4a58b0ab4d
Caches manifests under `manifests/$cacheKey` in the GCS bucket and introduces two-tiered retrieval of manifests from the caches (local first, bucket second). There is some cleanup to be done in this code, but the initial version works.
157 lines
3.8 KiB
Go
157 lines
3.8 KiB
Go
// Copyright 2019 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy of
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// the License at
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//
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// https://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, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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package builder
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import (
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"context"
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"io"
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"log"
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"os"
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"sync"
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"cloud.google.com/go/storage"
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"github.com/google/nixery/config"
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)
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type void struct{}
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// LocalCache implements the structure used for local caching of
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// manifests and layer uploads.
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type LocalCache struct {
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mmtx sync.RWMutex
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mcache map[string]string
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lmtx sync.RWMutex
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lcache map[string]void
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}
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func NewCache() LocalCache {
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return LocalCache{
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mcache: make(map[string]string),
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lcache: make(map[string]void),
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}
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}
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// Has this layer hash already been seen by this Nixery instance? If
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// yes, we can skip upload checking and such because it has already
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// been done.
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func (c *LocalCache) hasSeenLayer(hash string) bool {
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c.lmtx.RLock()
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defer c.lmtx.RUnlock()
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_, seen := c.lcache[hash]
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return seen
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}
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// Layer has now been seen and should be stored.
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func (c *LocalCache) sawLayer(hash string) {
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c.lmtx.Lock()
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defer c.lmtx.Unlock()
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c.lcache[hash] = void{}
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}
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// Retrieve a cached manifest if the build is cacheable and it exists.
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func (c *LocalCache) manifestFromLocalCache(key string) (string, bool) {
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c.mmtx.RLock()
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path, ok := c.mcache[key]
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c.mmtx.RUnlock()
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if !ok {
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return "", false
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}
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return path, true
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}
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// Adds the result of a manifest build to the local cache, if the
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// manifest is considered cacheable.
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func (c *LocalCache) localCacheManifest(key, path string) {
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c.mmtx.Lock()
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c.mcache[key] = path
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c.mmtx.Unlock()
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}
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// Retrieve a manifest from the cache(s). First the local cache is
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// checked, then the GCS-bucket cache.
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func manifestFromCache(ctx *context.Context, bucket *storage.BucketHandle, pkgs config.PkgSource, cache *LocalCache, image *Image) (string, bool) {
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key := pkgs.CacheKey(image.Packages, image.Tag)
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if key == "" {
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return "", false
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}
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path, cached := cache.manifestFromLocalCache(key)
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if cached {
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return path, true
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}
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obj := bucket.Object("manifests/" + key)
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// Probe whether the file exists before trying to fetch it.
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_, err := obj.Attrs(*ctx)
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if err != nil {
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return "", false
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}
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r, err := obj.NewReader(*ctx)
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if err != nil {
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log.Printf("Failed to retrieve manifest '%s' from cache: %s\n", key, err)
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return "", false
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}
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defer r.Close()
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path = os.TempDir() + "/" + key
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f, _ := os.Create(path)
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defer f.Close()
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_, err = io.Copy(f, r)
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if err != nil {
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log.Printf("Failed to read cached manifest for '%s': %s\n", key, err)
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}
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log.Printf("Retrieved manifest for '%s' (%s) from GCS\n", image.Name, key)
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cache.localCacheManifest(key, path)
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return path, true
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}
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func cacheManifest(ctx *context.Context, bucket *storage.BucketHandle, pkgs config.PkgSource, cache *LocalCache, image *Image, path string) {
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key := pkgs.CacheKey(image.Packages, image.Tag)
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if key == "" {
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return
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}
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cache.localCacheManifest(key, path)
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obj := bucket.Object("manifests/" + key)
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w := obj.NewWriter(*ctx)
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f, err := os.Open(path)
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if err != nil {
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log.Printf("failed to open '%s' manifest for cache upload: %s\n", image.Name, err)
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return
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}
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defer f.Close()
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size, err := io.Copy(w, f)
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if err != nil {
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log.Printf("failed to cache manifest sha1:%s: %s\n", key, err)
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return
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}
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if err = w.Close(); err != nil {
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log.Printf("failed to cache manifest sha1:%s: %s\n", key, err)
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return
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}
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log.Printf("Cached manifest sha1:%s (%v bytes written)\n", key, size)
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}
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