| package sarama |
| |
| import ( |
| "context" |
| "errors" |
| "fmt" |
| "sort" |
| "sync" |
| "time" |
| ) |
| |
| // ErrClosedConsumerGroup is the error returned when a method is called on a consumer group that has been closed. |
| var ErrClosedConsumerGroup = errors.New("kafka: tried to use a consumer group that was closed") |
| |
| // ConsumerGroup is responsible for dividing up processing of topics and partitions |
| // over a collection of processes (the members of the consumer group). |
| type ConsumerGroup interface { |
| // Consume joins a cluster of consumers for a given list of topics and |
| // starts a blocking ConsumerGroupSession through the ConsumerGroupHandler. |
| // |
| // The life-cycle of a session is represented by the following steps: |
| // |
| // 1. The consumers join the group (as explained in https://kafka.apache.org/documentation/#intro_consumers) |
| // and is assigned their "fair share" of partitions, aka 'claims'. |
| // 2. Before processing starts, the handler's Setup() hook is called to notify the user |
| // of the claims and allow any necessary preparation or alteration of state. |
| // 3. For each of the assigned claims the handler's ConsumeClaim() function is then called |
| // in a separate goroutine which requires it to be thread-safe. Any state must be carefully protected |
| // from concurrent reads/writes. |
| // 4. The session will persist until one of the ConsumeClaim() functions exits. This can be either when the |
| // parent context is cancelled or when a server-side rebalance cycle is initiated. |
| // 5. Once all the ConsumeClaim() loops have exited, the handler's Cleanup() hook is called |
| // to allow the user to perform any final tasks before a rebalance. |
| // 6. Finally, marked offsets are committed one last time before claims are released. |
| // |
| // Please note, that once a rebalance is triggered, sessions must be completed within |
| // Config.Consumer.Group.Rebalance.Timeout. This means that ConsumeClaim() functions must exit |
| // as quickly as possible to allow time for Cleanup() and the final offset commit. If the timeout |
| // is exceeded, the consumer will be removed from the group by Kafka, which will cause offset |
| // commit failures. |
| Consume(ctx context.Context, topics []string, handler ConsumerGroupHandler) error |
| |
| // Errors returns a read channel of errors that occurred during the consumer life-cycle. |
| // By default, errors are logged and not returned over this channel. |
| // If you want to implement any custom error handling, set your config's |
| // Consumer.Return.Errors setting to true, and read from this channel. |
| Errors() <-chan error |
| |
| // Close stops the ConsumerGroup and detaches any running sessions. It is required to call |
| // this function before the object passes out of scope, as it will otherwise leak memory. |
| Close() error |
| } |
| |
| type consumerGroup struct { |
| client Client |
| ownClient bool |
| |
| config *Config |
| consumer Consumer |
| groupID string |
| memberID string |
| errors chan error |
| |
| lock sync.Mutex |
| closed chan none |
| closeOnce sync.Once |
| } |
| |
| // NewConsumerGroup creates a new consumer group the given broker addresses and configuration. |
| func NewConsumerGroup(addrs []string, groupID string, config *Config) (ConsumerGroup, error) { |
| client, err := NewClient(addrs, config) |
| if err != nil { |
| return nil, err |
| } |
| |
| c, err := NewConsumerGroupFromClient(groupID, client) |
| if err != nil { |
| _ = client.Close() |
| return nil, err |
| } |
| |
| c.(*consumerGroup).ownClient = true |
| return c, nil |
| } |
| |
| // NewConsumerGroupFromClient creates a new consumer group using the given client. It is still |
| // necessary to call Close() on the underlying client when shutting down this consumer. |
| // PLEASE NOTE: consumer groups can only re-use but not share clients. |
