From 49260aea101f60eb112ef3a85e5d0a017b18de88 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Sun, 3 Jul 2016 10:07:47 -0700
Subject: [PATCH] start using a red black tree for in-memory databases.

---
 lib/bcoin/bst.js | 814 -----------------------------------------------
 lib/bcoin/ldb.js |  10 +-
 2 files changed, 5 insertions(+), 819 deletions(-)
 delete mode 100644 lib/bcoin/bst.js

diff --git a/lib/bcoin/bst.js b/lib/bcoin/bst.js
deleted file mode 100644
index 54c482e0..00000000
--- a/lib/bcoin/bst.js
+++ /dev/null
@@ -1,814 +0,0 @@
-/*!
- * bst.js - iterative binary search tree for bcoin
- * Copyright (c) 2016, Christopher Jeffrey (MIT License).
- * https://github.com/bcoin-org/bcoin
- */
-
-'use strict';
-
-var utils = require('./utils');
-var assert = utils.assert;
-var DUMMY = new Buffer([0]);
-
-/**
- * An iterative binary search tree.
- * Used for the mempool. Many of its
- * options, parameters, and methods
- * mimic the leveldown interface.
- * @exports BST
- * @constructor
- * @param {String?} location - Phony location.
- * @param {Object?} options
- * @param {Function} options.compare - Comparator.
- */
-
-function BST(location, options) {
-  if (!(this instanceof BST))
-    return new BST(location, options);
-
-  if (!options)
-    options = {};
-
-  this.options = options;
-  this.root = null;
-  this.compare = options.compare || utils.cmp;
-}
-
-/**
- * Do a key lookup.
- * @param {Buffer|String} key
- * @returns {Buffer?} value
- */
-
-BST.prototype.search = function search(key) {
-  var current = this.root;
-  var cmp;
-
-  if (typeof key === 'string')
-    key = new Buffer(key, 'ascii');
-
-  while (current) {
-    cmp = this.compare(key, current.key);
-    if (cmp === 0)
-      return current.value;
-    if (cmp < 0)
-      current = current.left;
-    else
-      current = current.right;
-  }
-};
-
-/**
- * Insert a record.
- * @param {Buffer|String} key
- * @param {Buffer} value
- */
-
-BST.prototype.insert = function insert(key, value) {
-  var current = this.root;
-  var left = false;
-  var parent, cmp, node;
-
-  if (typeof key === 'string')
-    key = new Buffer(key, 'ascii');
-
-  if (typeof value === 'string')
-    value = new Buffer(value, 'utf8');
-
-  while (current) {
-    cmp = this.compare(key, current.key);
-
-    if (cmp === 0) {
-      current.value = value;
-      return;
-    }
-
-    if (cmp < 0) {
-      parent = current;
-      left = true;
-      current = current.left;
-    } else {
-      parent = current;
-      left = false;
-      current = current.right;
-    }
-  }
-
-  node = new BSTNode(key, value);
-
-  if (!parent) {
-    this.root = node;
-    return;
-  }
-
-  if (left)
-    parent.left = node;
-  else
-    parent.right = node;
-};
-
-/**
- * Remove a record.
- * @param {Buffer|String} key
- * @returns {Boolean}
- */
-
-BST.prototype.remove = function remove(key) {
-  var current = this.root;
-  var left = false;
-  var cmp, parent, use;
-
-  if (typeof key === 'string')
-    key = new Buffer(key, 'ascii');
-
-  while (current) {
-    cmp = this.compare(key, current.key);
-
-    if (cmp === 0)
-      break;
-
-    if (cmp < 0) {
-      parent = current;
-      left = true;
-      current = current.left;
-    } else {
-      parent = current;
-      left = false;
-      current = current.right;
-    }
-  }
-
-  if (!current)
-    return false;
-
-  if (!current.left && !current.right) {
-    if (!parent) {
-      this.root = null;
-    } else {
-      if (left)
-        parent.left = null;
-      else
-        parent.right = null;
-    }
-
-    return true;
-  }
-
-  if (!current.left || !current.right) {
-    if (current.left)
-      current = current.left;
-    else
-      current = current.right;
-
-    if (!parent) {
-      this.root = current;
-    } else {
-      if (left)
-        parent.left = current;
-      else
-        parent.right = current;
-    }
-
-    return true;
-  }
-
-  parent = current;
-  use = current.left;
-  left = true;
-  while (use.right) {
-    parent = use;
-    use = use.right;
-    left = false;
-  }
-
-  current.key = use.key;
-  current.value = use.value;
-
-  if (left)
-    current.left = use.left;
-  else
-    parent.right = use.left;
-
-  return true;
-};
-
-/**
- * Take a snapshot and return a cloned root node.
