package merkle import ( "bytes" "container/list" "sync" "github.com/tendermint/tendermint/binary" . "github.com/tendermint/tendermint/common" dbm "github.com/tendermint/tendermint/db" ) /* Immutable AVL Tree (wraps the Node root) This tree is not goroutine safe. */ type IAVLTree struct { keyCodec binary.Codec valueCodec binary.Codec root *IAVLNode ndb *nodeDB } func NewIAVLTree(keyCodec, valueCodec binary.Codec, cacheSize int, db dbm.DB) *IAVLTree { if db == nil { // In-memory IAVLTree return &IAVLTree{ keyCodec: keyCodec, valueCodec: valueCodec, } } else { // Persistent IAVLTree return &IAVLTree{ keyCodec: keyCodec, valueCodec: valueCodec, ndb: newNodeDB(cacheSize, db), } } } // The returned tree and the original tree are goroutine independent. // That is, they can each run in their own goroutine. func (t *IAVLTree) Copy() Tree { if t.root == nil { return &IAVLTree{ keyCodec: t.keyCodec, valueCodec: t.valueCodec, root: nil, ndb: t.ndb, } } if t.ndb != nil && !t.root.persisted { // Saving a tree finalizes all the nodes. // It sets all the hashes recursively, // clears all the leftNode/rightNode values recursively, // and all the .persisted flags get set. panic("It is unsafe to Copy() an unpersisted tree.") } else if t.ndb == nil && t.root.hash == nil { // An in-memory IAVLTree is finalized when the hashes are // calculated. t.root.hashWithCount(t) } return &IAVLTree{ keyCodec: t.keyCodec, valueCodec: t.valueCodec, root: t.root, ndb: t.ndb, } } func (t *IAVLTree) Size() uint64 { if t.root == nil { return 0 } return t.root.size } func (t *IAVLTree) Height() uint8 { if t.root == nil { return 0 } return t.root.height } func (t *IAVLTree) Has(key interface{}) bool { if t.root == nil { return false } return t.root.has(t, key) } func (t *IAVLTree) Set(key interface{}, value interface{}) (updated bool) { if t.root == nil { t.root = NewIAVLNode(key, value) return false } t.root, updated = t.root.set(t, key, value) return updated } func (t *IAVLTree) Hash() []byte { if t.root == nil { return nil } hash, _ := t.root.hashWithCount(t) return hash } func (t *IAVLTree) HashWithCount() ([]byte, uint64) { if t.root == nil { return nil, 0 } return t.root.hashWithCount(t) } func (t *IAVLTree) Save() []byte { if t.root == nil { return nil } return t.root.save(t) } // Sets the root node by reading from db. // If the hash is empty, then sets root to nil. func (t *IAVLTree) Load(hash []byte) { if len(hash) == 0 { t.root = nil } else { t.root = t.ndb.GetNode(t, hash) } } func (t *IAVLTree) Get(key interface{}) (index uint64, value interface{}) { if t.root == nil { return 0, nil } return t.root.get(t, key) } func (t *IAVLTree) GetByIndex(index uint64) (key interface{}, value interface{}) { if t.root == nil { return nil, nil } return t.root.getByIndex(t, index) } func (t *IAVLTree) Remove(key interface{}) (value interface{}, removed bool) { if t.root == nil { return nil, false } newRootHash, newRoot, _, value, removed := t.root.remove(t, key) if !removed { return nil, false } if newRoot == nil && newRootHash != nil { t.root = t.ndb.GetNode(t, newRootHash) } else { t.root = newRoot } return value, true } func (t *IAVLTree) Iterate(fn func(key interface{}, value interface{}) bool) (stopped bool) { if t.root == nil { return false } return t.root.traverse(t, func(node *IAVLNode) bool { if node.height == 0 { return fn(node.key, node.value) } else { return false } }) } //----------------------------------------------------------------------------- type nodeElement struct { node *IAVLNode elem *list.Element } type nodeDB struct { mtx sync.Mutex cache map[string]nodeElement cacheSize int cacheQueue *list.List db dbm.DB } func newNodeDB(cacheSize int, db dbm.DB) *nodeDB { return &nodeDB{ cache: make(map[string]nodeElement), cacheSize: cacheSize, cacheQueue: list.New(), db: db, } } func (ndb *nodeDB) GetNode(t *IAVLTree, hash []byte) *IAVLNode { ndb.mtx.Lock() defer ndb.mtx.Unlock() // Check the cache. nodeElem, ok := ndb.cache[string(hash)] if ok { // Already exists. Move to back of cacheQueue. ndb.cacheQueue.MoveToBack(nodeElem.elem) return nodeElem.node } else { // Doesn't exist, load. buf := ndb.db.Get(hash) if len(buf) == 0 { ndb.db.(*dbm.LevelDB).Print() panic(Fmt("Value missing for key %X", hash)) } r := bytes.NewReader(buf) var n int64 var err error node := ReadIAVLNode(t, r, &n, &err) if err != nil { panic(Fmt("Error reading IAVLNode. bytes: %X error: %v", buf, err)) } node.persisted = true ndb.cacheNode(node) return node } } func (ndb *nodeDB) SaveNode(t *IAVLTree, node *IAVLNode) { ndb.mtx.Lock() defer ndb.mtx.Unlock() if node.hash == nil { panic("Expected to find node.hash, but none found.") } if node.persisted { panic("Shouldn't be calling save on an already persisted node.") } /*if _, ok := ndb.cache[string(node.hash)]; ok { panic("Shouldn't be calling save on an already cached node.") }*/ // Save node bytes to db buf := bytes.NewBuffer(nil) _, _, err := node.writeToCountHashes(t, buf) if err != nil { panic(err) } ndb.db.Set(node.hash, buf.Bytes()) node.persisted = true ndb.cacheNode(node) } func (ndb *nodeDB) cacheNode(node *IAVLNode) { // Create entry in cache and append to cacheQueue. elem := ndb.cacheQueue.PushBack(node.hash) ndb.cache[string(node.hash)] = nodeElement{node, elem} // Maybe expire an item. if ndb.cacheQueue.Len() > ndb.cacheSize { hash := ndb.cacheQueue.Remove(ndb.cacheQueue.Front()).([]byte) delete(ndb.cache, string(hash)) } }