136 lines
3 KiB
Go
136 lines
3 KiB
Go
// 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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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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"time"
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"github.com/drone/drone/core"
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"github.com/go-redis/redis/v8"
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)
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func newRedis(rdb *redis.Client) core.Pubsub {
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return &hubRedis{
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rdb: rdb,
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}
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}
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const channelPubSub = "drone-events"
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type hubRedis struct {
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rdb *redis.Client
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}
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func (h *hubRedis) Publish(ctx context.Context, e *core.Message) (err error) {
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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 = h.rdb.Publish(ctx, channelPubSub, 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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func (h *hubRedis) Subscribe(ctx context.Context) (<-chan *core.Message, <-chan error) {
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messageCh := make(chan *core.Message, 100)
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errCh := make(chan error)
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go func() {
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pubsub := h.rdb.Subscribe(ctx, channelPubSub)
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ch := pubsub.Channel(redis.WithChannelSize(100))
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defer func() {
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_ = pubsub.Close()
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close(messageCh)
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close(errCh)
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}()
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err := pubsub.Ping(ctx)
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if err != nil {
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errCh <- err
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return
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}
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for {
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select {
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case m, ok := <-ch:
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if !ok {
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errCh <- fmt.Errorf("pubsub/redis: channel=%s closed", channelPubSub)
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return
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}
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message := &core.Message{}
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err = json.Unmarshal([]byte(m.Payload), message)
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if err != nil {
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// This is a "should not happen" situation,
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// because messages are encoded as json above in Publish().
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_, _ = fmt.Fprintf(os.Stderr, "pubsub/redis: failed to unmarshal a message. %s\n", err)
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continue
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}
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messageCh <- message
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case <-ctx.Done():
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return
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}
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}
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}()
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return messageCh, errCh
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}
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func (h *hubRedis) Subscribers() (int, error) {
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ctx, cancelFunc := context.WithTimeout(context.Background(), 5*time.Second)
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defer cancelFunc()
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v, err := h.rdb.Do(ctx, "pubsub", "numsub", channelPubSub).Result()
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if err != nil {
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err = fmt.Errorf("pubsub/redis: failed to get number of subscribers. %w", err)
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return 0, err
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}
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values, ok := v.([]interface{}) // the result should be: [<channel_name:string>, <subscriber_count:int64>]
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if !ok || len(values) != 2 {
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err = fmt.Errorf("pubsub/redis: failed to extarct number of subscribers from: %v", values)
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return 0, err
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}
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switch n := values[1].(type) {
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case int:
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return n, nil
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case uint:
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return int(n), nil
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case int32:
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return int(n), nil
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case uint32:
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return int(n), nil
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case int64:
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return int(n), nil
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case uint64:
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return int(n), nil
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default:
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err = fmt.Errorf("pubsub/redis: unsupported type for number of subscribers: %T", values[1])
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return 0, err
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}
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}
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