- * @returns {BSTNode}
- */
-
-BST.prototype.snapshot = function snapshot() {
-  var current = this.root;
-  var stack = [];
-  var left = true;
-  var parent, copy, snapshot;
-
-  for (;;) {
-    if (current) {
-      if (left) {
-        copy = current.clone();
-        if (parent)
-          parent.left = copy;
-        else
-          snapshot = copy;
-      } else {
-        copy = current.clone();
-        if (parent)
-          parent.right = copy;
-        else
-          snapshot = copy;
-      }
-      stack.push(copy);
-      parent = copy;
-      left = true;
-      current = current.left;
-      continue;
-    }
-
-    if (stack.length === 0)
-      break;
-
-    current = stack.pop();
-    parent = current;
-    left = false;
-    current = current.right;
-  }
-
-  return snapshot;
-};
-
-/**
- * Traverse the key and filter records.
- * @param {Function} test
- * @returns {BSTNode[]} Records.
- */
-
-BST.prototype.traverse = function traverse(test) {
-  var current = this.root;
-  var stack = [];
-  var items = [];
-
-  for (;;) {
-    if (current) {
-      if (test(current))
-        items.push(current.copy());
-      stack.push(current);
-      current = current.left;
-      continue;
-    }
-
-    if (stack.length === 0)
-      break;
-
-    current = stack.pop();
-    current = current.right;
-  }
-
-  return items;
-};
-
-/**
- * Dump all records.
- * @returns {BSTNode[]} Records.
- */
-
-BST.prototype.dump = function dump() {
-  return this.traverse(function() { return true; });
-};
-
-/**
- * Traverse between a range of keys and collect records.
- * @param {Buffer} gte
- * @param {Buffer} lte
- * @returns {BSTNode[]} Records.
- */
-
-BST.prototype.range = function range(gte, lte) {
-  var current = this.root;
-  var stack = [];
-  var items = [];
-  var cmp;
-
-  if (typeof gte === 'string')
-    gte = new Buffer(gte, 'ascii');
-
-  if (typeof lte === 'string')
-    lte = new Buffer(lte, 'ascii');
-
-  for (;;) {
-    if (current) {
-      cmp = this.rangeCompare(current.key, gte, lte);
-      if (cmp === 0) {
-        items.push(current.copy());
-        stack.push(current);
-      }
-      if (cmp <= 0)
-        current = current.left;
-      else
-        current = current.right;
-      continue;
-    }
-
-    if (stack.length === 0)
-      break;
-
-    current = stack.pop();
-    current = current.right;
-  }
-
-  return items;
-};
-
-/**
- * Comparator for {@link BST#range}.
- * @param {Buffer} key
- * @param {Buffer} gteKey
- * @param {Buffer} lteKey
- * @returns {Number}
- */
-
-BST.prototype.rangeCompare = function rangeCompare(key, gteKey, lteKey) {
-  var gte, lte;
-
-  if (gteKey)
-    gte = this.compare(key, gteKey);
-  else
-    gte = 0;
-
-  if (lteKey)
-    lte = this.compare(key, lteKey);
-  else
-    lte = 0;
-
-  if (gte >= 0 && lte <= 0)
-    return 0;
-
-  if (lte > 0)
-    return -1;
-
-  if (gte < 0)
-    return 1;
-
-  assert(false);
-};
-
-/**
- * Open the database (leveldown method).
