Properly wait 1 second between runs of adb b2g-info

Summary: This slows down the phone less. In the future, it'd be nice to get timestamp on X axis.

Reviewed By: passy

Differential Revision: D19097154

fbshipit-source-id: e145f1b911dec368a6bb7de32790d6280c696eda

src/plugins/kaios-ram/index.tsx

@@ -9,7 +9,7 @@
 
 import React from 'react';
 
-import {FlipperDevicePlugin, Device, KaiOSDevice} from 'flipper';
+import {FlipperDevicePlugin, Device, KaiOSDevice, sleep} from 'flipper';
 
 import {FlexColumn, Button, Toolbar, Panel} from 'flipper';
 
@@ -74,33 +74,36 @@ export default class KaiOSGraphs extends FlipperDevicePlugin<State, any, any> {
     monitoring: false,
   };
 
-  intervalID: NodeJS.Timer | null = null;
-
   static supportsDevice(device: Device) {
     return device instanceof KaiOSDevice;
   }
 
+  teardown() {
+    this.onStopMonitor();
+  }
+
   onStartMonitor = () => {
-    if (this.intervalID) {
-      return;
-    }
-
-    this.intervalID = setInterval(this.updateFreeMem, 1000);
-
-    this.setState({
-      monitoring: true,
-    });
+    this.setState(
+      {
+        monitoring: true,
+      },
+      () => {
+        // no await because monitoring runs in the background
+        this.monitorInBackground();
+      },
+    );
   };
 
   onStopMonitor = () => {
-    if (!this.intervalID) {
-      return;
-    } else {
-      clearInterval(this.intervalID);
-      this.intervalID = null;
-      this.setState({
-        monitoring: false,
-      });
+    this.setState({
+      monitoring: false,
+    });
+  };
+
+  monitorInBackground = async () => {
+    while (this.state.monitoring) {
+      await this.updateFreeMem();
+      await sleep(1000);
     }
   };