From a3964326999c9eeefa00417f6396117bb27a1c85 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Thu, 1 Nov 2018 16:57:07 +0000
Subject: [PATCH] Asynchronous ground dataspace

---
 examples/box-and-client.js | 15 ++++-------
 src/ground.js              | 51 ++++++++++++++++++++++++++++++++++++++
 src/index.js               |  2 ++
 3 files changed, 58 insertions(+), 10 deletions(-)
 create mode 100644 src/ground.js

diff --git a/examples/box-and-client.js b/examples/box-and-client.js
index eb494c9..2fdc29e 100644
--- a/examples/box-and-client.js
+++ b/examples/box-and-client.js
@@ -21,6 +21,7 @@ const Immutable = require('immutable');
 const Syndicate = require('../src/index.js');
 const Skeleton = Syndicate.Skeleton;
 const Dataspace = Syndicate.Dataspace;
+const Ground = Syndicate.Ground.Ground;
 const Struct = Syndicate.Struct;
 const __ = Syndicate.__;
 const _$ = Syndicate._$;
@@ -32,7 +33,7 @@ const N = 100000;
 
 console.time('box-and-client-' + N.toString());
 
-let ds = new Dataspace(() => {
+new Ground(() => {
   Dataspace.spawn('box', function () {
     Dataspace.declareField(this, 'value', 0);
     Dataspace.currentFacet().addEndpoint(() => {
@@ -73,12 +74,6 @@ let ds = new Dataspace(() => {
       return [Syndicate.Observe(BoxState(_$)), handler];
     });
   });
-});
-
-// console.log('--- starting ---');
-while (ds.runScripts()) {
-  // console.log('--- runScripts boundary ---');
-}
-// console.log('--- done ---');
-
-console.timeEnd('box-and-client-' + N.toString());
+}).start().stopHandler = () => {
+  console.timeEnd('box-and-client-' + N.toString());
+};
diff --git a/src/ground.js b/src/ground.js
new file mode 100644
index 0000000..c6092a3
--- /dev/null
+++ b/src/ground.js
@@ -0,0 +1,51 @@
+"use strict";
+
+const Immutable = require('immutable');
+const Dataspace = require('./dataspace.js').Dataspace;
+
+function Ground(bootProc) {
+  this.stepperId = null;
+  this.stepping = false;
+  this.startingFuel = 1000;
+  this.dataspace = new Dataspace(bootProc);
+  this.stopHandler = function () {};
+}
+
+Ground.prototype.start = function () {
+  if (!this.stepperId) {
+    this.stepperId = setTimeout(() => {
+      this.stepperId = null;
+      this._step();
+    }, 0);
+  }
+  return this; // allows chaining start() immediately after construction
+};
+
+Ground.prototype._step = function () {
+  this.stepping = true;
+  try {
+    let stillBusy = false;
+    for (var fuel = this.startingFuel; fuel > 0; fuel--) {
+      stillBusy = this.dataspace.runScripts();
+      if (!stillBusy) break;
+    }
+    if (stillBusy) {
+      this.start();
+    } else {
+      if (this.stopHandler) {
+        this.stopHandler(this);
+      }
+    }
+  } finally {
+    this.stepping = false;
+  }
+};
+
+Ground.prototype.stop = function () {
+  if (this.stepperId) {
+    clearTimeout(this.stepperId);
+    this.stepperId = null;
+  }
+};
+
+module.exports.Ground = Ground;
diff --git a/src/index.js b/src/index.js
index 61a110a..f327be4 100644
--- a/src/index.js
+++ b/src/index.js
@@ -20,6 +20,7 @@
 const Struct = require('./struct.js');
 const Skeleton = require('./skeleton.js');
 const Dataspace = require('./dataspace.js');
+const Ground = require('./ground.js');
 const Assertions = require('./assertions.js');
 
 module.exports.Immutable = require('immutable');
@@ -33,6 +34,7 @@ module.exports._$ = Skeleton._$;
 
 module.exports._Dataspace = Dataspace;
 module.exports.Dataspace = Dataspace.Dataspace;
+module.exports.Ground = Ground;
 
 module.exports._Assertions = Assertions;
 module.exports.Observe = Assertions.Observe;