Modifier and Type	Class and Description
public static class	CycleDetectingLock.CycleDetectingLockFactory<ID> Wraps locks so they would never cause a deadlock.

Modifier and Type	Method and Description
public ListMultimap<Thread, ID>	lockOrDetectPotentialLocksCycle() Takes a lock in a blocking fashion in case no potential deadlocks are detected.
public void	unlock() Unlocks previously locked lock.

lockOrDetectPotentialLocksCycle	back to summary
public ListMultimap<Thread, ID> lockOrDetectPotentialLocksCycle() Takes a lock in a blocking fashion in case no potential deadlocks are detected. If the lock was successfully owned, returns an empty map indicating no detected potential deadlocks. Otherwise, a map indicating threads involved in a potential deadlock are returned. Map is ordered by dependency cycle and lists locks for each thread that are part of the loop in order, the last lock in the list is the one that the thread is currently waiting for. Returned map is created atomically. In case no cycle is detected performance is O(threads creating singletons), in case cycle is detected performance is O(singleton locks).

unlock	back to summary
public void unlock() Unlocks previously locked lock.

com.google.inject.internal back to summary

public Class CycleDetectingLock.CycleDetectingLockFactory<ID>

Class Inheritance

extends Object

java.lang.Object
com.google.inject.internal.CycleDetectingLock.CycleDetectingLockFactory

Wraps locks so they would never cause a deadlock. On each CycleDetectingLock#lockOrDetectPotentialLocksCycle we check for dependency cycles within locks created by the same factory. Either we detect a cycle and return it or take it atomically.

Important to note that we do not prevent deadlocks in the client code. As an example: Thread A takes lock L and creates singleton class CA depending on the singleton class CB. Meanwhile thread B is creating class CB and is waiting on the lock L. Issue happens due to client code creating interdependent classes and using locks, where no guarantees on the creation order from Guice are provided.

Instances of these locks are not intended to be exposed outside of SingletonScope.

Nested and Inner Type Summary

Modifier and Type	Class and Description
pack-priv static class	CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<ID> The implementation for `CycleDetectingLock`.

Field Summary

Modifier and Type	Field and Description
private static final Multimap<Thread, CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?>>	locksOwnedByThread Lists locks that thread owns.
private static Map<Thread, CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?>>	lockThreadIsWaitingOn Specifies lock that thread is currently waiting on to own it.

Constructor Summary

Access	Constructor and Description
public	CycleDetectingLockFactory()

Method Summary

Modifier and Type	Method and Description
pack-priv CycleDetectingLock<ID>	create(ID lock id that would be used to report lock cycles if detected userLockId) Creates new lock within this factory context.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

locksOwnedByThread back to summary

locksOwnedByThread	back to summary
private static final Multimap<Thread, CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?>> locksOwnedByThread Lists locks that thread owns. Used only to populate locks in a potential cycle when it is detected. Key: thread Value: stack of locks that were owned. Element is added inside `lockOrDetectPotentialLocksCycle()` after `Lock#lock` is called. Element is removed inside `unlock()` synchronously with `Lock#unlock()` call. Same lock can only be present several times for the same thread as locks are reentrant. Lock can not be owned by several different threads as the same time. Guarded by `CycleDetectingLockFactory.class`.

private static final Multimap<Thread, CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?>> locksOwnedByThread

Lists locks that thread owns. Used only to populate locks in a potential cycle when it is detected.

Key: thread
Value: stack of locks that were owned.

Element is added inside lockOrDetectPotentialLocksCycle() after Lock#lock is called. Element is removed inside unlock() synchronously with Lock#unlock() call.

Same lock can only be present several times for the same thread as locks are reentrant. Lock can not be owned by several different threads as the same time.

