Курнат Андрей
542 lines
17 KiB
Go
542 lines
17 KiB
Go
// Copyright 2022-2025 The NATS Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package jetstream
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import (
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"context"
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"crypto/sha256"
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"encoding/json"
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"fmt"
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"strings"
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"time"
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"github.com/nats-io/nats.go/internal/syncx"
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"github.com/nats-io/nuid"
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)
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type (
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// Consumer contains methods for fetching/processing messages from a stream,
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// as well as fetching consumer info.
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//
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// This package provides two implementations of Consumer interface:
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//
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// - Standard named/ephemeral pull consumers. These consumers are created using
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// CreateConsumer method on Stream or JetStream interface. They can be
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// explicitly configured (using [ConsumerConfig]) and managed by the user,
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// either from this package or externally.
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//
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// - Ordered consumers. These consumers are created using OrderedConsumer
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// method on Stream or JetStream interface. They are managed by the library
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// and provide a simple way to consume messages from a stream. Ordered
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// consumers are ephemeral in-memory pull consumers and are resilient to
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// deletes and restarts. They provide limited configuration options
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// using [OrderedConsumerConfig].
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//
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// Consumer provides methods for optimized continuous consumption of messages
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// using Consume and Messages methods, as well as simple one-off messages
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// retrieval using Fetch and Next methods.
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Consumer interface {
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// Fetch is used to retrieve up to a provided number of messages from a
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// stream. This method will send a single request and deliver either all
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// requested messages unless the timeout is met earlier. Fetch timeout
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// defaults to 30 seconds and can be configured using FetchMaxWait
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// option.
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//
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// By default, Fetch uses a 5s idle heartbeat for requests longer than
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// 10 seconds. For shorter requests, the idle heartbeat is disabled.
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// This can be configured using FetchHeartbeat option. If a client does
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// not receive a heartbeat message from a stream for more than 2 times
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// the idle heartbeat setting, Fetch will return [ErrNoHeartbeat].
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//
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// Fetch is non-blocking and returns MessageBatch, exposing a channel
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// for delivered messages.
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//
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// Messages channel is always closed, thus it is safe to range over it
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// without additional checks. After the channel is closed,
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// MessageBatch.Error() should be checked to see if there was an error
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// during message delivery (e.g. missing heartbeat).
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//
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// NOTE: Fetch has worse performance when used to continuously retrieve
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// messages in comparison to Messages or Consume methods, as it does not
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// perform any optimizations (e.g. overlapping pull requests) and new
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// subscription is created for each execution.
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Fetch(batch int, opts ...FetchOpt) (MessageBatch, error)
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// FetchBytes is used to retrieve up to a provided number of bytes from
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// the stream. This method will send a single request and deliver the
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// provided number of bytes unless the timeout is met earlier. FetchBytes
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// timeout defaults to 30 seconds and can be configured using
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// FetchMaxWait option.
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//
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// By default, FetchBytes uses a 5s idle heartbeat for requests longer than
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// 10 seconds. For shorter requests, the idle heartbeat is disabled.
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// This can be configured using FetchHeartbeat option. If a client does
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// not receive a heartbeat message from a stream for more than 2 times
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// the idle heartbeat setting, FetchBytes will return [ErrNoHeartbeat].
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//
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// FetchBytes is non-blocking and returns MessageBatch, exposing a channel
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// for delivered messages.
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//
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// Messages channel is always closed, thus it is safe to range over it
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// without additional checks. After the channel is closed,
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// MessageBatch.Error() should be checked to see if there was an error
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// during message delivery (e.g. missing heartbeat).
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//
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// NOTE: FetchBytes has worse performance when used to continuously
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// retrieve messages in comparison to Messages or Consume methods, as it
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// does not perform any optimizations (e.g. overlapping pull requests)
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// and new subscription is created for each execution.
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FetchBytes(maxBytes int, opts ...FetchOpt) (MessageBatch, error)
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// FetchNoWait is used to retrieve up to a provided number of messages
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// from a stream. Unlike Fetch, FetchNoWait will only deliver messages
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// that are currently available in the stream and will not wait for new
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// messages to arrive, even if batch size is not met.
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//
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// FetchNoWait is non-blocking and returns MessageBatch, exposing a
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// channel for delivered messages.
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//
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// Messages channel is always closed, thus it is safe to range over it
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// without additional checks. After the channel is closed,
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// MessageBatch.Error() should be checked to see if there was an error
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// during message delivery (e.g. missing heartbeat).
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//
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// NOTE: FetchNoWait has worse performance when used to continuously
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// retrieve messages in comparison to Messages or Consume methods, as it
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// does not perform any optimizations (e.g. overlapping pull requests)
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// and new subscription is created for each execution.
