Merge "Add rate-limiting to reduce CPU loading of IpClient"

import android.net.util.NetworkStackUtils;

import android.net.util.PacketReader;

import android.os.Handler;

import android.os.SystemClock;

import android.system.ErrnoException;

import android.system.Os;

import android.text.TextUtils;

import android.util.Log;

import com.android.internal.util.HexDump;

import com.android.internal.util.TokenBucket;

import java.io.FileDescriptor;

import java.io.IOException;

    private static final String MARK_STOP = "--- STOP ---";

    private static final String MARK_NAMED_START = "--- START (%s) ---";

    private static final String MARK_NAMED_STOP = "--- STOP (%s) ---";

    // Use a TokenBucket to limit CPU usage of logging packets in steady state.

    private static final int TOKEN_FILL_RATE = 50;   // Maximum one packet every 20ms.

    private static final int MAX_BURST_LENGTH = 100; // Maximum burst 100 packets.

    private final String mTag;

    private final LocalLog mLog;

    private final PacketReader mPacketListener;

    private final TokenBucket mTokenBucket = new TokenBucket(TOKEN_FILL_RATE, MAX_BURST_LENGTH);

    private long mLastRateLimitLogTimeMs = 0;

    private boolean mRunning;

    private String mDisplayName;

        @Override

        protected void handlePacket(byte[] recvbuf, int length) {

            if (!mTokenBucket.get()) {

                // Rate limited. Log once every second so the user knows packets are missing.

                final long now = SystemClock.elapsedRealtime();

                if (now >= mLastRateLimitLogTimeMs + 1000) {

                    addLogEntry("Warning: too many packets, rate-limiting to one every " +

                                TOKEN_FILL_RATE + "ms");

                    mLastRateLimitLogTimeMs = now;

                }

                return;

            }

            final String summary = ConnectivityPacketSummary.summarize(

                    mInterface.macAddr, recvbuf, length);

            if (summary == null) return;