/
pubsub.go
74 lines (61 loc) · 1.93 KB
/
pubsub.go
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// Copyright 2023 The Authors (see AUTHORS file)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package server
import (
"context"
"fmt"
"cloud.google.com/go/pubsub"
)
const (
MaxTopicDataBytes = 10_000_000
MaxTopicAttrValueBytes = 1024
)
// PubSubMessenger implements the Messenger interface for Google Cloud PubSub.
type PubSubMessenger struct {
topic *pubsub.Topic
}
// NewPubSubMessenger creates a new instance of the PubSubMessenger.
func NewPubSubMessenger(topic *pubsub.Topic) *PubSubMessenger {
return &PubSubMessenger{topic: topic}
}
func (p *PubSubMessenger) Send(ctx context.Context, data []byte, attr map[string]string) error {
m, err := limitedSizeMessage(data, attr)
if err != nil {
return fmt.Errorf("pubsub failed to publish message: %w", err)
}
result := p.topic.Publish(ctx, m)
if _, err := result.Get(ctx); err != nil {
return fmt.Errorf("pubsub failed to get result returned from publish : %w", err)
}
return nil
}
func limitedSizeMessage(data []byte, attr map[string]string) (*pubsub.Message, error) {
if len(data) > MaxTopicDataBytes {
return nil, fmt.Errorf("data length(%d) exceed max size allowed(%d)", len(data), MaxTopicDataBytes)
}
for key, value := range attr {
v := []byte(value)[:min(MaxTopicAttrValueBytes, len(value))]
attr[key] = string(v)
}
return &pubsub.Message{
Data: data,
Attributes: attr,
}, nil
}
func min(a, b int) int {
if a <= b {
return a
}
return b
}