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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;

import java.io.ObjectStreamException;
import java.io.Serializable;
import java.io.StreamCorruptedException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.TreeMap;
import java.util.logging.Logger;
import zipkin2.codec.SpanBytesDecoder;
import zipkin2.codec.SpanBytesEncoder;
import zipkin2.internal.Nullable;
import zipkin2.internal.Platform;

import static java.lang.String.format;
import static java.util.logging.Level.FINEST;
import static zipkin2.internal.HexCodec.HEX_DIGITS;

/**
 * A span is a single-host view of an operation. A trace is a series of spans (often RPC calls)
 * which nest to form a latency tree. Spans are in the same trace when they share the same trace ID.
 * The {@link #parentId} field establishes the position of one span in the tree.
 *
 * 

The root span is where {@link #parentId} is null and usually has the longest {@link * #duration} in the trace. However, nested asynchronous work can materialize as child spans whose * duration exceed the root span. * *

Spans usually represent remote activity such as RPC calls, or messaging producers and * consumers. However, they can also represent in-process activity in any position of the trace. For * example, a root span could represent a server receiving an initial client request. A root span * could also represent a scheduled job that has no remote context. * *

While span identifiers are packed into longs, they should be treated opaquely. ID encoding is * 16 or 32 character lower-hex, to avoid signed interpretation. * *

Relationship to {@code zipkin.Span}

* *

This type is intended to replace use of {@code zipkin.Span}. Particularly, tracers represent * a single-host view of an operation. By making one endpoint implicit for all data, this type does * not need to repeat endpoints on each data like {@code zipkin.Span} does. This results in simpler * and smaller data. */ //@Immutable public final class Span implements Serializable { // for Spark and Flink jobs static final Charset UTF_8 = Charset.forName("UTF-8"); static final Endpoint EMPTY_ENDPOINT = Endpoint.newBuilder().build(); static final int FLAG_DEBUG = 1 << 1; static final int FLAG_DEBUG_SET = 1 << 2; static final int FLAG_SHARED = 1 << 3; static final int FLAG_SHARED_SET = 1 << 4; private static final long serialVersionUID = 0L; /** * Trace identifier, set on all spans within it. * *

Encoded as 16 or 32 lowercase hex characters corresponding to 64 or 128 bits. For example, * a 128bit trace ID looks like {@code 4e441824ec2b6a44ffdc9bb9a6453df3}. * *

Some systems downgrade trace identifiers to 64bit by dropping the left-most 16 characters. * For example, {@code 4e441824ec2b6a44ffdc9bb9a6453df3} becomes {@code ffdc9bb9a6453df3}. */ public String traceId() { return traceId; } /** * The parent's {@link #id} or null if this the root span in a trace. * *

This is the same encoding as {@link #id}. For example {@code ffdc9bb9a6453df3} */ @Nullable public String parentId() { return parentId; } /** * Unique 64bit identifier for this operation within the trace. * *

Encoded as 16 lowercase hex characters. For example {@code ffdc9bb9a6453df3} * *

A span is uniquely identified in storage by ({@linkplain #traceId}, {@linkplain #id()}). */ public String id() { return id; } /** Indicates the primary span type. */ public enum Kind { CLIENT, SERVER, /** * When present, {@link #timestamp()} is the moment a producer sent a message to a destination. * {@link #duration()} represents delay sending the message, such as batching, while {@link * #remoteEndpoint()} indicates the destination, such as a broker. * *

Unlike {@link #CLIENT}, messaging spans never share a span ID. For example, the {@link * #CONSUMER} of the same message has {@link #parentId()} set to this span's {@link #id()}. */ PRODUCER, /** * When present, {@link #timestamp()} is the moment a consumer received a message from an * origin. {@link #duration()} represents delay consuming the message, such as from backlog, * while {@link #remoteEndpoint()} indicates the origin, such as a broker. * *

Unlike {@link #SERVER}, messaging spans never share a span ID. For example, the {@link * #PRODUCER} of this message is the {@link #parentId()} of this span. */ CONSUMER } /** When present, used to interpret {@link #remoteEndpoint} */ @Nullable public Kind kind() { return kind; } /** * Span name in lowercase, rpc method for example. * *

