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/*
Minetest
Copyright (C) 2013 sapier, <sapier AT gmx DOT net>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef CPP_API_ASYNC_EVENTS_HEADER
#define CPP_API_ASYNC_EVENTS_HEADER
#include <vector>
#include <deque>
#include <map>
#include "threading/semaphore.h"
#include "threading/thread.h"
#include "debug.h"
#include "lua.h"
#include "cpp_api/s_base.h"
// Forward declarations
class AsyncEngine;
// Declarations
// Data required to queue a job
struct LuaJobInfo
{
LuaJobInfo() = default;
// Function to be called in async environment
std::string serializedFunction = "";
// Parameter to be passed to function
std::string serializedParams = "";
// Result of function call
std::string serializedResult = "";
// JobID used to identify a job and match it to callback
unsigned int id = 0;
bool valid = false;
};
// Asynchronous working environment
class AsyncWorkerThread : public Thread, public ScriptApiBase {
public:
AsyncWorkerThread(AsyncEngine* jobDispatcher, const std::string &name);
virtual ~AsyncWorkerThread();
void *run();
private:
AsyncEngine *jobDispatcher = nullptr;
};
// Asynchornous thread and job management
class AsyncEngine {
friend class AsyncWorkerThread;
typedef void (*StateInitializer)(lua_State *L, int top);
public:
AsyncEngine() {};
~AsyncEngine();
/**
* Register function to be called on new states
* @param func C function to be called
*/
void registerStateInitializer(StateInitializer func);
/**
* Create async engine tasks and lock function registration
* @param numEngines Number of async threads to be started
*/
void initialize(unsigned int numEngines);
/**
* Queue an async job
* @param func Serialized lua function
* @param params Serialized parameters
* @return jobid The job is queued
*/
unsigned int queueAsyncJob(const std::string &func, const std::string ¶ms);
/**
* Engine step to process finished jobs
* the engine step is one way to pass events back, PushFinishedJobs another
* @param L The Lua stack
*/
void step(lua_State *L);
/**
* Push a list of finished jobs onto the stack
* @param L The Lua stack
*/
void pushFinishedJobs(lua_State *L);
protected:
/**
* Get a Job from queue to be processed
* this function blocks until a job is ready
* @return a job to be processed
*/
LuaJobInfo getJob();
/**
* Put a Job result back to result queue
* @param result result of completed job
*/
void putJobResult(const LuaJobInfo &result);
/**
* Initialize environment with current registred functions
* this function adds all functions registred by registerFunction to the
* passed lua stack
* @param L Lua stack to initialize
* @param top Stack position
*/
void prepareEnvironment(lua_State* L, int top);
private:
// Variable locking the engine against further modification
bool initDone = false;
// Internal store for registred state initializers
std::vector<StateInitializer> stateInitializers;
// Internal counter to create job IDs
unsigned int jobIdCounter = 0;
// Mutex to protect job queue
std::mutex jobQueueMutex;
// Job queue
std::deque<LuaJobInfo> jobQueue;
// Mutex to protect result queue
std::mutex resultQueueMutex;
// Result queue
std::deque<LuaJobInfo> resultQueue;
// List of current worker threads
std::vector<AsyncWorkerThread*> workerThreads;
// Counter semaphore for job dispatching
Semaphore jobQueueCounter;
};
#endif // CPP_API_ASYNC_EVENTS_HEADER
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