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TraceContextFormat.java
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TraceContextFormat.java
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/*
* Copyright 2018, OpenCensus 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.opencensus.implcore.trace.propagation;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Splitter;
import io.opencensus.trace.SpanContext;
import io.opencensus.trace.SpanId;
import io.opencensus.trace.TraceId;
import io.opencensus.trace.TraceOptions;
import io.opencensus.trace.Tracestate;
import io.opencensus.trace.propagation.SpanContextParseException;
import io.opencensus.trace.propagation.TextFormat;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.regex.Pattern;
/*>>>
import org.checkerframework.checker.nullness.qual.NonNull;
*/
/**
* Implementation of the TraceContext propagation protocol. See <a
* href=https://github.com/w3c/distributed-tracing>w3c/distributed-tracing</a>.
*/
public class TraceContextFormat extends TextFormat {
private static final Tracestate TRACESTATE_DEFAULT = Tracestate.builder().build();
@VisibleForTesting static final String TRACEPARENT = "traceparent";
@VisibleForTesting static final String TRACESTATE = "tracestate";
private static final List<String> FIELDS =
Collections.unmodifiableList(Arrays.asList(TRACEPARENT, TRACESTATE));
private static final String VERSION = "00";
private static final int VERSION_SIZE = 2;
private static final char TRACEPARENT_DELIMITER = '-';
private static final int TRACEPARENT_DELIMITER_SIZE = 1;
private static final int TRACE_ID_HEX_SIZE = 2 * TraceId.SIZE;
private static final int SPAN_ID_HEX_SIZE = 2 * SpanId.SIZE;
private static final int TRACE_OPTION_HEX_SIZE = 2 * TraceOptions.SIZE;
private static final int TRACE_ID_OFFSET = VERSION_SIZE + TRACEPARENT_DELIMITER_SIZE;
private static final int SPAN_ID_OFFSET =
TRACE_ID_OFFSET + TRACE_ID_HEX_SIZE + TRACEPARENT_DELIMITER_SIZE;
private static final int TRACE_OPTION_OFFSET =
SPAN_ID_OFFSET + SPAN_ID_HEX_SIZE + TRACEPARENT_DELIMITER_SIZE;
private static final int TRACEPARENT_HEADER_SIZE = TRACE_OPTION_OFFSET + TRACE_OPTION_HEX_SIZE;
private static final int TRACESTATE_MAX_SIZE = 512;
private static final int TRACESTATE_MAX_MEMBERS = 32;
private static final char TRACESTATE_KEY_VALUE_DELIMITER = '=';
private static final char TRACESTATE_ENTRY_DELIMITER = ',';
private static final Splitter TRACESTATE_ENTRY_DELIMITER_SPLITTER =
Splitter.on(Pattern.compile("[ \t]*" + TRACESTATE_ENTRY_DELIMITER + "[ \t]*"));
@Override
public List<String> fields() {
return FIELDS;
}
@Override
public <C /*>>> extends @NonNull Object*/> void inject(
SpanContext spanContext, C carrier, Setter<C> setter) {
checkNotNull(spanContext, "spanContext");
checkNotNull(setter, "setter");
checkNotNull(carrier, "carrier");
char[] chars = new char[TRACEPARENT_HEADER_SIZE];
chars[0] = VERSION.charAt(0);
chars[1] = VERSION.charAt(1);
chars[2] = TRACEPARENT_DELIMITER;
spanContext.getTraceId().copyLowerBase16To(chars, TRACE_ID_OFFSET);
chars[SPAN_ID_OFFSET - 1] = TRACEPARENT_DELIMITER;
spanContext.getSpanId().copyLowerBase16To(chars, SPAN_ID_OFFSET);
chars[TRACE_OPTION_OFFSET - 1] = TRACEPARENT_DELIMITER;
spanContext.getTraceOptions().copyLowerBase16To(chars, TRACE_OPTION_OFFSET);
setter.put(carrier, TRACEPARENT, new String(chars));
List<Tracestate.Entry> entries = spanContext.getTracestate().getEntries();
if (entries.isEmpty()) {
// No need to add an empty "tracestate" header.
return;
}
StringBuilder stringBuilder = new StringBuilder(TRACESTATE_MAX_SIZE);
for (Tracestate.Entry entry : entries) {
if (stringBuilder.length() != 0) {
stringBuilder.append(TRACESTATE_ENTRY_DELIMITER);
}
stringBuilder
.append(entry.getKey())
.append(TRACESTATE_KEY_VALUE_DELIMITER)
.append(entry.getValue());
}
setter.put(carrier, TRACESTATE, stringBuilder.toString());
}
@Override
public <C /*>>> extends @NonNull Object*/> SpanContext extract(C carrier, Getter<C> getter)
throws SpanContextParseException {
checkNotNull(carrier, "carrier");
checkNotNull(getter, "getter");
TraceId traceId;
SpanId spanId;
TraceOptions traceOptions;
String traceparent = getter.get(carrier, TRACEPARENT);
if (traceparent == null) {
throw new SpanContextParseException("Traceparent not present");
}
try {
// TODO(bdrutu): Do we need to verify that version is hex and that for the version
// the length is the expected one?
checkArgument(
traceparent.charAt(TRACE_OPTION_OFFSET - 1) == TRACEPARENT_DELIMITER
&& (traceparent.length() == TRACEPARENT_HEADER_SIZE
|| (traceparent.length() > TRACEPARENT_HEADER_SIZE
&& traceparent.charAt(TRACEPARENT_HEADER_SIZE) == TRACEPARENT_DELIMITER))
&& traceparent.charAt(SPAN_ID_OFFSET - 1) == TRACEPARENT_DELIMITER
&& traceparent.charAt(TRACE_OPTION_OFFSET - 1) == TRACEPARENT_DELIMITER,
"Missing or malformed TRACEPARENT.");
traceId = TraceId.fromLowerBase16(traceparent, TRACE_ID_OFFSET);
spanId = SpanId.fromLowerBase16(traceparent, SPAN_ID_OFFSET);
traceOptions = TraceOptions.fromLowerBase16(traceparent, TRACE_OPTION_OFFSET);
} catch (IllegalArgumentException e) {
throw new SpanContextParseException("Invalid traceparent: " + traceparent, e);
}
String tracestate = getter.get(carrier, TRACESTATE);
try {
if (tracestate == null || tracestate.isEmpty()) {
return SpanContext.create(traceId, spanId, traceOptions, TRACESTATE_DEFAULT);
}
Tracestate.Builder tracestateBuilder = Tracestate.builder();
List<String> listMembers = TRACESTATE_ENTRY_DELIMITER_SPLITTER.splitToList(tracestate);
checkArgument(
listMembers.size() <= TRACESTATE_MAX_MEMBERS, "Tracestate has too many elements.");
// Iterate in reverse order because when call builder set the elements is added in the
// front of the list.
for (int i = listMembers.size() - 1; i >= 0; i--) {
String listMember = listMembers.get(i);
int index = listMember.indexOf(TRACESTATE_KEY_VALUE_DELIMITER);
checkArgument(index != -1, "Invalid tracestate list-member format.");
tracestateBuilder.set(
listMember.substring(0, index), listMember.substring(index + 1, listMember.length()));
}
return SpanContext.create(traceId, spanId, traceOptions, tracestateBuilder.build());
} catch (IllegalArgumentException e) {
throw new SpanContextParseException("Invalid tracestate: " + tracestate, e);
}
}
}