From 2b82f1b71a50b8b1473421cce0eec1a0d7ddc360 Mon Sep 17 00:00:00 2001 From: Vincent Ambo Date: Mon, 11 Nov 2019 21:07:16 +0000 Subject: refactor: Reshuffle file structure for better code layout This gets rid of the package called "server" and instead moves everything into the project root, such that Go actually builds us a binary called `nixery`. This is the first step towards factoring out CLI-based functionality for Nixery. --- tools/nixery/builder/cache.go | 236 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 236 insertions(+) create mode 100644 tools/nixery/builder/cache.go (limited to 'tools/nixery/builder/cache.go') diff --git a/tools/nixery/builder/cache.go b/tools/nixery/builder/cache.go new file mode 100644 index 000000000000..a4ebe03e1c94 --- /dev/null +++ b/tools/nixery/builder/cache.go @@ -0,0 +1,236 @@ +// Copyright 2019 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 +// +// https://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 builder + +import ( + "bytes" + "context" + "encoding/json" + "io" + "io/ioutil" + "os" + "sync" + + "github.com/google/nixery/manifest" + log "github.com/sirupsen/logrus" +) + +// LocalCache implements the structure used for local caching of +// manifests and layer uploads. +type LocalCache struct { + // Manifest cache + mmtx sync.RWMutex + mdir string + + // Layer cache + lmtx sync.RWMutex + lcache map[string]manifest.Entry +} + +// Creates an in-memory cache and ensures that the local file path for +// manifest caching exists. +func NewCache() (LocalCache, error) { + path := os.TempDir() + "/nixery" + err := os.MkdirAll(path, 0755) + if err != nil { + return LocalCache{}, err + } + + return LocalCache{ + mdir: path + "/", + lcache: make(map[string]manifest.Entry), + }, nil +} + +// Retrieve a cached manifest if the build is cacheable and it exists. +func (c *LocalCache) manifestFromLocalCache(key string) (json.RawMessage, bool) { + c.mmtx.RLock() + defer c.mmtx.RUnlock() + + f, err := os.Open(c.mdir + key) + if err != nil { + // This is a debug log statement because failure to + // read the manifest key is currently expected if it + // is not cached. + log.WithError(err).WithField("manifest", key). + Debug("failed to read manifest from local cache") + + return nil, false + } + defer f.Close() + + m, err := ioutil.ReadAll(f) + if err != nil { + log.WithError(err).WithField("manifest", key). + Error("failed to read manifest from local cache") + + return nil, false + } + + return json.RawMessage(m), true +} + +// Adds the result of a manifest build to the local cache, if the +// manifest is considered cacheable. +// +// Manifests can be quite large and are cached on disk instead of in +// memory. +func (c *LocalCache) localCacheManifest(key string, m json.RawMessage) { + c.mmtx.Lock() + defer c.mmtx.Unlock() + + err := ioutil.WriteFile(c.mdir+key, []byte(m), 0644) + if err != nil { + log.WithError(err).WithField("manifest", key). + Error("failed to locally cache manifest") + } +} + +// Retrieve a layer build from the local cache. +func (c *LocalCache) layerFromLocalCache(key string) (*manifest.Entry, bool) { + c.lmtx.RLock() + e, ok := c.lcache[key] + c.lmtx.RUnlock() + + return &e, ok +} + +// Add a layer build result to the local cache. +func (c *LocalCache) localCacheLayer(key string, e manifest.Entry) { + c.lmtx.Lock() + c.lcache[key] = e + c.lmtx.Unlock() +} + +// Retrieve a manifest from the cache(s). First the local cache is +// checked, then the storage backend. +func manifestFromCache(ctx context.Context, s *State, key string) (json.RawMessage, bool) { + if m, cached := s.Cache.manifestFromLocalCache(key); cached { + return m, true + } + + r, err := s.Storage.Fetch(ctx, "manifests/"+key) + if err != nil { + log.WithError(err).WithFields(log.Fields{ + "manifest": key, + "backend": s.Storage.Name(), + }).Error("failed to fetch manifest from cache") + + return nil, false + } + defer r.Close() + + m, err := ioutil.ReadAll(r) + if err != nil { + log.WithError(err).WithFields(log.Fields{ + "manifest": key, + "backend": s.Storage.Name(), + }).Error("failed to read cached manifest from storage backend") + + return nil, false + } + + go s.Cache.localCacheManifest(key, m) + log.WithField("manifest", key).Info("retrieved manifest from GCS") + + return json.RawMessage(m), true +} + +// Add a manifest to the bucket & local caches +func cacheManifest(ctx context.Context, s *State, key string, m json.RawMessage) { + go s.Cache.localCacheManifest(key, m) + + path := "manifests/" + key + _, size, err := s.Storage.Persist(ctx, path, func(w io.Writer) (string, int64, error) { + size, err := io.Copy(w, bytes.NewReader([]byte(m))) + return "", size, err + }) + + if err != nil { + log.WithError(err).WithFields(log.Fields{ + "manifest": key, + "backend": s.Storage.Name(), + }).Error("failed to cache manifest to storage backend") + + return + } + + log.WithFields(log.Fields{ + "manifest": key, + "size": size, + "backend": s.Storage.Name(), + }).Info("cached manifest to storage backend") +} + +// Retrieve a layer build from the cache, first checking the local +// cache followed by the bucket cache. +func layerFromCache(ctx context.Context, s *State, key string) (*manifest.Entry, bool) { + if entry, cached := s.Cache.layerFromLocalCache(key); cached { + return entry, true + } + + r, err := s.Storage.Fetch(ctx, "builds/"+key) + if err != nil { + log.WithError(err).WithFields(log.Fields{ + "layer": key, + "backend": s.Storage.Name(), + }).Debug("failed to retrieve cached layer from storage backend") + + return nil, false + } + defer r.Close() + + jb := bytes.NewBuffer([]byte{}) + _, err = io.Copy(jb, r) + if err != nil { + log.WithError(err).WithFields(log.Fields{ + "layer": key, + "backend": s.Storage.Name(), + }).Error("failed to read cached layer from storage backend") + + return nil, false + } + + var entry manifest.Entry + err = json.Unmarshal(jb.Bytes(), &entry) + if err != nil { + log.WithError(err).WithField("layer", key). + Error("failed to unmarshal cached layer") + + return nil, false + } + + go s.Cache.localCacheLayer(key, entry) + return &entry, true +} + +func cacheLayer(ctx context.Context, s *State, key string, entry manifest.Entry) { + s.Cache.localCacheLayer(key, entry) + + j, _ := json.Marshal(&entry) + path := "builds/" + key + _, _, err := s.Storage.Persist(ctx, path, func(w io.Writer) (string, int64, error) { + size, err := io.Copy(w, bytes.NewReader(j)) + return "", size, err + }) + + if err != nil { + log.WithError(err).WithFields(log.Fields{ + "layer": key, + "backend": s.Storage.Name(), + }).Error("failed to cache layer") + } + + return +} -- cgit 1.4.1