Conventionally, when the span name isn't known, name = "unknown". */ @Nullable public String name() { return name; } /** * Epoch microseconds of the start of this span, possibly absent if this an incomplete span. * *

This value should be set directly by instrumentation, using the most precise value * possible. For example, {@code gettimeofday} or multiplying {@link System#currentTimeMillis} by * 1000. * *

There are three known edge-cases where this could be reported absent: * *

    *
  • A span was allocated but never started (ex not yet received a timestamp)
  • *
  • The span's start event was lost
  • *
  • Data about a completed span (ex tags) were sent after the fact
  • *
    * *

    Note: timestamps at or before epoch (0L == 1970) are invalid * * @see #duration() * @see #timestampAsLong() */ @Nullable public Long timestamp() { return timestamp > 0 ? timestamp : null; } /** * Like {@link #timestamp()} except returns a primitive where zero implies absent. * *

    Using this method will avoid allocation, so is encouraged when copying data. */ public long timestampAsLong() { return timestamp; } /** * Measurement in microseconds of the critical path, if known. Durations of less than one * microsecond must be rounded up to 1 microsecond. * *

    This value should be set directly, as opposed to implicitly via annotation timestamps. * Doing so encourages precision decoupled from problems of clocks, such as skew or NTP updates * causing time to move backwards. * *

    If this field is persisted as unset, zipkin will continue to work, except duration query * support will be implementation-specific. Similarly, setting this field non-atomically is * implementation-specific. * *

    This field is i64 vs i32 to support spans longer than 35 minutes. * * @see #durationAsLong() */ @Nullable public Long duration() { return duration > 0 ? duration : null; } /** * Like {@link #duration()} except returns a primitive where zero implies absent. * *

    Using this method will avoid allocation, so is encouraged when copying data. */ public long durationAsLong() { return duration; } /** * The host that recorded this span, primarily for query by service name. * *

    Instrumentation should always record this and be consistent as possible with the service * name as it is used in search. This is nullable for legacy reasons. */ // Nullable for data conversion especially late arriving data which might not have an annotation @Nullable public Endpoint localEndpoint() { return localEndpoint; } /** * When an RPC (or messaging) span, indicates the other side of the connection. * *

    By recording the remote endpoint, your trace will contain network context even if the peer * is not tracing. For example, you can record the IP from the {@code X-Forwarded-For} header or * the service name and socket of a remote peer. */ @Nullable public Endpoint remoteEndpoint() { return remoteEndpoint; } /** * Events that explain latency with a timestamp. Unlike log statements, annotations are often * short or contain codes: for example "brave.flush". Annotations are sorted ascending by * timestamp. */ public List annotations() { return annotations; } /** * Tags a span with context, usually to support query or aggregation. * *

    For example, a tag key could be {@code "http.path"}. */ public Map tags() { return tags; } /** True is a request to store this span even if it overrides sampling policy. */ @Nullable public Boolean debug() { return (flags & FLAG_DEBUG_SET) == FLAG_DEBUG_SET ? (flags & FLAG_DEBUG) == FLAG_DEBUG : null; } /** * True if we are contributing to a span started by another tracer (ex on a different host). * Defaults to null. When set, it is expected for {@link #kind()} to be {@link Kind#SERVER}. * *

