Added object pool for regular A*

Author: anvaka

a-star/NodeSearchState.js

@@ -6,7 +6,7 @@
 module.exports = aStarBi;
 
 var NodeHeap = require('./NodeHeap');
-var NodeSearchState = require('./NodeSearchState');
+var makeSearchStatePool = require('./makeSearchStatePool');
 var heuristics = require('./heuristics');
 var defaultSettings = require('./defaultSettings');
 
@@ -27,9 +27,7 @@ Object.assign(module.exports, heuristics);
  * 
  * @param {Object} options that configures search
  * @param {Function(a, b)} options.heuristic - a function that returns estimated distance between
- * nodes `a` and `b`. This function should never overestimate actual distance between two
- * nodes (otherwise the found path will not be the shortest). Defaults function returns 0,
- * which makes this search equivalent to Dijkstra search.
+ * nodes `a` and `b`.  Defaults function returns 0, which makes this search equivalent to Dijkstra search.
  * @param {Function(a, b)} options.distance - a function that returns actual distance between two
  * nodes `a` and `b`. By default this is set to return graph-theoretical distance (always 1);
  * 
@@ -45,6 +43,7 @@ function aStarBi(graph, options) {
 
   var distance = options.distance;
   if (!distance) distance = defaultSettings.distance;
+  var pool = makeSearchStatePool();
 
   return {
     find: find
@@ -60,6 +59,8 @@ function aStarBi(graph, options) {
 
     if (from === to) return [from]; // trivial case.
 
+    pool.reset();
+
     // Maps nodeId to NodeSearchState.
     var nodeState = new Map();
 
@@ -74,7 +75,7 @@ function aStarBi(graph, options) {
     });
 
 
-    var startNode = new NodeSearchState(from);
+    var startNode = pool.createNewState(from);
     nodeState.set(fromId, startNode);
 
     // For the first node, fScore is completely heuristic.
@@ -84,7 +85,7 @@ function aStarBi(graph, options) {
     openSetFrom.push(startNode);
     startNode.open = BY_FROM;
 
-    var endNode = new NodeSearchState(to);
+    var endNode = pool.createNewState(to);
     endNode.fScore = heuristic(to, from);
     endNode.distanceToSource = 0;
     openSetTo.push(endNode);
@@ -155,7 +156,7 @@ function aStarBi(graph, options) {
     function visitNode(otherNode, link, cameFrom) {
       var otherSearchState = nodeState.get(otherNode.id);
       if (!otherSearchState) {
-        otherSearchState = new NodeSearchState(otherNode);
+        otherSearchState = pool.createNewState(otherNode);
         nodeState.set(otherNode.id, otherSearchState);
       }
 

a-star/a-greedy-star.js

@@ -8,7 +8,7 @@
 module.exports = aStarPathSearch;
 
 var NodeHeap = require('./NodeHeap');
-var NodeSearchState = require('./NodeSearchState');
+var makeSearchStatePool = require('./makeSearchStatePool');
 var heuristics = require('./heuristics');
 var defaultSettings = require('./defaultSettings.js');
 
@@ -41,6 +41,7 @@ function aStarPathSearch(graph, options) {
 
   var distance = options.distance;
   if (!distance) distance = defaultSettings.distance;
+  var pool = makeSearchStatePool();
 
   return {
     /**
@@ -56,6 +57,7 @@ function aStarPathSearch(graph, options) {
     if (!from) throw new Error('fromId is not defined in this graph: ' + fromId);
     var to = graph.getNode(toId);
     if (!to) throw new Error('toId is not defined in this graph: ' + toId);
+    pool.reset();
 
     // Maps nodeId to NodeSearchState.
     var nodeState = new Map();
@@ -66,7 +68,7 @@ function aStarPathSearch(graph, options) {
       setNodeId: defaultSettings.setHeapIndex
     });
 
-    var startNode = new NodeSearchState(from);
+    var startNode = pool.createNewState(from);
     nodeState.set(fromId, startNode);
 
     // For the first node, fScore is completely heuristic.
@@ -94,7 +96,7 @@ function aStarPathSearch(graph, options) {
     function visitNeighbour(otherNode, link) {
       var otherSearchState = nodeState.get(otherNode.id);
       if (!otherSearchState) {
-        otherSearchState = new NodeSearchState(otherNode);
+        otherSearchState = pool.createNewState(otherNode);
         nodeState.set(otherNode.id, otherSearchState);
       }
 

a-star/a-star.js

@@ -0,0 +1,64 @@
+/**
+ * This class represents a single search node in the exploration tree for
+ * A* algorithm.
+ * 
+ * @param {Object} node  original node in the graph
+ */
+function NodeSearchState(node) {
+  this.node = node;
+
+  // How we came to this node?
+  this.parent = null;
+
+  this.closed = false;
+  this.open = 0;
+
+  this.distanceToSource = Number.POSITIVE_INFINITY;
+  // the f(n) = g(n) + h(n) value
+  this.fScore = Number.POSITIVE_INFINITY;
+
+  // used to reconstruct heap when fScore is updated.
+  this.heapIndex = -1;
+};
+
+function makeSearchStatePool() {
+  var currentInCache = 0;
+  var nodeCache = [];
+
+  return {
+    createNewState: createNewState,
+    reset: reset
+  };
+
+  function reset() {
+    currentInCache = 0;
+  }
+
+  function createNewState(node) {
+    var cached = nodeCache[currentInCache];
+    if (cached) {
+      // TODO: This almost duplicates constructor code. Not sure if
+      // it would impact performance if I move this code into a function
+      cached.node = node;
+      // How we came to this node?
+      cached.parent = null;
+
+      cached.closed = false;
+      cached.open = 0;
+
+      cached.distanceToSource = Number.POSITIVE_INFINITY;
+      // the f(n) = g(n) + h(n) value
+      cached.fScore = Number.POSITIVE_INFINITY;
+
+      // used to reconstruct heap when fScore is updated.
+      cached.heapIndex = -1;
+
+    } else {
+      cached = new NodeSearchState(node);
+      nodeCache[currentInCache] = cached;
+    }
+    currentInCache++;
+    return cached;
+  }
+}
+module.exports = makeSearchStatePool;

