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// Package weakcache implements Weak Cache, eviction of entries are controlled by GC |
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package weakcache |
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import ( |
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"encoding/json" |
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"fmt" |
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"github.com/arazmj/gerdu/cache" |
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"github.com/arazmj/gerdu/metrics" |
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"github.com/hashicorp/raft" |
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"github.com/ivanrad/go-weakref/weakref" |
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"io" |
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"sync" |
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) |
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// WeakCache data structure |
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type WeakCache struct { |
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sync.Map |
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cache.UnImplementedCache |
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} |
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// NewWeakCache constructor |
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func NewWeakCache() *WeakCache { |
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return &WeakCache{} |
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} |
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// Put a new key value pair |
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func (c *WeakCache) Put(key string, value string) (created bool) { |
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metrics.Adds.Inc() |
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ref := weakref.NewWeakRef(value) |
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c.Store(key, ref) |
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return true |
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} |
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// Get value by key |
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func (c *WeakCache) Get(key string) (value string, ok bool) { |
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v, ok := c.Load(key) |
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if ok { |
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ref := v.(*weakref.WeakRef) |
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if ref.IsAlive() { |
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metrics.Hits.Inc() |
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return ref.GetTarget().(string), true |
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} |
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metrics.Deletes.Inc() |
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c.Delete(key) |
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} |
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metrics.Miss.Inc() |
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return "", false |
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} |
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//Delete deletes the key |
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func (c *WeakCache) Delete(key string) bool { |
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metrics.Deletes.Inc() |
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c.Map.Delete(key) |
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return true |
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} |
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func (c *WeakCache) Snapshot() (raft.FSMSnapshot, error) { |
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o := make(map[string]string) |
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c.Map.Range(func(key, value interface{}) bool { |
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ref := value.(*weakref.WeakRef) |
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if ref.IsAlive() { |
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metrics.Hits.Inc() |
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o[fmt.Sprint(key)] = ref.GetTarget().(string) |
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} |
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return true |
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}) |
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return &fsmSnapshot{store: o}, nil |
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} |
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func (c *WeakCache) Restore(closer io.ReadCloser) error { |
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o := make(map[string]string) |
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if err := json.NewDecoder(closer).Decode(&o); err != nil { |
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return err |
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} |
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// Set the state from the snapshot, no lock required according to |
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// Hashicorp docs. |
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for k, v := range o { |
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c.Put(k, v) |
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} |
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return nil |
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} |
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type fsmSnapshot struct { |
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store map[string]string |
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} |
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func (f *fsmSnapshot) Persist(sink raft.SnapshotSink) error { |
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err := func() error { |
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// Encode data. |
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b, err := json.Marshal(f.store) |
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if err != nil { |
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return err |
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} |
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// Write data to sink. |
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if _, err := sink.Write(b); err != nil { |
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return err |
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} |
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// Close the sink. |
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return sink.Close() |
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}() |
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if err != nil { |
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sink.Cancel() |
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} |
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return err |
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} |
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func (f *fsmSnapshot) Release() {} |
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arazmj /
gerdu
