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/*
* Author: Sven Gothel <sgothel@jausoft.com>
* Copyright (c) 2022 Gothel Software e.K.
*
* 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 JAU_SERVICERUNNER_HPP_
#define JAU_SERVICERUNNER_HPP_
#include <cstring>
#include <string>
#include <cstdint>
#include <limits>
#include <atomic>
#include <memory>
#include <mutex>
#include <condition_variable>
#include <thread>
#include <algorithm>
#include <jau/cpp_lang_util.hpp>
#include <jau/basic_types.hpp>
#include <jau/ordered_atomic.hpp>
#include <jau/function_def.hpp>
namespace jau {
/**
* Service runner, a reusable dedicated thread performing custom user services.
*/
class service_runner {
public:
typedef service_runner& service_runner_ref;
typedef FunctionDef<void, service_runner_ref> Callback;
static const pid_t pid_self;
private:
std::string name;
/**
* Maximum time in milliseconds to wait for a thread shutdown.
*/
nsize_t service_shutdown_timeout_ms;
Callback service_work;
Callback service_init_locked;
Callback service_end_locked;
Callback service_end_post_notify;
jau::sc_atomic_bool shall_stop;
jau::sc_atomic_bool running;
pthread_t thread_id;
std::mutex mtx_lifecycle;
std::condition_variable cv_init;
void workerThread();
static bool install_sighandler() noexcept;
public:
/**
* Remove the sighandler
*/
static bool remove_sighandler() noexcept;
/**
* Install the singleton SIGALRM sighandler instance.
* - First call will install the sighandler
* - Should be called at least once within the application using jau::service_runner
*/
static bool singleton_sighandler() noexcept {
/**
* Thread safe starting with C++11 6.7:
*
* If control enters the declaration concurrently while the variable is being initialized,
* the concurrent execution shall wait for completion of the initialization.
*
* (Magic Statics)
*
* Avoiding non-working double checked locking.
*/
static bool r = install_sighandler();
return r;
}
/**
* Service runner constructor.
*
* start() shall be issued to kick off this service.
*
* @param name service name
* @param service_shutdown_timeout_ms maximum time in milliseconds to wait for a thread shutdown, may be nullptr
* @param service_work service working function
* @param service_init_locked optional service init function, lifecycle mutex is locked
* @param service_end_locked optional service end function, lifecycle mutex is locked
* @param service_end_post_notify optional service end function post mutex lock and notify
*/
service_runner(const std::string& name,
const nsize_t service_shutdown_timeout_ms,
Callback service_work,
Callback service_init_locked = Callback(),
Callback service_end_locked = Callback(),
Callback service_end_post_notify = Callback()) noexcept;
/**
* Service runner destructor.
*
* Issues stop()
*/
~service_runner() noexcept;
/**
* Return the given name of this service
*/
const std::string& get_name() const noexcept { return name; }
/**
* Return the thread-id of this service worker thread, zero if not running.
*/
pthread_t get_threadid() const noexcept { return thread_id; }
/**
* Returns true if service is running
*/
bool is_running() const noexcept { return running; }
/**
* Returns true if service shall stop.
*
* This flag can be used by the service_work Callback to determine whether to skip lengthly tasks,
* or even to skip stopping this service (again).
*/
bool get_shall_stop() const noexcept { return shall_stop; }
/**
* Starts this service, if not running already.
*
* @see is_running()
*/
void start() noexcept;
/**
* Stops this service, if running.
*
* Method attempts to stop the worker thread
* - by flagging `shall stop`
* - sending `SIGALRM` to the worker thread
* - waiting until worker thread has stopped or timeout occurred
*
* Implementation requires a `SIGALRM` handler to be install,
* e.g. using singleton_sighandler().
*
* @see is_running()
* @see singleton_sighandler()
*/
void stop() noexcept;
/**
* Only marks the worker thread to stop in due process
* by flagging `shall stop`.
*/
void set_shall_stop() noexcept { shall_stop = true; }
/**
* Returns a string representation of this service
*/
std::string toString() const noexcept;
};
} // namespace jau
#endif /* JAU_SERVICERUNNER_HPP_ */
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