Package org.apache.jackrabbit.oak.segment.tool.iotrace

Class IOTracer

java.lang.Object

org.apache.jackrabbit.oak.segment.tool.iotrace.IOTracer

public class IOTracer
extends Object

This utility class allows collecting IO traces of read accesses to segments caused by reading specific items.

An instance of Trace is used to specify a read pattern. Segment reads are recorded in CSV format:

 timestamp,file,segmentId,length,elapsed
 1522147945084,data01415a.tar,f81378df-b3f8-4b25-0000-00000002c450,181328,171849
 1522147945096,data01415a.tar,f81378df-b3f8-4b25-0000-00000002c450,181328,131272
 1522147945097,data01415a.tar,f81378df-b3f8-4b25-0000-00000002c450,181328,142766
 ...
 

Trace implementations can specify an additional context, which is recorded with each line of the CSV output. A context is simply a list of additional fields as specified during instantiation of an IOTracer.

Method Summary

Modifier and Type	Method	Description
void	collectTrace(@NotNull Trace trace)	Collect a IO trace.
static @NotNull IOTracer	newIOTracer(@NotNull Function<IOMonitor,FileStore> fileStoreFactory, @NotNull Writer output, @Nullable String contextSpec)	Create a new IOTracer instance.
void	setContext(@NotNull List<String> context)	Set the context to be added to each line of the IOTrace going forward.

Methods inherited from class java.lang.Object

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

Method Detail

newIOTracer

@NotNull
public static @NotNull IOTracer newIOTracer(@NotNull
                                            @NotNull Function<IOMonitor,FileStore> fileStoreFactory,
                                            @NotNull
                                            @NotNull Writer output,
                                            @Nullable
                                            @Nullable String contextSpec)

Create a new IOTracer instance.

Parameters:

fileStoreFactory - A factory for creating a FileStore with the passed IOMonitor for monitoring segment IO.

output - The target for the CSV formatted IO trace.

contextSpec - The specification of additional context provided by the traces being run. A trace consists of a comma separated list of values, which must match the list of values passed to setContext(List).

Returns:

A new IOTracer instance.

collectTrace

public void collectTrace(@NotNull
                         @NotNull Trace trace)

Collect a IO trace.

Parameters:

trace -

setContext

public void setContext(@NotNull
                       @NotNull List<String> context)

Set the context to be added to each line of the IOTrace going forward. The list of values needs to match the context specification passed to newIOTracer(Function, Writer, String).

Parameters:

context -