cached file store (#1739)

* cached file store

store/cache/cache.go

@@ -1,152 +1,128 @@
-// Package cache implements a faulting style read cache on top of multiple micro stores
 package cache
 
 import (
-	"fmt"
-
 	"github.com/micro/go-micro/v2/store"
 	"github.com/micro/go-micro/v2/store/memory"
-	"github.com/pkg/errors"
 )
 
+// cache store is a store with caching to reduce IO where applicable.
+// A memory store is used to cache reads from the given backing store.
+// Reads are read through, writes are write-through
 type cache struct {
-	stores []store.Store
+	m       store.Store // the memory store
+	b       store.Store // the backing store, could be file, cockroach etc
+	options store.Options
 }
 
-// Cache is a cpu register style cache for the store.
+// NewStore returns a new cache store
-// It syncs between N stores in a faulting manner.
+func NewStore(store store.Store, opts ...store.Option) store.Store {
-type Cache interface {
+	cf := &cache{
-	// Implements the store interface
+		m: memory.NewStore(opts...),
-	store.Store
+		b: store,
+	}
+	return cf
+
 }
 
-// NewCache returns a new store using the underlying stores, which must be already Init()ialised
+func (c *cache) init(opts ...store.Option) error {
-func NewCache(stores ...store.Store) Cache {
+	for _, o := range opts {
-	if len(stores) == 0 {
+		o(&c.options)
-		stores = []store.Store{
-			memory.NewStore(),
 	}
-	}
-
-	// TODO: build in an in memory cache
-	c := &cache{
-		stores: stores,
-	}
-
-	return c
-}
-
-func (c *cache) Close() error {
 	return nil
 }
 
+// Init initialises the underlying stores
 func (c *cache) Init(opts ...store.Option) error {
-	// pass to the stores
+	if err := c.init(opts...); err != nil {
-	for _, store := range c.stores {
-		if err := store.Init(opts...); err != nil {
 		return err
 	}
+	if err := c.m.Init(opts...); err != nil {
+		return err
 	}
-	return nil
+	return c.b.Init(opts...)
 }
 
+// Options allows you to view the current options.
 func (c *cache) Options() store.Options {
-	// return from first store
+	return c.options
-	return c.stores[0].Options()
-}
-
-func (c *cache) String() string {
-	stores := make([]string, len(c.stores))
-	for i, s := range c.stores {
-		stores[i] = s.String()
-	}
-	return fmt.Sprintf("cache %v", stores)
 }
 
+// Read takes a single key name and optional ReadOptions. It returns matching []*Record or an error.
 func (c *cache) Read(key string, opts ...store.ReadOption) ([]*store.Record, error) {
-	readOpts := store.ReadOptions{}
+	recs, err := c.m.Read(key, opts...)
-	for _, o := range opts {
+	if err != nil && err != store.ErrNotFound {
-		o(&readOpts)
+		return nil, err
-	}
-
-	if readOpts.Prefix || readOpts.Suffix {
-		// List, then try cached gets for each key
-		var lOpts []store.ListOption
-		if readOpts.Prefix {
-			lOpts = append(lOpts, store.ListPrefix(key))
-		}
-		if readOpts.Suffix {
-			lOpts = append(lOpts, store.ListSuffix(key))
-		}
-		if readOpts.Limit > 0 {
-			lOpts = append(lOpts, store.ListLimit(readOpts.Limit))
-		}
-		if readOpts.Offset > 0 {
-			lOpts = append(lOpts, store.ListOffset(readOpts.Offset))
-		}
-		keys, err := c.List(lOpts...)
-		if err != nil {
-			return []*store.Record{}, errors.Wrap(err, "cache.List failed")
-		}
-		recs := make([]*store.Record, len(keys))
-		for i, k := range keys {
-			r, err := c.readOne(k, opts...)
-			if err != nil {
-				return recs, errors.Wrap(err, "cache.readOne failed")
-			}
-			recs[i] = r
 	}
+	if len(recs) > 0 {
 		return recs, nil
 	}
-
+	recs, err = c.b.Read(key, opts...)
-	// Otherwise just try cached get
-	r, err := c.readOne(key, opts...)
-	if err != nil {
-		return []*store.Record{}, err // preserve store.ErrNotFound
-	}
-	return []*store.Record{r}, nil
-}
-
-func (c *cache) readOne(key string, opts ...store.ReadOption) (*store.Record, error) {
-	for i, s := range c.stores {
-		// ReadOne ignores all options
-		r, err := s.Read(key)
 	if err == nil {
-			if len(r) > 1 {
+		for _, rec := range recs {
-				return nil, errors.Wrapf(err, "read from L%d cache (%s) returned multiple records", i, c.stores[i].String())
+			if err := c.m.Write(rec); err != nil {
-			}
+				return nil, err
-			for j := i - 1; j >= 0; j-- {
-				err := c.stores[j].Write(r[0])
-				if err != nil {
-					return nil, errors.Wrapf(err, "could not write to L%d cache (%s)", j, c.stores[j].String())
 			}
 		}
-			return r[0], nil
 	}
-	}
+	return recs, err
-	return nil, store.ErrNotFound
 }
 
