/*
The MIT License (MIT)

Copyright (c) 2013-2015 winlin

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#ifndef SRS_APP_THREAD_HPP
#define SRS_APP_THREAD_HPP

/*
#include <srs_app_thread.hpp>
*/
#include <srs_core.hpp>

#include <srs_app_st.hpp>

/**
* the handler for the thread, callback interface.
* the thread model defines as:
*     handler->on_thread_start()
*     while loop:
*        handler->on_before_cycle()
*        handler->cycle()
*        handler->on_end_cycle()
*        if !loop then break for user stop thread.
*        sleep(CycleIntervalMilliseconds)
*     handler->on_thread_stop()
* when stop, the thread will interrupt the st_thread,
* which will cause the socket to return error and 
* terminate the cycle thread.
*
* Usage 1: stop by other thread.
*       user can create thread and stop then start again and again,
*       generally must provides a start and stop method, @see SrsIngester.
*       the step to create a thread stop by other thread:
*       1. create SrsThread field, with joinable true.
*       2. must use stop to stop and join the thread.
*       for example:
*           class SrsIngester : public ISrsThreadHandler {
*               public: SrsIngester() { pthread = new SrsThread("ingest", this, SRS_AUTO_INGESTER_SLEEP_US, true); }
*               public: virtual int start() { return pthread->start(); }
*               public: virtual void stop() { pthread->stop(); }
*               public: virtual int cycle() { 
*                   // check status, start ffmpeg when stopped. 
*               }
*           };
*
* Usage 2: stop by thread itself.
*       user can create thread which stop itself,
*       generally only need to provides a start method, 
*       the object will destroy itself then terminate the thread, @see SrsConnection
*       1. create SrsThread field, with joinable false.
*       2. owner stop thread loop, destroy itself when thread stop.
*       for example:
*           class SrsConnection : public ISrsThreadHandler {
*               public: SrsConnection() { pthread = new SrsThread("conn", this, 0, false); }
*               public: virtual int start() { return pthread->start(); }
*               public: virtual int cycle() { 
*                   // serve client.
*                   // set loop to stop to quit, stop thread itself.
*                   pthread->stop_loop();
*               }
*               public: virtual int on_thread_stop() { 
*                   // remove the connection in thread itself.
*                   server->remove(this); 
*               }
*           };
* 
* Usage 3: loop in the cycle method.
*       user can use loop code in the cycle method, @see SrsForwarder
*       1. create SrsThread field, with or without joinable is ok.
*       2. loop code in cycle method, check the can_loop() for thread to quit.
*       for example:
*           class SrsForwarder : public ISrsThreadHandler {
*               public: virtual int cycle() {
*                   while (pthread->can_loop()) {
*                       // read msgs from queue and forward to server.
*                   }
*               }
*           };
*
* @remark why should check can_loop() in cycle method?
*       when thread interrupt, the socket maybe not got EINT,
*       espectially on st_usleep(), so the cycle must check the loop,
*       when handler->cycle() has loop itself, for example:
*               while (true):
*                   if (read_from_socket(skt) < 0) break;
*       if thread stop when read_from_socket, it's ok, the loop will break,
*       but when thread stop interrupt the s_usleep(0), then the loop is
*       death loop.
*       in a word, the handler->cycle() must:
*               while (pthread->can_loop()):
*                   if (read_from_socket(skt) < 0) break;
*       check the loop, then it works.
*
* @remark why should use stop_loop() to terminate thread in itself?
*       in the thread itself, that is the cycle method,
*       if itself want to terminate the thread, should never use stop(),
*       but use stop_loop() to set the loop to false and terminate normally.
* 
* @remark when should set the interval_us, and when not?
*       the cycle will invoke util cannot loop, eventhough the return code of cycle is error,
*       so the interval_us used to sleep for each cycle. 
*/
class ISrsThreadHandler
{
public:
    ISrsThreadHandler();
    virtual ~ISrsThreadHandler();
public:
    virtual void on_thread_start();
    virtual int on_before_cycle();
    virtual int cycle() = 0;
    virtual int on_end_cycle();
    virtual void on_thread_stop();
};

/**
* provides servies from st_thread_t,
* for common thread usage.
*/
class SrsThread
{
private:
    st_thread_t tid;
    int _cid;
    bool loop;
    bool can_run;
    bool really_terminated;
    bool _joinable;
    const char* _name;
private:
    ISrsThreadHandler* handler;
    int64_t cycle_interval_us;
public:
    /**
    * initialize the thread.
    * @param name, human readable name for st debug.
    * @param thread_handler, the cycle handler for the thread.
    * @param interval_us, the sleep interval when cycle finished.
    * @param joinable, if joinable, other thread must stop the thread.
    * @remark if joinable, thread never quit itself, or memory leak. 
    * @see: https://github.com/winlinvip/simple-rtmp-server/issues/78
    * @remark about st debug, see st-1.9/README, _st_iterate_threads_flag
    */
    /**
    * TODO: FIXME: maybe all thread must be reap by others threads, 
    * @see: https://github.com/winlinvip/simple-rtmp-server/issues/77
    */
    SrsThread(const char* name, ISrsThreadHandler* thread_handler, int64_t interval_us, bool joinable);
    virtual ~SrsThread();
public:
    /**
    * get the context id. @see: ISrsThreadContext.get_id().
    * used for parent thread to get the id.
    * @remark when start thread, parent thread will block and wait for this id ready.
    */
    virtual int cid();
    /**
    * start the thread, invoke the cycle of handler util
    * user stop the thread.
    * @remark ignore any error of cycle of handler.
    * @remark user can start multiple times, ignore if already started.
    * @remark wait for the cid is set by thread pfn.
    */
    virtual int start();
    /**
    * stop the thread, wait for the thread to terminate.
    * @remark user can stop multiple times, ignore if already stopped.
    */
    virtual void stop();
public:
    /**
    * whether the thread should loop,
    * used for handler->cycle() which has a loop method,
    * to check this method, break if false.
    */
    virtual bool can_loop();
    /**
    * for the loop thread to stop the loop.
    * other thread can directly use stop() to stop loop and wait for quit.
    * this stop loop method only set loop to false.
    */
    virtual void stop_loop();
private:
    virtual void thread_cycle();
    static void* thread_fun(void* arg);
};

#endif