net.openhft.affinity

Class AffinityLock

java.lang.Object

net.openhft.affinity.AffinityLock

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

NonForkingAffinityLock

public class AffinityLock
extends Object
implements Closeable

This utility class support locking a thread to a single core, or reserving a whole core for a thread.

Author:

peter.lawrey

Field Summary

Fields

Modifier and Type	Field and Description
static String	AFFINITY_RESERVED
static long	BASE_AFFINITY
static int	PROCESSORS
static long	RESERVED_AFFINITY

Method Summary

Methods

Modifier and Type	Method and Description
static AffinityLock	acquireCore() Assign any free core to this thread.
static AffinityLock	acquireCore(boolean bind) Assign a core(and all its cpus) which can be bound to the current thread or another thread.
static AffinityLock	acquireLock() Assign any free cpu to this thread.
AffinityLock	acquireLock(AffinityStrategy... strategies) Give another affinity lock relative to this one based on a list of strategies.
static AffinityLock	acquireLock(boolean bind) Assign a cpu which can be bound to the current thread or another thread.
void	bind() Bind the current thread to this reservable lock.
void	bind(boolean wholeCore) Bind the current thread to this reservable lock.
void	close()
int	cpuId()
static CpuLayout	cpuLayout()
static void	cpuLayout(CpuLayout cpuLayout) Set the CPU layout for this machine.
static String	dumpLocks()
protected void	finalize()
boolean	isAllocated()
boolean	isBound()
static void	main(String[] args)
void	release() Release the current AffinityLock which can be discarded.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

AFFINITY_RESERVED

public static final String AFFINITY_RESERVED

See Also:

Constant Field Values

PROCESSORS

public static final int PROCESSORS

BASE_AFFINITY

public static final long BASE_AFFINITY

RESERVED_AFFINITY

public static final long RESERVED_AFFINITY

Method Detail

cpuLayout

public static void cpuLayout(@NotNull
             CpuLayout cpuLayout)

Set the CPU layout for this machine. CPUs which are not mentioned will be ignored.

Changing the layout will have no impact on thread which have already been assigned. It only affects subsequent assignments.

Parameters:

cpuLayout - for this application to use for this machine.

cpuLayout

@NotNull
public static CpuLayout cpuLayout()

Returns:

The current CpuLayout for the application.

acquireLock

public static AffinityLock acquireLock()

Assign any free cpu to this thread.

Returns:

A handle for the current AffinityLock.

acquireCore

public static AffinityLock acquireCore()

Assign any free core to this thread.

In reality, only one cpu is assigned, the rest of the threads for that core are reservable so they are not used.

Returns:

A handle for the current AffinityLock.

acquireLock

public static AffinityLock acquireLock(boolean bind)

Assign a cpu which can be bound to the current thread or another thread.

This can be used for defining your thread layout centrally and passing the handle via dependency injection.

Parameters:

bind - if true, bind the current thread, if false, reserve a cpu which can be bound later.

Returns:

A handle for an affinity lock.

acquireCore

public static AffinityLock acquireCore(boolean bind)

Assign a core(and all its cpus) which can be bound to the current thread or another thread.

This can be used for defining your thread layout centrally and passing the handle via dependency injection.

Parameters:

bind - if true, bind the current thread, if false, reserve a cpu which can be bound later.

Returns:

A handle for an affinity lock.

dumpLocks

@NotNull
public static String dumpLocks()

Returns:

All the current locks as a String.

bind

public void bind()

Bind the current thread to this reservable lock.

bind

public void bind(boolean wholeCore)

Bind the current thread to this reservable lock.

Parameters:

wholeCore - if true, also reserve the whole core.

acquireLock

public AffinityLock acquireLock(AffinityStrategy... strategies)

Give another affinity lock relative to this one based on a list of strategies.

The strategies are evaluated in order to (like a search path) to find the next appropriate thread. If ANY is not the last strategy, a warning is logged and no cpu is assigned (leaving the OS to choose)

Parameters:

strategies - To determine if you want the same/different core/socket.

Returns:

A matching AffinityLock.

release

public void release()

Release the current AffinityLock which can be discarded.

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

finalize

protected void finalize()
                 throws Throwable

Overrides:

finalize in class Object

Throws:

Throwable

cpuId

public int cpuId()

Returns:

unique id for this CPI or -1 if not allocated.

isAllocated

public boolean isAllocated()

Returns:

Was a cpu found to bind this lock to.

isBound

public boolean isBound()

Returns:

Has this AffinityLock been bound?

toString

public String toString()

Overrides:

toString in class Object

main

public static void main(String[] args)