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Add comments for major class in agent-core.

This commit is contained in:
wusheng 2017-07-08 13:52:52 +08:00
parent 1b1f8d49c1
commit 95f65beb93
7 changed files with 92 additions and 11 deletions
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8
apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/ContextManager.java
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@ -119,7 +119,9 @@ public class ContextManager implements TracingContextListener, BootService, Igno
if (carrier == null) {
throw new IllegalArgumentException("ContextCarrier can't be null.");
}
get().extract(carrier);
if (carrier.isValid()) {
get().extract(carrier);
}
}
public ContextSnapshot capture() {
@ -130,7 +132,9 @@ public class ContextManager implements TracingContextListener, BootService, Igno
if (snapshot == null) {
throw new IllegalArgumentException("ContextSnapshot can't be null.");
}
get().continued(snapshot);
if (snapshot.isValid()) {
get().continued(snapshot);
}
}
public static AbstractSpan activeSpan() {

16
apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/ContextSnapshot.java
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@ -4,13 +4,20 @@ import java.util.List;
import org.skywalking.apm.agent.core.context.ids.DistributedTraceId;
/**
* The <code>ContextSnapshot</code> is a snapshot for current context.
* The <code>ContextSnapshot</code> is a snapshot for current context. The snapshot carries the info for building
* reference between two segments in two thread, but have a causal relationship.
*
* @author wusheng
*/
public class ContextSnapshot {
/**
* trace segment id of the parent trace segment.
*/
private String traceSegmentId;
/**
* span id of the parent span, in parent trace segment.
*/
private int spanId = -1;
/**
@ -36,4 +43,11 @@ public class ContextSnapshot {
public int getSpanId() {
return spanId;
}
public boolean isValid() {
return traceSegmentId != null
&& spanId > -1
&& distributedTraceIds != null
&& distributedTraceIds.size() > 0;
}
}

5
apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/IgnoredTracerContext.java
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@ -7,8 +7,9 @@ import org.skywalking.apm.agent.core.context.trace.NoopSpan;
/**
* The <code>IgnoredTracerContext</code> represent a context should be ignored.
* So it just maintains the stack with integer depth.
* All operations through this <code>IgnoredTracerContext</code> will be ignored, with low gc cost.
* So it just maintains the stack with an integer depth field.
*
* All operations through this will be ignored, and keep the memory and gc cost as low as possible.
*
* @author wusheng
*/

56
apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/TracingContext.java
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@ -112,12 +112,24 @@ public class TracingContext implements AbstractTracerContext {
carrier.setDistributedTraceIds(this.segment.getRelatedGlobalTraces());
}
/**
* Extract the carrier to build the reference for the pre segment.
*
* @param carrier carried the context from a cross-process segment.
* @see {@link AbstractTracerContext#extract(ContextCarrier)}
*/
@Override
public void extract(ContextCarrier carrier) {
this.segment.ref(new TraceSegmentRef(carrier));
this.segment.relatedGlobalTraces(carrier.getDistributedTraceIds());
}
/**
* Capture the snapshot of current context.
*
* @return the snapshot of context for cross-thread propagation
* @see {@link AbstractTracerContext#capture()}
*/
@Override
public ContextSnapshot capture() {
return new ContextSnapshot(segment.getTraceSegmentId(),
@ -126,17 +138,33 @@ public class TracingContext implements AbstractTracerContext {
);
}
/**
* Continue the context from the given snapshot of parent thread.
*
* @param snapshot from {@link #capture()} in the parent thread.
* @see {@link AbstractTracerContext#continued(ContextSnapshot)}
*/
@Override
public void continued(ContextSnapshot snapshot) {
this.segment.ref(new TraceSegmentRef(snapshot));
this.segment.relatedGlobalTraces(snapshot.getDistributedTraceIds());
}
/**
* @return the first global trace id.
*/
@Override
public String getGlobalTraceId() {
return segment.getRelatedGlobalTraces().get(0).get();
}
/**
* Create an entry span
*
* @param operationName most likely a service name
* @return span instance.
* @see {@link EntrySpan}
*/
@Override
public AbstractSpan createEntrySpan(final String operationName) {
AbstractTracingSpan entrySpan;
@ -174,6 +202,13 @@ public class TracingContext implements AbstractTracerContext {
}
}
/**
* Create a local span
*
* @param operationName most likely a local method signature, or business name.
* @return the span represents a local logic block.
* @see {@link LocalSpan}
*/
@Override
public AbstractSpan createLocalSpan(final String operationName) {
AbstractTracingSpan parentSpan = peek();
@ -195,6 +230,14 @@ public class TracingContext implements AbstractTracerContext {
return push(span);
}
/**
* Create an exit span
*
* @param operationName most likely a service name of remote
* @param remotePeer the network id(ip:port, hostname:port or ip1:port1,ip2,port, etc.)
* @return the span represent an exit point of this segment.
* @see {@link ExitSpan}
*/
@Override
public AbstractSpan createExitSpan(final String operationName, final String remotePeer) {
AbstractTracingSpan exitSpan;
@ -236,6 +279,9 @@ public class TracingContext implements AbstractTracerContext {
return exitSpan;
}
/**
* @return the active span of current context, the top element of {@link #activeSpanStack}
*/
@Override
public AbstractTracingSpan activeSpan() {
AbstractTracingSpan span = peek();
@ -245,6 +291,12 @@ public class TracingContext implements AbstractTracerContext {
return span;
}
/**
* Stop the given span, if and only if this one is the top element of {@link #activeSpanStack}.
* Because the tracing core must make sure the span must match in a stack module, like any program did.
*
* @param span to finish
*/
@Override
public void stopSpan(AbstractSpan span) {
AbstractTracingSpan lastSpan = peek();
@ -281,6 +333,10 @@ public class TracingContext implements AbstractTracerContext {
TracingContext.ListenerManager.notifyFinish(finishedSegment);
}
/**
* The <code>ListenerManager</code> represents an event notify for every registered listener, which are notified
* when the <cdoe>TracingContext</cdoe> finished, and {@link #segment} is ready for further process.
*/
public static class ListenerManager {
private static List<TracingContextListener> LISTENERS = new LinkedList<TracingContextListener>();