| func NewConsumerGroupFromClient(groupID string, client Client) (ConsumerGroup, error) { |
| config := client.Config() |
| if !config.Version.IsAtLeast(V0_10_2_0) { |
| return nil, ConfigurationError("consumer groups require Version to be >= V0_10_2_0") |
| } |
| |
| consumer, err := NewConsumerFromClient(client) |
| if err != nil { |
| return nil, err |
| } |
| |
| return &consumerGroup{ |
| client: client, |
| consumer: consumer, |
| config: config, |
| groupID: groupID, |
| errors: make(chan error, config.ChannelBufferSize), |
| closed: make(chan none), |
| }, nil |
| } |
| |
| // Errors implements ConsumerGroup. |
| func (c *consumerGroup) Errors() <-chan error { return c.errors } |
| |
| // Close implements ConsumerGroup. |
| func (c *consumerGroup) Close() (err error) { |
| c.closeOnce.Do(func() { |
| close(c.closed) |
| |
| c.lock.Lock() |
| defer c.lock.Unlock() |
| |
| // leave group |
| if e := c.leave(); e != nil { |
| err = e |
| } |
| |
| // drain errors |
| go func() { |
| close(c.errors) |
| }() |
| for e := range c.errors { |
| err = e |
| } |
| |
| if c.ownClient { |
| if e := c.client.Close(); e != nil { |
| err = e |
| } |
| } |
| }) |
| return |
| } |
| |
| // Consume implements ConsumerGroup. |
| func (c *consumerGroup) Consume(ctx context.Context, topics []string, handler ConsumerGroupHandler) error { |
| // Ensure group is not closed |
| select { |
| case <-c.closed: |
| return ErrClosedConsumerGroup |
| default: |
| } |
| |
| c.lock.Lock() |
| defer c.lock.Unlock() |
| |
| // Quick exit when no topics are provided |
| if len(topics) == 0 { |
| return fmt.Errorf("no topics provided") |
| } |
| |
| // Refresh metadata for requested topics |
| if err := c.client.RefreshMetadata(topics...); err != nil { |
| return err |
| } |
| |
| // Get coordinator |
| coordinator, err := c.client.Coordinator(c.groupID) |
| if err != nil { |
| return err |
| } |
| |
| // Init session |
| sess, err := c.newSession(ctx, coordinator, topics, handler, c.config.Consumer.Group.Rebalance.Retry.Max) |
| if err == ErrClosedClient { |
| return ErrClosedConsumerGroup |
| } else if err != nil { |
| return err |
| } |
| |
| // Wait for session exit signal |
| <-sess.ctx.Done() |
| |
| // Gracefully release session claims |
| return sess.release(true) |
| } |
| |
| func (c *consumerGroup) newSession(ctx context.Context, coordinator *Broker, topics []string, handler ConsumerGroupHandler, retries int) (*consumerGroupSession, error) { |
| // Join consumer group |
| join, err := c.joinGroupRequest(coordinator, topics) |
| if err != nil { |
| _ = coordinator.Close() |
| return nil, err |
| } |
| switch join.Err { |
| case ErrNoError: |
| c.memberID = join.MemberId |
| case ErrUnknownMemberId, ErrIllegalGeneration: // reset member ID and retry immediately |
| c.memberID = "" |
| return c.newSession(ctx, coordinator, topics, handler, retries) |
| case ErrRebalanceInProgress: // retry after backoff |
| if retries <= 0 { |
| return nil, join.Err |
| } |
| |
| select { |
| case <-c.closed: |
| return nil, ErrClosedConsumerGroup |
| case <-time.After(c.config.Consumer.Group.Rebalance.Retry.Backoff): |
| } |
| |
| return c.newSession(ctx, coordinator, topics, handler, retries-1) |
| default: |
| return nil, join.Err |
| } |
| |
| // Prepare distribution plan if we joined as the leader |
| var plan BalanceStrategyPlan |
| if join.LeaderId == join.MemberId { |
| members, err := join.GetMembers() |
| if err != nil { |
| return nil, err |
| } |
| |
| plan, err = c.balance(members) |
| if err != nil { |
| return nil, err |
| } |
| } |
| |
| // Sync consumer group |
| sync, err := c.syncGroupRequest(coordinator, plan, join.GenerationId) |
| if err != nil { |
| _ = coordinator.Close() |
| return nil, err |
| } |
| switch sync.Err { |
| case ErrNoError: |
| case ErrUnknownMemberId, ErrIllegalGeneration: // reset member ID and retry immediately |
| c.memberID = "" |
| return c.newSession(ctx, coordinator, topics, handler, retries) |
