96 lines
2.3 KiB
Go
96 lines
2.3 KiB
Go
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// 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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"sync"
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"time"
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)
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// recencyThreshold is the amount of time that a manifest build will be cached
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// for. When using the channel mechanism for retrieving nixpkgs, Nix will
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// occasionally re-fetch the channel so things can in fact change while the
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// instance is running.
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const recencyThreshold = time.Duration(6) * time.Hour
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type manifestEntry struct {
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built time.Time
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path string
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}
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type void struct{}
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type BuildCache struct {
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mmtx sync.RWMutex
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mcache map[string]manifestEntry
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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() BuildCache {
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return BuildCache{
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mcache: make(map[string]manifestEntry),
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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 *BuildCache) 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 *BuildCache) 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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// Has this manifest been built already? If yes, we can reuse the
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// result given that the build happened recently enough.
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func (c *BuildCache) manifestFromCache(image *Image) (string, bool) {
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c.mmtx.RLock()
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entry, ok := c.mcache[image.Name+image.Tag]
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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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if time.Since(entry.built) > recencyThreshold {
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return "", false
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}
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return entry.path, true
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}
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// Adds the result of a manifest build to the cache.
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func (c *BuildCache) cacheManifest(image *Image, path string) {
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entry := manifestEntry{
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built: time.Now(),
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path: path,
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}
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c.mmtx.Lock()
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c.mcache[image.Name+image.Tag] = entry
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c.mmtx.Unlock()
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}
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