous invocation
       has finished. Thus one pattern of use is to embed a backgroundjob
       in your object and reuse it (or same thing with inheritance).
    */

    class BackgroundJob {
    protected:
        /* define this to do your work! */
        virtual void run() = 0;

    public:
        enum State {
            NotStarted,
            Running,
            Done
        };
        State getState() const {
            return state;
        }
        bool running() const {
            return state == Running;
        }

        bool deleteSelf; // delete self when Done?

        BackgroundJob() {
            deleteSelf = false;
            state = NotStarted;
        }
        virtual ~BackgroundJob() { }

        // start job.  returns before it's finished.
        BackgroundJob& go();

        // wait for completion.  this spins with sleep() so not terribly efficient.
        // returns true if did not time out.
        //
        // note you can call wait() more than once if the first call times out.
        bool wait(int msMax = 0);

    private:
        static BackgroundJob *grab;
        static boost::mutex mutex;
        static void thr();
        volatile State state;
    };

} // namespace mongo