fix stop() logic

packages/deps/deps.js

@@ -78,8 +78,9 @@
     invalidate: function () {
       if (! this.invalidated) {
         if (! this.active)
-          // an active computation is enqueued at
-          // end of _run instead.
+          // an active computation is either already being
+          // processed or, on first run, is enqueued at
+          // the end of _run
           this._enqueue();
         this.invalidated = true;
       }
@@ -113,7 +114,7 @@
         Deps.active = !! Deps.currentComputation;
       }
 
-      if (self.invalidated)
+      if (self.firstRun && self.invalidated)
         self._enqueue();
     },
 
@@ -135,7 +136,8 @@
           }
         }
 
-        if (! self.stopped) {
+        var wasStopped = self.stopped;
+        if (! wasStopped) {
           try {
             self._run();
           } catch (e) {
@@ -152,13 +154,16 @@
           }
         }
 
-        if (self.stopped)
+        if (wasStopped)
           break;
 
-        // If we're not stopped but we are invalidated, also loop.
-        // It's valid in some cases for a computation to invalidate
-        // itself (or for afterInvalidate to invalid it), but we
-        // could add a run-away loop counter here.
+        // If _run() stopped us, we loop around to handle callbacks.
+        // If _run() invalidated us, we run again immediately.
+        // A computation that invalidates itself indefinitely is an
+        // infinite loop, of course.
+        //
+        // We could put an iteration counter here and catch run-away
+        // loops.
       }
     }
   });

packages/deps/deps_tests.js

@@ -246,6 +246,8 @@ Tinytest.add("deps - lifecycle", function (test) {
     };
   };
 
+  var shouldStop = false;
+
   var c1 = Deps.run(function (c) {
     test.isTrue(Deps.active);
     test.equal(c, Deps.currentComputation);
@@ -268,6 +270,9 @@ Tinytest.add("deps - lifecycle", function (test) {
       Deps.afterInvalidate(makeCb());
     });
     runCount++;
+
+    if (shouldStop)
+      c.stop();
   });
 
   test.throws(function () {
@@ -293,5 +298,21 @@ Tinytest.add("deps - lifecycle", function (test) {
 
   test.equal(runCount, 2);
   test.equal(c1.invalidated, false);
+  // 5/6, 11/12, etc. are from the nested run, whose
+  // invalidation is scheduled each time by the outer
+  // rerun.
+  // 1/3 are onInvalidate and 2/4 are afterInvalidate.
   test.equal(buf, [5, 6, 1, 3, 2, 4, 11, 12]);
+
+  // test self-stop
+  buf.length = 0;
+  shouldStop = true;
+  c1.invalidate();
+  Deps.flush();
+  // when the computation stops itself, all the
+  // callbacks from last time and this time should
+  // get called consecutively, followed by the inner
+  // computation's 17/18.
+  test.equal(buf, [7, 9, 8, 10, 13, 15, 14, 16, 17, 18]);
+
 });