open-nomad/client/allocrunner/taskrunner/stats_hook.go
2019-01-07 14:49:40 -08:00

139 lines
3.2 KiB
Go

package taskrunner
import (
"context"
"sync"
"time"
hclog "github.com/hashicorp/go-hclog"
"github.com/hashicorp/nomad/client/allocrunner/interfaces"
cstructs "github.com/hashicorp/nomad/client/structs"
bstructs "github.com/hashicorp/nomad/plugins/base/structs"
)
// StatsUpdater is the interface required by the StatsHook to update stats.
// Satisfied by TaskRunner.
type StatsUpdater interface {
UpdateStats(*cstructs.TaskResourceUsage)
}
// statsHook manages the task stats collection goroutine.
type statsHook struct {
updater StatsUpdater
interval time.Duration
// stopCh is closed by Exited or Canceled
stopCh chan struct{}
mu sync.Mutex
logger hclog.Logger
}
func newStatsHook(su StatsUpdater, interval time.Duration, logger hclog.Logger) *statsHook {
h := &statsHook{
updater: su,
interval: interval,
}
h.logger = logger.Named(h.Name())
return h
}
func (*statsHook) Name() string {
return "stats_hook"
}
func (h *statsHook) Poststart(ctx context.Context, req *interfaces.TaskPoststartRequest, _ *interfaces.TaskPoststartResponse) error {
h.mu.Lock()
defer h.mu.Unlock()
// This shouldn't happen, but better safe than risk leaking a goroutine
if h.stopCh != nil {
h.logger.Debug("poststart called twice without exiting between")
close(h.stopCh)
}
h.stopCh = make(chan struct{})
go h.collectResourceUsageStats(req.DriverStats, h.stopCh)
return nil
}
func (h *statsHook) Exited(context.Context, *interfaces.TaskExitedRequest, *interfaces.TaskExitedResponse) error {
h.mu.Lock()
defer h.mu.Unlock()
if h.stopCh == nil {
// No stats running
return nil
}
// Close chan to stop stats collection
close(h.stopCh)
// Clear chan so we don't double close for any reason
h.stopCh = nil
return nil
}
// collectResourceUsageStats starts collecting resource usage stats of a Task.
// Collection ends when the passed channel is closed
func (h *statsHook) collectResourceUsageStats(handle interfaces.DriverStats, stopCh <-chan struct{}) {
// start collecting the stats right away and then start collecting every
// collection interval
next := time.NewTimer(0)
defer next.Stop()
for {
select {
case <-next.C:
// Reset the timer
next.Reset(h.interval)
// Collect stats from driver
ru, err := handle.Stats()
if err != nil {
// Check if the driver doesn't implement stats
if err.Error() == cstructs.DriverStatsNotImplemented.Error() {
h.logger.Debug("driver does not support stats")
return
}
// We do not log when the plugin is shutdown as this is either:
// - A race between the stopCollection channel being closed and
// calling Stats on the handle.
// - The driver plugin has unexpectedly exited
//
// In either case sleeping and trying again or returning based
// on the stop channel is the correct behavior
if err != bstructs.ErrPluginShutdown {
h.logger.Debug("error fetching stats of task", "error", err)
}
continue
}
// Update stats on TaskRunner and emit them
h.updater.UpdateStats(ru)
case <-stopCh:
return
}
}
}
func (h *statsHook) Shutdown() {
h.mu.Lock()
defer h.mu.Unlock()
if h.stopCh == nil {
return
}
select {
case <-h.stopCh:
// Already closed
default:
close(h.stopCh)
}
}