refactor: move the flatten map to internal/cache

Signed-off-by: Rueian <[email protected]>

Author: rueian

cache.go

@@ -2,10 +2,11 @@ package rueidis
 
 import (
 	"context"
-	"runtime"
 	"sync"
+	"sync/atomic"
 	"time"
-	"unsafe"
+
+	"github.com/redis/rueidis/internal/cache"
 )
 
 // NewCacheStoreFn can be provided in ClientOption for using a custom CacheStore implementation
@@ -191,250 +192,73 @@ func (a *adapterEntry) Wait(ctx context.Context) (RedisMessage, error) {
 	}
 }
 
-type flatentry struct {
-	ovfl *flatentry
-	next unsafe.Pointer
-	prev unsafe.Pointer
-	cmd  string
-	key  string
-	val  []byte
-	ttl  int64
-	size int64
-	mark int64
-	mu   sync.RWMutex
-}
-
-func (f *flatentry) insert(e *flatentry) {
-	f.size += e.size
-	f.ttl = e.ttl
-	f.mu.Lock()
-	e.ovfl = f.ovfl
-	f.ovfl = e
-	f.mu.Unlock()
-}
-
-func (f *flatentry) find(cmd string, ts int64) ([]byte, bool) {
-	if f != nil && ts >= f.ttl {
-		return nil, true
-	}
-	for next := f; next != nil; {
-		if cmd == next.cmd {
-			return next.val, false
-		}
-		next.mu.RLock()
-		ovfl := next.ovfl
-		next.mu.RUnlock()
-		next = ovfl
-	}
-	return nil, false
-}
-
-const lrBatchSize = 64
-const flattEntrySize = unsafe.Sizeof(flatentry{})
-
-type lrBatch struct {
-	m map[*flatentry]struct{}
-}
-
 func NewFlattenCache(limit int) CacheStore {
-	f := &flatten{
-		flights: make(map[string]*adapterEntry),
-		cache:   make(map[string]*flatentry),
-		head:    &flatentry{},
-		tail:    &flatentry{},
-		size:    0,
-		limit:   int64(limit),
+	return &flatten{
+		flights: cache.NewDoubleMap[*adapterEntry](64),
+		cache:   cache.NewLRUDoubleMap[[]byte](64, int64(limit)),
 	}
-	f.head.next = unsafe.Pointer(f.tail)
-	f.tail.prev = unsafe.Pointer(f.head)
-	f.lrup = sync.Pool{New: func() any {
-		b := &lrBatch{m: make(map[*flatentry]struct{}, lrBatchSize)}
-		runtime.SetFinalizer(b, func(b *lrBatch) {
-			if len(b.m) >= 0 {
-				f.mu.Lock()
-				f.llTailBatch(b)
-				f.mu.Unlock()
-			}
-		})
-		return b
-	}}
-	return f
 }
 
 type flatten struct {
-	flights map[string]*adapterEntry
-	cache   map[string]*flatentry
-	head    *flatentry
-	tail    *flatentry
-	lrup    sync.Pool
-	mark    int64
-	size    int64
-	limit   int64
-	mu      sync.RWMutex
-}
-
-func (f *flatten) llAdd(e *flatentry) {
-	e.mark = f.mark
-	e.prev = f.tail.prev
-	e.next = unsafe.Pointer(f.tail)
-	f.tail.prev = unsafe.Pointer(e)
-	(*flatentry)(e.prev).next = unsafe.Pointer(e)
-}
-
-func (f *flatten) llDel(e *flatentry) {
-	(*flatentry)(e.prev).next = e.next
-	(*flatentry)(e.next).prev = e.prev
-	e.mark = -1
-}
-
-func (f *flatten) llTail(e *flatentry) {
-	f.llDel(e)
-	f.llAdd(e)
-}
-
-func (f *flatten) llTailBatch(b *lrBatch) {
-	for e := range b.m {
-		if e.mark == f.mark {
-			f.llTail(e)
-		}
-	}
-	clear(b.m)
-}
-
-func (f *flatten) remove(e *flatentry) {
-	f.size -= e.size
-	f.llDel(e)
-	delete(f.cache, e.key)
+	flights *cache.DoubleMap[*adapterEntry]
+	cache   *cache.LRUDoubleMap[[]byte]
+	close   int32
 }
 
 func (f *flatten) Flight(key, cmd string, ttl time.Duration, now time.Time) (RedisMessage, CacheEntry) {
-	f.mu.RLock()
-	e := f.cache[key]
-	f.mu.RUnlock()
-	ts := now.UnixMilli()
-	if v, _ := e.find(cmd, ts); v != nil {
-		batch := f.lrup.Get().(*lrBatch)
-		batch.m[e] = struct{}{}
-		if len(batch.m) >= lrBatchSize {
-			f.mu.Lock()
-			f.llTailBatch(batch)
-			f.mu.Unlock()
-		}
-		f.lrup.Put(batch)
-		var ret RedisMessage
-		_ = ret.CacheUnmarshalView(v)
-		return ret, nil
+	if atomic.LoadInt32(&f.close) == 1 {
+		return RedisMessage{}, nil
 	}
-	fk := key + cmd
-	f.mu.RLock()
-	af := f.flights[fk]
-	f.mu.RUnlock()
-	if af != nil {
-		return RedisMessage{}, af
-	}
-	f.mu.Lock()
-	e = f.cache[key]
-	v, expired := e.find(cmd, ts)
-	if v != nil {
-		f.llTail(e)
-		f.mu.Unlock()
+	ts := now.UnixMilli()
+	if e, ok := f.cache.Find(key, cmd, ts); ok {
 		var ret RedisMessage
-		_ = ret.CacheUnmarshalView(v)
+		_ = ret.CacheUnmarshalView(e)
 		return ret, nil
 	}
-	defer f.mu.Unlock()
-	if expired {
-		f.remove(e)
-	}
-	if af = f.flights[fk]; af != nil {
+	xat := ts + ttl.Milliseconds()
+	if af, ok := f.flights.FindOrInsert(key, cmd, func() *adapterEntry {
+		return &adapterEntry{ch: make(chan struct{}), xat: xat}
+	}); ok {
 		return RedisMessage{}, af
 	}
-	if f.flights != nil {
-		f.flights[fk] = &adapterEntry{ch: make(chan struct{}), xat: ts + ttl.Milliseconds()}
-	}
 	return RedisMessage{}, nil
 }
 