    When an RPC trace is client-originated, it will be sampled and the same span ID is used for * the server side. However, the server shouldn't set span.timestamp or duration since it didn't * start the span. */ @Nullable public Boolean shared() { return (flags & FLAG_SHARED_SET) == FLAG_SHARED_SET ? (flags & FLAG_SHARED) == FLAG_SHARED : null; } @Nullable public String localServiceName() { Endpoint localEndpoint = localEndpoint(); return localEndpoint != null ? localEndpoint.serviceName() : null; } @Nullable public String remoteServiceName() { Endpoint remoteEndpoint = remoteEndpoint(); return remoteEndpoint != null ? remoteEndpoint.serviceName() : null; } public static Builder newBuilder() { return new Builder(); } public Builder toBuilder() { return new Builder(this); } public static final class Builder { String traceId, parentId, id; Kind kind; String name; long timestamp, duration; // zero means null Endpoint localEndpoint, remoteEndpoint; ArrayList annotations; TreeMap tags; int flags = 0; // bit field for timestamp and duration public Builder clear() { traceId = null; parentId = null; id = null; kind = null; name = null; timestamp = 0L; duration = 0L; localEndpoint = null; remoteEndpoint = null; if (annotations != null) annotations.clear(); if (tags != null) tags.clear(); flags = 0; return this; } @Override public Builder clone() { Builder result = new Builder(); result.traceId = traceId; result.parentId = parentId; result.id = id; result.kind = kind; result.name = name; result.timestamp = timestamp; result.duration = duration; result.localEndpoint = localEndpoint; result.remoteEndpoint = remoteEndpoint; if (annotations != null) { result.annotations = (ArrayList) annotations.clone(); } if (tags != null) { result.tags = (TreeMap) tags.clone(); } result.flags = flags; return result; } Builder(Span source) { traceId = source.traceId; parentId = source.parentId; id = source.id; kind = source.kind; name = source.name; timestamp = source.timestamp; duration = source.duration; localEndpoint = source.localEndpoint; remoteEndpoint = source.remoteEndpoint; if (!source.annotations.isEmpty()) { annotations = new ArrayList<>(source.annotations.size()); annotations.addAll(source.annotations); } if (!source.tags.isEmpty()) { tags = new TreeMap<>(); tags.putAll(source.tags); } flags = source.flags; } /** * Used to merge multiple incomplete spans representing the same operation on the same host. Do * not use this to merge spans that occur on different hosts. */ public Builder merge(Span source) { if (traceId == null) traceId = source.traceId; if (id == null) id = source.id; if (parentId == null) parentId = source.parentId; if (kind == null) kind = source.kind; if (name == null) name = source.name; if (timestamp == 0L) timestamp = source.timestamp; if (duration == 0L) duration = source.duration; if (localEndpoint == null) { localEndpoint = source.localEndpoint; } else if (source.localEndpoint != null) { localEndpoint = localEndpoint.toBuilder().merge(source.localEndpoint).build(); } if (remoteEndpoint == null) { remoteEndpoint = source.remoteEndpoint; } else if (source.remoteEndpoint != null) { remoteEndpoint = remoteEndpoint.toBuilder().merge(source.remoteEndpoint).build(); } if (!source.annotations.isEmpty()) { if (annotations == null) { annotations = new ArrayList<>(source.annotations.size()); } annotations.addAll(source.annotations); } if (!source.tags.isEmpty()) { if (tags == null) tags = new TreeMap<>(); tags.putAll(source.tags); } flags = flags | source.flags; return this; } @Nullable public Kind kind() { return kind; } @Nullable public Endpoint localEndpoint() { return localEndpoint; } /** * @throws IllegalArgumentException if not lower-hex format * @see Span#id() */ public Builder traceId(String traceId) { this.traceId = normalizeTraceId(traceId); return this; } /** * Encodes 64 or 128 bits from the input into a hex trace ID. * * @param high Upper 64bits of the trace ID. Zero means the trace ID is 64-bit. * @param low Lower 64bits of the trace ID. * @throws IllegalArgumentException if both values are zero */ public Builder traceId(long high, long low) { if (high == 0L && low == 0L) throw new IllegalArgumentException("empty trace ID"); char[] data = Platform.shortStringBuffer(); int pos = 0; if (high != 0L) { writeHexLong(data, pos, high); pos += 16; } writeHexLong(data, pos, low); this.traceId = new String(data, 0, high != 0L ? 