Golang Stopper.ShouldStop方法代码示例

func (e *eventDemux) start(stopper *util.Stopper) {
	stopper.RunWorker(func() {
		for {
			select {
			case event := <-e.events:
				switch event := event.(type) {
				case *EventLeaderElection:
					e.LeaderElection <- event

				case *EventCommandCommitted:
					e.CommandCommitted <- event

				case *EventMembershipChangeCommitted:
					e.MembershipChangeCommitted <- event

				default:
					panic(fmt.Sprintf("got unknown event type %T", event))
				}

			case <-stopper.ShouldStop():
				close(e.CommandCommitted)
				close(e.MembershipChangeCommitted)
				close(e.LeaderElection)
				return
			}
		}
	})
}

// maybeWarnAboutInit looks for signs indicating a cluster which
// hasn't been initialized and warns. There's no absolutely sure way
// to determine whether the current node is simply waiting to be
// bootstrapped to an existing cluster vs. the operator having failed
// to initialize the cluster via the "cockroach init" command, so
// we can only warn.
//
// This method checks whether all gossip bootstrap hosts are
// connected, and whether the node itself is a bootstrap host, but
// there is still no sentinel gossip.
func (g *Gossip) maybeWarnAboutInit(stopper *util.Stopper) {
	stopper.RunWorker(func() {
		// Wait 5s before first check.
		select {
		case <-stopper.ShouldStop():
			return
		case <-time.After(5 * time.Second):
		}
		retryOptions := retry.Options{
			Tag:         "check cluster initialization",
			Backoff:     5 * time.Second,  // first backoff at 5s
			MaxBackoff:  60 * time.Second, // max backoff is 60s
			Constant:    2,                // doubles
			MaxAttempts: 0,                // indefinite retries
			Stopper:     stopper,          // stop no matter what on stopper
		}
		// will never error because infinite retries
		_ = retry.WithBackoff(retryOptions, func() (retry.Status, error) {
			g.mu.Lock()
			hasSentinel := g.is.getInfo(KeySentinel) != nil
			g.mu.Unlock()
			// If we have the sentinel, exit the retry loop.
			if hasSentinel {
				return retry.Break, nil
			}
			// Otherwise, if all bootstrap hosts are connected, warn.
			if g.triedAll {
				log.Warningf("connected to gossip but missing sentinel. Has the cluster been initialized? " +
					"Use \"cockroach init\" to initialize.")
			}
			return retry.Continue, nil
		})
	})
}

// bootstrap connects the node to the gossip network. Bootstrapping
// commences in the event there are no connected clients or the
// sentinel gossip info is not available. After a successful bootstrap
// connection, this method will block on the stalled condvar, which
// receives notifications that gossip network connectivity has been
// lost and requires re-bootstrapping.
func (g *Gossip) bootstrap(stopper *util.Stopper) {
	stopper.RunWorker(func() {
		for {
			g.mu.Lock()
			if g.closed {
				g.mu.Unlock()
				return
			}
			// Check whether or not we need bootstrap.
			haveClients := g.outgoing.len() > 0
			haveSentinel := g.is.getInfo(KeySentinel) != nil
			if !haveClients || !haveSentinel {
				// Try to get another bootstrap address from the resolvers.
				if addr := g.getNextBootstrapAddress(); addr != nil {
					g.startClient(addr, g.bsRPCContext, stopper)
				}
			}
			g.mu.Unlock()

			// Block until we need bootstrapping again.
			select {
			case <-g.stalled:
				// continue
			case <-stopper.ShouldStop():
				return
			}
		}
	})
}