- * @param {Object?} options
- * @param {Function} callback
- */
-
-BST.prototype.open = function open(options, callback) {
-  if (!callback) {
-    callback = options;
-    options = null;
-  }
-
-  if (!options)
-    options = {};
-
-  this.options = options;
-
-  return utils.nextTick(callback);
-};
-
-/**
- * Close the database (leveldown method).
- * @param {Function} callback
- */
-
-BST.prototype.close = function close(callback) {
-  return utils.nextTick(callback);
-};
-
-/**
- * Retrieve a record (leveldown method).
- * @param {Buffer|String} key
- * @param {Object?} options
- * @param {Function} callback - Returns [Error, Buffer].
- */
-
-BST.prototype.get = function get(key, options, callback) {
-  var value, err;
-
-  if (!callback) {
-    callback = options;
-    options = null;
-  }
-
-  if (!options)
-    options = {};
-
-  value = this.search(key);
-
-  if (!value) {
-    err = new Error('BST_NOTFOUND: Key not found.');
-    err.notFound = true;
-    err.type = 'NotFoundError';
-    return utils.asyncify(callback)(err);
-  }
-
-  if (options.asBuffer === false)
-    value = value.toString('utf8');
-
-  return utils.asyncify(callback)(null, value);
-};
-
-/**
- * Insert a record (leveldown method).
- * @param {Buffer|String} key
- * @param {Buffer} value
- * @param {Object?} options
- * @param {Function} callback
- */
-
-BST.prototype.put = function put(key, value, options, callback) {
-  if (!callback) {
-    callback = options;
-    options = null;
-  }
-
-  if (!options)
-    options = {};
-
-  this.insert(key, value);
-
-  return utils.nextTick(callback);
-};
-
-/**
- * Remove a record (leveldown method).
- * @param {Buffer|String} key
- * @param {Object?} options
- * @param {Function} callback
- */
-
-BST.prototype.del = function del(key, options, callback) {
-  if (!callback) {
-    callback = options;
-    options = null;
-  }
-
-  if (!options)
-    options = {};
-
-  this.remove(key);
-
-  return utils.nextTick(callback);
-};
-
-/**
- * Create an atomic batch (leveldown method).
- * @see Leveldown.Batch
- * @param {Object[]?} ops
- * @param {Object?} options
- * @param {Function} callback
- * @returns {Leveldown.Batch}
- */
-
-BST.prototype.batch = function batch(ops, options, callback) {
-  var batch;
-
-  if (!callback) {
-    callback = options;
-    options = null;
-  }
-
-  if (!options)
-    options = {};
-
-  batch = new Batch(this, options);
-
-  if (ops) {
-    batch.ops = ops.slice();
-    return batch.write(callback);
-  }
-
-  return batch;
-};
-
-/**
- * Create an iterator (leveldown method).
- * @param {Object} options - See {Leveldown.Iterator}.
- * @returns {Leveldown.Iterator}.
- */
-
-BST.prototype.iterator = function iterator(options) {
-  return new Iterator(this, options);
-};
-
-/**
- * Get a database property (leveldown method) (NOP).
- * @param {String} name - Property name.
- * @returns {String}
- */
-
-BST.prototype.getProperty = function getProperty(name) {
-  return '';
-};
-
-/**
- * Calculate approximate database size (leveldown method).
- * @param {Buffer|String} start - Start key.
- * @param {Buffer|String} end - End key.
- * @param {Function} callback - Returns [Error, Number].
- */
-
-BST.prototype.approximateSize = function approximateSize(start, end, callback) {
-  var items = this.range(start, end);
-  var size = 0;
-  var i, item;
-
-  for (i = 0; i < items.length; i++) {
-    item = items[i];
-    size += item.key.length;
-    size += item.value.length;
-  }
-
-  return utils.asyncify(callback)(null, size);
-};
-
-/**
- * Destroy the database (leveldown function) (NOP).
