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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 zipkin2.internal;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import zipkin2.Endpoint;
import zipkin2.Span;
public class Trace {
/*
* Spans can be sent in multiple parts. Also client and server spans can share the same ID. This
* merges both scenarios.
*/
public static List merge(List spans) {
int length = spans.size();
if (length <= 1) return spans;
List result = new ArrayList<>(spans);
Collections.sort(result, CLEANUP_COMPARATOR);
// Let's cleanup any spans and pick the longest ID
String traceId = result.get(0).traceId();
for (int i = 1; i < length; i++) {
String nextTraceId = result.get(i).traceId();
if (traceId.length() != 32) traceId = nextTraceId;
}
// Now start any fixes or merging
Span last = null;
for (int i = 0; i < length; i++) {
Span span = result.get(i);
//String previousId = last.id();
boolean spanShared = Boolean.TRUE.equals(span.shared());
// Choose the longest trace ID
Span.Builder replacement = null;
if (span.traceId().length() != traceId.length()) {
replacement = span.toBuilder().traceId(traceId);
}
EndpointTracker localEndpoint = null;
while (i + 1 < length) {
Span next = result.get(i + 1);
String nextId = next.id();
if (!nextId.equals(span.id())) break;
if (localEndpoint == null) {
localEndpoint = new EndpointTracker();
localEndpoint.tryMerge(span.localEndpoint());
}
// This cautiously merges with the next span, if we think it was sent in multiple pieces.
boolean nextShared = Boolean.TRUE.equals(next.shared());
if (spanShared == nextShared && localEndpoint.tryMerge(next.localEndpoint())) {
if (replacement == null) replacement = span.toBuilder();
replacement.merge(next);
// remove the merged element
length--;
result.remove(i + 1);
continue;
}
break;
}
// Zipkin and B3 originally used the same span ID between client and server. Some
// instrumentation are inconsistent about adding the shared flag on the server side. Since we
// have the entire trace, and it is ordered client-first, we can correct a missing shared flag.
if (last != null && last.id().equals(span.id())) {
// Backfill missing shared flag as some instrumentation doesn't add it
if (last.kind() == Span.Kind.CLIENT && span.kind() == Span.Kind.SERVER && !spanShared) {
spanShared = true;
if (replacement == null) replacement = span.toBuilder();
replacement.shared(true);
}
if (spanShared && span.parentId() == null && last.parentId() != null) {
// handle a shared RPC server span that wasn't propagated its parent span ID
if (replacement == null) replacement = span.toBuilder();
replacement.parentId(last.parentId());
}
}
if (replacement != null) {
span = replacement.build();
result.set(i, span);
}
last = span;
}
return result;
}
static final Comparator CLEANUP_COMPARATOR = new Comparator() {
@Override public int compare(Span left, Span right) {
if (left.equals(right)) return 0;
int bySpanId = left.id().compareTo(right.id());
if (bySpanId != 0) return bySpanId;
int byShared = compareShared(left, right);
if (byShared != 0) return byShared;
return compareEndpoint(left.localEndpoint(), right.localEndpoint());
}
};
// false or null first (client first)
static int compareShared(Span left, Span right) {
// If either are shared put it last
boolean leftShared = Boolean.TRUE.equals(left.shared());
boolean rightShared = Boolean.TRUE.equals(right.shared());
if (leftShared && rightShared) return 0; // both are shared, so skip out
if (leftShared) return 1;
if (rightShared) return -1;
// neither are shared, put the client spans first
boolean leftClient = Span.Kind.CLIENT.equals(left.kind());
boolean rightClient = Span.Kind.CLIENT.equals(right.kind());
if (leftClient && rightClient) return 0;
if (leftClient) return -1;
if (rightClient) return 1;
return 0; // neither are client spans
}
/**
* Put spans with null endpoints first, so that their data can be attached to the first span with
* the same ID and endpoint. It is possible that a server can get the same request on a different
* port. Not addressing this.
*/
static int compareEndpoint(Endpoint left, Endpoint right) {
if (left == null) { // nulls first
return (right == null) ? 0 : -1;
} else if (right == null) {
return 1;
}
int byService = nullSafeCompareTo(left.serviceName(), right.serviceName(), false);
if (byService != 0) return byService;
int byIpV4 = nullSafeCompareTo(left.ipv4(), right.ipv4(), false);
if (byIpV4 != 0) return byIpV4;
return nullSafeCompareTo(left.ipv6(), right.ipv6(), false);
}
static > int nullSafeCompareTo(T left, T right, boolean nullFirst) {
if (left == null) {
return (right == null) ? 0 : (nullFirst ? -1 : 1);
} else if (right == null) {
return nullFirst ? 1 : -1;
} else {
return left.compareTo(right);
}
}
/**
* Sometimes endpoints can be sent in pieces. This tracks the whether we should merge with
* something, or if it has a different identity.
*/
static final class EndpointTracker {
String serviceName, ipv4, ipv6;
int port;
boolean tryMerge(Endpoint endpoint) {
if (endpoint == null) return true;
if (serviceName != null &&
endpoint.serviceName() != null && !serviceName.equals(endpoint.serviceName())) {
return false;
}
if (ipv4 != null && endpoint.ipv4() != null && !ipv4.equals(endpoint.ipv4())) {
return false;
}
if (ipv6 != null && endpoint.ipv6() != null && !ipv6.equals(endpoint.ipv6())) {
return false;
}
if (port != 0 && endpoint.portAsInt() != 0 && port != endpoint.portAsInt()) {
return false;
}
if (serviceName == null) serviceName = endpoint.serviceName();
if (ipv4 == null) ipv4 = endpoint.ipv4();
if (ipv6 == null) ipv6 = endpoint.ipv6();
if (port == 0) port = endpoint.portAsInt();
return true;
}
}
Trace() {
}
}