Description:

This class is a simple wrapper around C++ standard library type std::recursive_mutex. Thus, it is used to implement mutual exclusive access to resources by protecting critical code sections from being executed in parallel in concurrent threads.

When a pair of AcquireRecursive and ReleaseRecursive invocations is performed within the same code block, then it is recommended to use a stack instantiation of class OwnerRecursive to acquire and release objects of this class. Such a use is highly simplified with macros ALIB_LOCK_RECURSIVE and ALIB_LOCK_RECURSIVE_WITH.

Nested acquisitions are supported with this type. An instance of this class is released when an equal number of invocations to AcquireRecursive and ReleaseRecursive have been performed.
This class has slightly reduced performance in comparison to non-recursive type Lock. Not only for this reason, non-nested locking is the preferred technique. But there are situations where nested locks are just unavoidable.

Debug-Features

Public member Dbg is available with debug-compilations. It offers the following features:

The object stores the actual owning thread and the source code position of the last acquirement.
Releasing non-acquired instances, as well as destructing acquired one, raise an assertion.
A warning threshold for the number of nested acquisitions can be defined with public member DbgLockAsserter::RecursionLimit.
Field WaitTimeLimit enables the raise of ALib warnings in case a certain wait time is exceeded. Note that instead of wrapping std::recursive_mutex, with debug-compilations class std::recursive_timed_mutex is wrapped.

Availability: This type is not available if the compiler-symbol ALIB_SINGLE_THREADED is set.

See also

Chapter 3. Locks of the Programmer's Manual of the module ALib Threads.
Chapter A.5 Collecting Caller Information of the General Programmer's Manual.

Definition at line 48 of file recursivelock.inl.

Inheritance diagram for alib::threads::RecursiveLock:

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Collaboration diagram for alib::threads::RecursiveLock:

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Public Field Index:
DbgLockAsserter	Dbg
	The debug tool instance.

Public Method Index:
	~RecursiveLock () override
	Destructor. With debug-compilations, asserts that this lock is not acquired.

ALIB_DLL void	AcquireRecursive (ALIB_DBG_TAKE_CI)

virtual ALIB_DLL bool	DCSIsAcquired () const override

virtual ALIB_DLL bool	DCSIsSharedAcquired () const override

ALIB_DLL void	ReleaseRecursive (ALIB_DBG_TAKE_CI)

ALIB_DLL bool	TryAcquire (ALIB_DBG_TAKE_CI)

Public Method Index: inherited from alib::lang::DbgCriticalSections::AssociatedLock
virtual	~AssociatedLock ()
	Virtual Destructor.

Protected Field Index:
std::recursive_mutex	mutex

Field Details:

◆ Dbg

DbgLockAsserter alib::threads::RecursiveLock::Dbg

The debug tool instance.

Definition at line 68 of file recursivelock.inl.

◆ mutex

std::recursive_mutex alib::threads::RecursiveLock::mutex

protected

The internal object to lock on.

Note: With debug-compilations, this is of type std::recursive_timed_mutex.

Definition at line 61 of file recursivelock.inl.

Constructor(s) / Destructor Details:

◆ ~RecursiveLock()

alib::threads::RecursiveLock::~RecursiveLock ( )

inlineoverride

Destructor. With debug-compilations, asserts that this lock is not acquired.

Definition at line 74 of file recursivelock.inl.

Method Details:

◆ AcquireRecursive()

void alib::threads::RecursiveLock::AcquireRecursive ( ALIB_DBG_TAKE_CI )

Thread which invokes this method gets registered as the current owner of this object, until the same thread releases the ownership invoking ReleaseRecursive. In the case that this object is already owned by another thread, the invoking thread is suspended until ownership can be gained. Multiple (nested) calls to this method are counted and the object is only released when the same number of Release() calls have been made.

Debug Parameter:: Pass macro ALIB_CALLER_PRUNED with invocations.

Definition at line 211 of file locks.cpp.

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◆ DCSIsAcquired()

bool alib::threads::RecursiveLock::DCSIsAcquired ( ) const

overridevirtual

Returns: true if the lock is acquired (in non-shared mode), false otherwise.

Implements alib::lang::DbgCriticalSections::AssociatedLock.

Definition at line 763 of file locks.cpp.

◆ DCSIsSharedAcquired()

bool alib::threads::RecursiveLock::DCSIsSharedAcquired ( ) const

overridevirtual

Returns: true if the lock is shared-acquired (by at least any thread). Otherwise, returns false.

Implements alib::lang::DbgCriticalSections::AssociatedLock.

Definition at line 764 of file locks.cpp.

◆ ReleaseRecursive()

void alib::threads::RecursiveLock::ReleaseRecursive ( ALIB_DBG_TAKE_CI )

Releases ownership of this object. If AcquireRecursive was called multiple times before, the same number of calls to this method has to be performed to release ownership.

Debug Parameter:: Pass macro ALIB_CALLER_PRUNED with invocations.

Definition at line 280 of file locks.cpp.

◆ TryAcquire()

bool alib::threads::RecursiveLock::TryAcquire ( ALIB_DBG_TAKE_CI )

nodiscard

Tries to acquire this lock. Successful calls to this method are counted, as if AcquireRecursive was called and an according invocation of ReleaseRecursive has to be performed.

Debug Parameter:: Pass macro ALIB_CALLER_PRUNED with invocations.

Returns: true if the lock was not acquired by a different thread and thus, this call was successful. false otherwise.

Definition at line 256 of file locks.cpp.

The documentation for this class was generated from the following files: