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-rw-r--r--vendor/github.com/syndtr/goleveldb/leveldb/cache/cache.go705
1 files changed, 705 insertions, 0 deletions
diff --git a/vendor/github.com/syndtr/goleveldb/leveldb/cache/cache.go b/vendor/github.com/syndtr/goleveldb/leveldb/cache/cache.go
new file mode 100644
index 0000000..c5940b2
--- /dev/null
+++ b/vendor/github.com/syndtr/goleveldb/leveldb/cache/cache.go
@@ -0,0 +1,705 @@
+// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Package cache provides interface and implementation of a cache algorithms.
+package cache
+
+import (
+ "sync"
+ "sync/atomic"
+ "unsafe"
+
+ "github.com/syndtr/goleveldb/leveldb/util"
+)
+
+// Cacher provides interface to implements a caching functionality.
+// An implementation must be safe for concurrent use.
+type Cacher interface {
+ // Capacity returns cache capacity.
+ Capacity() int
+
+ // SetCapacity sets cache capacity.
+ SetCapacity(capacity int)
+
+ // Promote promotes the 'cache node'.
+ Promote(n *Node)
+
+ // Ban evicts the 'cache node' and prevent subsequent 'promote'.
+ Ban(n *Node)
+
+ // Evict evicts the 'cache node'.
+ Evict(n *Node)
+
+ // EvictNS evicts 'cache node' with the given namespace.
+ EvictNS(ns uint64)
+
+ // EvictAll evicts all 'cache node'.
+ EvictAll()
+
+ // Close closes the 'cache tree'
+ Close() error
+}
+
+// Value is a 'cacheable object'. It may implements util.Releaser, if
+// so the the Release method will be called once object is released.
+type Value interface{}
+
+// NamespaceGetter provides convenient wrapper for namespace.
+type NamespaceGetter struct {
+ Cache *Cache
+ NS uint64
+}
+
+// Get simply calls Cache.Get() method.
+func (g *NamespaceGetter) Get(key uint64, setFunc func() (size int, value Value)) *Handle {
+ return g.Cache.Get(g.NS, key, setFunc)
+}
+
+// The hash tables implementation is based on:
+// "Dynamic-Sized Nonblocking Hash Tables", by Yujie Liu,
+// Kunlong Zhang, and Michael Spear.
+// ACM Symposium on Principles of Distributed Computing, Jul 2014.
+
+const (
+ mInitialSize = 1 << 4
+ mOverflowThreshold = 1 << 5
+ mOverflowGrowThreshold = 1 << 7
+)
+
+type mBucket struct {
+ mu sync.Mutex
+ node []*Node
+ frozen bool
+}
+
+func (b *mBucket) freeze() []*Node {
+ b.mu.Lock()
+ defer b.mu.Unlock()
+ if !b.frozen {
+ b.frozen = true
+ }
+ return b.node
+}
+
+func (b *mBucket) get(r *Cache, h *mNode, hash uint32, ns, key uint64, noset bool) (done, added bool, n *Node) {
+ b.mu.Lock()
+
+ if b.frozen {
+ b.mu.Unlock()
+ return
+ }
+
+ // Scan the node.
+ for _, n := range b.node {
+ if n.hash == hash && n.ns == ns && n.key == key {
+ atomic.AddInt32(&n.ref, 1)
+ b.mu.Unlock()
+ return true, false, n
+ }
+ }
+
+ // Get only.
+ if noset {
+ b.mu.Unlock()
+ return true, false, nil
+ }
+
+ // Create node.
+ n = &Node{
+ r: r,
+ hash: hash,
+ ns: ns,
+ key: key,
+ ref: 1,
+ }
+ // Add node to bucket.
+ b.node = append(b.node, n)
+ bLen := len(b.node)
+ b.mu.Unlock()
+
+ // Update counter.
+ grow := atomic.AddInt32(&r.nodes, 1) >= h.growThreshold
+ if bLen > mOverflowThreshold {
+ grow = grow || atomic.AddInt32(&h.overflow, 1) >= mOverflowGrowThreshold
+ }
+
+ // Grow.
+ if grow && atomic.CompareAndSwapInt32(&h.resizeInProgess, 0, 1) {
+ nhLen := len(h.buckets) << 1
+ nh := &mNode{
+ buckets: make([]unsafe.Pointer, nhLen),
+ mask: uint32(nhLen) - 1,
+ pred: unsafe.Pointer(h),
+ growThreshold: int32(nhLen * mOverflowThreshold),
+ shrinkThreshold: int32(nhLen >> 1),
+ }
+ ok := atomic.CompareAndSwapPointer(&r.mHead, unsafe.Pointer(h), unsafe.Pointer(nh))
+ if !ok {
+ panic("BUG: failed swapping head")
+ }
+ go nh.initBuckets()
+ }
+
+ return true, true, n
+}
+
+func (b *mBucket) delete(r *Cache, h *mNode, hash uint32, ns, key uint64) (done, deleted bool) {
+ b.mu.Lock()
+
+ if b.frozen {
+ b.mu.Unlock()
+ return
+ }
+
+ // Scan the node.
+ var (
+ n *Node
+ bLen int
+ )
+ for i := range b.node {
+ n = b.node[i]
+ if n.ns == ns && n.key == key {
+ if atomic.LoadInt32(&n.ref) == 0 {
+ deleted = true
+
+ // Call releaser.
+ if n.value != nil {
+ if r, ok := n.value.(util.Releaser); ok {
+ r.Release()
+ }
+ n.value = nil
+ }
+
+ // Remove node from bucket.
+ b.node = append(b.node[:i], b.node[i+1:]...)
+ bLen = len(b.node)
+ }
+ break
+ }
+ }
+ b.mu.Unlock()
+
+ if deleted {
+ // Call OnDel.
+ for _, f := range n.onDel {
+ f()
+ }
+
+ // Update counter.
+ atomic.AddInt32(&r.size, int32(n.size)*-1)
+ shrink := atomic.AddInt32(&r.nodes, -1) < h.shrinkThreshold
+ if bLen >= mOverflowThreshold {
+ atomic.AddInt32(&h.overflow, -1)
+ }
+
+ // Shrink.
+ if shrink && len(h.buckets) > mInitialSize && atomic.CompareAndSwapInt32(&h.resizeInProgess, 0, 1) {
+ nhLen := len(h.buckets) >> 1
+ nh := &mNode{
+ buckets: make([]unsafe.Pointer, nhLen),
+ mask: uint32(nhLen) - 1,
+ pred: unsafe.Pointer(h),
+ growThreshold: int32(nhLen * mOverflowThreshold),
+ shrinkThreshold: int32(nhLen >> 1),
+ }
+ ok := atomic.CompareAndSwapPointer(&r.mHead, unsafe.Pointer(h), unsafe.Pointer(nh))
+ if !ok {
+ panic("BUG: failed swapping head")
+ }
+ go nh.initBuckets()
+ }
+ }
+
+ return true, deleted
+}
+
+type mNode struct {
+ buckets []unsafe.Pointer // []*mBucket
+ mask uint32
+ pred unsafe.Pointer // *mNode
+ resizeInProgess int32
+
+ overflow int32
+ growThreshold int32
+ shrinkThreshold int32
+}
+
+func (n *mNode) initBucket(i uint32) *mBucket {
+ if b := (*mBucket)(atomic.LoadPointer(&n.buckets[i])); b != nil {
+ return b
+ }
+
+ p := (*mNode)(atomic.LoadPointer(&n.pred))
+ if p != nil {
+ var node []*Node
+ if n.mask > p.mask {
+ // Grow.
+ pb := (*mBucket)(atomic.LoadPointer(&p.buckets[i&p.mask]))
+ if pb == nil {
+ pb = p.initBucket(i & p.mask)
+ }
+ m := pb.freeze()
+ // Split nodes.
+ for _, x := range m {
+ if x.hash&n.mask == i {
+ node = append(node, x)
+ }
+ }
+ } else {
+ // Shrink.
