org.apache.hadoop.io.wrappedio

Class WrappedStatistics

java.lang.Object

org.apache.hadoop.io.wrappedio.WrappedStatistics

@InterfaceAudience.Public
 @InterfaceStability.Unstable
public final class WrappedStatistics
extends Object

Reflection-friendly access to IOStatistics APIs. All Serializable arguments/return values are actually IOStatisticsSource instances; passing in the wrong value will raise IllegalArgumentExceptions.

Method Summary

Modifier and Type	Method and Description
static <T> T	applyToIOStatisticsSnapshot(Serializable source, org.apache.hadoop.util.functional.FunctionRaisingIOE<IOStatisticsSnapshot,T> fun) Apply a function to an object which may be an IOStatisticsSnapshot.
static Map<String,Long>	iostatistics_counters(Serializable source) Get the counters of an IOStatisticsSnapshot.
static Map<String,Long>	iostatistics_gauges(Serializable source) Get the gauges of an IOStatisticsSnapshot.
static Map<String,Long>	iostatistics_maximums(Serializable source) Get the maximums of an IOStatisticsSnapshot.
static Map<String,Map.Entry<Long,Long>>	iostatistics_means(Serializable source) Get the means of an IOStatisticsSnapshot.
static Map<String,Long>	iostatistics_minimums(Serializable source) Get the minimums of an IOStatisticsSnapshot.
static String	iostatistics_toPrettyString(Object statistics) Convert IOStatistics to a string form, with all the metrics sorted and empty value stripped.
static boolean	iostatisticsContext_aggregate(Object source) Aggregate into the IOStatistics context the statistics passed in via IOStatistics/source parameter.
static boolean	iostatisticsContext_enabled() Static probe to check if the thread-level IO statistics enabled.
static Object	iostatisticsContext_getCurrent() Get the context's IOStatisticsContext which implements IOStatisticsSource.
static void	iostatisticsContext_reset() Reset the context's IOStatistics.
static void	iostatisticsContext_setThreadIOStatisticsContext(Object statisticsContext) Set the IOStatisticsContext for the current thread.
static Serializable	iostatisticsContext_snapshot() Take a snapshot of the context IOStatistics.
static boolean	iostatisticsSnapshot_aggregate(Serializable snapshot, Object statistics) Aggregate an existing IOStatisticsSnapshot with the supplied statistics.
static Serializable	iostatisticsSnapshot_create() Create a new IOStatisticsSnapshot instance.
static Serializable	iostatisticsSnapshot_create(Object source) Create a new IOStatisticsSnapshot instance.
static Serializable	iostatisticsSnapshot_fromJsonString(String json) Load IOStatisticsSnapshot from a JSON string.
static Serializable	iostatisticsSnapshot_load(FileSystem fs, Path path) Load IOStatisticsSnapshot from a Hadoop filesystem.
static Serializable	iostatisticsSnapshot_retrieve(Object source) Extract the IOStatistics from an object in a serializable form.
static void	iostatisticsSnapshot_save(Serializable snapshot, FileSystem fs, Path path, boolean overwrite) Save IOStatisticsSnapshot to a Hadoop filesystem as a JSON file.
static String	iostatisticsSnapshot_toJsonString(Serializable snapshot) Save IOStatisticsSnapshot to a JSON string.
static boolean	isIOStatistics(Object object) Probe for an object being an instance of IOStatistics.
static boolean	isIOStatisticsSnapshot(Serializable object) Probe for an object being an instance of IOStatisticsSnapshot.
static boolean	isIOStatisticsSource(Object object) Probe for an object being an instance of IOStatisticsSource.

Methods inherited from class java.lang.Object

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

Method Detail

isIOStatisticsSource

public static boolean isIOStatisticsSource(Object object)

Probe for an object being an instance of IOStatisticsSource.

Parameters:

object - object to probe

Returns:

true if the object is the right type.

isIOStatistics

public static boolean isIOStatistics(Object object)

Probe for an object being an instance of IOStatistics.

Parameters:

object - object to probe

Returns:

true if the object is the right type.

isIOStatisticsSnapshot

public static boolean isIOStatisticsSnapshot(Serializable object)

Probe for an object being an instance of IOStatisticsSnapshot.

Parameters:

object - object to probe

Returns:

true if the object is the right type.

iostatisticsSnapshot_aggregate

public static boolean iostatisticsSnapshot_aggregate(Serializable snapshot,
                                                     @Nullable
                                                     Object statistics)

Aggregate an existing IOStatisticsSnapshot with the supplied statistics.

Parameters:

snapshot - snapshot to update

statistics - IOStatistics to add

Returns:

true if the snapshot was updated.

Throws:

IllegalArgumentException - if the statistics argument is not null but not an instance of IOStatistics, or if snapshot is invalid.

iostatisticsSnapshot_create

public static Serializable iostatisticsSnapshot_create()

Create a new IOStatisticsSnapshot instance.

Returns:

an empty IOStatisticsSnapshot.

iostatisticsSnapshot_create

public static Serializable iostatisticsSnapshot_create(@Nullable
                                                       Object source)

Create a new IOStatisticsSnapshot instance.

Parameters:

source - optional source statistics

Returns:

an IOStatisticsSnapshot.

Throws:

ClassCastException - if the source is not null and not an IOStatistics instance

iostatisticsSnapshot_load

public static Serializable iostatisticsSnapshot_load(FileSystem fs,
                                                     Path path)

Load IOStatisticsSnapshot from a Hadoop filesystem.