5
apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/EntrySpan.java
View File

@ -6,11 +6,14 @@ import org.skywalking.apm.network.trace.component.Component;
/**
* The <code>EntrySpan</code> represents a service provider point, such as Tomcat server entrance.
*
* It is a start point of {@link TraceSegment}, even in a complex application, there maybe have multi entry point,
* It is a start point of {@link TraceSegment}, even in a complex application, there maybe have multi-layer entry point,
* the <code>EntrySpan</code> only represents the first one.
*
* But with the last <code>EntrySpan</code>'s tags and logs, which have more details about a service provider.
*
* Such as: Tomcat Embed -> Dubbox
* The <code>EntrySpan</code> represents the Dubbox span.
*
* @author wusheng
*/
public class EntrySpan extends AbstractTracingSpan {

7
apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/ExitSpan.java
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@ -5,13 +5,16 @@ import org.skywalking.apm.network.proto.SpanObject;
import org.skywalking.apm.network.trace.component.Component;
/**
* The <code>ExitSpan</code> represents a service consumer point, such as Feign, Okhttp discovery for a Http service.
* The <code>ExitSpan</code> represents a service consumer point, such as Feign, Okhttp client for a Http service.
*
* It is an exit point or a leaf span(our old name) of trace tree.
* In a single rpc call, because of a combination of discovery libs, there maybe contain multi exit point.
* In a single rpc call, because of a combination of discovery libs, there maybe contain multi-layer exit point:
*
* The <code>ExitSpan</code> only presents the first one.
*
* Such as: Dubbox -> Apache Httpcomponent -> ....(Remote)
* The <code>ExitSpan</code> represents the Dubbox span, and ignore the httpcomponent span's info.
*
* @author wusheng
*/
public class ExitSpan extends AbstractTracingSpan {

6
apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/NoopSpan.java
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@ -5,7 +5,8 @@ import org.skywalking.apm.network.trace.component.Component;
/**
* The <code>NoopSpan</code> represents a span implementation without any actual operation.
* This span implementation is for {@link IgnoredTracerContext}.
* This span implementation is for {@link IgnoredTracerContext},
* for keeping the memory and gc cost as low as possible.
*
* @author wusheng
*/
@ -13,7 +14,6 @@ public class NoopSpan implements AbstractSpan {
public NoopSpan() {
}
@Override
public AbstractSpan log(Throwable t) {
return this;
@ -23,7 +23,7 @@ public class NoopSpan implements AbstractSpan {
return null;
}
public void finish(){
public void finish() {
}