From 8a295d2adcaf37172f5928daa7dbb6eb5c97a88c Mon Sep 17 00:00:00 2001
From: Yun Lai <lyonlai1984@gmail.com>
Date: Sat, 31 Oct 2015 16:32:33 +1100
Subject: [PATCH 1/2] instead evaluate the same getter repeatly on every single
 notifier. group the notifier by getters, evaluate once then notify all.

---
 src/reactor.js | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/reactor.js b/src/reactor.js
index b31cb21..c88f5d3 100644
--- a/src/reactor.js
+++ b/src/reactor.js
@@ -208,15 +208,26 @@ class Reactor {
       })
     })
 
-    observerIdsToNotify.forEach((observerId) => {
-      const entry = this.observerState.getIn(['observersMap', observerId])
-      if (!entry) {
-        // don't notify here in the case a handler called unobserve on another observer
-        return
+    //generates a map with getter as key and an arrays of observer id as value.
+    const getterObserverMap = observerIdsToNotify.reduce((map, observerId) => {
+      const entry = this.observerState.getIn(['observersMap', observerId]);
+      const getter = entry.get('getter');
+      const handler = entry.get('handler');
+
+      let handlerList = map.get(getter);
+
+      if (!handlerList) {
+        handlerList = Immutable.List();
       }
 
-      const getter = entry.get('getter')
-      const handler = entry.get('handler')
+      handlerList = handlerList.push(handler);
+
+      return map.set(getter, handlerList);
+
+    }, Immutable.Map());
+
+    // for each getter, evaluate the getter once, then notify all the observers relies on it
+    getterObserverMap.forEach((handlerList, getter) => {
 
       const prevEvaluateResult = fns.evaluate(this.prevReactorState, getter)
       const currEvaluateResult = fns.evaluate(this.reactorState, getter)
@@ -225,9 +236,10 @@ class Reactor {
       const currValue = currEvaluateResult.result
 
       if (!Immutable.is(prevValue, currValue)) {
-        handler.call(null, currValue)
+        handlerList.forEach(handler => handler.call(null, currValue));
       }
-    })
+
+    });
 
     const nextReactorState = fns.resetDirtyStores(this.reactorState)
 

From 065ea151a339d643a9655846fa1bb774450e58d7 Mon Sep 17 00:00:00 2001
From: Yun Lai <lyonlai1984@gmail.com>
Date: Sun, 1 Nov 2015 09:41:32 +1100
Subject: [PATCH 2/2] fixed the caching problem as pointed out by Jordan.

---
 src/reactor.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/reactor.js b/src/reactor.js
index c88f5d3..6483be0 100644
--- a/src/reactor.js
+++ b/src/reactor.js
@@ -232,6 +232,9 @@ class Reactor {
       const prevEvaluateResult = fns.evaluate(this.prevReactorState, getter)
       const currEvaluateResult = fns.evaluate(this.reactorState, getter)
 
+      this.prevReactorState = prevEvaluateResult.reactorState
+      this.reactorState = currEvaluateResult.reactorState
+
       const prevValue = prevEvaluateResult.result
       const currValue = currEvaluateResult.result