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Commit eb61ab9a authored by Xiao Ma's avatar Xiao Ma
Browse files

Separate the timeout behavior from PacketRetransmittingState class. 

The purpose is to make subclass that only requires timeout method
could extend from TimeoutState instead of PacketRetransmittingState,
avoiding the anti-pattern of using inheritance for code reuse only.

After refactoring, class inheritance relationship looks like:

LoggingState <-- TimeoutState <-- PacketRetransmittingState <-- DhcpInitState

Bug: 140223017
Test: atest FrameworksNetTests NetworkStackTests
Test: atest NetworkStackIntegrationTests

Change-Id: I1fed3ff3ef8b0bdf3645188949e38c3a332f9d6e
parent f3f5f36d

src/android/net/dhcp/DhcpClient.java

+44 −19
Original line number Diff line number Diff line
@@ -829,6 +829,42 @@ public class DhcpClient extends StateMachine { 
                (leaseTimeMillis > 0) ? SystemClock.elapsedRealtime() + leaseTimeMillis : 0;

    }



    abstract class TimeoutState extends LoggingState {

        protected int mTimeout = 0;



        @Override

        public void enter() {

            super.enter();

            maybeInitTimeout();

        }



        @Override

        public boolean processMessage(Message message) {

            super.processMessage(message);

            switch (message.what) {

                case CMD_TIMEOUT:

                    timeout();

                    return HANDLED;

                default:

                    return NOT_HANDLED;

            }

        }



        @Override

        public void exit() {

            super.exit();

            mTimeoutAlarm.cancel();

        }



        protected abstract void timeout();

        private void maybeInitTimeout() {

            if (mTimeout > 0) {

                long alarmTime = SystemClock.elapsedRealtime() + mTimeout;

                mTimeoutAlarm.schedule(alarmTime);

            }

        }

    }



    /**

     * Retransmits packets using jittered exponential backoff with an optional timeout. Packet

     * transmission is triggered by CMD_KICK, which is sent by an AlarmManager alarm. If a subclass
@@ -840,22 +876,22 @@ public class DhcpClient extends StateMachine { 
     * packet needs to be transmitted, and receivePacket, which is triggered by CMD_RECEIVED_PACKET

     * sent by the receive thread. They may also set mTimeout and implement timeout.

     */

    abstract class PacketRetransmittingState extends LoggingState {



    abstract class PacketRetransmittingState extends TimeoutState {

        private int mTimer;

        protected int mTimeout = 0;



        @Override

        public void enter() {

            super.enter();

            initTimer();

            maybeInitTimeout();

            sendMessage(CMD_KICK);

        }



        @Override

        public boolean processMessage(Message message) {

            super.processMessage(message);

            if (super.processMessage(message) == HANDLED) {

                return HANDLED;

            }



            switch (message.what) {

                case CMD_KICK:

                    sendPacket();
@@ -864,9 +900,6 @@ public class DhcpClient extends StateMachine { 
                case CMD_RECEIVED_PACKET:

                    receivePacket((DhcpPacket) message.obj);

                    return HANDLED;

                case CMD_TIMEOUT:

                    timeout();

                    return HANDLED;

                default:

                    return NOT_HANDLED;

            }
@@ -876,11 +909,10 @@ public class DhcpClient extends StateMachine { 
        public void exit() {

            super.exit();

            mKickAlarm.cancel();

            mTimeoutAlarm.cancel();

        }



        abstract protected boolean sendPacket();

        abstract protected void receivePacket(DhcpPacket packet);

        protected abstract boolean sendPacket();

        protected abstract void receivePacket(DhcpPacket packet);

        protected void timeout() {}



        protected void initTimer() {
@@ -903,13 +935,6 @@ public class DhcpClient extends StateMachine { 
                mTimer = MAX_TIMEOUT_MS;

            }

        }



        protected void maybeInitTimeout() {

            if (mTimeout > 0) {

                long alarmTime = SystemClock.elapsedRealtime() + mTimeout;

                mTimeoutAlarm.schedule(alarmTime);

            }

        }

    }



    class ObtainingConfigurationState extends LoggingState {
@@ -1167,7 +1192,7 @@ public class DhcpClient extends StateMachine { 
            startNewTransaction();

        }



        abstract protected Inet4Address packetDestination();

        protected abstract Inet4Address packetDestination();



        protected boolean sendPacket() {

            return sendRequestPacket(