| case ErrRebalanceInProgress: // retry after backoff |
| if retries <= 0 { |
| return nil, sync.Err |
| } |
| |
| select { |
| case <-c.closed: |
| return nil, ErrClosedConsumerGroup |
| case <-time.After(c.config.Consumer.Group.Rebalance.Retry.Backoff): |
| } |
| |
| return c.newSession(ctx, coordinator, topics, handler, retries-1) |
| default: |
| return nil, sync.Err |
| } |
| |
| // Retrieve and sort claims |
| var claims map[string][]int32 |
| if len(sync.MemberAssignment) > 0 { |
| members, err := sync.GetMemberAssignment() |
| if err != nil { |
| return nil, err |
| } |
| claims = members.Topics |
| |
| for _, partitions := range claims { |
| sort.Sort(int32Slice(partitions)) |
| } |
| } |
| |
| return newConsumerGroupSession(ctx, c, claims, join.MemberId, join.GenerationId, handler) |
| } |
| |
| func (c *consumerGroup) joinGroupRequest(coordinator *Broker, topics []string) (*JoinGroupResponse, error) { |
| req := &JoinGroupRequest{ |
| GroupId: c.groupID, |
| MemberId: c.memberID, |
| SessionTimeout: int32(c.config.Consumer.Group.Session.Timeout / time.Millisecond), |
| ProtocolType: "consumer", |
| } |
| if c.config.Version.IsAtLeast(V0_10_1_0) { |
| req.Version = 1 |
| req.RebalanceTimeout = int32(c.config.Consumer.Group.Rebalance.Timeout / time.Millisecond) |
| } |
| |
| meta := &ConsumerGroupMemberMetadata{ |
| Topics: topics, |
| UserData: c.config.Consumer.Group.Member.UserData, |
| } |
| strategy := c.config.Consumer.Group.Rebalance.Strategy |
| if err := req.AddGroupProtocolMetadata(strategy.Name(), meta); err != nil { |
| return nil, err |
| } |
| |
| return coordinator.JoinGroup(req) |
| } |
| |
| func (c *consumerGroup) syncGroupRequest(coordinator *Broker, plan BalanceStrategyPlan, generationID int32) (*SyncGroupResponse, error) { |
| req := &SyncGroupRequest{ |
| GroupId: c.groupID, |
| MemberId: c.memberID, |
| GenerationId: generationID, |
| } |
| for memberID, topics := range plan { |
| err := req.AddGroupAssignmentMember(memberID, &ConsumerGroupMemberAssignment{ |
| Topics: topics, |
| }) |
| if err != nil { |
| return nil, err |
| } |
| } |
| return coordinator.SyncGroup(req) |
| } |
| |
| func (c *consumerGroup) heartbeatRequest(coordinator *Broker, memberID string, generationID int32) (*HeartbeatResponse, error) { |
| req := &HeartbeatRequest{ |
| GroupId: c.groupID, |
| MemberId: memberID, |
| GenerationId: generationID, |
| } |
| |
| return coordinator.Heartbeat(req) |
| } |
| |
| func (c *consumerGroup) balance(members map[string]ConsumerGroupMemberMetadata) (BalanceStrategyPlan, error) { |
| topics := make(map[string][]int32) |
| for _, meta := range members { |
| for _, topic := range meta.Topics { |
| topics[topic] = nil |
| } |
| } |
| |
| for topic := range topics { |
| partitions, err := c.client.Partitions(topic) |
| if err != nil { |
| return nil, err |
| } |
| topics[topic] = partitions |
| } |
| |
| strategy := c.config.Consumer.Group.Rebalance.Strategy |
| return strategy.Plan(members, topics) |
| } |
| |
| // Leaves the cluster, called by Close, protected by lock. |
| func (c *consumerGroup) leave() error { |
| if c.memberID == "" { |
| return nil |
| } |
| |
| coordinator, err := c.client.Coordinator(c.groupID) |
| if err != nil { |
| return err |
| } |
| |
| resp, err := coordinator.LeaveGroup(&LeaveGroupRequest{ |
| GroupId: c.groupID, |
| MemberId: c.memberID, |
| }) |
| if err != nil { |
| _ = coordinator.Close() |
| return err |
| } |
| |
| // Unset memberID |
| c.memberID = "" |
| |
| // Check response |
| switch resp.Err { |
| case ErrRebalanceInProgress, ErrUnknownMemberId, ErrNoError: |
| return nil |
| default: |
| return resp.Err |
| } |
| } |
| |
| func (c *consumerGroup) handleError(err error, topic string, partition int32) { |
| select { |
| case <-c.closed: |
| return |
| default: |
| } |
| |
| if _, ok := err.(*ConsumerError); !ok && topic != "" && partition > -1 { |
| err = &ConsumerError{ |
| Topic: topic, |
| Partition: partition, |
