feat: in memory adapter for entity caching cache #3137
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| Original file line number | Diff line number | Diff line change | ||||||||
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| @@ -0,0 +1,116 @@ | ||||||||||
| package in_memory | ||||||||||
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| import ( | ||||||||||
| "bytes" | ||||||||||
| "context" | ||||||||||
| "fmt" | ||||||||||
| "math" | ||||||||||
| "sync" | ||||||||||
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| "github.com/dgraph-io/ristretto/v2" | ||||||||||
| enginecache "github.com/wundergraph/graphql-go-tools/v2/pkg/entitycaching" | ||||||||||
| ) | ||||||||||
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| const entryCost = 1 | ||||||||||
| const maxSize = math.MaxInt32 | ||||||||||
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| type InMemoryCache struct { | ||||||||||
| cache *ristretto.Cache[string, []byte] | ||||||||||
| // closeOnce keeps Close idempotent, so two shutdown paths reaching it is | ||||||||||
| // not a panic on a channel ristretto has already closed. | ||||||||||
| closeOnce sync.Once | ||||||||||
| } | ||||||||||
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| // NewInMemoryCache returns a cache holding at most maxEntries entries. The | ||||||||||
| // caller owns it and must Close it. | ||||||||||
| func NewInMemoryCache(maxEntries int64) (*InMemoryCache, error) { | ||||||||||
| if maxEntries <= 0 { | ||||||||||
| return nil, fmt.Errorf("in memory entity cache needs a positive size, got %d", maxEntries) | ||||||||||
| } | ||||||||||
| if maxEntries > maxSize { | ||||||||||
| return nil, fmt.Errorf("in memory entity cache size is too large: %d", maxEntries) | ||||||||||
| } | ||||||||||
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| cache, err := ristretto.NewCache(&ristretto.Config[string, []byte]{ | ||||||||||
| MaxCost: maxEntries, | ||||||||||
| NumCounters: maxEntries * 10, | ||||||||||
| IgnoreInternalCost: true, | ||||||||||
| BufferItems: 64, | ||||||||||
| }) | ||||||||||
| if err != nil { | ||||||||||
| return nil, fmt.Errorf("failed to create in memory entity cache: %w", err) | ||||||||||
| } | ||||||||||
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| return &InMemoryCache{cache: cache}, nil | ||||||||||
| } | ||||||||||
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| // GetMany returns the entries it found, keyed by the key they were asked for. | ||||||||||
|
Contributor
There was a problem hiding this comment. Since it's an implementation of the engines interface method I'd simply write
Suggested change
Any behaviour, guard logic and rules should be documented on the interface method godic as a contract for any implementor (imo) |
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| func (c *InMemoryCache) GetMany(ctx context.Context, keys []string) (map[string]enginecache.Item, error) { | ||||||||||
| if err := ctx.Err(); err != nil { | ||||||||||
| return nil, err | ||||||||||
| } | ||||||||||
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| if len(keys) == 0 { | ||||||||||
| return nil, nil | ||||||||||
| } | ||||||||||
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| results := make(map[string]enginecache.Item, len(keys)) | ||||||||||
| for _, key := range keys { | ||||||||||
| // In case there are duplicate keys, ignore duplicate fetches | ||||||||||
| if _, found := results[key]; found { | ||||||||||
| continue | ||||||||||
| } | ||||||||||
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| // We need to do getTTL OR store the expiration date on the entry | ||||||||||
| // however doing the latter still means that its a different value | ||||||||||
| // from the expiration date the ristretto uses internally | ||||||||||
| value, getOk := c.cache.Get(key) | ||||||||||
| ttl, ttlOk := c.cache.GetTTL(key) | ||||||||||
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||||||||||
| // Either the key does not exist, or it just expired now | ||||||||||
| if !getOk || !ttlOk || ttl <= 0 { | ||||||||||
| continue | ||||||||||
| } | ||||||||||
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| results[key] = enginecache.Item{Key: key, Value: bytes.Clone(value), TTL: ttl} | ||||||||||
| } | ||||||||||
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| return results, nil | ||||||||||
| } | ||||||||||
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| // SetMany stores every item, all of which must carry a positive TTL. A single | ||||||||||
| // item without one fails the whole batch with an ErrMissingTTL and nothing is | ||||||||||
| // stored. It otherwise only fails on a cancelled context. | ||||||||||
|
Comment on lines
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Contributor
There was a problem hiding this comment. Since it's an implementation of the engines interface method I'd simply write
Suggested change
Any behaviour, guard logic and rules should be documented on the interface method godic as a contract for any implementor (imo) |
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| func (c *InMemoryCache) SetMany(ctx context.Context, items []enginecache.Item) error { | ||||||||||
| if err := ctx.Err(); err != nil { | ||||||||||
| return err | ||||||||||
| } | ||||||||||
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||||||||||
| if len(items) == 0 { | ||||||||||
| return nil | ||||||||||
| } | ||||||||||
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| // Map used for deduplications | ||||||||||
| last := make(map[string]enginecache.Item, len(items)) | ||||||||||
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| for _, item := range items { | ||||||||||
| if item.TTL <= 0 { | ||||||||||
| return fmt.Errorf("%w: key %q", enginecache.ErrMissingTTL, item.Key) | ||||||||||
|
Contributor
There was a problem hiding this comment. On the lib version currently referred to by the routers go.mod there is no |
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| } | ||||||||||
| // In case user sends same key, use the last entry to save | ||||||||||
| last[item.Key] = item | ||||||||||
| } | ||||||||||
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| for _, item := range last { | ||||||||||
| c.cache.SetWithTTL(item.Key, bytes.Clone(item.Value), entryCost, item.TTL) | ||||||||||
| } | ||||||||||
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| c.cache.Wait() | ||||||||||
| return nil | ||||||||||
| } | ||||||||||
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| // Close stops the goroutines ristretto runs behind the cache. It is safe to | ||||||||||
| // call more than once, but not while a GetMany or a SetMany is in flight. | ||||||||||
|
Comment on lines
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Contributor
There was a problem hiding this comment.
We can't control this from here right? I checked and Ristretto will actually panic if you close the cache during a concurrent write. Can you secure it with an RWMutex? |
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| func (c *InMemoryCache) Close() { | ||||||||||
| c.closeOnce.Do(c.cache.Close) | ||||||||||
| } | ||||||||||
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I'd probably go for something much smaller, like a million or so. This blows OOM way before we reach maxInt32