32 : 16); return this; } /** * Encodes 64 bits from the input into a hex parent ID. Unsets the {@link Span#parentId()} if * the input is 0. * * @see Span#parentId() */ public Builder parentId(long parentId) { this.parentId = parentId != 0L ? toLowerHex(parentId) : null; return this; } /** * @throws IllegalArgumentException if not lower-hex format * @see Span#parentId() */ public Builder parentId(@Nullable String parentId) { if (parentId == null) { this.parentId = null; return this; } int length = parentId.length(); if (length == 0) throw new IllegalArgumentException("parentId is empty"); if (length > 16) throw new IllegalArgumentException("parentId.length > 16"); if (validateHexAndReturnZeroPrefix(parentId) == length) { this.parentId = null; } else { this.parentId = length < 16 ? padLeft(parentId, 16) : parentId; } return this; } /** * Encodes 64 bits from the input into a hex span ID. * * @throws IllegalArgumentException if the input is zero * @see Span#id() */ public Builder id(long id) { if (id == 0L) throw new IllegalArgumentException("empty id"); this.id = toLowerHex(id); return this; } /** * @throws IllegalArgumentException if not lower-hex format * @see Span#id() */ public Builder id(String id) { if (id == null) throw new NullPointerException("id == null"); int length = id.length(); if (length == 0) throw new IllegalArgumentException("id is empty"); if (length > 16) throw new IllegalArgumentException("id.length > 16"); if (validateHexAndReturnZeroPrefix(id) == 16) { throw new IllegalArgumentException("id is all zeros"); } this.id = length < 16 ? padLeft(id, 16) : id; return this; } /** @see Span#kind */ public Builder kind(@Nullable Kind kind) { this.kind = kind; return this; } /** @see Span#name */ public Builder name(@Nullable String name) { this.name = name == null || name.isEmpty() ? null : name.toLowerCase(Locale.ROOT); return this; } /** @see Span#timestampAsLong() */ public Builder timestamp(long timestamp) { if (timestamp < 0L) timestamp = 0L; this.timestamp = timestamp; return this; } /** @see Span#timestamp() */ public Builder timestamp(@Nullable Long timestamp) { if (timestamp == null || timestamp < 0L) timestamp = 0L; this.timestamp = timestamp; return this; } /** @see Span#durationAsLong() */ public Builder duration(long duration) { if (duration < 0L) duration = 0L; this.duration = duration; return this; } /** @see Span#duration() */ public Builder duration(@Nullable Long duration) { if (duration == null || duration < 0L) duration = 0L; this.duration = duration; return this; } /** @see Span#localEndpoint */ public Builder localEndpoint(@Nullable Endpoint localEndpoint) { if (EMPTY_ENDPOINT.equals(localEndpoint)) localEndpoint = null; this.localEndpoint = localEndpoint; return this; } /** @see Span#remoteEndpoint */ public Builder remoteEndpoint(@Nullable Endpoint remoteEndpoint) { if (EMPTY_ENDPOINT.equals(remoteEndpoint)) remoteEndpoint = null; this.remoteEndpoint = remoteEndpoint; return this; } /** @see Span#annotations */ public Builder addAnnotation(long timestamp, String value) { if (annotations == null) annotations = new ArrayList<>(2); annotations.add(Annotation.create(timestamp, value)); return this; } /** @see Span#annotations */ public Builder clearAnnotations() { if (annotations == null) return this; annotations.clear(); return this; } /** @see Span#tags */ public Builder putTag(String key, String value) { if (tags == null) tags = new TreeMap<>(); if (key == null) throw new NullPointerException("key == null"); if (value == null) throw new NullPointerException("value