// maybeWarnAboutInit looks for signs indicating a cluster which
// hasn't been initialized and warns. There's no absolutely sure way
// to determine whether the current node is simply waiting to be
// bootstrapped to an existing cluster vs. the operator having failed
// to initialize the cluster via the "cockroach init" command, so
// we can only warn.
//
// This method checks whether all gossip bootstrap hosts are
// connected, and whether the node itself is a bootstrap host, but
// there is still no sentinel gossip.
func (g *Gossip) maybeWarnAboutInit(stopper *util.Stopper) {
	stopper.RunWorker(func() {
		// Wait 5s before first check.
		select {
		case <-stopper.ShouldStop():
			return
		case <-time.After(5 * time.Second):
		}
		retryOptions := retry.Options{
			InitialBackoff: 5 * time.Second,  // first backoff at 5s
			MaxBackoff:     60 * time.Second, // max backoff is 60s
			Multiplier:     2,                // doubles
			Stopper:        stopper,          // stop no matter what on stopper
		}
		// will never error because infinite retries
		for r := retry.Start(retryOptions); r.Next(); {
			g.mu.Lock()
			hasSentinel := g.is.getInfo(KeySentinel) != nil
			g.mu.Unlock()
			// If we have the sentinel, exit the retry loop.
			if hasSentinel {
				break
			}
			// Otherwise, if all bootstrap hosts are connected, warn.
			if g.triedAll {
				log.Warningf("connected to gossip but missing sentinel. Has the cluster been initialized? " +
					"Use \"cockroach init\" to initialize.")
			}
		}
	})
}

// waitAndProcess waits for the pace interval and processes the range
// if rng is not nil. The method returns true when the scanner needs
// to be stopped. The method also removes a range from queues when it
// is signaled via the removed channel.
func (rs *rangeScanner) waitAndProcess(start time.Time, clock *hlc.Clock, stopper *util.Stopper,
	rng *Range) bool {
	waitInterval := rs.paceInterval(start, time.Now())
	nextTime := time.After(waitInterval)
	if log.V(6) {
		log.Infof("Wait time interval set to %s", waitInterval)
	}
	for {
		select {
		case <-nextTime:
			if rng == nil {
				return false
			}
			if !stopper.StartTask() {
				return true
			}
			// Try adding range to all queues.
			for _, q := range rs.queues {
				q.MaybeAdd(rng, clock.Now())
			}
			stopper.FinishTask()
			return false
		case rng := <-rs.removed:
			// Remove range from all queues as applicable.
			for _, q := range rs.queues {
				q.MaybeRemove(rng)
			}
			if log.V(6) {
				log.Infof("removed range %s", rng)
			}
		case <-stopper.ShouldStop():
			return true
		}
	}
}

// scanLoop loops endlessly, scanning through ranges available via
// the range iterator, or until the scanner is stopped. The iteration
// is paced to complete a full scan in approximately the scan interval.
func (rs *rangeScanner) scanLoop(clock *hlc.Clock, stopper *util.Stopper) {
	start := time.Now()
	stats := &storeStats{}

	for {
		elapsed := time.Now().Sub(start)
		remainingNanos := rs.interval.Nanoseconds() - elapsed.Nanoseconds()
		if remainingNanos < 0 {
			remainingNanos = 0
		}
		nextIteration := time.Duration(remainingNanos)
		if count := rs.iter.EstimatedCount(); count > 0 {
			nextIteration = time.Duration(remainingNanos / int64(count))
		}
		log.V(6).Infof("next range scan iteration in %s", nextIteration)

		select {
		case <-time.After(nextIteration):
			rng := rs.iter.Next()
			if rng != nil {
				// Try adding range to all queues.
				for _, q := range rs.queues {
					q.MaybeAdd(rng, clock.Now())
				}
				stats.RangeCount++
				stats.MVCC.Accumulate(rng.stats.GetMVCC())
			} else {
				// Otherwise, we're done with the iteration. Reset iteration and start time.
				rs.iter.Reset()
				start = time.Now()
				// Increment iteration counter.
				atomic.AddInt64(&rs.count, 1)
				// Store the most recent scan results in the scanner's stats.
				atomic.StorePointer(&rs.stats, unsafe.Pointer(stats))
				stats = &storeStats{}
				log.V(6).Infof("reset range scan iteration")
			}

		case rng := <-rs.removed:
			// Remove range from all queues as applicable.
			for _, q := range rs.queues {
				q.MaybeRemove(rng)
			}
			log.V(6).Infof("removed range %s", rng)

		case <-stopper.ShouldStop():
			// Exit the loop.
			stopper.SetStopped()
			return
		}
	}
}