| Err: err, |
| } |
| } |
| |
| if c.config.Consumer.Return.Errors { |
| select { |
| case c.errors <- err: |
| default: |
| } |
| } else { |
| Logger.Println(err) |
| } |
| } |
| |
| // -------------------------------------------------------------------- |
| |
| // ConsumerGroupSession represents a consumer group member session. |
| type ConsumerGroupSession interface { |
| // Claims returns information about the claimed partitions by topic. |
| Claims() map[string][]int32 |
| |
| // MemberID returns the cluster member ID. |
| MemberID() string |
| |
| // GenerationID returns the current generation ID. |
| GenerationID() int32 |
| |
| // MarkOffset marks the provided offset, alongside a metadata string |
| // that represents the state of the partition consumer at that point in time. The |
| // metadata string can be used by another consumer to restore that state, so it |
| // can resume consumption. |
| // |
| // To follow upstream conventions, you are expected to mark the offset of the |
| // next message to read, not the last message read. Thus, when calling `MarkOffset` |
| // you should typically add one to the offset of the last consumed message. |
| // |
| // Note: calling MarkOffset does not necessarily commit the offset to the backend |
| // store immediately for efficiency reasons, and it may never be committed if |
| // your application crashes. This means that you may end up processing the same |
| // message twice, and your processing should ideally be idempotent. |
| MarkOffset(topic string, partition int32, offset int64, metadata string) |
| |
| // ResetOffset resets to the provided offset, alongside a metadata string that |
| // represents the state of the partition consumer at that point in time. Reset |
| // acts as a counterpart to MarkOffset, the difference being that it allows to |
| // reset an offset to an earlier or smaller value, where MarkOffset only |
| // allows incrementing the offset. cf MarkOffset for more details. |
| ResetOffset(topic string, partition int32, offset int64, metadata string) |
| |
| // MarkMessage marks a message as consumed. |
| MarkMessage(msg *ConsumerMessage, metadata string) |
| |
| // Context returns the session context. |
| Context() context.Context |
| } |
| |
| type consumerGroupSession struct { |
| parent *consumerGroup |
| memberID string |
| generationID int32 |
| handler ConsumerGroupHandler |
| |
| claims map[string][]int32 |
| offsets *offsetManager |
| ctx context.Context |
| cancel func() |
| |
| waitGroup sync.WaitGroup |
| releaseOnce sync.Once |
| hbDying, hbDead chan none |
| } |
| |
| func newConsumerGroupSession(ctx context.Context, parent *consumerGroup, claims map[string][]int32, memberID string, generationID int32, handler ConsumerGroupHandler) (*consumerGroupSession, error) { |
| // init offset manager |
| offsets, err := newOffsetManagerFromClient(parent.groupID, memberID, generationID, parent.client) |
| if err != nil { |
| return nil, err |
| } |
| |
| // init context |
| ctx, cancel := context.WithCancel(ctx) |
| |
| // init session |
| sess := &consumerGroupSession{ |
| parent: parent, |
| memberID: memberID, |
| generationID: generationID, |
| handler: handler, |
| offsets: offsets, |
| claims: claims, |
| ctx: ctx, |
| cancel: cancel, |
| hbDying: make(chan none), |
| hbDead: make(chan none), |
| } |
| |
| // start heartbeat loop |
| go sess.heartbeatLoop() |
| |
| // create a POM for each claim |
| for topic, partitions := range claims { |
| for _, partition := range partitions { |
| pom, err := offsets.ManagePartition(topic, partition) |
| if err != nil { |
| _ = sess.release(false) |
| return nil, err |
| } |
| |
| // handle POM errors |
| go func(topic string, partition int32) { |
| for err := range pom.Errors() { |
| sess.parent.handleError(err, topic, partition) |
| } |
| }(topic, partition) |
| } |
| } |
| |
| // perform setup |
| if err := handler.Setup(sess); err != nil { |