+ pb0 := (*mBucket)(atomic.LoadPointer(&p.buckets[i]))
+ if pb0 == nil {
+ pb0 = p.initBucket(i)
+ }
+ pb1 := (*mBucket)(atomic.LoadPointer(&p.buckets[i+uint32(len(n.buckets))]))
+ if pb1 == nil {
+ pb1 = p.initBucket(i + uint32(len(n.buckets)))
+ }
+ m0 := pb0.freeze()
+ m1 := pb1.freeze()
+ // Merge nodes.
+ node = make([]*Node, 0, len(m0)+len(m1))
+ node = append(node, m0...)
+ node = append(node, m1...)
+ }
+ b := &mBucket{node: node}
+ if atomic.CompareAndSwapPointer(&n.buckets[i], nil, unsafe.Pointer(b)) {
+ if len(node) > mOverflowThreshold {
+ atomic.AddInt32(&n.overflow, int32(len(node)-mOverflowThreshold))
+ }
+ return b
+ }
+ }
+
+ return (*mBucket)(atomic.LoadPointer(&n.buckets[i]))
+}
+
+func (n *mNode) initBuckets() {
+ for i := range n.buckets {
+ n.initBucket(uint32(i))
+ }
+ atomic.StorePointer(&n.pred, nil)
+}
+
+// Cache is a 'cache map'.
+type Cache struct {
+ mu sync.RWMutex
+ mHead unsafe.Pointer // *mNode
+ nodes int32
+ size int32
+ cacher Cacher
+ closed bool
+}
+
+// NewCache creates a new 'cache map'. The cacher is optional and
+// may be nil.
+func NewCache(cacher Cacher) *Cache {
+ h := &mNode{
+ buckets: make([]unsafe.Pointer, mInitialSize),
+ mask: mInitialSize - 1,
+ growThreshold: int32(mInitialSize * mOverflowThreshold),
+ shrinkThreshold: 0,
+ }
+ for i := range h.buckets {
+ h.buckets[i] = unsafe.Pointer(&mBucket{})
+ }
+ r := &Cache{
+ mHead: unsafe.Pointer(h),
+ cacher: cacher,
+ }
+ return r
+}
+
+func (r *Cache) getBucket(hash uint32) (*mNode, *mBucket) {
+ h := (*mNode)(atomic.LoadPointer(&r.mHead))
+ i := hash & h.mask
+ b := (*mBucket)(atomic.LoadPointer(&h.buckets[i]))
+ if b == nil {
+ b = h.initBucket(i)
+ }
+ return h, b
+}
+
+func (r *Cache) delete(n *Node) bool {
+ for {
+ h, b := r.getBucket(n.hash)
+ done, deleted := b.delete(r, h, n.hash, n.ns, n.key)
+ if done {
+ return deleted
+ }
+ }
+ return false
+}
+
+// Nodes returns number of 'cache node' in the map.
+func (r *Cache) Nodes() int {
+ return int(atomic.LoadInt32(&r.nodes))
+}
+
+// Size returns sums of 'cache node' size in the map.
+func (r *Cache) Size() int {
+ return int(atomic.LoadInt32(&r.size))
+}
+
+// Capacity returns cache capacity.
+func (r *Cache) Capacity() int {
+ if r.cacher == nil {
+ return 0
+ }
+ return r.cacher.Capacity()
+}
+
+// SetCapacity sets cache capacity.
+func (r *Cache) SetCapacity(capacity int) {
+ if r.cacher != nil {
+ r.cacher.SetCapacity(capacity)
+ }
+}
+
+// Get gets 'cache node' with the given namespace and key.
+// If cache node is not found and setFunc is not nil, Get will atomically creates
+// the 'cache node' by calling setFunc. Otherwise Get will returns nil.
+//
+// The returned 'cache handle' should be released after use by calling Release
+// method.
+func (r *Cache) Get(ns, key uint64, setFunc func() (size int, value Value)) *Handle {
+ r.mu.RLock()
+ defer r.mu.RUnlock()
+ if r.closed {
+ return nil
+ }
+
+ hash := murmur32(ns, key, 0xf00)
+ for {
+ h, b := r.getBucket(hash)
+ done, _, n := b.get(r, h, hash, ns, key, setFunc == nil)
+ if done {
+ if n != nil {
+ n.mu.Lock()
+ if n.value == nil {
+ if setFunc == nil {
+ n.mu.Unlock()
+ n.unref()
+ return nil
+ }
+
+ n.size, n.value = setFunc()
+ if n.value == nil {
+ n.size = 0
+ n.mu.Unlock()
+ n.unref()
+ return nil
+ }
+ atomic.AddInt32(&r.size, int32(n.size))
+ }
+ n.mu.Unlock()
+ if r.cacher != nil {
+ r.cacher.Promote(n)
+ }
+ return &Handle{unsafe.Pointer(n)}
+ }
+
+ break
+ }
+ }
+ return nil
+}
+
+// Delete removes and ban 'cache node' with the given namespace and key.
+// A banned 'cache node' will never inserted into the 'cache tree'. Ban
+// only attributed to the particular 'cache node', so when a 'cache node'
+// is recreated it will not be banned.
+//
+// If onDel is not nil, then it will be executed if such 'cache node'
+// doesn't exist or once the 'cache node' is released.
+//
+// Delete return true is such 'cache node' exist.
+func (r *Cache) Delete(ns, key uint64, onDel func()) bool {
+ r.mu.RLock()
+ defer r.mu.RUnlock()
+ if r.closed {
+ return false
+ }
+
+ hash := murmur32(ns, key, 0xf00)
+ for {
+ h, b := r.getBucket(hash)
+ done, _, n := b.get(r, h, hash, ns, key, true)
+ if done {
+ if n != nil {
+ if onDel != nil {
+ n.mu.Lock()
+ n.onDel = append(n.onDel, onDel)
+ n.mu.Unlock()
+ }
+ if r.cacher != nil {
+ r.cacher.Ban(n)
+ }
+ n.unref()
+ return true
+ }
+
+ break
+ }
+ }
+
+ if onDel != nil {
+ onDel()
+ }
+
+ return false
+}
+
+// Evict evicts 'cache node' with the given namespace and key. This will
+// simply call Cacher.Evict.
+//
+// Evict return true is such 'cache node' exist.
+func (r *Cache) Evict(ns, key uint64) bool {
+ r.mu.RLock()
+ defer r.mu.RUnlock()
+ if r.closed {
+ return false
+ }
+
+ hash := murmur32(ns, key, 0xf00)
+ for {
+ h, b := r.getBucket(hash)
+ done, _, n := b.get(r, h, hash, ns, key, true)
+ if done {
+ if n != nil {
+ if r.cacher != nil {
+ r.cacher.Evict(n)
+ }
+ n.unref()
+ return true
+ }
+
+ break
+ }
+ }
+
+ return false
+}
+
+// EvictNS evicts 'cache node' with the given namespace. This will
+// simply call Cacher.EvictNS.
+func (r *Cache) EvictNS(ns uint64) {
+ r.mu.RLock()
+ defer r.mu.RUnlock()
+ if r.closed {
+ return
+ }
+
+ if r.cacher != nil {
+ r.cacher.EvictNS(ns)
+ }
+}
+
+// EvictAll evicts all 'cache node'. This will simply call Cacher.EvictAll.
+func (r *Cache) EvictAll() {
+ r.mu.RLock()
+ defer r.mu.RUnlock()
+ if r.closed {
+ return
+ }
+
+ if r.cacher != nil {
+ r.cacher.EvictAll()
+ }
+}
+
+// Close closes the 'cache map' and forcefully releases all 'cache node'.
+func (r *Cache) Close() error {
+ r.mu.Lock()
+ if !r.closed {
+ r.closed = true
+
+ h := (*mNode)(r.mHead)
+ h.initBuckets()
+
+ for i := range h.buckets {
+ b := (*mBucket)(h.buckets[i])
+ for _, n := range b.node {
+ // Call releaser.
+ if n.value != nil {
+ if r, ok := n.value.(util.Releaser); ok {
+ r.Release()
+ }
+ n.value = nil
+ }
+
+ // Call OnDel.
+ for _, f := range n.onDel {
+ f()
+ }
+ n.onDel = nil
+ }
+ }
+ }
+ r.mu.Unlock()
+
+ // Avoid deadlock.
