refacor/Taskpool: 统一内外中断信号+修复bug

[longyue0521]

• 将shutdownCtx、shutdownNowCtx合并为一个interruptCtx
• 重构方法、抽取方法、清理过期注释
• 修复隐秘bug

[codecov]

Codecov Report

Merging #184 (f860c5f) into dev (a120775) will increase coverage by 0.09%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev     #184      +/-   ##
==========================================
+ Coverage   95.85%   95.95%   +0.09%     
==========================================
  Files          44       44              
  Lines        2415     2396      -19     
==========================================
- Hits         2315     2299      -16     
+ Misses         79       77       -2     
+ Partials       21       20       -1     

Impacted Files	Coverage Δ
pool/task_pool.go	99.12% <100.00%> (-0.05%)	⬇️

... and 1 file with indirect coverage changes

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[longyue0521]

@flycash

当我在pool包内执行命令

 go test -run=Test -failfast -timeout=0 -count=1000 -v > a.out

会被卡死(因为设置了-timeout=0不会自动超时),经过排查发现:

atomic.AddInt32(&b.numGoRunningTasks, 1)
if !ok {
    // 1. G1执行atomic.LoadInt32(&b.state) == stateClosing为true后时间片用完,此时b.numGoRunningTasks==1
    // 2. G2先将b.numGoRunningTasks改为2,再进入这里因if判断条件为false,G2在下方2.1“else case”处用完时间片
    //      此时b.numGoRunningTasks == 2
    // 3. G1再次获得时间片,发现atomic.CompareAndSwapInt32(&b.numGoRunningTasks, 1, 0)为false
   // 从而导致atomic.CompareAndSwapInt32(&b.state, stateClosing, stateStopped)和b.shutdownCancel()永远不会被执行
   // 也导致了外部调用者的无限等待!!!!
    if atomic.LoadInt32(&b.state) == stateClosing && atomic.CompareAndSwapInt32(&b.numGoRunningTasks, 1, 0) {
	if atomic.CompareAndSwapInt32(&b.state, stateClosing, stateStopped) {
	    // 显示通知外部调用者
	    b.shutdownCancel()
        }
	b.decreaseTotalGo(1)
	return
    }

    // 2.1 "else case" G2在此处时间片用完,此时b.numGoRunningTasks == 2
    atomic.AddInt32(&b.numGoRunningTasks, -1)
    b.decreaseTotalGo(1)
    return
}

修复后使用命令

 go test -run=Test -failfast -timeout=0 -count=10000 -v > a.out

所有测试也能PASS,就是耗时很长

PASS
ok  	github.com/ecodeclub/ekit/pool	3439.027s