| _ = sess.release(true) |
| return nil, err |
| } |
| |
| // start consuming |
| for topic, partitions := range claims { |
| for _, partition := range partitions { |
| sess.waitGroup.Add(1) |
| |
| go func(topic string, partition int32) { |
| defer sess.waitGroup.Done() |
| |
| // cancel the as session as soon as the first |
| // goroutine exits |
| defer sess.cancel() |
| |
| // consume a single topic/partition, blocking |
| sess.consume(topic, partition) |
| }(topic, partition) |
| } |
| } |
| return sess, nil |
| } |
| |
| func (s *consumerGroupSession) Claims() map[string][]int32 { return s.claims } |
| func (s *consumerGroupSession) MemberID() string { return s.memberID } |
| func (s *consumerGroupSession) GenerationID() int32 { return s.generationID } |
| |
| func (s *consumerGroupSession) MarkOffset(topic string, partition int32, offset int64, metadata string) { |
| if pom := s.offsets.findPOM(topic, partition); pom != nil { |
| pom.MarkOffset(offset, metadata) |
| } |
| } |
| |
| func (s *consumerGroupSession) ResetOffset(topic string, partition int32, offset int64, metadata string) { |
| if pom := s.offsets.findPOM(topic, partition); pom != nil { |
| pom.ResetOffset(offset, metadata) |
| } |
| } |
| |
| func (s *consumerGroupSession) MarkMessage(msg *ConsumerMessage, metadata string) { |
| s.MarkOffset(msg.Topic, msg.Partition, msg.Offset+1, metadata) |
| } |
| |
| func (s *consumerGroupSession) Context() context.Context { |
| return s.ctx |
| } |
| |
| func (s *consumerGroupSession) consume(topic string, partition int32) { |
| // quick exit if rebalance is due |
| select { |
| case <-s.ctx.Done(): |
| return |
| case <-s.parent.closed: |
| return |
| default: |
| } |
| |
| // get next offset |
| offset := s.parent.config.Consumer.Offsets.Initial |
| if pom := s.offsets.findPOM(topic, partition); pom != nil { |
| offset, _ = pom.NextOffset() |
| } |
| |
| // create new claim |
| claim, err := newConsumerGroupClaim(s, topic, partition, offset) |
| if err != nil { |
| s.parent.handleError(err, topic, partition) |
| return |
| } |
| |
| // handle errors |
| go func() { |
| for err := range claim.Errors() { |
| s.parent.handleError(err, topic, partition) |
| } |
| }() |
| |
| // trigger close when session is done |
| go func() { |
| select { |
| case <-s.ctx.Done(): |
| case <-s.parent.closed: |
| } |
| claim.AsyncClose() |
| }() |
| |
| // start processing |
| if err := s.handler.ConsumeClaim(s, claim); err != nil { |
| s.parent.handleError(err, topic, partition) |
| } |
| |
| // ensure consumer is closed & drained |
| claim.AsyncClose() |
| for _, err := range claim.waitClosed() { |
| s.parent.handleError(err, topic, partition) |
| } |
| } |
| |
| func (s *consumerGroupSession) release(withCleanup bool) (err error) { |
| // signal release, stop heartbeat |
| s.cancel() |
| |
| // wait for consumers to exit |
| s.waitGroup.Wait() |
| |
| // perform release |
| s.releaseOnce.Do(func() { |
| if withCleanup { |
| if e := s.handler.Cleanup(s); e != nil { |
| s.parent.handleError(err, "", -1) |
| err = e |
| } |
| } |
| |
| if e := s.offsets.Close(); e != nil { |
| err = e |
| } |
| |
| close(s.hbDying) |
| <-s.hbDead |
| }) |
| |
| return |
| } |
| |
| func (s *consumerGroupSession) heartbeatLoop() { |
| defer close(s.hbDead) |
| defer s.cancel() // trigger the end of the session on exit |
| |
| pause := time.NewTicker(s.parent.config.Consumer.Group.Heartbeat.Interval) |
| defer pause.Stop() |
| |
| retries := s.parent.config.Metadata.Retry.Max |
| for { |
| coordinator, err := s.parent.client.Coordinator(s.parent.groupID) |
| if err != nil { |
| if retries <= 0 { |
| s.parent.handleError(err, "", -1) |
| return |
| } |
| |
| select { |
| case <-s.hbDying: |
| return |
| case <-time.After(s.parent.config.Metadata.Retry.Backoff): |
| retries-- |
| } |
| continue |
| } |
| |
| resp, err := s.parent.heartbeatRequest(coordinator, s.memberID, s.generationID) |
| if err != nil { |
