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subscription.go
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subscription.go
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package logbroker
import (
"context"
"fmt"
"strings"
"sync"
events "github.com/docker/go-events"
"github.com/docker/swarmkit/api"
"github.com/docker/swarmkit/log"
"github.com/docker/swarmkit/manager/state"
"github.com/docker/swarmkit/manager/state/store"
"github.com/docker/swarmkit/watch"
)
type subscription struct {
mu sync.RWMutex
wg sync.WaitGroup
store *store.MemoryStore
message *api.SubscriptionMessage
changed *watch.Queue
ctx context.Context
cancel context.CancelFunc
errors []error
nodes map[string]struct{}
pendingTasks map[string]struct{}
}
func newSubscription(store *store.MemoryStore, message *api.SubscriptionMessage, changed *watch.Queue) *subscription {
return &subscription{
store: store,
message: message,
changed: changed,
nodes: make(map[string]struct{}),
pendingTasks: make(map[string]struct{}),
}
}
func (s *subscription) follow() bool {
return s.message.Options != nil && s.message.Options.Follow
}
func (s *subscription) Contains(nodeID string) bool {
s.mu.RLock()
defer s.mu.RUnlock()
_, ok := s.nodes[nodeID]
return ok
}
func (s *subscription) Nodes() []string {
s.mu.RLock()
defer s.mu.RUnlock()
nodes := make([]string, 0, len(s.nodes))
for node := range s.nodes {
nodes = append(nodes, node)
}
return nodes
}
func (s *subscription) Run(ctx context.Context) {
s.ctx, s.cancel = context.WithCancel(ctx)
if s.follow() {
wq := s.store.WatchQueue()
ch, cancel := state.Watch(wq, api.EventCreateTask{}, api.EventUpdateTask{})
go func() {
defer cancel()
s.watch(ch)
}()
}
s.match()
}
func (s *subscription) Stop() {
if s.cancel != nil {
s.cancel()
}
}
func (s *subscription) Wait(ctx context.Context) <-chan struct{} {
// Follow subscriptions never end
if s.follow() {
return nil
}
ch := make(chan struct{})
go func() {
defer close(ch)
s.wg.Wait()
}()
return ch
}
func (s *subscription) Done(nodeID string, err error) {
s.mu.Lock()
defer s.mu.Unlock()
if err != nil {
s.errors = append(s.errors, err)
}
if s.follow() {
return
}
if _, ok := s.nodes[nodeID]; !ok {
return
}
delete(s.nodes, nodeID)
s.wg.Done()
}
func (s *subscription) Err() error {
s.mu.RLock()
defer s.mu.RUnlock()
if len(s.errors) == 0 && len(s.pendingTasks) == 0 {
return nil
}
messages := make([]string, 0, len(s.errors))
for _, err := range s.errors {
messages = append(messages, err.Error())
}
for t := range s.pendingTasks {
messages = append(messages, fmt.Sprintf("task %s has not been scheduled", t))
}
return fmt.Errorf("warning: incomplete log stream. some logs could not be retrieved for the following reasons: %s", strings.Join(messages, ", "))
}
func (s *subscription) Close() {
s.mu.Lock()
s.message.Close = true
s.mu.Unlock()
}
func (s *subscription) Closed() bool {
s.mu.RLock()
defer s.mu.RUnlock()
return s.message.Close
}
func (s *subscription) match() {
s.mu.Lock()
defer s.mu.Unlock()
add := func(t *api.Task) {
if t.NodeID == "" {
s.pendingTasks[t.ID] = struct{}{}
return
}
if _, ok := s.nodes[t.NodeID]; !ok {
s.nodes[t.NodeID] = struct{}{}
s.wg.Add(1)
}
}
s.store.View(func(tx store.ReadTx) {
for _, nid := range s.message.Selector.NodeIDs {
s.nodes[nid] = struct{}{}
}
for _, tid := range s.message.Selector.TaskIDs {
if task := store.GetTask(tx, tid); task != nil {
add(task)
}
}
for _, sid := range s.message.Selector.ServiceIDs {
tasks, err := store.FindTasks(tx, store.ByServiceID(sid))
if err != nil {
log.L.Warning(err)
continue
}
for _, task := range tasks {
// if we're not following, don't add tasks that aren't running yet
if !s.follow() && task.Status.State < api.TaskStateRunning {
continue
}
add(task)
}
}
})
}
func (s *subscription) watch(ch <-chan events.Event) error {
matchTasks := map[string]struct{}{}
for _, tid := range s.message.Selector.TaskIDs {
matchTasks[tid] = struct{}{}
}
matchServices := map[string]struct{}{}
for _, sid := range s.message.Selector.ServiceIDs {
matchServices[sid] = struct{}{}
}
add := func(t *api.Task) {
// this mutex does not have a deferred unlock, because there is work
// we need to do after we release it.
s.mu.Lock()
// Un-allocated task.
if t.NodeID == "" {
s.pendingTasks[t.ID] = struct{}{}
s.mu.Unlock()
return
}
delete(s.pendingTasks, t.ID)
if _, ok := s.nodes[t.NodeID]; !ok {
s.nodes[t.NodeID] = struct{}{}
s.mu.Unlock()
// if we try to call Publish before we release the lock, we can end
// up in a situation where the receiver is trying to acquire a read
// lock on it. it's hard to explain.
s.changed.Publish(s)
return
}
s.mu.Unlock()
}
for {
var t *api.Task
select {
case <-s.ctx.Done():
return s.ctx.Err()
case event := <-ch:
switch v := event.(type) {
case api.EventCreateTask:
t = v.Task
case api.EventUpdateTask:
t = v.Task
}
}
if t == nil {
panic("received invalid task from the watch queue")
}
if _, ok := matchTasks[t.ID]; ok {
add(t)
}
if _, ok := matchServices[t.ServiceID]; ok {
add(t)
}
}
}