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FetchNoWait(batch int) (MessageBatch, error)
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// Consume will continuously receive messages and handle them
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// with the provided callback function. Consume can be configured using
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// PullConsumeOpt options:
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//
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// - Error handling and monitoring can be configured using ConsumeErrHandler
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// option, which provides information about errors encountered during
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// consumption (both transient and terminal)
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// - Consume can be configured to stop after a certain number of
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// messages have been received using StopAfter option.
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// - Consume can be optimized for throughput or memory usage using
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// PullExpiry, PullMaxMessages, PullMaxBytes and PullHeartbeat options.
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// Unless there is a specific use case, these options should not be used.
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//
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// Consume returns a ConsumeContext, which can be used to stop or drain
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// the consumer.
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Consume(handler MessageHandler, opts ...PullConsumeOpt) (ConsumeContext, error)
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// Messages returns MessagesContext, allowing continuous iteration
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// over messages in a stream. Messages can be configured using
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// PullMessagesOpt options:
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//
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// - Messages can be optimized for throughput or memory usage using
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// PullExpiry, PullMaxMessages, PullMaxBytes and PullHeartbeat options.
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// Unless there is a specific use case, these options should not be used.
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// - WithMessagesErrOnMissingHeartbeat can be used to enable/disable
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// erroring out on MessagesContext.Next when a heartbeat is missing.
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// This option is enabled by default.
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Messages(opts ...PullMessagesOpt) (MessagesContext, error)
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// Next is used to retrieve the next message from the consumer. This
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// method will block until the message is retrieved or the timeout
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// is reached.
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Next(opts ...FetchOpt) (Msg, error)
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// Info fetches current ConsumerInfo from the server.
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Info(context.Context) (*ConsumerInfo, error)
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// CachedInfo returns ConsumerInfo currently cached on this consumer.
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// This method does not perform any network requests. The cached
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// ConsumerInfo is updated on every call to Info and Update.
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CachedInfo() *ConsumerInfo
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}
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PushConsumer interface {
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// Consume will continuously receive messages and handle them
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// with the provided callback function. Consume can be configured using
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// PushConsumeOpt options:
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//
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// - Error handling and monitoring can be configured using ConsumeErrHandler.
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Consume(handler MessageHandler, opts ...PushConsumeOpt) (ConsumeContext, error)
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// Info fetches current ConsumerInfo from the server.
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Info(context.Context) (*ConsumerInfo, error)
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// CachedInfo returns ConsumerInfo currently cached on this consumer.
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CachedInfo() *ConsumerInfo
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}
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createConsumerRequest struct {
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Stream string `json:"stream_name"`
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Config *ConsumerConfig `json:"config"`
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Action string `json:"action"`
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}
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)
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// Info fetches current ConsumerInfo from the server.
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func (p *pullConsumer) Info(ctx context.Context) (*ConsumerInfo, error) {
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ctx, cancel := p.js.wrapContextWithoutDeadline(ctx)
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if cancel != nil {
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defer cancel()
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}
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infoSubject := fmt.Sprintf(apiConsumerInfoT, p.stream, p.name)
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var resp consumerInfoResponse
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if _, err := p.js.apiRequestJSON(ctx, infoSubject, &resp); err != nil {
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return nil, err
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}
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if resp.Error != nil {
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if resp.Error.ErrorCode == JSErrCodeConsumerNotFound {
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return nil, ErrConsumerNotFound
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}
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return nil, resp.Error
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}
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if resp.Error == nil && resp.ConsumerInfo == nil {
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return nil, ErrConsumerNotFound
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}
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p.info = resp.ConsumerInfo
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return resp.ConsumerInfo, nil
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}
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// CachedInfo returns ConsumerInfo currently cached on this consumer.
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// This method does not perform any network requests. The cached
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// ConsumerInfo is updated on every call to Info and Update.
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func (p *pullConsumer) CachedInfo() *ConsumerInfo {
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return p.info
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}
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// Info fetches current ConsumerInfo from the server.
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func (p *pushConsumer) Info(ctx context.Context) (*ConsumerInfo, error) {
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ctx, cancel := p.js.wrapContextWithoutDeadline(ctx)
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if cancel != nil {
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defer cancel()
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}
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infoSubject := fmt.Sprintf(apiConsumerInfoT, p.stream, p.name)
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var resp consumerInfoResponse
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if _, err := p.js.apiRequestJSON(ctx, infoSubject, &resp); err != nil {
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return nil, err
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}
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if resp.Error != nil {
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if resp.Error.ErrorCode == JSErrCodeConsumerNotFound {
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return nil, ErrConsumerNotFound
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}
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return nil, resp.Error
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}
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if resp.Error == nil && resp.ConsumerInfo == nil {
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return nil, ErrConsumerNotFound
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}
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p.info = resp.ConsumerInfo
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return resp.ConsumerInfo, nil
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}
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// CachedInfo returns ConsumerInfo currently cached on this consumer.
