org.apache.htrace.core

Class Tracer

java.lang.Object

org.apache.htrace.core.Tracer

All Implemented Interfaces:

Closeable, AutoCloseable

public class Tracer
extends Object
implements Closeable

Use a Tracer instance inside a 'process' to collect and distribute its trace Spans. Example processes are an HDFS DataNode or an HBase RegionServer. A Tracer instance is your one-stop shop for all things tracing.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Tracer.Builder

Field Summary

Fields

Modifier and Type	Field and Description
static String	SAMPLER_CLASSES_KEY
static String	SPAN_RECEIVER_CLASSES_KEY

Method Summary

Methods

Modifier and Type	Method and Description
boolean	addSampler(Sampler sampler) Add a new Sampler.
void	close()
static Tracer	curThreadTracer()
boolean	equals(Object other) Compare two tracer objects.
static Span	getCurrentSpan()
static SpanId	getCurrentSpanId()
Sampler[]	getSamplers() Returns an array of all the current Samplers.
String	getTracerId()
TracerPool	getTracerPool()
int	hashCode() Get the hash code of a Tracer object.
TraceScope	newNullScope() Return a null trace scope.
TraceScope	newScope(String description) Create a new trace scope.
TraceScope	newScope(String description, SpanId parentId) Create a new trace scope.
TraceExecutorService	newTraceExecutorService(ExecutorService impl, String scopeName)
boolean	removeSampler(Sampler sampler) Remove a SpanReceiver.
String	toString()
<V> Callable<V>	wrap(Callable<V> callable, String description) Wrap the callable in a TraceCallable, if tracing.
Runnable	wrap(Runnable runnable, String description) Wrap the runnable in a TraceRunnable, if tracing

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

SPAN_RECEIVER_CLASSES_KEY

public static final String SPAN_RECEIVER_CLASSES_KEY

See Also:

Constant Field Values

SAMPLER_CLASSES_KEY

public static final String SAMPLER_CLASSES_KEY

See Also:

Constant Field Values

Method Detail

curThreadTracer

public static Tracer curThreadTracer()

Returns:

If the current thread is tracing, this function returns the Tracer that is being used; otherwise, it returns null.

getTracerId

public String getTracerId()

newScope

public TraceScope newScope(String description,
                  SpanId parentId)

Create a new trace scope. If there are no scopes above the current scope, we will apply our configured samplers. Otherwise, we will create a trace Span only if this thread is already tracing, or if the passed parentID was valid.

Parameters:

description - The description of the new span to create.

parentId - If this is a valid span ID, it will be added to the parents of the new span we create.

Returns:

The new trace scope.

newScope

public TraceScope newScope(String description)

Create a new trace scope. If there are no scopes above the current scope, we will apply our configured samplers. Otherwise, we will create a trace Span only if this thread is already tracing.

Parameters:

description - The description of the new span to create.

Returns:

The new trace scope.

newNullScope

public TraceScope newNullScope()

Return a null trace scope.

wrap

public <V> Callable<V> wrap(Callable<V> callable,
                   String description)

Wrap the callable in a TraceCallable, if tracing.

Returns:

The callable provided, wrapped if tracing, 'callable' if not.

wrap

public Runnable wrap(Runnable runnable,
            String description)

Wrap the runnable in a TraceRunnable, if tracing

Returns:

The runnable provided, wrapped if tracing, 'runnable' if not.

newTraceExecutorService

public TraceExecutorService newTraceExecutorService(ExecutorService impl,
                                           String scopeName)

getTracerPool

public TracerPool getTracerPool()

getSamplers

public Sampler[] getSamplers()

Returns an array of all the current Samplers. Note that if the current Samplers change, those changes will not be reflected in this array. In other words, this array may be stale.

addSampler

public boolean addSampler(Sampler sampler)

Add a new Sampler.

Parameters:

sampler - The new sampler to add. You cannot add a particular Sampler object more than once. You may add multiple Sampler objects of the same type, although this is not recommended.

Returns:

True if the sampler was added; false if it already had been added earlier.

removeSampler

public boolean removeSampler(Sampler sampler)

Remove a SpanReceiver.

Parameters:

sampler - The sampler to remove.

getCurrentSpan

public static Span getCurrentSpan()

getCurrentSpanId

public static SpanId getCurrentSpanId()

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

hashCode

public int hashCode()

Get the hash code of a Tracer object. This hash code is based on object identity. This is used in TracerPool to create a hash table of Tracers.

Overrides:

hashCode in class Object

equals

public boolean equals(Object other)

Compare two tracer objects. Tracer objects are always compared by object equality. This is used in TracerPool to create a hash table of Tracers.

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object