| /* |
| * Copyright 2017 The gRPC Authors |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package io.grpc.netty; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.common.base.Preconditions; |
| import java.util.concurrent.TimeUnit; |
| import javax.annotation.CheckReturnValue; |
| |
| /** Monitors the client's PING usage to make sure the rate is permitted. */ |
| class KeepAliveEnforcer { |
| @VisibleForTesting |
| static final int MAX_PING_STRIKES = 2; |
| @VisibleForTesting |
| static final long IMPLICIT_PERMIT_TIME_NANOS = TimeUnit.HOURS.toNanos(2); |
| |
| private final boolean permitWithoutCalls; |
| private final long minTimeNanos; |
| private final Ticker ticker; |
| private final long epoch; |
| |
| private long lastValidPingTime; |
| private boolean hasOutstandingCalls; |
| private int pingStrikes; |
| |
| public KeepAliveEnforcer(boolean permitWithoutCalls, long minTime, TimeUnit unit) { |
| this(permitWithoutCalls, minTime, unit, SystemTicker.INSTANCE); |
| } |
| |
| @VisibleForTesting |
| KeepAliveEnforcer(boolean permitWithoutCalls, long minTime, TimeUnit unit, Ticker ticker) { |
| Preconditions.checkArgument(minTime >= 0, "minTime must be non-negative"); |
| |
| this.permitWithoutCalls = permitWithoutCalls; |
| this.minTimeNanos = Math.min(unit.toNanos(minTime), IMPLICIT_PERMIT_TIME_NANOS); |
| this.ticker = ticker; |
| this.epoch = ticker.nanoTime(); |
| lastValidPingTime = epoch; |
| } |
| |
| /** Returns {@code false} when client is misbehaving and should be disconnected. */ |
| @CheckReturnValue |
| public boolean pingAcceptable() { |
| long now = ticker.nanoTime(); |
| boolean valid; |
| if (!hasOutstandingCalls && !permitWithoutCalls) { |
| valid = compareNanos(lastValidPingTime + IMPLICIT_PERMIT_TIME_NANOS, now) <= 0; |
| } else { |
| valid = compareNanos(lastValidPingTime + minTimeNanos, now) <= 0; |
| } |
| if (!valid) { |
| pingStrikes++; |
| return !(pingStrikes > MAX_PING_STRIKES); |
| } else { |
| lastValidPingTime = now; |
| return true; |
| } |
| } |
| |
| /** |
| * Reset any counters because PINGs are allowed in response to something sent. Typically called |
| * when sending HEADERS and DATA frames. |
| */ |
| public void resetCounters() { |
| lastValidPingTime = epoch; |
| pingStrikes = 0; |
| } |
| |
| /** There are outstanding RPCs on the transport. */ |
| public void onTransportActive() { |
| hasOutstandingCalls = true; |
| } |
| |
| /** There are no outstanding RPCs on the transport. */ |
| public void onTransportIdle() { |
| hasOutstandingCalls = false; |
| } |
| |
| /** |
| * Positive when time1 is greater; negative when time2 is greater; 0 when equal. It is important |
| * to use something like this instead of directly comparing nano times. See {@link |
| * System#nanoTime}. |
| */ |
| private static long compareNanos(long time1, long time2) { |
| // Possibility of overflow/underflow is on purpose and necessary for correctness |
| return time1 - time2; |
| } |
| |
| @VisibleForTesting |
| interface Ticker { |
| long nanoTime(); |
| } |
| |
| @VisibleForTesting |
| static class SystemTicker implements Ticker { |
| public static final SystemTicker INSTANCE = new SystemTicker(); |
| |
| @Override |
| public long nanoTime() { |
| return System.nanoTime(); |
| } |
| } |
| } |