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// This method does not perform any network requests. The cached
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// ConsumerInfo is updated on every call to Info and Update.
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func (p *pushConsumer) CachedInfo() *ConsumerInfo {
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return p.info
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}
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func upsertPullConsumer(ctx context.Context, js *jetStream, stream string, cfg ConsumerConfig, action string) (Consumer, error) {
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resp, err := upsertConsumer(ctx, js, stream, cfg, action)
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if err != nil {
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return nil, err
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}
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return &pullConsumer{
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js: js,
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stream: stream,
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name: resp.Name,
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durable: cfg.Durable != "",
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info: resp.ConsumerInfo,
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subs: syncx.Map[string, *pullSubscription]{},
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}, nil
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}
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func upsertPushConsumer(ctx context.Context, js *jetStream, stream string, cfg ConsumerConfig, action string) (PushConsumer, error) {
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if cfg.DeliverSubject == "" {
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return nil, ErrNotPushConsumer
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}
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resp, err := upsertConsumer(ctx, js, stream, cfg, action)
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if err != nil {
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return nil, err
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}
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return &pushConsumer{
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js: js,
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stream: stream,
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name: resp.Name,
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info: resp.ConsumerInfo,
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}, nil
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}
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func upsertConsumer(ctx context.Context, js *jetStream, stream string, cfg ConsumerConfig, action string) (*consumerInfoResponse, error) {
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ctx, cancel := js.wrapContextWithoutDeadline(ctx)
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if cancel != nil {
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defer cancel()
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}
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req := createConsumerRequest{
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Stream: stream,
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Config: &cfg,
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Action: action,
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}
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reqJSON, err := json.Marshal(req)
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if err != nil {
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return nil, err
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}
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consumerName := cfg.Name
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if consumerName == "" {
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if cfg.Durable != "" {
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consumerName = cfg.Durable
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} else {
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consumerName = generateConsName()
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}
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}
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if err := validateConsumerName(consumerName); err != nil {
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return nil, err
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}
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var ccSubj string
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if cfg.FilterSubject != "" && len(cfg.FilterSubjects) == 0 {
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if err := validateSubject(cfg.FilterSubject); err != nil {
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return nil, err
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}
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ccSubj = fmt.Sprintf(apiConsumerCreateWithFilterSubjectT, stream, consumerName, cfg.FilterSubject)
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} else {
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ccSubj = fmt.Sprintf(apiConsumerCreateT, stream, consumerName)
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}
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var resp consumerInfoResponse
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if _, err := js.apiRequestJSON(ctx, ccSubj, &resp, reqJSON); err != nil {
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return nil, err
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}
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if resp.Error != nil {
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if resp.Error.ErrorCode == JSErrCodeStreamNotFound {
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return nil, ErrStreamNotFound
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}
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if resp.Error.ErrorCode == JSErrCodeMaximumConsumersLimit {
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return nil, ErrMaximumConsumersLimit
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}
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return nil, resp.Error
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}
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if resp.Error == nil && resp.ConsumerInfo == nil {
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return nil, ErrConsumerCreationResponseEmpty
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}
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// check whether multiple filter subjects (if used) are reflected in the returned ConsumerInfo
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if len(cfg.FilterSubjects) != 0 && len(resp.Config.FilterSubjects) == 0 {
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return nil, ErrConsumerMultipleFilterSubjectsNotSupported
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}
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return &resp, nil
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}
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const (
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consumerActionCreate = "create"
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consumerActionUpdate = "update"
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consumerActionCreateOrUpdate = ""
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)
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func generateConsName() string {
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name := nuid.Next()
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sha := sha256.New()
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sha.Write([]byte(name))
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b := sha.Sum(nil)
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for i := 0; i < 8; i++ {
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b[i] = rdigits[int(b[i]%base)]
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}
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return string(b[:8])
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}
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func getConsumer(ctx context.Context, js *jetStream, stream, name string) (Consumer, error) {
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info, err := fetchConsumerInfo(ctx, js, stream, name)
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if err != nil {
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return nil, err
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}
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if info.Config.DeliverSubject != "" {
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return nil, ErrNotPullConsumer
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}
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cons := &pullConsumer{
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js: js,
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stream: stream,
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name: name,
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durable: info.Config.Durable != "",
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info: info,
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subs: syncx.Map[string, *pullSubscription]{},
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}
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return cons, nil
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}
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func getPushConsumer(ctx context.Context, js *jetStream, stream, name string) (PushConsumer, error) {
