123 lines
2.8 KiB
Go
123 lines
2.8 KiB
Go
package store
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import (
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"github.com/lbryio/lbry.go/v2/extras/errors"
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"github.com/lbryio/lbry.go/v2/stream"
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"github.com/lbryio/reflector.go/internal/metrics"
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golru "github.com/hashicorp/golang-lru"
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)
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// LRUStore adds a max cache size and LRU eviction to a BlobStore
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type LRUStore struct {
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// underlying store
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store BlobStore
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// lru implementation
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lru *golru.Cache
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}
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// NewLRUStore initialize a new LRUStore
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func NewLRUStore(component string, store BlobStore, maxItems int) *LRUStore {
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l := &LRUStore{
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store: store,
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}
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lru, err := golru.NewWithEvict(maxItems, func(key interface{}, value interface{}) {
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metrics.CacheLRUEvictCount.With(metrics.CacheLabels(l.Name(), component)).Inc()
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_ = store.Delete(key.(string)) // TODO: log this error. may happen if underlying entry is gone but cache entry still there
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})
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if err != nil {
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panic(err)
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}
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l.lru = lru
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go func() {
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if lstr, ok := store.(lister); ok {
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err = l.loadExisting(lstr, maxItems)
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if err != nil {
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panic(err) // TODO: what should happen here? panic? return nil? just keep going?
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}
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}
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}()
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return l
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}
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// Name is the cache type name
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func (l *LRUStore) Name() string {
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return "lru_" + l.store.Name()
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}
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// Has returns whether the blob is in the store, without updating the recent-ness.
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func (l *LRUStore) Has(hash string) (bool, error) {
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return l.lru.Contains(hash), nil
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}
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// Get returns the blob or an error if the blob doesn't exist.
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func (l *LRUStore) Get(hash string) (stream.Blob, error) {
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_, has := l.lru.Get(hash)
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if !has {
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return nil, errors.Err(ErrBlobNotFound)
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}
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blob, err := l.store.Get(hash)
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if errors.Is(err, ErrBlobNotFound) {
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// Blob disappeared from underlying store
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l.lru.Remove(hash)
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}
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return blob, err
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}
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// Put stores the blob
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func (l *LRUStore) Put(hash string, blob stream.Blob) error {
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err := l.store.Put(hash, blob)
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if err != nil {
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return err
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}
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l.lru.Add(hash, true)
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return nil
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}
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// PutSD stores the sd blob
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func (l *LRUStore) PutSD(hash string, blob stream.Blob) error {
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err := l.store.PutSD(hash, blob)
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if err != nil {
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return err
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}
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l.lru.Add(hash, true)
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return nil
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}
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// Delete deletes the blob from the store
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func (l *LRUStore) Delete(hash string) error {
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err := l.store.Delete(hash)
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if err != nil {
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return err
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}
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// This must come after store.Delete()
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// Remove triggers onEvict function, which also tries to delete blob from store
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// We need to delete it manually first so any errors can be propagated up
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l.lru.Remove(hash)
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return nil
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}
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// loadExisting imports existing blobs from the underlying store into the LRU cache
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func (l *LRUStore) loadExisting(store lister, maxItems int) error {
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existing, err := store.list()
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if err != nil {
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return err
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}
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added := 0
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for _, h := range existing {
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l.lru.Add(h, true)
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added++
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if maxItems > 0 && added >= maxItems { // underlying cache is bigger than LRU cache
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break
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}
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}
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return nil
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}
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