org.apache.skywalking.apm.agent.core.context

Class TracingContext

java.lang.Object

org.apache.skywalking.apm.agent.core.context.TracingContext

All Implemented Interfaces:

AbstractTracerContext

public class TracingContext
extends Object
implements AbstractTracerContext

The TracingContext represents a core tracing logic controller. It build the final TracingContext, by the stack mechanism, which is similar with the codes work. In opentracing concept, it means, all spans in a segment tracing context(thread) are CHILD_OF relationship, but no FOLLOW_OF. In skywalking core concept, FOLLOW_OF is an abstract concept when cross-process MQ or cross-thread async/batch tasks happen, we used TraceSegmentRef for these scenarios. Check TraceSegmentRef which is from ContextCarrier or ContextSnapshot.

Author:

wusheng, zhang xin

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	TracingContext.ListenerManager The ListenerManager represents an event notify for every registered listener, which are notified when the TracingContext finished, and segment is ready for further process.

Method Summary

Modifier and Type	Method and Description
AbstractSpan	activeSpan()
void	asyncStop(AsyncSpan span) The given span could be stopped officially.
AbstractTracerContext	awaitFinishAsync() Notify this context, current span is going to be finished async in another thread.
ContextSnapshot	capture() Capture the snapshot of current context.
void	continued(ContextSnapshot snapshot) Continue the context from the given snapshot of parent thread.
AbstractSpan	createEntrySpan(String operationName) Create an entry span
AbstractSpan	createExitSpan(String operationName, String remotePeer) Create an exit span
AbstractSpan	createLocalSpan(String operationName) Create a local span
void	extract(ContextCarrier carrier) Extract the carrier to build the reference for the pre segment.
String	getReadableGlobalTraceId() Get the global trace id, if needEnhance.
void	inject(ContextCarrier carrier) Inject the context into the given carrier, only when the active span is an exit one.
boolean	stopSpan(AbstractSpan span) Stop the given span, if and only if this one is the top element of activeSpanStack.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

inject

public void inject(ContextCarrier carrier)

Inject the context into the given carrier, only when the active span is an exit one.

Specified by:

inject in interface AbstractTracerContext

Parameters:

carrier - to carry the context for crossing process.

Throws:

IllegalStateException - if the active span isn't an exit one. Ref to AbstractTracerContext.inject(ContextCarrier)

extract

public void extract(ContextCarrier carrier)

Extract the carrier to build the reference for the pre segment.

Specified by:

extract in interface AbstractTracerContext

Parameters:

carrier - carried the context from a cross-process segment. Ref to AbstractTracerContext.extract(ContextCarrier)

capture

public ContextSnapshot capture()

Capture the snapshot of current context.

Specified by:

capture in interface AbstractTracerContext

Returns:

the snapshot of context for cross-thread propagation Ref to AbstractTracerContext.capture()

continued

public void continued(ContextSnapshot snapshot)

Continue the context from the given snapshot of parent thread.

Specified by:

continued in interface AbstractTracerContext

Parameters:

snapshot - from capture() in the parent thread. Ref to AbstractTracerContext.continued(ContextSnapshot)

getReadableGlobalTraceId

public String getReadableGlobalTraceId()

Description copied from interface: AbstractTracerContext

Get the global trace id, if needEnhance. How to build, depends on the implementation.

Specified by:

getReadableGlobalTraceId in interface AbstractTracerContext

Returns:

the first global trace id.

createEntrySpan

public AbstractSpan createEntrySpan(String operationName)

Create an entry span

Specified by:

createEntrySpan in interface AbstractTracerContext

Parameters:

operationName - most likely a service name

Returns:

span instance. Ref to EntrySpan

createLocalSpan

public AbstractSpan createLocalSpan(String operationName)

Create a local span

Specified by:

createLocalSpan in interface AbstractTracerContext

Parameters:

operationName - most likely a local method signature, or business name.

Returns:

the span represents a local logic block. Ref to LocalSpan

createExitSpan

public AbstractSpan createExitSpan(String operationName,
                                   String remotePeer)

Create an exit span

Specified by:

createExitSpan in interface AbstractTracerContext

Parameters:

operationName - most likely a service name of remote

remotePeer - the network id(ip:port, hostname:port or ip1:port1,ip2,port, etc.)

Returns:

the span represent an exit point of this segment.

See Also:

ExitSpan

activeSpan

public AbstractSpan activeSpan()

Specified by:

activeSpan in interface AbstractTracerContext

Returns:

the active span of current context, the top element of activeSpanStack

stopSpan

public boolean stopSpan(AbstractSpan span)

Stop the given span, if and only if this one is the top element of activeSpanStack. Because the tracing core must make sure the span must match in a stack module, like any program did.

Specified by:

stopSpan in interface AbstractTracerContext

Parameters:

span - to finish

Returns:

true when context should be clear.

awaitFinishAsync

public AbstractTracerContext awaitFinishAsync()

Description copied from interface: AbstractTracerContext

Notify this context, current span is going to be finished async in another thread.

Specified by:

awaitFinishAsync in interface AbstractTracerContext

Returns:

The current context

asyncStop

public void asyncStop(AsyncSpan span)

Description copied from interface: AbstractTracerContext

The given span could be stopped officially.

Specified by:

asyncStop in interface AbstractTracerContext

Parameters:

span - to be stopped.