- * @param {String} location
- * @param {Function} callback
- */
-
-BST.destroy = function destroy(location, callback) {
-  return utils.nextTick(callback);
-};
-
-/**
- * Repair the database (leveldown function) (NOP).
- * @param {String} location
- * @param {Function} callback
- */
-
-BST.repair = function repair(location, callback) {
-  return utils.nextTick(callback);
-};
-
-/**
- * BST Node
- * @constructor
- * @private
- * @param {Buffer} key
- * @param {Buffer} value
- * @property {Buffer} key
- * @property {Buffer} value
- * @property {BSTNode|null} left
- * @property {BSTNode|null} right
- */
-
-function BSTNode(key, value) {
-  this.key = key;
-  this.value = value;
-  this.left = null;
-  this.right = null;
-}
-
-/**
- * Clone the node.
- * @returns {BSTNode}
- */
-
-BSTNode.prototype.clone = function clone() {
-  var node = new BSTNode(this.key, this.value);
-  node.left = this.left;
-  node.right = this.right;
-  return node;
-};
-
-/**
- * Clone the node (key/value only).
- * @returns {BSTNode}
- */
-
-BSTNode.prototype.copy = function copy() {
-  return new BSTNode(this.key, this.value);
-};
-
-/**
- * Batch
- * @constructor
- * @private
- * @param {BST} tree
- * @param {Object?} options
- */
-
-function Batch(tree, options) {
-  this.options = options || {};
-  this.ops = [];
-  this.tree = tree;
-}
-
-/**
- * Insert a record.
- * @param {Buffer|String} key
- * @param {Buffer} value
- */
-
-Batch.prototype.put = function(key, value) {
-  assert(this.tree, 'Already written.');
-  this.ops.push(new BatchOp('put', key, value));
-  return this;
-};
-
-/**
- * Remove a record.
- * @param {Buffer|String} key
- */
-
-Batch.prototype.del = function del(key) {
-  assert(this.tree, 'Already written.');
-  this.ops.push(new BatchOp('del', key));
-  return this;
-};
-
-/**
- * Commit the batch.
- * @param {Function} callback
- */
-
-Batch.prototype.write = function write(callback) {
-  var i, op;
-
-  if (!this.tree)
-    return callback(new Error('Already written.'));
-
-  for (i = 0; i < this.ops.length; i++) {
-    op = this.ops[i];
-    if (op.type === 'put')
-      this.tree.insert(op.key, op.value);
-    else if (op.type === 'del')
-      this.tree.remove(op.key);
-    else
-      assert(false);
-  }
-
-  this.ops.length = 0;
-  this.ops = null;
-  this.options = null;
-  this.tree = null;
-
-  utils.nextTick(callback);
-
-  return this;
-};
-
-/**
- * Clear batch of all ops.
- */
-
-Batch.prototype.clear = function clear() {
-  assert(this.tree, 'Already written.');
-  this.ops.length = 0;
-  return this;
-};
-
-/**
- * Batch Operation
- * @constructor
- * @private
- * @param {String} type
- * @param {Buffer} key
- * @param {Buffer|null} value
- */
-
-function BatchOp(type, key, value) {
-  this.type = type;
-  this.key = key;
-  this.value = value;
-}
-
-/**
- * Iterator
- * @constructor
- * @private
- * @param {BST} tree
- * @param {Object?} options
- */
-
-function Iterator(tree, options) {
-  if (!options)
-    options = {};
-
-  assert(!options.lt, 'LT is not implemented.');
-  assert(!options.gt, 'GT is not implemented.');
-
-  this.options = {
-    keys: options.keys,
-    values: options.values,
-    gte: options.gte || options.start,
-    lte: options.lte || options.end,
-    keyAsBuffer: options.keyAsBuffer,
-    valueAsBuffer: options.valueAsBuffer,
-    reverse: options.reverse,
-    limit: options.limit
-  };
-
-  this.tree = tree;
-  this.ended = false;
-  this.snapshot = this.tree.range(this.options.gte, this.options.lte);
-  this.index = this.options.reverse ? this.snapshot.length - 1 : 0;
-  this.total = 0;
-}
-
-/**
- * Seek to the next key.