of " + key + " == null"); this.tags.put(key, value); return this; } /** @see Span#tags */ public Builder clearTags() { if (tags == null) return this; tags.clear(); return this; } /** @see Span#debug */ public Builder debug(boolean debug) { flags |= FLAG_DEBUG_SET; if (debug) { flags |= FLAG_DEBUG; } else { flags &= ~FLAG_DEBUG; } return this; } /** @see Span#debug */ public Builder debug(@Nullable Boolean debug) { if (debug != null) return debug((boolean) debug); flags &= ~(FLAG_DEBUG_SET | FLAG_DEBUG); return this; } /** @see Span#shared */ public Builder shared(boolean shared) { flags |= FLAG_SHARED_SET; if (shared) { flags |= FLAG_SHARED; } else { flags &= ~FLAG_SHARED; } return this; } /** @see Span#shared */ public Builder shared(@Nullable Boolean shared) { if (shared != null) return shared((boolean) shared); flags &= ~(FLAG_SHARED_SET | FLAG_SHARED); return this; } public Span build() { String missing = ""; if (traceId == null) missing += " traceId"; if (id == null) missing += " id"; if (!"".equals(missing)) throw new IllegalStateException("Missing :" + missing); if (id.equals(parentId)) { // edge case, so don't require a logger field Logger logger = Logger.getLogger(Span.class.getName()); if (logger.isLoggable(FINEST)) { logger.fine(format("undoing circular dependency: traceId=%s, spanId=%s", traceId, id)); } parentId = null; } // shared is for the server side, unset it if accidentally set on the client side if ((flags & FLAG_SHARED) == FLAG_SHARED && kind == Kind.CLIENT) { Logger logger = Logger.getLogger(Span.class.getName()); if (logger.isLoggable(FINEST)) { logger.fine(format("removing shared flag on client: traceId=%s, spanId=%s", traceId, id)); } shared(null); } return new Span(this); } Builder() { } } @Override public String toString() { return new String(SpanBytesEncoder.JSON_V2.encode(this), UTF_8); } /** * Returns a valid lower-hex trace ID, padded left as needed to 16 or 32 characters. * * @throws IllegalArgumentException if oversized or not lower-hex */ public static String normalizeTraceId(String traceId) { if (traceId == null) throw new NullPointerException("traceId == null"); int length = traceId.length(); if (length == 0) throw new IllegalArgumentException("traceId is empty"); if (length > 32) throw new IllegalArgumentException("traceId.length > 32"); int zeros = validateHexAndReturnZeroPrefix(traceId); if (zeros == length) throw new IllegalArgumentException("traceId is all zeros"); if (length == 32 || length == 16) { if (length == 32 && zeros >= 16) return traceId.substring(16); return traceId; } else if (length < 16) { return padLeft(traceId, 16); } else { return padLeft(traceId, 32); } } static final String THIRTY_TWO_ZEROS; static { char[] zeros = new char[32]; Arrays.fill(zeros, '0'); THIRTY_TWO_ZEROS = new String(zeros); } static String padLeft(String id, int desiredLength) { int length = id.length(); int numZeros = desiredLength - length; char[] data = Platform.shortStringBuffer(); THIRTY_TWO_ZEROS.getChars(0, numZeros, data, 0); id.getChars(0, length, data, numZeros); return new String(data, 0, desiredLength); } static String toLowerHex(long v) { char[] data = Platform.shortStringBuffer(); writeHexLong(data, 0, v); return new String(data, 0, 16); } /** Inspired by {@code okio.Buffer.writeLong} */ static void writeHexLong(char[] data, int pos, long v) { writeHexByte(data, pos + 0, (byte) ((v >>> 56L) & 0xff)); writeHexByte(data, pos + 2, (byte) ((v >>> 48L) & 0xff)); writeHexByte(data, pos + 4, (byte) ((v >>> 40L) & 0xff)); writeHexByte(data, pos + 6, (byte) ((v >>> 32L) & 0xff)); writeHexByte(data, pos + 8, (byte) ((v >>> 24L) & 0xff)); writeHexByte(data, pos + 10, (byte) ((v >>> 16L) & 0xff)); writeHexByte(data, pos + 12, (byte) ((v >>> 8L) & 0xff)); writeHexByte(data, pos + 14, (byte) (v & 0xff)); } static void writeHexByte(char[] data, int pos, byte b) { data[pos + 0] = HEX_DIGITS[(b >> 4) & 0xf]; data[pos + 1] = HEX_DIGITS[b & 0xf]; } static int validateHexAndReturnZeroPrefix(String