cv/internal/gerrit/caching.go

// Copyright 2021 The LUCI Authors.
//
// 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 gerrit

import (
	"context"
	"time"

	"go.chromium.org/luci/common/data/caching/lru"
)

// CachingFactory caches clients produced by another Factory.
func CachingFactory(lruSize int, f Factory) Factory {
	return &cachingFactory{Factory: f, cache: lru.New[string, Client](lruSize)}
}

type cachingFactory struct {
	Factory
	cache *lru.Cache[string, Client]
}

// MakeClient implements Factory.
func (c cachingFactory) MakeClient(ctx context.Context, gerritHost string, luciProject string) (Client, error) {
	key := luciProject + "/" + gerritHost
	client, err := c.cache.GetOrCreate(ctx, key, func() (value Client, ttl time.Duration, err error) {
		// Default ttl of 0 means never expire. Note that specific authorization
		// token is still loaded per each request (see transport() function).
		value, err = c.Factory.MakeClient(ctx, gerritHost, luciProject)
		return
	})
	if err != nil {
		return nil, err
	}
	return client, nil
}