Guarded by CycleDetectingLockFactory.class.

lockThreadIsWaitingOn back to summary

lockThreadIsWaitingOn	back to summary
private static Map<Thread, CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?>> lockThreadIsWaitingOn Specifies lock that thread is currently waiting on to own it. Used only for purposes of locks cycle detection. Key: thread Value: lock that is being waited on Element is added inside `lockOrDetectPotentialLocksCycle()` before `Lock#lock` is called. Element is removed inside `lockOrDetectPotentialLocksCycle()` after `Lock#lock` and synchronously with adding it to `locksOwnedByThread`. Same lock can be added for several threads in case all of them are trying to take it. Guarded by `CycleDetectingLockFactory.class`.

private static Map<Thread, CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?>> lockThreadIsWaitingOn

Specifies lock that thread is currently waiting on to own it. Used only for purposes of locks cycle detection.

Key: thread
Value: lock that is being waited on

Element is added inside lockOrDetectPotentialLocksCycle() before Lock#lock is called. Element is removed inside lockOrDetectPotentialLocksCycle() after Lock#lock and synchronously with adding it to locksOwnedByThread.

Same lock can be added for several threads in case all of them are trying to take it.

Guarded by CycleDetectingLockFactory.class.

Constructor Detail

CycleDetectingLockFactory	back to summary
public CycleDetectingLockFactory()

Method Detail

create	back to summary
pack-priv CycleDetectingLock<ID> create(ID userLockId) Creates new lock within this factory context. We can guarantee that locks created by the same factory would not deadlock. Parameters userLockId:ID lock id that would be used to report lock cycles if detected

create

back to summary

pack-priv CycleDetectingLock<ID> create(ID userLockId)

Creates new lock within this factory context. We can guarantee that locks created by the same factory would not deadlock.

Parameters

userLockId:ID: lock id that would be used to report lock cycles if detected

com.google.inject.internal back to summary

pack-priv Class CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<ID>

Class Inheritance

extends Object
implements CycleDetectingLock<ID>

java.lang.Object
com.google.inject.internal.CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock

All Implemented Interfaces

com.google.inject.internal.CycleDetectingLock

The implementation for CycleDetectingLock.

Field Summary

Modifier and Type	Field and Description
private final CycleDetectingLock.CycleDetectingLockFactory<ID>	lockFactory Factory that was used to create this lock.
private final Lock	lockImplementation Underlying lock used for actual waiting when no potential deadlocks are detected.
private Thread	lockOwnerThread Thread that owns this lock.
private int	lockReentranceCount Number of times that thread owned this lock.
private final ID	userLockId User id for this lock.

Constructor Summary

Access	Constructor and Description
pack-priv	ReentrantCycleDetectingLock(CycleDetectingLock.CycleDetectingLockFactory<ID> lockFactory, ID userLockId, Lock lockImplementation)

Method Summary

Modifier and Type	Method and Description
private CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?>	addAllLockIdsAfter(Thread thread, CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?> lock, ListMultimap<Thread, ID> potentialLocksCycle) Adds all locks held by the given thread that are after the given lock and then returns the lock the thread is currently waiting on, if any
pack-priv void	checkState() Check consistency of an internal state.
private ListMultimap<Thread, ID>	detectPotentialLocksCycle() Algorithm to detect a potential lock cycle.
public ListMultimap<Thread, ID>	lockOrDetectPotentialLocksCycle() Implements com.google.inject.internal.CycleDetectingLock.lockOrDetectPotentialLocksCycle. Takes a lock in a blocking fashion in case no potential deadlocks are detected.
public String	toString() Overrides java.lang.Object.toString. Returns a string representation of the object.
public void	unlock() Implements com.google.inject.internal.CycleDetectingLock.unlock. Unlocks previously locked lock.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll wait wait wait

Field Detail

lockFactory	back to summary
private final CycleDetectingLock.CycleDetectingLockFactory<ID> lockFactory Factory that was used to create this lock.

lockImplementation	back to summary
private final Lock lockImplementation Underlying lock used for actual waiting when no potential deadlocks are detected.

lockOwnerThread	back to summary
private Thread lockOwnerThread Thread that owns this lock. Nullable. Guarded by `CycleDetectingLockFactory.this`.

lockReentranceCount	back to summary
private int lockReentranceCount Number of times that thread owned this lock. Guarded by `CycleDetectingLockFactory.this`.

userLockId	back to summary
private final ID userLockId User id for this lock.