 func (f *flatten) Update(key, cmd string, val RedisMessage) (sxat int64) {
-	fk := key + cmd
-	f.mu.RLock()
-	af := f.flights[fk]
-	f.mu.RUnlock()
-	if af != nil {
+	if af, ok := f.flights.Find(key, cmd); ok {
 		sxat = val.getExpireAt()
 		if af.xat < sxat || sxat == 0 {
 			sxat = af.xat
 			val.setExpireAt(sxat)
 		}
 		bs := val.CacheMarshal(nil)
-		fe := &flatentry{cmd: cmd, val: bs, ttl: sxat, size: int64(len(bs)+len(key)+len(cmd)) + int64(flattEntrySize) + 64} // 64 for 2 map entries
-		f.mu.Lock()
-		if f.flights != nil {
-			delete(f.flights, fk)
-			f.size += fe.size
-			for ep := f.head.next; f.size > f.limit && ep != unsafe.Pointer(f.tail); {
-				e := (*flatentry)(ep)
-				f.remove(e)
-				ep = e.next
-			}
-			e := f.cache[key]
-			if e != nil && e.cmd == cmd {
-				f.size -= e.size
-				f.llDel(e)
-				e = nil
-			}
-			if e == nil {
-				fe.key = key
-				f.cache[key] = fe
-				f.llAdd(fe)
-			} else {
-				e.insert(fe)
-			}
-		}
-		f.mu.Unlock()
+		f.cache.Insert(key, cmd, int64(len(bs)+len(key)+len(cmd))+int64(cache.LRUEntrySize)+64, sxat, bs)
+		f.flights.Delete(key, cmd)
 		af.setVal(val)
 	}
 	return sxat
 }
 
 func (f *flatten) Cancel(key, cmd string, err error) {
-	fk := key + cmd
-	f.mu.Lock()
-	defer f.mu.Unlock()
-	if af := f.flights[fk]; af != nil {
-		delete(f.flights, fk)
+	if af, ok := f.flights.Find(key, cmd); ok {
+		f.flights.Delete(key, cmd)
 		af.setErr(err)
 	}
 }
 
 func (f *flatten) Delete(keys []RedisMessage) {
-	f.mu.Lock()
-	defer f.mu.Unlock()
 	if keys == nil {
-		f.cache = make(map[string]*flatentry, len(f.cache))
-		f.head.next = unsafe.Pointer(f.tail)
-		f.tail.prev = unsafe.Pointer(f.head)
-		f.mark++
-		f.size = 0
+		f.cache.DeleteAll()
 	} else {
 		for _, k := range keys {
-			if e := f.cache[k.string]; e != nil {
-				f.remove(e)
-			}
+			f.cache.Delete(k.string)
 		}
 	}
 }
 
 func (f *flatten) Close(err error) {
-	f.mu.Lock()
-	flights := f.flights
-	f.flights = nil
-	f.cache = nil
-	f.tail = nil
-	f.head = nil
-	f.mark++
-	f.mu.Unlock()
-	for _, entry := range flights {
+	atomic.StoreInt32(&f.close, 1)
+	f.flights.Iterate(func(entry *adapterEntry) {
 		entry.setErr(err)
-	}
+	})
 }

internal/cache/chain.go

@@ -0,0 +1,72 @@
+package cache
+
+type node[V any] struct {
+	key  string
+	next *node[V]
+	val  V
+}
+type chain[V any] struct {
+	node[V]
+}
+
+func (h *chain[V]) find(key string) (val V, ok bool) {
+	if h.node.key == key {
+		return h.node.val, true
+	}
+	for curr := h.node.next; curr != nil; curr = curr.next {
+		if curr.key == key {
+			return curr.val, true
+		}
+	}
+	return val, ok
+}
+
+func (h *chain[V]) insert(key string, val V) {
+	if h.node.key == "" {
+		h.node.key = key
+		h.node.val = val
+	} else if h.node.key == key {
+		h.node.val = val
+	} else {
+		n := &node[V]{key: key, val: val}
+		n.next = h.node.next
+		h.node.next = n
+	}
+}
+
+func (h *chain[V]) empty() bool {
+	return h.node.next == nil && h.node.key == ""
+}
+
+func (h *chain[V]) delete(key string) bool {
+	var zero V
+	if h.node.key == key {
+		h.node.key = ""
+		h.node.val = zero
+		return h.node.next == nil
+	}
+
+	if h.node.next == nil {
+		return h.node.key == ""
+	}
+
+	if h.node.next.key == key {
+		h.node.next.key = ""
+		h.node.next.val = zero
+		h.node.next, h.node.next.next = h.node.next.next, nil
+		return h.empty()
+	}
+
+	prev := h.node.next
+	curr := h.node.next.next
+	for curr != nil {
+		if curr.key == key {
+			curr.key = ""
+			curr.val = zero
+			prev.next, curr.next = curr.next, nil
+			break
+		}
+		prev, curr = curr, curr.next
+	}
+	return h.empty()
+}