From 3ac2b40dcf4b60f13184ff8b97f9099a6a22852e Mon Sep 17 00:00:00 2001
From: kumavis <aaron@kumavis.me>
Date: Tue, 21 Aug 2018 16:30:11 -0700
Subject: [PATCH 1/3] metamask controller - track active controller connections

---
 app/scripts/metamask-controller.js | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index 29838ad2d..9082daac9 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -67,6 +67,10 @@ module.exports = class MetamaskController extends EventEmitter {
     const initState = opts.initState || {}
     this.recordFirstTimeInfo(initState)
 
+    // this keeps track of how many "controllerStream" connections are open
+    // the only thing that uses controller connections are open metamask UI instances
+    this.activeControllerConnections = 0
+
     // platform-specific api
     this.platform = opts.platform
 
@@ -1209,11 +1213,19 @@ module.exports = class MetamaskController extends EventEmitter {
   setupControllerConnection (outStream) {
     const api = this.getApi()
     const dnode = Dnode(api)
+    // report new active controller connection
+    this.activeControllerConnections++
+    this.emit('controllerConnectionChanged', this.activeControllerConnections)
+    // connect dnode api to remote connection
     pump(
       outStream,
       dnode,
       outStream,
       (err) => {
+        // report new active controller connection
+        this.activeControllerConnections--
+        this.emit('controllerConnectionChanged', this.activeControllerConnections)
+        // report any error
         if (err) log.error(err)
       }
     )

From a2654108bed88db5cd09c22049471c5c3f1199d6 Mon Sep 17 00:00:00 2001
From: kumavis <aaron@kumavis.me>
Date: Tue, 21 Aug 2018 16:49:24 -0700
Subject: [PATCH 2/3] account-tracker - only track blocks when there are
 activeControllerConnections

---
 app/scripts/lib/account-tracker.js | 18 ++++++++++++++++--
 app/scripts/metamask-controller.js |  8 ++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/app/scripts/lib/account-tracker.js b/app/scripts/lib/account-tracker.js
index b7e2c7cbe..3a52d5e8d 100644
--- a/app/scripts/lib/account-tracker.js
+++ b/app/scripts/lib/account-tracker.js
@@ -43,10 +43,24 @@ class AccountTracker {
     this._provider = opts.provider
     this._query = pify(new EthQuery(this._provider))
     this._blockTracker = opts.blockTracker
-    // subscribe to latest block
-    this._blockTracker.on('latest', this._updateForBlock.bind(this))
     // blockTracker.currentBlock may be null
     this._currentBlockNumber = this._blockTracker.getCurrentBlock()
+    // bind function for easier listener syntax
+    this._updateForBlock = this._updateForBlock.bind(this)
+  }
+
+  start () {
+    // remove first to avoid double add
+    this._blockTracker.removeListener('latest', this._updateForBlock)
+    // add listener
+    this._blockTracker.addListener('latest', this._updateForBlock)
+    // fetch account balances
+    this._updateAccounts()
+  }
+
+  stop () {
+    // remove listener
+    this._blockTracker.removeListener('latest', this._updateForBlock)
   }
 
   /**
diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index 9082daac9..71df45ba0 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -131,6 +131,14 @@ module.exports = class MetamaskController extends EventEmitter {
       provider: this.provider,
       blockTracker: this.blockTracker,
     })
+    // start and stop polling for balances based on activeControllerConnections
+    this.on('controllerConnectionChanged', (activeControllerConnections) => {
+      if (activeControllerConnections > 0) {
+        this.accountTracker.start()
+      } else {
+        this.accountTracker.stop()
+      }
+    })
 
     // key mgmt
     const additionalKeyrings = [TrezorKeyring, LedgerBridgeKeyring]

From bf6d624e769eb5486b5c491165fad1862435669b Mon Sep 17 00:00:00 2001
From: Dan Finlay <dan@danfinlay.com>
Date: Wed, 22 Aug 2018 12:05:41 -0700
Subject: [PATCH 3/3] Add todo to dedupe UI tracking in background

---
 app/scripts/metamask-controller.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/app/scripts/metamask-controller.js b/app/scripts/metamask-controller.js
index 71df45ba0..4aa901e31 100644
--- a/app/scripts/metamask-controller.js
+++ b/app/scripts/metamask-controller.js
@@ -1444,6 +1444,7 @@ module.exports = class MetamaskController extends EventEmitter {
     }
   }
 
+  // TODO: Replace isClientOpen methods with `controllerConnectionChanged` events.
   /**
    * A method for recording whether the MetaMask user interface is open or not.
    * @private