// start runs the storage loop in a goroutine.
func (w *writeTask) start(stopper *util.Stopper) {
	stopper.RunWorker(func() {
		for {
			var request *writeRequest
			select {
			case <-w.ready:
				continue
			case <-stopper.ShouldStop():
				return
			case request = <-w.in:
			}
			if log.V(6) {
				log.Infof("writeTask got request %#v", *request)
			}
			response := &writeResponse{make(map[proto.RaftID]*groupWriteResponse)}

			for groupID, groupReq := range request.groups {
				group := w.storage.GroupStorage(groupID)
				if group == nil {
					if log.V(4) {
						log.Infof("dropping write to group %v", groupID)
					}
					continue
				}
				groupResp := &groupWriteResponse{raftpb.HardState{}, -1, -1, groupReq.entries}
				response.groups[groupID] = groupResp
				if !raft.IsEmptyHardState(groupReq.state) {
					err := group.SetHardState(groupReq.state)
					if err != nil {
						panic(err) // TODO(bdarnell): mark this node dead on storage errors
					}
					groupResp.state = groupReq.state
				}
				if !raft.IsEmptySnap(groupReq.snapshot) {
					err := group.ApplySnapshot(groupReq.snapshot)
					if err != nil {
						panic(err) // TODO(bdarnell)
					}
				}
				if len(groupReq.entries) > 0 {
					err := group.Append(groupReq.entries)
					if err != nil {
						panic(err) // TODO(bdarnell)
					}
				}
			}
			w.out <- response
		}
	})
}

// manage manages outgoing clients. Periodically, the infostore is
// scanned for infos with hop count exceeding maxToleratedHops()
// threshold. If the number of outgoing clients doesn't exceed
// MaxPeers, a new gossip client is connected to a randomly selected
// peer beyond maxToleratedHops threshold. Otherwise, the least useful
// peer node is cut off to make room for a replacement. Disconnected
// clients are processed via the disconnected channel and taken out of
// the outgoing address set. If there are no longer any outgoing
// connections or the sentinel gossip is unavailable, the bootstrapper
// is notified via the stalled conditional variable.
func (g *Gossip) manage(stopper *util.Stopper) {
	stopper.RunWorker(func() {
		// Loop until closed and there are no remaining outgoing connections.
		for {
			select {
			case <-stopper.ShouldStop():
				return
			case c := <-g.disconnected:
				g.doDisconnected(stopper, c)
			case <-time.After(g.jitteredGossipInterval()):
				g.doCheckTimeout(stopper)
			}
		}
	})
}

// startGossip loops on a periodic ticker to gossip node-related
// information. Starts a goroutine to loop until the node is closed.
func (n *Node) startGossip(stopper *util.Stopper) {
	stopper.RunWorker(func() {
		ticker := time.NewTicker(gossipInterval)
		defer ticker.Stop()
		n.gossipCapacities() // one-off run before going to sleep
		for {
			select {
			case <-ticker.C:
				n.gossipCapacities()
			case <-stopper.ShouldStop():
				return
			}
		}
	})
}

// processEventsUntil reads and acknowledges messages from the given channel
// until either the given conditional returns true, the channel is closed or a
// read on the channel times out.
func processEventsUntil(ch <-chan *interceptMessage, stopper *util.Stopper, f func(*RaftMessageRequest) bool) {
	for {
		select {
		case e, ok := <-ch:
			if !ok {
				return
			}
			e.ack <- struct{}{}
			if f(e.args.(*RaftMessageRequest)) {
				return
			}
		case <-stopper.ShouldStop():
			return
		}
	}
}

// runHeartbeat sends periodic heartbeats to client. Closes the
// connection on error. Heartbeats are sent in an infinite loop until
// an error is encountered.
func (c *Client) runHeartbeat(stopper *util.Stopper) {
	if log.V(2) {
		log.Infof("client %s starting heartbeat", c.Addr())
	}

	for {
		select {
		case <-stopper.ShouldStop():
			return
		case <-time.After(heartbeatInterval):
			if err := c.heartbeat(); err != nil {
				log.Infof("client %s heartbeat failed: %v; recycling...", c.Addr(), err)
				return
			}
		}
	}
}

