cache.go

/*
Copyright 2020 Google LLC

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 config

import (
	"sync/atomic"

	"google.golang.org/protobuf/encoding/prototext"
	"google.golang.org/protobuf/proto"
)

// CachedTargets provides a in-memory cached copy of targets.
type CachedTargets struct {
	Value atomic.Value
}

var _ ReadonlyTargets = (*CachedTargets)(nil)

// Store atomically stores a TargetsConfig.
func (ct *CachedTargets) Store(t *TargetsConfig) {
	ct.Value.Store(t)
}

// Load atomically loads a stored TargetsConfig.
// If there was no TargetsConfig stored, nil will be returned.
func (ct *CachedTargets) Load() *TargetsConfig {
	return ct.Value.Load().(*TargetsConfig)
}

// RangeAllTargets ranges over all targets.
// Do not modify the given Target copy.
func (ct *CachedTargets) RangeAllTargets(f func(*Target) bool) {
	val := ct.Load()
	if val == nil {
		return
	}
	for _, b := range val.Brokers {
		for _, t := range b.Targets {
			if c := f(t); !c {
				return
			}
		}
	}
}

// GetTarget returns a target.
// Do not modify the returned Target copy.
func (ct *CachedTargets) GetTarget(namespace, brokerName, targetName string) (*Target, bool) {
	Broker, ok := ct.GetBroker(namespace, brokerName)
	if !ok {
		return nil, false
	}
	t, ok := Broker.Targets[targetName]
	return t, ok
}

// GetTargetByKey returns a target by its trigger key. The format of trigger key is namespace/brokerName/targetName.
// Do not modify the returned Target copy.
func (ct *CachedTargets) GetTargetByKey(key string) (*Target, bool) {
	namespace, brokerName, targetName := SplitTriggerKey(key)
	return ct.GetTarget(namespace, brokerName, targetName)
}

// GetBroker returns a broker and its targets if it exists.
// Do not modify the returned Broker copy.
func (ct *CachedTargets) GetBroker(namespace, name string) (*Broker, bool) {
	return ct.GetBrokerByKey(BrokerKey(namespace, name))
}

// GetBrokerByKey returns a broker and its targets if it exists.
// Do not modify the returned Broker copy.
func (ct *CachedTargets) GetBrokerByKey(key string) (*Broker, bool) {
	val := ct.Load()
	if val == nil || val.Brokers == nil {
		return nil, false
	}
	b, ok := val.Brokers[key]
	return b, ok
}

// RangeBrokers ranges over all brokers.
// Do not modify the given Broker copy.
func (ct *CachedTargets) RangeBrokers(f func(*Broker) bool) {
	val := ct.Load()
	if val == nil {
		return
	}
	for _, b := range val.Brokers {
		if c := f(b); !c {
			break
		}
	}
}

// Bytes serializes all the targets.
func (ct *CachedTargets) Bytes() ([]byte, error) {
	val := ct.Load()
	return proto.Marshal(val)
}

// String returns the text format of all the targets.
func (ct *CachedTargets) String() string {
	val := ct.Load()
	return prototext.MarshalOptions{}.Format(val)
}

// EqualsBytes checks if the current targets config equals the given
// targets config in bytes.
func (ct *CachedTargets) EqualsBytes(b []byte) bool {
	self := ct.Load()
	var other TargetsConfig
	if err := proto.Unmarshal(b, &other); err != nil {
		return false
	}
	return proto.Equal(self, &other)
}

// EqualsString checks if the current targets config equals the given
// targets config in string.
func (ct *CachedTargets) EqualsString(s string) bool {
	self := ct.Load()
	var other TargetsConfig
	if err := prototext.Unmarshal([]byte(s), &other); err != nil {
		return false
	}
	return proto.Equal(self, &other)
}