package GPool
//
//import (
//	"fmt"
//	"log"
//	"sync"
//	"sync/atomic"
//)
//
//package GPool
//
import (
	"log"
	"sync"
	"sync/atomic"
	"time"
)

type tq struct {
	T *task
	next *tq
}

// PoolForTaskChain 任务链表方式实现的Pool
// 所有的task存在名为taskQueue的链表里，而非channel中
// 此种方式不适合使用并发模式来添加task，因为task入链时需要上锁，
// 锁会影响task并发添加的性能。同时，如果非并发添加task，那么task数量
// 过多时会占用大量内存
type PoolForTaskChain struct {
	taskQueue *tq
	cap int32
	running int32 // finder的数量
	workGroup sync.WaitGroup // 执行任务是否完成
	workerHead *finder
	mux sync.Mutex
	isClose int32
	workerCache sync.Pool
	recoveryTime time.Duration
}

func NewPoolForTaskChain(cap int32) *PoolForTaskChain {
	if cap <= 0 {
		cap = defaultSize
	}
	return &PoolForTaskChain{
		taskQueue:  &tq{
			T:    nil,
			next: nil,
		},
		cap:        cap,
		running:    0,
		workGroup:  sync.WaitGroup{},
		workerHead: &finder{
			W:    nil,
			next: nil,
		},
		mux:        sync.Mutex{},
		isClose:    0,
		workerCache: sync.Pool{},
		recoveryTime: 1 * time.Second,
	}
}

func (p *PoolForTaskChain) AddTaskToTQ(target func(...interface{}), args []interface{}) {
	if target == nil {
		return
	}
	newTask := &task{
		workFunc: target,
		args:     args,
	}
	if p.taskQueue.next == nil {
		p.taskQueue.next = &tq{
			T:    newTask,
			next: nil,
		}
		return
	}
	newTQ := &tq{
		T:    newTask,
		next: nil,
	}
	newTQ.next = p.taskQueue.next
	p.taskQueue.next = newTQ
}

func (p *PoolForTaskChain) getTask() (*task, bool) {
	//p.mux.Lock()
	//defer p.mux.Unlock()
	if p.taskQueue.next == nil {
		return nil, false
	}
	T := p.taskQueue.next
	p.taskQueue.next = T.next
	T.next = nil
	return T.T, true
}

func (p *PoolForTaskChain) recoverWorker() {
	for {
		if p.workerHead == nil {
			return
		}
		currentTime := time.Now()
		p.mux.Lock()
		for you := p.workerHead; you != nil; you = you.next {
			cur := you.next
			if cur == nil {
				break
			}
			if currentTime.Sub(cur.W.heartTime) >= p.recoveryTime {
				you.next = cur.next
				cur.next = nil
				p.workerCache.Put(cur.W)
			}
		}
		p.mux.Unlock()
		time.Sleep(1 * time.Second)
	}
}

func (p *PoolForTaskChain) addFinder(w *worker) {
	p.mux.Lock()
	defer p.mux.Unlock()
	p.running++
	newFinder := &finder{
		W: w,
		next: nil,
	}
	if atomic.LoadInt32(&p.running) == 0 {
		p.workerHead.next = newFinder
		return
	}
	newFinder.next = p.workerHead.next
	p.workerHead.next = newFinder
}



func (p *PoolForTaskChain) getWorker() *worker {
	//if isPoolClosed(p) {
	//	return nil
	//}
		for {
			for h := p.workerHead.next; h != nil; h = h.next {
				if h.W.status == FREE {
					h.W.mux.Lock()
					h.W.status = RUNNING
					h.W.heartTime = time.Now() // 更新心跳时间
					h.W.mux.Unlock()
					return h.W
				}
			}
			var newWorker *worker
			if atomic.LoadInt32(&p.running) < p.cap {
				if one := p.workerCache.Get(); one != nil {
					newWorker = one.(*worker)
				} else {
					newWorker = &worker{
						status: RUNNING,
						work: nil,
						mux: sync.Mutex{},
						heartTime: time.Now(),
					}
				}
				p.addFinder(newWorker)
				return newWorker
			}
		}
}

func (p *PoolForTaskChain) Run_taskChain() {
	go p.recoverWorker()
	for {
		t, err := p.getTask()
		if !err {
			break
		}
		p.workGroup.Add(1)
		go func() {
			oneWorker := p.getWorker()
			defer func(w *worker) {
				if err := recover(); err != nil {
					log.Println(err)
				}
				p.workGroup.Done()
				w.mux.Lock()
				w.status = FREE
				w.mux.Unlock()
			}(oneWorker)
			oneWorker.work = t
			oneWorker.run()
		}()
	}
	p.workGroup.Wait()
	p.workerHead = nil
}