reflector.go/store/caching.go
2021-07-24 01:03:51 +02:00

112 lines
3.5 KiB
Go

package store
import (
"time"
"github.com/lbryio/lbry.go/v2/extras/errors"
"github.com/lbryio/lbry.go/v2/stream"
"github.com/lbryio/reflector.go/shared"
log "github.com/sirupsen/logrus"
"github.com/lbryio/reflector.go/internal/metrics"
)
// CachingStore combines two stores, typically a local and a remote store, to improve performance.
// Accessed blobs are stored in and retrieved from the cache. If they are not in the cache, they
// are retrieved from the origin and cached. Puts are cached and also forwarded to the origin.
type CachingStore struct {
origin, cache BlobStore
component string
}
// NewCachingStore makes a new caching disk store and returns a pointer to it.
func NewCachingStore(component string, origin, cache BlobStore) *CachingStore {
return &CachingStore{
component: component,
origin: WithSingleFlight(component, origin),
cache: WithSingleFlight(component, cache),
}
}
const nameCaching = "caching"
// Name is the cache type name
func (c *CachingStore) Name() string { return nameCaching }
// Has checks the cache and then the origin for a hash. It returns true if either store has it.
func (c *CachingStore) Has(hash string) (bool, error) {
has, err := c.cache.Has(hash)
if has || err != nil {
return has, err
}
return c.origin.Has(hash)
}
// Get tries to get the blob from the cache first, falling back to the origin. If the blob comes
// from the origin, it is also stored in the cache.
func (c *CachingStore) Get(hash string) (stream.Blob, shared.BlobTrace, error) {
start := time.Now()
blob, trace, err := c.cache.Get(hash)
if err == nil || !errors.Is(err, ErrBlobNotFound) {
metrics.CacheHitCount.With(metrics.CacheLabels(c.cache.Name(), c.component)).Inc()
rate := float64(len(blob)) / 1024 / 1024 / time.Since(start).Seconds()
metrics.CacheRetrievalSpeed.With(map[string]string{
metrics.LabelCacheType: c.cache.Name(),
metrics.LabelComponent: c.component,
metrics.LabelSource: "cache",
}).Set(rate)
return blob, trace.Stack(time.Since(start), c.Name()), err
}
metrics.CacheMissCount.With(metrics.CacheLabels(c.cache.Name(), c.component)).Inc()
blob, trace, err = c.origin.Get(hash)
if err != nil {
return nil, trace.Stack(time.Since(start), c.Name()), err
}
// there is no need to wait for the blob to be stored before we return it
// TODO: however this should be refactored to limit the amount of routines that the process can spawn to avoid a possible DoS
metrics.RoutinesQueue.WithLabelValues("store", "cache-put").Inc()
go func() {
defer metrics.RoutinesQueue.WithLabelValues("store", "cache-put").Dec()
err = c.cache.Put(hash, blob)
if err != nil {
log.Errorf("error saving blob to underlying cache: %s", errors.FullTrace(err))
}
}()
return blob, trace.Stack(time.Since(start), c.Name()), nil
}
// Put stores the blob in the origin and the cache
func (c *CachingStore) Put(hash string, blob stream.Blob) error {
err := c.origin.Put(hash, blob)
if err != nil {
return err
}
return c.cache.Put(hash, blob)
}
// PutSD stores the sd blob in the origin and the cache
func (c *CachingStore) PutSD(hash string, blob stream.Blob) error {
err := c.origin.PutSD(hash, blob)
if err != nil {
return err
}
return c.cache.PutSD(hash, blob)
}
// Delete deletes the blob from the origin and the cache
func (c *CachingStore) Delete(hash string) error {
err := c.origin.Delete(hash)
if err != nil {
return err
}
return c.cache.Delete(hash)
}
// Shutdown shuts down the store gracefully
func (c *CachingStore) Shutdown() {
c.origin.Shutdown()
c.cache.Shutdown()
return
}