1 /* 2 * Copyright 2018 The gRPC Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package io.grpc.internal; 18 19 import static com.google.common.base.Preconditions.checkArgument; 20 import static com.google.common.base.Preconditions.checkNotNull; 21 22 import io.grpc.InternalChannelz.ChannelStats; 23 import io.grpc.InternalChannelz.ChannelTrace; 24 import io.grpc.InternalChannelz.ChannelTrace.Event; 25 import java.util.ArrayDeque; 26 import java.util.ArrayList; 27 import java.util.Collection; 28 import java.util.List; 29 import javax.annotation.concurrent.GuardedBy; 30 31 /** 32 * Tracks a collections of channel tracing events for a channel/subchannel. 33 */ 34 final class ChannelTracer { 35 private final Object lock = new Object(); 36 @GuardedBy("lock") 37 private final Collection<Event> events; 38 private final long channelCreationTimeNanos; 39 40 @GuardedBy("lock") 41 private int eventsLogged; 42 43 /** 44 * Creates a channel tracer and log the creation event of the underlying channel. 45 * 46 * @param channelType Chennel, Subchannel, or OobChannel 47 */ ChannelTracer(final int maxEvents, long channelCreationTimeNanos, String channelType)48 ChannelTracer(final int maxEvents, long channelCreationTimeNanos, String channelType) { 49 checkArgument(maxEvents > 0, "maxEvents must be greater than zero"); 50 checkNotNull(channelType, "channelType"); 51 events = new ArrayDeque<Event>() { 52 @GuardedBy("lock") 53 @Override 54 public boolean add(Event event) { 55 if (size() == maxEvents) { 56 removeFirst(); 57 } 58 eventsLogged++; 59 return super.add(event); 60 } 61 }; 62 this.channelCreationTimeNanos = channelCreationTimeNanos; 63 64 reportEvent(new ChannelTrace.Event.Builder() 65 .setDescription(channelType + " created") 66 .setSeverity(ChannelTrace.Event.Severity.CT_INFO) 67 // passing the timestamp in as a parameter instead of computing it right here because when 68 // parent channel and subchannel both report the same event of the subchannel (e.g. creation 69 // event of the subchannel) we want the timestamps to be exactly the same. 70 .setTimestampNanos(channelCreationTimeNanos) 71 .build()); 72 } 73 reportEvent(Event event)74 void reportEvent(Event event) { 75 synchronized (lock) { 76 events.add(event); 77 } 78 } 79 updateBuilder(ChannelStats.Builder builder)80 void updateBuilder(ChannelStats.Builder builder) { 81 List<Event> eventsSnapshot; 82 int eventsLoggedSnapshot; 83 synchronized (lock) { 84 eventsLoggedSnapshot = eventsLogged; 85 eventsSnapshot = new ArrayList<>(events); 86 } 87 builder.setChannelTrace(new ChannelTrace.Builder() 88 .setNumEventsLogged(eventsLoggedSnapshot) 89 .setCreationTimeNanos(channelCreationTimeNanos) 90 .setEvents(eventsSnapshot) 91 .build()); 92 } 93 } 94