harness-drone/plugin/converter/memoize.go
2019-09-02 23:05:30 -07:00

86 lines
2.4 KiB
Go

// Copyright 2019 Drone IO, Inc.
//
// 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 converter
import (
"context"
"fmt"
"github.com/drone/drone/core"
lru "github.com/hashicorp/golang-lru"
)
// cache key pattern used in the cache, comprised of the
// repository slug and commit sha.
const keyf = "%d/%s"
// Memoize caches the conversion results for subsequent calls.
// This micro-optimization is intended for multi-pipeline
// projects that would otherwise covert the file for each
// pipeline execution.
func Memoize(base core.ConvertService) core.ConvertService {
// simple cache prevents the same yaml file from being
// requested multiple times in a short period.
cache, _ := lru.New(25)
return &memoize{base: base, cache: cache}
}
type memoize struct {
base core.ConvertService
cache *lru.Cache
}
func (c *memoize) Convert(ctx context.Context, req *core.ConvertArgs) (*core.Config, error) {
// this is a minor optimization that prevents caching if the
// base converter is a remote converter and is disabled.
if remote, ok := c.base.(*remote); ok == true && remote.endpoint == "" {
return nil, nil
}
// generate the key used to cache the converted file.
key := fmt.Sprintf(keyf, req.Repo.ID, req.Build.After)
// some source control management systems (gogs) do not provide
// the commit sha for tag webhooks. If no commit sha is available
// the ref is used.
if req.Build.After == "" {
key = fmt.Sprintf(keyf, req.Repo.ID, req.Build.Ref)
}
// check the cache for the file and return if exists.
cached, ok := c.cache.Get(key)
if ok {
return cached.(*core.Config), nil
}
// else convert the configuration file.
config, err := c.base.Convert(ctx, req)
if err != nil {
return nil, err
}
if config == nil {
return nil, nil
}
if config.Data == "" {
return nil, nil
}
// if the configuration file was converted
// it is temporarily cached.
c.cache.Add(key, config)
return config, nil
}