+// Write() writes a record to the store, and returns an error if the record was not written.
+// If the write succeeds in writing to memory but fails to write through to file, you'll receive an error
+// but the value may still reside in memory so appropriate action should be taken.
 func (c *cache) Write(r *store.Record, opts ...store.WriteOption) error {
-	// Write to all layers in reverse
+	if err := c.m.Write(r, opts...); err != nil {
-	for i := len(c.stores) - 1; i >= 0; i-- {
+		return err
-		if err := c.stores[i].Write(r, opts...); err != nil {
-			return errors.Wrapf(err, "could not write to L%d cache (%s)", i, c.stores[i].String())
 	}
-	}
+	return c.b.Write(r, opts...)
-	return nil
 }
 
+// Delete removes the record with the corresponding key from the store.
+// If the delete succeeds in writing to memory but fails to write through to file, you'll receive an error
+// but the value may still reside in memory so appropriate action should be taken.
 func (c *cache) Delete(key string, opts ...store.DeleteOption) error {
-	for i, s := range c.stores {
+	if err := c.m.Delete(key, opts...); err != nil {
-		if err := s.Delete(key, opts...); err != nil {
+		return err
-			return errors.Wrapf(err, "could not delete from L%d cache (%s)", i, c.stores[i].String())
 	}
-	}
+	return c.b.Delete(key, opts...)
-	return nil
 }
 
+// List returns any keys that match, or an empty list with no error if none matched.
 func (c *cache) List(opts ...store.ListOption) ([]string, error) {
-	// List only makes sense from the top level
+	keys, err := c.m.List(opts...)
-	return c.stores[len(c.stores)-1].List(opts...)
+	if err != nil && err != store.ErrNotFound {
+		return nil, err
+	}
+	if len(keys) > 0 {
+		return keys, nil
+	}
+	keys, err = c.b.List(opts...)
+	if err == nil {
+		for _, key := range keys {
+			recs, err := c.b.Read(key)
+			if err != nil {
+				return nil, err
+			}
+			for _, r := range recs {
+				if err := c.m.Write(r); err != nil {
+					return nil, err
+				}
+			}
+
+		}
+	}
+	return keys, err
+}
+
+// Close the store and the underlying store
+func (c *cache) Close() error {
+	if err := c.m.Close(); err != nil {
+		return err
+	}
+	return c.b.Close()
+}
+
+// String returns the name of the implementation.
+func (c *cache) String() string {
+	return "cache"
 }

store/cache/cache_test.go

@@ -1,99 +1,102 @@
 package cache
 
 import (
-	"sort"
+	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/micro/go-micro/v2/store"
-	"github.com/micro/go-micro/v2/store/memory"
+	"github.com/micro/go-micro/v2/store/file"
 	"github.com/stretchr/testify/assert"
 )
 
-func TestCache(t *testing.T) {
+func cleanup(db string, s store.Store) {
-	l0, l1, l2 := memory.NewStore(store.Database("l0")), memory.NewStore(store.Table("l1")), memory.NewStore()
+	s.Close()
-	_, _, _ = l0.Init(), l1.Init(), l2.Init()
+	dir := filepath.Join(file.DefaultDir, db+"/")
+	os.RemoveAll(dir)
+}
 
-	assert := assert.New(t)
+func TestRead(t *testing.T) {
+	cf := NewStore(file.NewStore())
+	cf.Init()
+	cfInt := cf.(*cache)
+	defer cleanup(file.DefaultDatabase, cf)
 