| _ = coordinator.Close() |
| retries-- |
| continue |
| } |
| |
| switch resp.Err { |
| case ErrNoError: |
| retries = s.parent.config.Metadata.Retry.Max |
| case ErrRebalanceInProgress, ErrUnknownMemberId, ErrIllegalGeneration: |
| return |
| default: |
| s.parent.handleError(err, "", -1) |
| return |
| } |
| |
| select { |
| case <-pause.C: |
| case <-s.hbDying: |
| return |
| } |
| } |
| } |
| |
| // -------------------------------------------------------------------- |
| |
| // ConsumerGroupHandler instances are used to handle individual topic/partition claims. |
| // It also provides hooks for your consumer group session life-cycle and allow you to |
| // trigger logic before or after the consume loop(s). |
| // |
| // PLEASE NOTE that handlers are likely be called from several goroutines concurrently, |
| // ensure that all state is safely protected against race conditions. |
| type ConsumerGroupHandler interface { |
| // Setup is run at the beginning of a new session, before ConsumeClaim. |
| Setup(ConsumerGroupSession) error |
| |
| // Cleanup is run at the end of a session, once all ConsumeClaim goroutines have exited |
| // but before the offsets are committed for the very last time. |
| Cleanup(ConsumerGroupSession) error |
| |
| // ConsumeClaim must start a consumer loop of ConsumerGroupClaim's Messages(). |
| // Once the Messages() channel is closed, the Handler must finish its processing |
| // loop and exit. |
| ConsumeClaim(ConsumerGroupSession, ConsumerGroupClaim) error |
| } |
| |
| // ConsumerGroupClaim processes Kafka messages from a given topic and partition within a consumer group. |
| type ConsumerGroupClaim interface { |
| // Topic returns the consumed topic name. |
| Topic() string |
| |
| // Partition returns the consumed partition. |
| Partition() int32 |
| |
| // InitialOffset returns the initial offset that was used as a starting point for this claim. |
| InitialOffset() int64 |
| |
| // HighWaterMarkOffset returns the high water mark offset of the partition, |
| // i.e. the offset that will be used for the next message that will be produced. |
| // You can use this to determine how far behind the processing is. |
| HighWaterMarkOffset() int64 |
| |
| // Messages returns the read channel for the messages that are returned by |
| // the broker. The messages channel will be closed when a new rebalance cycle |
| // is due. You must finish processing and mark offsets within |
| // Config.Consumer.Group.Session.Timeout before the topic/partition is eventually |
| // re-assigned to another group member. |
| Messages() <-chan *ConsumerMessage |
| } |
| |
| type consumerGroupClaim struct { |
| topic string |
| partition int32 |
| offset int64 |
| PartitionConsumer |
| } |
| |
| func newConsumerGroupClaim(sess *consumerGroupSession, topic string, partition int32, offset int64) (*consumerGroupClaim, error) { |
| pcm, err := sess.parent.consumer.ConsumePartition(topic, partition, offset) |
| if err == ErrOffsetOutOfRange { |
| offset = sess.parent.config.Consumer.Offsets.Initial |
| pcm, err = sess.parent.consumer.ConsumePartition(topic, partition, offset) |
| } |
| if err != nil { |
| return nil, err |
| } |
| |
| go func() { |
| for err := range pcm.Errors() { |
| sess.parent.handleError(err, topic, partition) |
| } |
| }() |
| |
| return &consumerGroupClaim{ |
| topic: topic, |
| partition: partition, |
| offset: offset, |
| PartitionConsumer: pcm, |
| }, nil |
| } |
| |
| func (c *consumerGroupClaim) Topic() string { return c.topic } |
| func (c *consumerGroupClaim) Partition() int32 { return c.partition } |
| func (c *consumerGroupClaim) InitialOffset() int64 { return c.offset } |
| |
| // Drains messages and errors, ensures the claim is fully closed. |
| func (c *consumerGroupClaim) waitClosed() (errs ConsumerErrors) { |
| go func() { |
| for range c.Messages() { |
| } |
| }() |
| |
| for err := range c.Errors() { |
| errs = append(errs, err) |
| } |
| return |
| } |