- * @param {Function} callback
- */
-
-Iterator.prototype.next = function(callback) {
-  var item, key, value;
-
-  if (this.ended)
-    return utils.asyncify(callback)(new Error('Cannot call next after end.'));
-
-  if (this.options.reverse)
-    item = this.snapshot[this.index--];
-  else
-    item = this.snapshot[this.index++];
-
-  if (this.options.limit != null) {
-    if (this.total++ >= this.options.limit) {
-      this._end();
-      return utils.nextTick(callback);
-    }
-  }
-
-  if (!item) {
-    this._end();
-    return utils.nextTick(callback);
-  }
-
-  key = item.key;
-  value = item.value;
-
-  if (this.options.keys === false)
-    key = DUMMY;
-
-  if (this.options.values === false)
-    value = DUMMY;
-
-  if (this.options.keyAsBuffer === false)
-    key = key.toString('ascii');
-
-  if (this.options.valueAsBuffer === false)
-    value = value.toString('utf8');
-
-  utils.asyncify(callback)(null, key, value);
-};
-
-/**
- * Seek to a key gte to `key`.
- * @param {String|Buffer} key
- */
-
-Iterator.prototype.seek = function seek(key) {
-  var self = this;
-
-  assert(!this.ended, 'Already ended.');
-
-  if (typeof key === 'string')
-    key = new Buffer(key, 'ascii');
-
-  this.index = utils.binarySearch(this.snapshot, key, function(a, b) {
-    return self.tree.compare(a.key, b);
-  }, true);
-};
-
-/**
- * Clean up the iterator.
- * @private
- */
-
-Iterator.prototype._end = function end() {
-  if (!this.tree)
-    return;
-
-  this.tree = null;
-  this.snapshot.length = 0;
-  this.snapshot = null;
-};
-
-/**
- * End the iterator. Free up snapshot.
- * @param {Buffer} callback
- */
-
-Iterator.prototype.end = function end(callback) {
-  if (this.ended)
-    return utils.asyncify(callback)(new Error('Already ended.'));
-
-  this.ended = true;
-  this._end();
-
-  return utils.nextTick(callback);
-};
-
-/*
- * Expose
- */
-
-module.exports = BST;
diff --git a/lib/bcoin/ldb.js b/lib/bcoin/ldb.js
index a8e02115..936a3a60 100644
--- a/lib/bcoin/ldb.js
+++ b/lib/bcoin/ldb.js
@@ -34,7 +34,7 @@ function ldb(options) {
   options = ldb.parseOptions(options);
 
   if (!db[options.location]) {
-    if (options.backend !== 'bst' && !bcoin.isBrowser)
+    if (options.backend !== 'rbt' && !bcoin.isBrowser)
       bcoin.mkdir(options.location, true);
 
     db[options.location] = new LowlevelUp(options.location, {
@@ -80,7 +80,7 @@ ldb.getBackend = function getBackend(db) {
   else if (db === 'lmdb')
     name = 'lmdb';
   else if (db === 'memory')
-    name = 'bst';
+    name = 'rbt';
   else
     name = db;
 
@@ -94,7 +94,7 @@ ldb.getBackend = function getBackend(db) {
     case 'lmdb':
       ext = 'lmdb';
       break;
-    case 'bst':
+    case 'rbt':
       ext = 'mem';
       break;
     default:
@@ -125,8 +125,8 @@ ldb.parseOptions = function parseOptions(options) {
     location += '/' + options.name + '.' + backend.ext;
   }
 
-  if (backend.name === 'bst')
-    db = require('./bst');
+  if (backend.name === 'rbt')
+    db = require('./rbt');
   else if (bcoin.isBrowser)
     db = require('level-js');
   else