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fn: make call.End() to blocking to reduce complexity (#1208)

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agent/lb-agent/runner roles execute call.End() in the background
in some cases to reduce latency. With this change, we simplify this
and switch to non-background execution of call.End(). This fixes
hard to detect issues such as non-deterministic calculation of
call.CompletedAt or incomplete Call.Stats in runners.

Downstream projects if impacted by the now blocking call.End()
latency should take steps to handle this according to their requirements.
This commit is contained in:
Tolga Ceylan
2018-09-13 03:28:11 -07:00
committed by Reed Allman
parent 54ba179078
commit 586d5c4735
3 changed files with 21 additions and 98 deletions
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31
api/agent/lb_agent.go
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@@ -6,7 +6,6 @@ import (
"errors"
"io"
"io/ioutil"
"sync/atomic"
"github.com/sirupsen/logrus"
"go.opencensus.io/trace"
@@ -25,7 +24,6 @@ type lbAgent struct {
placer pool.Placer
callOverrider CallOverrider
shutWg *common.WaitGroup
callEndCount int64
}
type LBAgentOption func(*lbAgent) error
@@ -158,11 +156,6 @@ func (a *lbAgent) Submit(callI Call) error {
statsEnqueue(ctx)
// first check any excess case of call.End() stacking.
if atomic.LoadInt64(&a.callEndCount) >= int64(a.cfg.MaxCallEndStacking) {
a.handleCallEnd(ctx, call, context.DeadlineExceeded, false)
}
err := call.Start(ctx)
if err != nil {
return a.handleCallEnd(ctx, call, err, false)
@@ -242,31 +235,17 @@ func (a *lbAgent) Enqueue(context.Context, *models.Call) error {
return errors.New("Enqueue not implemented")
}
func (a *lbAgent) scheduleCallEnd(fn func()) {
atomic.AddInt64(&a.callEndCount, 1)
go func() {
fn()
atomic.AddInt64(&a.callEndCount, -1)
a.shutWg.DoneSession()
}()
}
func (a *lbAgent) handleCallEnd(ctx context.Context, call *call, err error, isStarted bool) error {
if isStarted {
a.scheduleCallEnd(func() {
ctx = common.BackgroundContext(ctx)
ctx, cancel := context.WithTimeout(ctx, a.cfg.CallEndTimeout)
call.End(ctx, err)
cancel()
})
if isStarted {
call.End(ctx, err)
handleStatsEnd(ctx, err)
return transformTimeout(err, false)
} else {
handleStatsDequeue(ctx, err)
}
a.shutWg.DoneSession()
handleStatsDequeue(ctx, err)
return transformTimeout(err, true)
return transformTimeout(err, !isStarted)
}
var _ Agent = &lbAgent{}