Constructor Detail

ReentrantCycleDetectingLock	back to summary
pack-priv ReentrantCycleDetectingLock(CycleDetectingLock.CycleDetectingLockFactory<ID> lockFactory, ID userLockId, Lock lockImplementation)

Method Detail

addAllLockIdsAfter	back to summary
private CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?> addAllLockIdsAfter(Thread thread, CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<?> lock, ListMultimap<Thread, ID> potentialLocksCycle) Adds all locks held by the given thread that are after the given lock and then returns the lock the thread is currently waiting on, if any

checkState	back to summary
pack-priv void checkState() throws IllegalStateException Check consistency of an internal state.

detectPotentialLocksCycle back to summary

detectPotentialLocksCycle	back to summary
private ListMultimap<Thread, ID> detectPotentialLocksCycle() Algorithm to detect a potential lock cycle. For lock's thread owner check which lock is it trying to take. Repeat recursively. When current thread is found a potential cycle is detected. See Also `CycleDetectingLock#lockOrDetectPotentialLocksCycle()`

private ListMultimap<Thread, ID> detectPotentialLocksCycle()

Algorithm to detect a potential lock cycle.

For lock's thread owner check which lock is it trying to take. Repeat recursively. When current thread is found a potential cycle is detected.

See Also: CycleDetectingLock#lockOrDetectPotentialLocksCycle()

lockOrDetectPotentialLocksCycle	back to summary
public ListMultimap<Thread, ID> lockOrDetectPotentialLocksCycle() Implements com.google.inject.internal.CycleDetectingLock.lockOrDetectPotentialLocksCycle. Doc from com.google.inject.internal.CycleDetectingLock.lockOrDetectPotentialLocksCycle. Takes a lock in a blocking fashion in case no potential deadlocks are detected. If the lock was successfully owned, returns an empty map indicating no detected potential deadlocks. Otherwise, a map indicating threads involved in a potential deadlock are returned. Map is ordered by dependency cycle and lists locks for each thread that are part of the loop in order, the last lock in the list is the one that the thread is currently waiting for. Returned map is created atomically. In case no cycle is detected performance is O(threads creating singletons), in case cycle is detected performance is O(singleton locks). Annotations @Override

lockOrDetectPotentialLocksCycle

back to summary

public ListMultimap<Thread, ID> lockOrDetectPotentialLocksCycle()

Implements com.google.inject.internal.CycleDetectingLock.lockOrDetectPotentialLocksCycle.

Doc from com.google.inject.internal.CycleDetectingLock.lockOrDetectPotentialLocksCycle.

Takes a lock in a blocking fashion in case no potential deadlocks are detected. If the lock was successfully owned, returns an empty map indicating no detected potential deadlocks.

Otherwise, a map indicating threads involved in a potential deadlock are returned. Map is ordered by dependency cycle and lists locks for each thread that are part of the loop in order, the last lock in the list is the one that the thread is currently waiting for. Returned map is created atomically.

In case no cycle is detected performance is O(threads creating singletons), in case cycle is detected performance is O(singleton locks).

Annotations

@Override

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Doc from java.lang.Object.toString. Returns a string representation of the object. Returns:String a string representation of the object Annotations @Override

toString

back to summary

public String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object.

Returns:String

a string representation of the object

Annotations

@Override

unlock	back to summary
public void unlock() Implements com.google.inject.internal.CycleDetectingLock.unlock. Doc from com.google.inject.internal.CycleDetectingLock.unlock. Unlocks previously locked lock. Annotations @Override

unlock

back to summary

public void unlock()

Implements com.google.inject.internal.CycleDetectingLock.unlock.

Doc from com.google.inject.internal.CycleDetectingLock.unlock.

Unlocks previously locked lock.

Annotations

@Override

pack-priv Interface CycleDetectingLock<ID>

Nested and Inner Type Summary

Method Summary

Method Detail

public Class CycleDetectingLock.CycleDetectingLockFactory<ID>

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

pack-priv Class CycleDetectingLock.CycleDetectingLockFactory.ReentrantCycleDetectingLock<ID>

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail