diff options
Diffstat (limited to 'vendor/github.com/syndtr/goleveldb/leveldb/cache')
-rw-r--r-- | vendor/github.com/syndtr/goleveldb/leveldb/cache/cache.go | 705 | ||||
-rw-r--r-- | vendor/github.com/syndtr/goleveldb/leveldb/cache/lru.go | 195 |
2 files changed, 900 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 000000000..c5940b232 --- /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 +} diff --git a/vendor/github.com/syndtr/goleveldb/leveldb/cache/lru.go b/vendor/github.com/syndtr/goleveldb/leveldb/cache/lru.go new file mode 100644 index 000000000..d9a84cde1 --- /dev/null +++ b/vendor/github.com/syndtr/goleveldb/leveldb/cache/lru.go @@ -0,0 +1,195 @@ +// 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 + +import ( + "sync" + "unsafe" +) + +type lruNode struct { + n *Node + h *Handle + ban bool + + next, prev *lruNode +} + +func (n *lruNode) insert(at *lruNode) { + x := at.next + at.next = n + n.prev = at + n.next = x + x.prev = n +} + +func (n *lruNode) remove() { + if n.prev != nil { + n.prev.next = n.next + n.next.prev = n.prev + n.prev = nil + n.next = nil + } else { + panic("BUG: removing removed node") + } +} + +type lru struct { + mu sync.Mutex + capacity int + used int + recent lruNode +} + +func (r *lru) reset() { + r.recent.next = &r.recent + r.recent.prev = &r.recent + r.used = 0 +} + +func (r *lru) Capacity() int { + r.mu.Lock() + defer r.mu.Unlock() + return r.capacity +} + +func (r *lru) SetCapacity(capacity int) { + var evicted []*lruNode + + r.mu.Lock() + r.capacity = capacity + for r.used > r.capacity { + rn := r.recent.prev + if rn == nil { + panic("BUG: invalid LRU used or capacity counter") + } + rn.remove() + rn.n.CacheData = nil + r.used -= rn.n.Size() + evicted = append(evicted, rn) + } + r.mu.Unlock() + + for _, rn := range evicted { + rn.h.Release() + } +} + +func (r *lru) Promote(n *Node) { + var evicted []*lruNode + + r.mu.Lock() + if n.CacheData == nil { + if n.Size() <= r.capacity { + rn := &lruNode{n: n, h: n.GetHandle()} + rn.insert(&r.recent) + n.CacheData = unsafe.Pointer(rn) + r.used += n.Size() + + for r.used > r.capacity { + rn := r.recent.prev + if rn == nil { + panic("BUG: invalid LRU used or capacity counter") + } + rn.remove() + rn.n.CacheData = nil + r.used -= rn.n.Size() + evicted = append(evicted, rn) + } + } + } else { + rn := (*lruNode)(n.CacheData) + if !rn.ban { + rn.remove() + rn.insert(&r.recent) + } + } + r.mu.Unlock() + + for _, rn := range evicted { + rn.h.Release() + } +} + +func (r *lru) Ban(n *Node) { + r.mu.Lock() + if n.CacheData == nil { + n.CacheData = unsafe.Pointer(&lruNode{n: n, ban: true}) + } else { + rn := (*lruNode)(n.CacheData) + if !rn.ban { + rn.remove() + rn.ban = true + r.used -= rn.n.Size() + r.mu.Unlock() + + rn.h.Release() + rn.h = nil + return + } + } + r.mu.Unlock() +} + +func (r *lru) Evict(n *Node) { + r.mu.Lock() + rn := (*lruNode)(n.CacheData) + if rn == nil || rn.ban { + r.mu.Unlock() + return + } + n.CacheData = nil + r.mu.Unlock() + + rn.h.Release() +} + +func (r *lru) EvictNS(ns uint64) { + var evicted []*lruNode + + r.mu.Lock() + for e := r.recent.prev; e != &r.recent; { + rn := e + e = e.prev + if rn.n.NS() == ns { + rn.remove() + rn.n.CacheData = nil + r.used -= rn.n.Size() + evicted = append(evicted, rn) + } + } + r.mu.Unlock() + + for _, rn := range evicted { + rn.h.Release() + } +} + +func (r *lru) EvictAll() { + r.mu.Lock() + back := r.recent.prev + for rn := back; rn != &r.recent; rn = rn.prev { + rn.n.CacheData = nil + } + r.reset() + r.mu.Unlock() + + for rn := back; rn != &r.recent; rn = rn.prev { + rn.h.Release() + } +} + +func (r *lru) Close() error { + return nil +} + +// NewLRU create a new LRU-cache. +func NewLRU(capacity int) Cacher { + r := &lru{capacity: capacity} + r.reset() + return r +} |