a-star/makeSearchStatePool.js

@@ -1,68 +1,9 @@
 module.exports = nba;
 
-var NodeHeap = require('./NodeHeap');
-var heuristics = require('./heuristics');
-var defaultSettings = require('./defaultSettings.js');
-
-function makeSearchStatePool() {
-  var currentInCache = 0;
-  var nodeCache = [];
-
-  return {
-    createNewState: createNewState,
-    reset: reset
-  };
-
-  function reset() {
-    currentInCache = 0;
-  }
-
-  function createNewState(node) {
-    var cached = nodeCache[currentInCache];
-    if (cached) {
-      cached.node = node;
-
-      // How we came to this node?
-      cached.p1 = null;
-      cached.p2 = null;
-
-      cached.closed = false;
-
-      cached.g1 = Number.POSITIVE_INFINITY;
-      cached.g2 = Number.POSITIVE_INFINITY;
-      cached.f1 = Number.POSITIVE_INFINITY;
-      cached.f2 = Number.POSITIVE_INFINITY;
-
-      // used to reconstruct heap when fScore is updated.
-      cached.h1 = -1;
-      cached.h2 = -1;
-    } else {
-      cached = new NBASearchState(node);
-      nodeCache[currentInCache] = cached;
-    }
-    currentInCache++;
-    return cached;
-  }
-}
-
-function NBASearchState(node) {
-  this.node = node;
-
-  // How we came to this node?
-  this.p1 = null;
-  this.p2 = null;
-
-  this.closed = false;
-
-  this.g1 = Number.POSITIVE_INFINITY;
-  this.g2 = Number.POSITIVE_INFINITY;
-  this.f1 = Number.POSITIVE_INFINITY;
-  this.f2 = Number.POSITIVE_INFINITY;
-
-  // used to reconstruct heap when fScore is updated.
-  this.h1 = -1;
-  this.h2 = -1;
-}
+var NodeHeap = require('../NodeHeap');
+var heuristics = require('../heuristics');
+var defaultSettings = require('../defaultSettings.js');
+var makeNBASearchStatePool = require('./makeNBASearchStatePool.js');
 
 var NO_PATH = defaultSettings.NO_PATH;
 
@@ -78,7 +19,7 @@ function nba(graph, options) {
 
   var distance = options.distance;
   if (!distance) distance = defaultSettings.distance;
-  var pool = makeSearchStatePool();
+  var pool = makeNBASearchStatePool();
 
   return {
     /**

a-star/nba.js a-star/nba/index.js

@@ -0,0 +1,63 @@
+module.exports = makeNBASearchStatePool;
+
+function makeNBASearchStatePool() {
+  var currentInCache = 0;
+  var nodeCache = [];
+
+  return {
+    createNewState: createNewState,
+    reset: reset
+  };
+
+  function reset() {
+    currentInCache = 0;
+  }
+
+  function createNewState(node) {
+    var cached = nodeCache[currentInCache];
+    if (cached) {
+      // TODO: This almost duplicates constructor code. Not sure if
+      // it would impact performance if I move this code into a function
+      cached.node = node;
+
+      // How we came to this node?
+      cached.p1 = null;
+      cached.p2 = null;
+
+      cached.closed = false;
+
+      cached.g1 = Number.POSITIVE_INFINITY;
+      cached.g2 = Number.POSITIVE_INFINITY;
+      cached.f1 = Number.POSITIVE_INFINITY;
+      cached.f2 = Number.POSITIVE_INFINITY;
+
+      // used to reconstruct heap when fScore is updated.
+      cached.h1 = -1;
+      cached.h2 = -1;
+    } else {
+      cached = new NBASearchState(node);
+      nodeCache[currentInCache] = cached;
+    }
+    currentInCache++;
+    return cached;
+  }
+}
+
+function NBASearchState(node) {
+  this.node = node;
+
+  // How we came to this node?
+  this.p1 = null;
+  this.p2 = null;
+
+  this.closed = false;
+
+  this.g1 = Number.POSITIVE_INFINITY;
+  this.g2 = Number.POSITIVE_INFINITY;
+  this.f1 = Number.POSITIVE_INFINITY;
+  this.f2 = Number.POSITIVE_INFINITY;
+
+  // used to reconstruct heap when fScore is updated.
+  this.h1 = -1;
+  this.h2 = -1;
+}

a-star/nba/makeNBASearchStatePool.js

@@ -1,5 +1,5 @@
 module.exports = {
   aStar: require('./a-star/a-star.js'),
   aGreedy: require('./a-star/a-greedy-star'),
-  nba: require('./a-star/nba'),
+  nba: require('./a-star/nba/index.js'),
 }