Add runtime.dispose.

mbostock · mbostock · commit a45d4757fea3 · 2019-05-16T14:44:31.000-07:00
diff --git a/README.md b/README.md
@@ -100,6 +100,10 @@ If *define* is specified, it is a function which defines the new module’s [var
 
 If an *observer* factory function is specified, it is called for each named variable in the returned module, being passed the variable’s name. The [standard inspector](#inspector) is available as a ready-made observer: it displays DOM elements “as-is” and renders interactive displays for other arbitrary values such as numbers and objects.
 
+<a href="#runtime_dispose" name="runtime_dispose">#</a> <i>runtime</i>.<b>dispose</b>() [<>](https://github.com/observablehq/runtime/blob/master/src/runtime.js "Source")
+
+Disposes this runtime, invalidating all active variables and disabling future computation.
+
 ### Modules
 
 A module is a namespace for [variables](#variables); within a module, variables should typically have unique names. [Imports](#variable_import) allow variables to be referenced across modules.
diff --git a/src/runtime.js b/src/runtime.js
@@ -18,6 +18,8 @@ export default function Runtime(builtins = new Library, global = window_global)
     _updates: {value: new Set},
     _computing: {value: null, writable: true},
     _modules: {value: new Map},
+    _variables: {value: new Set},
+    _disposed: {value: false, writable: true},
     _builtin: {value: builtin},
     _global: {value: global}
   });
@@ -34,9 +36,19 @@ Object.defineProperties(Runtime.prototype, {
   _compute: {value: runtime_compute, writable: true, configurable: true},
   _computeSoon: {value: runtime_computeSoon, writable: true, configurable: true},
   _computeNow: {value: runtime_computeNow, writable: true, configurable: true},
+  dispose: {value: runtime_dispose, writable: true, configurable: true},
   module: {value: runtime_module, writable: true, configurable: true}
 });
 
+function runtime_dispose() {
+  this._computing = Promise.resolve();
+  this._disposed = true;
+  this._variables.forEach(v => {
+    v._invalidate();
+    v._version = NaN;
+  });
+}
+
 function runtime_module(define, observer = noop) {
   if (define === undefined) return new Module(this);
   let module = this._modules.get(define);
@@ -54,7 +66,7 @@ function runtime_computeSoon() {
   return new Promise(function(resolve) {
     frame(function() {
       resolve();
-      runtime._computeNow();
+      runtime._disposed || runtime._computeNow();
     });
   });
 }
diff --git a/src/variable.js b/src/variable.js
@@ -97,6 +97,10 @@ function variable_defineImpl(name, inputs, definition) {
   this._definition = definition;
   this._value = undefined;
 
+  // Is this an active variable (that may require disposal)?
+  if (definition === noop) runtime._variables.delete(this);
+  else runtime._variables.add(this);
+
   // Did the variable’s name change? Time to patch references!
   if (name == this._name && scope.get(name) === this) {
     this._outputs.forEach(runtime._updates.add, runtime._updates);
diff --git a/test/dispose.html b/test/dispose.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<script type=module>
+
+import {Runtime, Inspector} from "/dist/runtime.js";
+
+const runtime = new Runtime();
+const main = runtime.module();
+
+main.variable(true).define(["invalidation"], async invalidation => {
+  await invalidation;
+  console.log("invalidation");
+});
+
+main.variable(true).define([], function*() {
+  try { while (true) yield; }
+  finally { console.log("return"); }
+});
+
+setTimeout(() => runtime.dispose(), 1000);
+
+</script>