-	nonCache := NewCache(nil)
+	_, err := cf.Read("key1")
-	assert.Equal(len(nonCache.(*cache).stores), 1, "Expected a cache initialised with just 1 store to fail")
+	assert.Error(t, err, "Unexpected record")
-
+	cfInt.b.Write(&store.Record{
-	// Basic functionality
+		Key:   "key1",
-	cachedStore := NewCache(l0, l1, l2)
+		Value: []byte("foo"),
-	assert.Equal(cachedStore.Options(), l0.Options(), "Options on store/cache are nonsensical")
+	})
-	expectedString := "cache [memory memory memory]"
+	recs, err := cf.Read("key1")
-	assert.Equal(cachedStore.String(), expectedString, "Cache couldn't describe itself as expected")
+	assert.NoError(t, err)
-
+	assert.Len(t, recs, 1, "Expected a record to be pulled from file store")
-	// Read/Write tests
+	recs, err = cfInt.m.Read("key1")
-	_, err := cachedStore.Read("test")
+	assert.NoError(t, err)
-	assert.Equal(store.ErrNotFound, err, "Read non existant key")
+	assert.Len(t, recs, 1, "Expected a memory store to be populatedfrom file store")
-	r1 := &store.Record{
+
-		Key:      "aaa",
+}
-		Value:    []byte("bbb"),
+
-		Metadata: map[string]interface{}{},
+func TestWrite(t *testing.T) {
-	}
+	cf := NewStore(file.NewStore())
-	r2 := &store.Record{
+	cf.Init()
-		Key:      "aaaa",
+	cfInt := cf.(*cache)
-		Value:    []byte("bbbb"),
+	defer cleanup(file.DefaultDatabase, cf)
-		Metadata: map[string]interface{}{},
+
-	}
+	cf.Write(&store.Record{
-	r3 := &store.Record{
+		Key:   "key1",
-		Key:      "aaaaa",
+		Value: []byte("foo"),
-		Value:    []byte("bbbbb"),
+	})
-		Metadata: map[string]interface{}{},
+	recs, _ := cfInt.m.Read("key1")
-	}
+	assert.Len(t, recs, 1, "Expected a record in the memory store")
-	// Write 3 records directly to l2
+	recs, _ = cfInt.b.Read("key1")
-	l2.Write(r1)
+	assert.Len(t, recs, 1, "Expected a record in the file store")
-	l2.Write(r2)
+
-	l2.Write(r3)
+}
-	// Ensure it's not in l0
+
-	assert.Equal(store.ErrNotFound, func() error { _, err := l0.Read(r1.Key); return err }())
+func TestDelete(t *testing.T) {
-	// Read from cache, ensure it's in all 3 stores
+	cf := NewStore(file.NewStore())
-	results, err := cachedStore.Read(r1.Key)
+	cf.Init()
-	assert.Nil(err, "cachedStore.Read() returned error")
+	cfInt := cf.(*cache)
-	assert.Len(results, 1, "cachedStore.Read() should only return 1 result")
+	defer cleanup(file.DefaultDatabase, cf)
-	assert.Equal(r1, results[0], "Cached read didn't return the record that was put in")
+
-	results, err = l0.Read(r1.Key)
+	cf.Write(&store.Record{
-	assert.Nil(err)
+		Key:   "key1",
-	assert.Equal(r1, results[0], "l0 not coherent")
+		Value: []byte("foo"),
-	results, err = l1.Read(r1.Key)
+	})
-	assert.Nil(err)
+	recs, _ := cfInt.m.Read("key1")
-	assert.Equal(r1, results[0], "l1 not coherent")
+	assert.Len(t, recs, 1, "Expected a record in the memory store")
-	results, err = l2.Read(r1.Key)
+	recs, _ = cfInt.b.Read("key1")
-	assert.Nil(err)
+	assert.Len(t, recs, 1, "Expected a record in the file store")
-	assert.Equal(r1, results[0], "l2 not coherent")
+	cf.Delete("key1")
-	// Multiple read
+
-	results, err = cachedStore.Read("aa", store.ReadPrefix())
+	_, err := cfInt.m.Read("key1")
-	assert.Nil(err, "Cachedstore multiple read errored")
+	assert.Error(t, err, "Expected no records in memory store")
-	assert.Len(results, 3, "ReadPrefix should have read all records")
+	_, err = cfInt.b.Read("key1")
-	// l1 should now have all 3 records
+	assert.Error(t, err, "Expected no records in file store")
-	l1results, err := l1.Read("aa", store.ReadPrefix())
+
-	assert.Nil(err, "l1.Read failed")
+}
-	assert.Len(l1results, 3, "l1 didn't contain a full cache")
+
-	sort.Slice(results, func(i, j int) bool { return results[i].Key < results[j].Key })
+func TestList(t *testing.T) {
-	sort.Slice(l1results, func(i, j int) bool { return l1results[i].Key < l1results[j].Key })
+	cf := NewStore(file.NewStore())
-	assert.Equal(results[0], l1results[0], "l1 cache not coherent")
+	cf.Init()
-	assert.Equal(results[1], l1results[1], "l1 cache not coherent")
+	cfInt := cf.(*cache)
-	assert.Equal(results[2], l1results[2], "l1 cache not coherent")
+	defer cleanup(file.DefaultDatabase, cf)
-
+
-	// Test List and Delete
+	keys, err := cf.List()
-	keys, err := cachedStore.List(store.ListPrefix("a"))
+	assert.NoError(t, err)
-	assert.Nil(err, "List should not error")
+	assert.Len(t, keys, 0)
-	assert.Len(keys, 3, "List should return 3 keys")
+	cfInt.b.Write(&store.Record{
-	for _, k := range keys {
+		Key:   "key1",
-		err := cachedStore.Delete(k)
+		Value: []byte("foo"),
-		assert.Nil(err, "Delete should not error")
+	})
-		_, err = cachedStore.Read(k)
+
-		// N.B. - this may not pass on stores that are eventually consistent
+	cfInt.b.Write(&store.Record{
-		assert.Equal(store.ErrNotFound, err, "record should be gone")
+		Key:   "key2",
-	}
+		Value: []byte("foo"),
-
+	})
-	// Test Write
+	keys, err = cf.List()
-	err = cachedStore.Write(r1)
+	assert.NoError(t, err)
-	assert.Nil(err, "Write shouldn't fail")
+	assert.Len(t, keys, 2)
-	l2result, err := l2.Read(r1.Key)
-	assert.Nil(err)
-	assert.Len(l2result, 1)
-	assert.Equal(r1, l2result[0], "Write didn't make it all the way through to l2")
 
 }