+ if r.cacher != nil {
+ if err := r.cacher.Close(); err != nil {
+ return err
+ }
+ }
+ return nil
+}
+
+// CloseWeak closes the 'cache map' and evict all 'cache node' from cacher, but
+// unlike Close it doesn't forcefully releases 'cache node'.
+func (r *Cache) CloseWeak() error {
+ r.mu.Lock()
+ if !r.closed {
+ r.closed = true
+ }
+ r.mu.Unlock()
+
+ // Avoid deadlock.
+ if r.cacher != nil {
+ r.cacher.EvictAll()
+ if err := r.cacher.Close(); err != nil {
+ return err
+ }
+ }
+ return nil
+}
+
+// Node is a 'cache node'.
+type Node struct {
+ r *Cache
+
+ hash uint32
+ ns, key uint64
+
+ mu sync.Mutex
+ size int
+ value Value
+
+ ref int32
+ onDel []func()
+
+ CacheData unsafe.Pointer
+}
+
+// NS returns this 'cache node' namespace.
+func (n *Node) NS() uint64 {
+ return n.ns
+}
+
+// Key returns this 'cache node' key.
+func (n *Node) Key() uint64 {
+ return n.key
+}
+
+// Size returns this 'cache node' size.
+func (n *Node) Size() int {
+ return n.size
+}
+
+// Value returns this 'cache node' value.
+func (n *Node) Value() Value {
+ return n.value
+}
+
+// Ref returns this 'cache node' ref counter.
+func (n *Node) Ref() int32 {
+ return atomic.LoadInt32(&n.ref)
+}
+
+// GetHandle returns an handle for this 'cache node'.
+func (n *Node) GetHandle() *Handle {
+ if atomic.AddInt32(&n.ref, 1) <= 1 {
+ panic("BUG: Node.GetHandle on zero ref")
+ }
+ return &Handle{unsafe.Pointer(n)}
+}
+
+func (n *Node) unref() {
+ if atomic.AddInt32(&n.ref, -1) == 0 {
+ n.r.delete(n)
+ }
+}
+
+func (n *Node) unrefLocked() {
+ if atomic.AddInt32(&n.ref, -1) == 0 {
+ n.r.mu.RLock()
+ if !n.r.closed {
+ n.r.delete(n)
+ }
+ n.r.mu.RUnlock()
+ }
+}
+
+// Handle is a 'cache handle' of a 'cache node'.
+type Handle struct {
+ n unsafe.Pointer // *Node
+}
+
+// Value returns the value of the 'cache node'.
+func (h *Handle) Value() Value {
+ n := (*Node)(atomic.LoadPointer(&h.n))
+ if n != nil {
+ return n.value
+ }
+ return nil
+}
+
+// Release releases this 'cache handle'.
+// It is safe to call release multiple times.
+func (h *Handle) Release() {
+ nPtr := atomic.LoadPointer(&h.n)
+ if nPtr != nil && atomic.CompareAndSwapPointer(&h.n, nPtr, nil) {
+ n := (*Node)(nPtr)
+ n.unrefLocked()
+ }
+}
+
+func murmur32(ns, key uint64, seed uint32) uint32 {
+ const (
+ m = uint32(0x5bd1e995)
+ r = 24
+ )
+
+ k1 := uint32(ns >> 32)
+ k2 := uint32(ns)
+ k3 := uint32(key >> 32)
+ k4 := uint32(key)
+
+ k1 *= m
+ k1 ^= k1 >> r
+ k1 *= m
+
+ k2 *= m
+ k2 ^= k2 >> r
+ k2 *= m
+
+ k3 *= m
+ k3 ^= k3 >> r
+ k3 *= m
+
+ k4 *= m
+ k4 ^= k4 >> r
+ k4 *= m
+
+ h := seed
+
+ h *= m
+ h ^= k1
+ h *= m
+ h ^= k2
+ h *= m
+ h ^= k3
+ h *= m
+ h ^= k4
+
+ h ^= h >> 13
+ h *= m
+ h ^= h >> 15
+
+ return h
+}
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