id) { int zeros = 0; boolean inZeroPrefix = id.charAt(0) == '0'; for (int i = 0, length = id.length(); i < length; i++) { char c = id.charAt(i); if ((c < '0' || c > '9') && (c < 'a' || c > 'f')) { throw new IllegalArgumentException(id + " should be lower-hex encoded with no prefix"); } if (c != '0') { inZeroPrefix = false; } else if (inZeroPrefix) { zeros++; } } return zeros; } static > List sortedList(@Nullable List in) { if (in == null || in.isEmpty()) return Collections.emptyList(); if (in.size() == 1) return Collections.singletonList(in.get(0)); Object[] array = in.toArray(); Arrays.sort(array); // dedupe int j = 0, i = 1; while (i < array.length) { if (!array[i].equals(array[j])) { array[++j] = array[i]; } i++; } List result = Arrays.asList(i == j + 1 ? array : Arrays.copyOf(array, j + 1)); return Collections.unmodifiableList(result); } // Custom impl to reduce GC churn and Kryo which cannot handle AutoValue subclass // See https://github.com/apache/incubator-zipkin/issues/1879 final String traceId, parentId, id; final Kind kind; final String name; final long timestamp, duration; // zero means null, saving 2 object references final Endpoint localEndpoint, remoteEndpoint; final List annotations; final Map tags; final int flags; // bit field for timestamp and duration, saving 2 object references Span(Builder builder) { traceId = builder.traceId; // prevent self-referencing spans parentId = builder.id.equals(builder.parentId) ? null : builder.parentId; id = builder.id; kind = builder.kind; name = builder.name; timestamp = builder.timestamp; duration = builder.duration; localEndpoint = builder.localEndpoint; remoteEndpoint = builder.remoteEndpoint; annotations = sortedList(builder.annotations); tags = builder.tags == null ? Collections.emptyMap() : new LinkedHashMap<>(builder.tags); flags = builder.flags; } @Override public boolean equals(Object o) { if (o == this) return true; if (!(o instanceof Span)) return false; Span that = (Span) o; return traceId.equals(that.traceId) && (parentId == null ? that.parentId == null : parentId.equals(that.parentId)) && id.equals(that.id) && (kind == null ? that.kind == null : kind.equals(that.kind)) && (name == null ? that.name == null : name.equals(that.name)) && timestamp == that.timestamp && duration == that.duration && (localEndpoint == null ? that.localEndpoint == null : localEndpoint.equals(that.localEndpoint)) && (remoteEndpoint == null ? that.remoteEndpoint == null : remoteEndpoint.equals(that.remoteEndpoint)) && annotations.equals(that.annotations) && tags.equals(that.tags) && flags == that.flags; } @Override public int hashCode() { int h = 1; h *= 1000003; h ^= traceId.hashCode(); h *= 1000003; h ^= (parentId == null) ? 0 : parentId.hashCode(); h *= 1000003; h ^= id.hashCode(); h *= 1000003; h ^= (kind == null) ? 0 : kind.hashCode(); h *= 1000003; h ^= (name == null) ? 0 : name.hashCode(); h *= 1000003; h ^= (int) (h ^ ((timestamp >>> 32) ^ timestamp)); h *= 1000003; h ^= (int) (h ^ ((duration >>> 32) ^ duration)); h *= 1000003; h ^= (localEndpoint == null) ? 0 : localEndpoint.hashCode(); h *= 1000003; h ^= (remoteEndpoint == null) ? 0 : remoteEndpoint.hashCode(); h *= 1000003; h ^= annotations.hashCode(); h *= 1000003; h ^= tags.hashCode(); h *= 1000003; h ^= flags; return h; } // This is an immutable object, and our encoder is faster than java's: use a serialization proxy. final Object writeReplace() throws ObjectStreamException { return new SerializedForm(SpanBytesEncoder.PROTO3.encode(this)); } private static final class SerializedForm implements Serializable { private static final long serialVersionUID = 0L; final byte[] bytes; SerializedForm(byte[] bytes) { this.bytes = bytes; } Object readResolve() throws ObjectStreamException { try { return SpanBytesDecoder.PROTO3.decodeOne(bytes); } catch (IllegalArgumentException e) { throw new StreamCorruptedException(e.getMessage()); } } } }





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