com.google.cloud.dataflow.sdk.util.common.worker

Class StateSampler

java.lang.Object

java.util.TimerTask

com.google.cloud.dataflow.sdk.util.common.worker.StateSampler

All Implemented Interfaces:

AutoCloseable, Runnable

@ThreadSafe
public class StateSampler
extends TimerTask
implements AutoCloseable

A StateSampler object may be used to obtain an approximate breakdown of the time spent by an execution context in various states, as a fraction of the total time. The sampling is taken at regular intervals, with adjustment for scheduling delay.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	StateSampler.ScopedState A nested class that is used to account for states and state transitions based on lexical scopes.

Field Summary

Fields

Modifier and Type	Field and Description
static long	DEFAULT_SAMPLING_PERIOD_MS

Constructor Summary

Constructors

Constructor and Description
StateSampler(String prefix, CounterSet.AddCounterMutator counterSetMutator) Constructs a new StateSampler that can be used to obtain an approximate breakdown of the time spent by an execution context in various states, as a fraction of the total time.
StateSampler(String prefix, CounterSet.AddCounterMutator counterSetMutator, long samplingPeriodMs) Constructs a new StateSampler that can be used to obtain an approximate breakdown of the time spent by an execution context in various states, as a fraction of the total time.

Method Summary

Modifier and Type	Method and Description
void	close()
void	run()
StateSampler.ScopedState	scopedState(int state) Returns an AutoCloseable StateSampler.ScopedState that will perform a state transition to the given state, and will automatically reset the state to the prior state upon closing.
int	setState(int state) Sets the current thread state.
int	setState(String name) Sets the current thread state.
int	stateForName(String name) Returns the state associated with a name; creating a new state if necessary.

Methods inherited from class java.util.TimerTask

cancel, scheduledExecutionTime

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_SAMPLING_PERIOD_MS

public static final long DEFAULT_SAMPLING_PERIOD_MS

See Also:

Constant Field Values

Constructor Detail

StateSampler

public StateSampler(String prefix,
                    CounterSet.AddCounterMutator counterSetMutator,
                    long samplingPeriodMs)

Constructs a new StateSampler that can be used to obtain an approximate breakdown of the time spent by an execution context in various states, as a fraction of the total time.

Parameters:

prefix - the prefix of the counter names for the states

counterSetMutator - the CounterSet.AddCounterMutator used to create a counter for each distinct state

samplingPeriodMs - the sampling period in milliseconds

StateSampler

public StateSampler(String prefix,
                    CounterSet.AddCounterMutator counterSetMutator)

Constructs a new StateSampler that can be used to obtain an approximate breakdown of the time spent by an execution context in various states, as a fraction of the total time.

Parameters:

prefix - the prefix of the counter names for the states

counterSetMutator - the CounterSet.AddCounterMutator used to create a counter for each distinct state

Method Detail

run

public void run()

Specified by:

run in interface Runnable

Specified by:

run in class TimerTask

close

public void close()

Specified by:

close in interface AutoCloseable

stateForName

public int stateForName(String name)

Returns the state associated with a name; creating a new state if necessary. Using states instead of state names during state transitions is done for efficiency.

Returns:

the state associated with the state name

setState

public int setState(int state)

Sets the current thread state.

Parameters:

state - the new state to transition to

Returns:

the previous state

setState

public int setState(String name)

Sets the current thread state.

Parameters:

name - the name of the new state to transition to

Returns:

the previous state

scopedState

public StateSampler.ScopedState scopedState(int state)

Returns an AutoCloseable StateSampler.ScopedState that will perform a state transition to the given state, and will automatically reset the state to the prior state upon closing.

Parameters:

state - the new state to transition to

Returns:

a StateSampler.ScopedState that automatically resets the state to the prior state