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info, err := fetchConsumerInfo(ctx, js, stream, name)
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if err != nil {
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return nil, err
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}
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if info.Config.DeliverSubject == "" {
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return nil, ErrNotPushConsumer
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}
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cons := &pushConsumer{
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js: js,
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stream: stream,
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name: name,
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info: info,
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}
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return cons, nil
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}
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func fetchConsumerInfo(ctx context.Context, js *jetStream, stream, name string) (*ConsumerInfo, error) {
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ctx, cancel := js.wrapContextWithoutDeadline(ctx)
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if cancel != nil {
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defer cancel()
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}
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if err := validateConsumerName(name); err != nil {
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return nil, err
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}
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infoSubject := fmt.Sprintf(apiConsumerInfoT, stream, name)
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var resp consumerInfoResponse
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if _, err := js.apiRequestJSON(ctx, infoSubject, &resp); err != nil {
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return nil, err
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}
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if resp.Error != nil {
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if resp.Error.ErrorCode == JSErrCodeConsumerNotFound {
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return nil, ErrConsumerNotFound
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}
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return nil, resp.Error
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}
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if resp.Error == nil && resp.ConsumerInfo == nil {
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return nil, ErrConsumerNotFound
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}
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return resp.ConsumerInfo, nil
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}
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func deleteConsumer(ctx context.Context, js *jetStream, stream, consumer string) error {
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ctx, cancel := js.wrapContextWithoutDeadline(ctx)
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if cancel != nil {
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defer cancel()
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}
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if err := validateConsumerName(consumer); err != nil {
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return err
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}
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deleteSubject := fmt.Sprintf(apiConsumerDeleteT, stream, consumer)
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var resp consumerDeleteResponse
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if _, err := js.apiRequestJSON(ctx, deleteSubject, &resp); err != nil {
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return err
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}
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if resp.Error != nil {
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if resp.Error.ErrorCode == JSErrCodeConsumerNotFound {
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return ErrConsumerNotFound
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}
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return resp.Error
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}
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return nil
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}
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func pauseConsumer(ctx context.Context, js *jetStream, stream, consumer string, pauseUntil *time.Time) (*ConsumerPauseResponse, error) {
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ctx, cancel := js.wrapContextWithoutDeadline(ctx)
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if cancel != nil {
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defer cancel()
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}
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if err := validateConsumerName(consumer); err != nil {
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return nil, err
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}
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subject := fmt.Sprintf(apiConsumerPauseT, stream, consumer)
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var resp consumerPauseApiResponse
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req, err := json.Marshal(consumerPauseRequest{
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PauseUntil: pauseUntil,
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})
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if err != nil {
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return nil, err
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}
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if _, err := js.apiRequestJSON(ctx, subject, &resp, req); err != nil {
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return nil, err
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}
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if resp.Error != nil {
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if resp.Error.ErrorCode == JSErrCodeConsumerNotFound {
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return nil, ErrConsumerNotFound
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}
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return nil, resp.Error
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}
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return &ConsumerPauseResponse{
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Paused: resp.Paused,
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PauseUntil: resp.PauseUntil,
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PauseRemaining: resp.PauseRemaining,
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}, nil
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}
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func resumeConsumer(ctx context.Context, js *jetStream, stream, consumer string) (*ConsumerPauseResponse, error) {
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return pauseConsumer(ctx, js, stream, consumer, nil)
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}
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func validateConsumerName(name string) error {
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if name == "" {
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return fmt.Errorf("%w: name is required", ErrInvalidConsumerName)
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}
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if strings.ContainsAny(name, ">*. /\\\t\r\n") {
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return fmt.Errorf("%w: %q", ErrInvalidConsumerName, name)
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}
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return nil
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}
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func unpinConsumer(ctx context.Context, js *jetStream, stream, consumer, group string) error {
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ctx, cancel := js.wrapContextWithoutDeadline(ctx)
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if cancel != nil {
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defer cancel()
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}
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if err := validateConsumerName(consumer); err != nil {
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return err
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}
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unpinSubject := fmt.Sprintf(apiConsumerUnpinT, stream, consumer)
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var req = consumerUnpinRequest{
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Group: group,
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}
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reqJSON, err := json.Marshal(req)
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if err != nil {
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return err
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}
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var resp apiResponse
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if _, err := js.apiRequestJSON(ctx, unpinSubject, &resp, reqJSON); err != nil {
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return err
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}
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|
if resp.Error != nil {
|
|
if resp.Error.ErrorCode == JSErrCodeConsumerNotFound {
|
|
return ErrConsumerNotFound
|
|
}
|
|
return resp.Error
|
|
}
|
|
|
|
return nil
|
|
}
|