Reduce battery usage - optimize performance critical block

src/main/scala/com/github/shadowsocks/BaseService.scala

@@ -87,8 +87,7 @@ trait BaseService extends Service {
           val task = new TimerTask {
             def run {
               TrafficMonitor.updateRate()
-              updateTrafficRate(TrafficMonitor.getTxRate, TrafficMonitor.getRxRate,
-                TrafficMonitor.getTxTotal, TrafficMonitor.getRxTotal)
+              updateTrafficRate()
             }
           }
           timer = new Timer(true)
@@ -122,7 +121,7 @@ trait BaseService extends Service {
 
   def stopRunner() {
     // Make sure update total traffic when stopping the runner
-    updateTrafficTotal(TrafficMonitor.getDeltaTx, TrafficMonitor.getDeltaRx)
+    updateTrafficTotal(TrafficMonitor.txTotal, TrafficMonitor.rxTotal)
 
     TrafficMonitor.reset()
     if (trafficMonitorThread != null) {
@@ -132,19 +131,16 @@ trait BaseService extends Service {
   }
 
   def updateTrafficTotal(tx: Long, rx: Long) {
-    val handler = new Handler(getContext.getMainLooper)
-    handler.post(() => {
-      val config = this.config  // avoid race conditions without locking
-      if (config != null) {
-        ShadowsocksApplication.profileManager.getProfile(config.profileId) match {
-          case Some(profile) =>
-            profile.tx += tx
-            profile.rx += rx
-            ShadowsocksApplication.profileManager.updateProfile(profile)
-          case None => // Ignore
-        }
+    val config = this.config  // avoid race conditions without locking
+    if (config != null) {
+      ShadowsocksApplication.profileManager.getProfile(config.profileId) match {
+        case Some(profile) =>
+          profile.tx += tx
+          profile.rx += rx
+          ShadowsocksApplication.profileManager.updateProfile(profile)
+        case None => // Ignore
       }
-    })
+    }
   }
 
   def stopBackgroundService()
@@ -162,10 +158,14 @@ trait BaseService extends Service {
     changeState(s, null)
   }
 
-  def updateTrafficRate(txRate: String, rxRate: String, txTotal: String, rxTotal: String) {
+  def updateTrafficRate() {
     val handler = new Handler(getContext.getMainLooper)
     handler.post(() => {
       if (callbackCount > 0) {
+        val txRate = TrafficMonitor.getTxRate
+        val rxRate = TrafficMonitor.getRxRate
+        val txTotal = TrafficMonitor.getTxTotal
+        val rxTotal = TrafficMonitor.getRxTotal
         val n = callbacks.beginBroadcast()
         for (i <- 0 until n) {
           try {

src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala

@@ -5,26 +5,19 @@ import java.text.DecimalFormat
 
 import com.github.shadowsocks.{R, ShadowsocksApplication}
 
-case class Traffic(tx: Long, rx: Long, timestamp: Long)
-
 object TrafficMonitor {
-  var last: Traffic = getTraffic(0, 0)
-
   // Bytes per second
-  var txRate: Long = 0
-  var rxRate: Long = 0
+  var txRate: Long = _
+  var rxRate: Long = _
 
   // Bytes for the current session
-  var txTotal: Long = 0
-  var rxTotal: Long = 0
+  var txTotal: Long = _
+  var rxTotal: Long = _
 
   // Bytes for the last query
-  var txLast: Long = 0
-  var rxLast: Long = 0
-
-  def getTraffic(tx: Long, rx: Long): Traffic = {
-    new Traffic(tx, rx, System.currentTimeMillis())
-  }
+  var txLast: Long = _
+  var rxLast: Long = _
+  var timestampLast: Long = _
 
   private val units = Array("KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB", "BB", "NB", "DB", "CB")
   private val numberFormat = new DecimalFormat("@@@")
@@ -40,15 +33,15 @@ object TrafficMonitor {
   }
 
   def updateRate() {
-    val now = getTraffic(txTotal, rxTotal)
-    val delta = now.timestamp - last.timestamp
-    val deltaTx = now.tx - last.tx
-    val deltaRx = now.rx - last.rx
+    val now = System.currentTimeMillis()
+    val delta = now - timestampLast
     if (delta != 0) {
-      txRate = deltaTx * 1000 / delta
-      rxRate = deltaRx * 1000 / delta
+      txRate = (txTotal - txLast) * 1000 / delta
+      rxRate = (rxTotal - rxLast) * 1000 / delta
+      txLast = txTotal
+      rxLast = rxTotal
+      timestampLast = now
     }
-    last = now
   }
 
   def update(tx: Long, rx: Long) {
@@ -63,7 +56,6 @@ object TrafficMonitor {
     rxTotal = 0
     txLast = 0
     rxLast = 0
-    last = getTraffic(0, 0)
   }
 
   def getTxTotal(): String = {
@@ -89,17 +81,5 @@ object TrafficMonitor {
   def getRate(): String = {
     formatTraffic(txRate + rxRate)
   }
-
-  def getDeltaTx(): Long = {
-    val last = txLast
-    txLast = txTotal
-    txTotal - last
-  }
-
-  def getDeltaRx(): Long = {
-    val last = rxLast
-    rxLast = rxTotal
-    rxTotal - last
-  }
 }