125 lines
2.9 KiB
Go
125 lines
2.9 KiB
Go
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// Copyright 2021 Drone IO, Inc.
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//
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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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// +build !oss
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package pubsub
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import (
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"context"
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"encoding/json"
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"fmt"
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"os"
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"sync"
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"github.com/drone/drone/core"
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"github.com/drone/drone/service/redisdb"
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)
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const (
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redisPubSubEvents = "drone-events"
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redisPubSubCapacity = 100
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)
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func newHubRedis(r redisdb.RedisDB) core.Pubsub {
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h := &hubRedis{
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rdb: r,
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subscribers: make(map[chan<- *core.Message]struct{}),
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}
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go r.Subscribe(context.Background(), redisPubSubEvents, redisPubSubCapacity, h)
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return h
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}
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type hubRedis struct {
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sync.Mutex
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rdb redisdb.RedisDB
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subscribers map[chan<- *core.Message]struct{}
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}
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// Publish publishes a new message. All subscribers will get it.
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func (h *hubRedis) Publish(ctx context.Context, e *core.Message) (err error) {
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client := h.rdb.Client()
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data, err := json.Marshal(e)
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if err != nil {
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return
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}
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_, err = client.Publish(ctx, redisPubSubEvents, data).Result()
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if err != nil {
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return
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}
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return
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}
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// Subscribe add a new subscriber. The subscriber gets event until its context is not finished.
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func (h *hubRedis) Subscribe(ctx context.Context) (<-chan *core.Message, <-chan error) {
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chMessage := make(chan *core.Message, redisPubSubCapacity)
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chErr := make(chan error)
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h.Lock()
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h.subscribers[chMessage] = struct{}{}
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h.Unlock()
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go func() {
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<-ctx.Done()
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h.Lock()
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delete(h.subscribers, chMessage)
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h.Unlock()
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close(chMessage)
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close(chErr)
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}()
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return chMessage, chErr
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}
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// Subscribers returns number of subscribers.
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func (h *hubRedis) Subscribers() (int, error) {
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h.Lock()
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n := len(h.subscribers)
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h.Unlock()
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return n, nil
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}
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// ProcessMessage relays the message to all subscribers listening to drone events.
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// It is a part of redisdb.PubSubProcessor implementation and it's called internally by redisdb.Subscribe.
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func (h *hubRedis) ProcessMessage(s string) {
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message := &core.Message{}
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err := json.Unmarshal([]byte(s), message)
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if err != nil {
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// Ignore invalid messages. This is a "should not happen" situation,
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// because messages are encoded as json in Publish().
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_, _ = fmt.Fprintf(os.Stderr, "pubsub/redis: failed to unmarshal a message. %s\n", err)
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return
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}
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h.Lock()
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for ss := range h.subscribers {
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select {
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case ss <- message:
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default: // messages are lost if a subscriber channel reaches its capacity
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}
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}
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h.Unlock()
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}
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// ProcessError is a part of redisdb.PubSubProcessor implementation.
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func (h *hubRedis) ProcessError(error) {}
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