// startPublishStatuses starts a loop which periodically instructs each store to
// publish its current status to the event feed.
func (n *Node) startPublishStatuses(stopper *util.Stopper) {
	stopper.RunWorker(func() {
		// Publish status at the same frequency as metrics are collected.
		ticker := time.NewTicker(publishStatusInterval)
		defer ticker.Stop()
		for {
			select {
			case <-ticker.C:
				err := n.publishStoreStatuses()
				if err != nil {
					log.Error(err)
				}
			case <-stopper.ShouldStop():
				return
			}
		}
	})
}

func (tq *testQueue) Start(clock *hlc.Clock, stopper *util.Stopper) {
	stopper.RunWorker(func() {
		for {
			select {
			case <-time.After(1 * time.Millisecond):
				tq.Lock()
				if !tq.disabled && len(tq.ranges) > 0 {
					tq.ranges = tq.ranges[1:]
					tq.processed++
				}
				tq.Unlock()
			case <-stopper.ShouldStop():
				tq.Lock()
				tq.done = true
				tq.Unlock()
				return
			}
		}
	})
}

// start initializes the infostore with the rpc server address and
// then begins processing connecting clients in an infinite select
// loop via goroutine. Periodically, clients connected and awaiting
// the next round of gossip are awoken via the conditional variable.
func (s *server) start(rpcServer *rpc.Server, stopper *util.Stopper) {
	s.is.NodeAddr = rpcServer.Addr()
	if err := rpcServer.RegisterName("Gossip", s); err != nil {
		log.Fatalf("unable to register gossip service with RPC server: %s", err)
	}
	rpcServer.AddCloseCallback(s.onClose)

	stopper.RunWorker(func() {
		// Periodically wakeup blocked client gossip requests.
		for {
			select {
			case <-time.After(s.jitteredGossipInterval()):
				// Wakeup all blocked gossip requests.
				s.ready.Broadcast()
			case <-stopper.ShouldStop():
				s.stop()
				return
			}
		}
	})
}

// MonitorRemoteOffsets periodically checks that the offset of this server's
// clock from the true cluster time is within MaxOffset. If the offset exceeds
// MaxOffset, then this method will trigger a fatal error, causing the node to
// suicide.
func (r *RemoteClockMonitor) MonitorRemoteOffsets(stopper *util.Stopper) {
	if log.V(1) {
		log.Infof("monitoring cluster offset")
	}
	for {
		select {
		case <-stopper.ShouldStop():
			return
		case <-time.After(monitorInterval):
			offsetInterval, err := r.findOffsetInterval()
			// By the contract of the hlc, if the value is 0, then safety checking
			// of the max offset is disabled. However we may still want to
			// propagate the information to a status node.
			// TODO(embark): once there is a framework for collecting timeseries
			// data about the db, propagate the offset status to that.
			// Don't forget to protect r.offsets through the Mutex if those
			// Fatalf's below ever turn into something less destructive.
			if r.lClock.MaxOffset() != 0 {
				if err != nil {
					log.Fatalf("clock offset from the cluster time "+
						"for remote clocks %v could not be determined: %s",
						r.offsets, err)
				}

				if !isHealthyOffsetInterval(offsetInterval, r.lClock.MaxOffset()) {
					log.Fatalf("clock offset from the cluster time "+
						"for remote clocks: %v is in interval: %s, which "+
						"indicates that the true offset is greater than %s",
						r.offsets, offsetInterval, time.Duration(r.lClock.MaxOffset()))
				}
				if log.V(1) {
					log.Infof("healthy cluster offset: %s", offsetInterval)
				}
			}
			r.mu.Lock()
			r.lastMonitoredAt = r.lClock.PhysicalNow()
			r.mu.Unlock()
		}
	}
}