package main

// thread.go: handling of worker threads

import (
	"sync"
	"time"
)

func init() {
	registerParam("threads", 3, "how many threads to use")
	registerParam("thread-delay-ms", 10, "separate threads at startup for this amount of ms")

	// using a very high limit for now, but this should actually be set to -1
	registerParam("task-max-deferrals", 30000, "how many deferrals are allowed for a single task. -1 to disable")

	registerAlias("t", "threads")
}

// maxSafeThreads is a safeguard to prevent creation of too many threads at once.
const maxSafeThreads = 5000

// ThreadService creates, starts up and waits for all threads.
func ThreadService() {
	numThreads := getParamInt("threads")
	failIf(numThreads > maxSafeThreads, "too many threads (max %v)", maxSafeThreads)

	log("thread", 1, "initializing %v threads", numThreads)

	c := make(chan bool)
	var wg sync.WaitGroup
	for i := 1; i <= numThreads; i++ {
		wg.Add(1)
		go threadEntryPoint(c, i, &wg)
	}

	threadDelay := getParamDurationMS("thread-delay-ms")
	log("thread", 0, "starting %v threads", numThreads)
	for i := 1; i <= numThreads; i++ {
		c <- true
		if threadDelay > 0 {
			time.Sleep(threadDelay)
		}
	}

	wg.Wait()
	log("thread", 1, "finished threads")
}

// threadEntryPoint is the main entrypoint for a work thread.
func threadEntryPoint(c chan bool, threadIdx int, wg *sync.WaitGroup) {
	<-c

	log("thread", 3, "starting loop for thread %v", threadIdx)

	for threadWork(threadIdx) {
	}

	log("thread", 3, "exiting thread %v", threadIdx)
	wg.Done()
}

// threadWork processes a single work item for a thread.
func threadWork(threadIdx int) bool {
	task, delay := CreateTask(threadIdx)
	if task == nil {
		if delay > 0 {
			log("thread", 3, "no work currently available, sleeping for %v in thread %v", delay, threadIdx)
			time.Sleep(delay)
			return true
		} else if delay == 0 {
			log("thread", 2, "no more work for thread %v", threadIdx)
			return false
		} else {
			panic("negative task creation delay: " + delay.String())
		}
	}

	log("thread", 4, "got task %v", task)

	conn, err := NewConnection(task.e)
	if err != nil {
		task.EventWithParm(TE_NoResponse, err)
		return true
	}

	task.Event(TN_Connected)

	log("thread", 2, "trying %v", task)

	res, err := TryLogin(task, conn)
	if err != nil {
		task.Event(TE_ProtocolError)
	} else {
		if res && err == nil {
			task.EventWithParm(TE_Good, task.login)
		} else {
			task.Event(TE_Bad)
		}
	}

	return true
}