Parameters:

fs - filesystem

path - path

Returns:

the loaded snapshot

Throws:

UncheckedIOException - Any IO exception.

iostatisticsSnapshot_retrieve

public static Serializable iostatisticsSnapshot_retrieve(@Nullable
                                                         Object source)

Extract the IOStatistics from an object in a serializable form.

Parameters:

source - source object, may be null/not a statistics source/instance

Returns:

IOStatisticsSnapshot or null if the object is null/doesn't have statistics

iostatisticsSnapshot_save

public static void iostatisticsSnapshot_save(@Nullable
                                             Serializable snapshot,
                                             FileSystem fs,
                                             Path path,
                                             boolean overwrite)

Save IOStatisticsSnapshot to a Hadoop filesystem as a JSON file.

Parameters:

snapshot - statistics

fs - filesystem

path - path

overwrite - should any existing file be overwritten?

Throws:

UncheckedIOException - Any IO exception.

iostatisticsSnapshot_toJsonString

public static String iostatisticsSnapshot_toJsonString(@Nullable
                                                       Serializable snapshot)

Save IOStatisticsSnapshot to a JSON string.

Parameters:

snapshot - statistics; may be null or of an incompatible type

Returns:

JSON string value

Throws:

UncheckedIOException - Any IO/jackson exception.

IllegalArgumentException - if the supplied class is not a snapshot

iostatisticsSnapshot_fromJsonString

public static Serializable iostatisticsSnapshot_fromJsonString(String json)

Load IOStatisticsSnapshot from a JSON string.

Parameters:

json - JSON string value.

Returns:

deserialized snapshot.

Throws:

UncheckedIOException - Any IO/jackson exception.

iostatistics_counters

public static Map<String,Long> iostatistics_counters(Serializable source)

Get the counters of an IOStatisticsSnapshot.

Parameters:

source - source of statistics.

Returns:

the map of counters.

iostatistics_gauges

public static Map<String,Long> iostatistics_gauges(Serializable source)

Get the gauges of an IOStatisticsSnapshot.

Parameters:

source - source of statistics.

Returns:

the map of gauges.

iostatistics_minimums

public static Map<String,Long> iostatistics_minimums(Serializable source)

Get the minimums of an IOStatisticsSnapshot.

Parameters:

source - source of statistics.

Returns:

the map of minimums.

iostatistics_maximums

public static Map<String,Long> iostatistics_maximums(Serializable source)

Get the maximums of an IOStatisticsSnapshot.

Parameters:

source - source of statistics.

Returns:

the map of maximums.

iostatistics_means

public static Map<String,Map.Entry<Long,Long>> iostatistics_means(Serializable source)

Get the means of an IOStatisticsSnapshot. Each value in the map is the (sample, sum) tuple of the values; the mean is then calculated by dividing sum/sample wherever sample count is non-zero.

Parameters:

source - source of statistics.

Returns:

a map of mean key to (sample, sum) tuples.

iostatisticsContext_getCurrent

public static Object iostatisticsContext_getCurrent()

Get the context's IOStatisticsContext which implements IOStatisticsSource. This is either a thread-local value or a global empty context.

Returns:

instance of IOStatisticsContext.

iostatisticsContext_setThreadIOStatisticsContext

public static void iostatisticsContext_setThreadIOStatisticsContext(@Nullable
                                                                    Object statisticsContext)

Set the IOStatisticsContext for the current thread.

Parameters:

statisticsContext - IOStatistics context instance for the current thread. If null, the context is reset.

iostatisticsContext_enabled

public static boolean iostatisticsContext_enabled()

Static probe to check if the thread-level IO statistics enabled.

Returns:

true if the thread-level IO statistics are enabled.

iostatisticsContext_reset

public static void iostatisticsContext_reset()

Reset the context's IOStatistics. IOStatisticsContext.reset()

iostatisticsContext_snapshot

public static Serializable iostatisticsContext_snapshot()

Take a snapshot of the context IOStatistics. IOStatisticsContext.snapshot()

Returns:

an instance of IOStatisticsSnapshot.

iostatisticsContext_aggregate

public static boolean iostatisticsContext_aggregate(Object source)

Aggregate into the IOStatistics context the statistics passed in via IOStatistics/source parameter.

Returns false if the source is null or does not contain any statistics.

Parameters:

source - implementation of IOStatisticsSource or IOStatistics

Returns:

true if the the source object was aggregated.

iostatistics_toPrettyString

public static String iostatistics_toPrettyString(@Nullable
                                                 Object statistics)

Convert IOStatistics to a string form, with all the metrics sorted and empty value stripped.

Parameters:

statistics - A statistics instance; may be null

Returns:

string value or the empty string if null

applyToIOStatisticsSnapshot

public static <T> T applyToIOStatisticsSnapshot(Serializable source,
                                                org.apache.hadoop.util.functional.FunctionRaisingIOE<IOStatisticsSnapshot,T> fun)

Apply a function to an object which may be an IOStatisticsSnapshot.

Type Parameters:

T - return type

Parameters:

source - statistics snapshot

fun - function to invoke if source is valid.

Returns:

the applied value

Throws:

UncheckedIOException - Any IO exception.

IllegalArgumentException - if the supplied class is not a snapshot