stk::sync::Mutex Class Reference

Recursive mutex primitive that allows the same thread to acquire the lock multiple times. More...

#include <stk_sync_mutex.h>

Inheritance diagram for stk::sync::Mutex:

Collaboration diagram for stk::sync::Mutex:

Public Member Functions
	Mutex ()
	Constructor.
	~Mutex ()
	Destructor.
bool	TimedLock (Timeout timeout_ticks)
	Acquire lock.
void	Lock () override
	Acquire lock.
bool	TryLock ()
	Acquire the lock.
void	Unlock () override
	Release lock.
TId	GetOwner () const
	Get owner of the mutex.
void	SetTraceName (const char *name)
	Set name.
const char *	GetTraceName () const
	Get name.

Private Types
typedef DLHeadType	ListHeadType
	List head type for ISyncObject elements.
typedef DLEntryType	ListEntryType
	List entry type of ISyncObject elements.
enum
	A tag for type-safe casts done by CastListEntryToParent. More...
typedef DListEntry< ISyncObject, TClosedLoop >	DLEntryType
	Convenience alias for this entry type. Used to avoid repeating the full template spelling.
typedef DListHead< ISyncObject, TClosedLoop >	DLHeadType
	Convenience alias for the corresponding list head type.

Private Member Functions
	Mutex (const Mutex &)=delete
Mutex &	operator= (const Mutex &)=delete
void	AddWaitObject (IWaitObject *wobj) override
	Called by kernel when a new task starts waiting on this event.
void	RemoveWaitObject (IWaitObject *wobj) override
	Called by kernel when a waiting task is being removed (timeout expired, wait aborted, task terminated etc.).
const IWaitObject::ListHeadType &	GetWaitList () const override
	Get list of tasks blocked on this object.
IWaitObject::ListHeadType &	GetWaitList () override
	Get list of tasks blocked on this object.
void	WakeOne () override
	Wake the first task in the wait list (FIFO order).
void	WakeAll () override
	Wake all tasks currently in the wait list.
virtual bool	Tick (Timeout elapsed_ticks)
	Called by kernel on every system tick to handle timeout logic of waiting tasks.
Weight	FindWeightHigherThan (Weight comp) const
	Find higher weight within linked wait objects.
DLHeadType *	GetHead ()
	Get the list head this entry currently belongs to.
DLEntryType *	GetNext ()
	Get the next entry in the list.
DLEntryType *	GetPrev ()
	Get the previous entry in the list.
bool	IsLinked () const
	Check whether this entry is currently a member of any list.
	operator ISyncObject * ()
	Implicit conversion to a mutable pointer to the host object (T).
	operator const ISyncObject * () const
	Implicit conversion to a const pointer to the host object (T).
void	Link (DLHeadType *head, DLEntryType *next, DLEntryType *prev)
	Wire this entry into a list between prev and next.
void	Unlink ()
	Remove this entry from its current list.

Static Private Member Functions
static void	AddWaitObject (IWaitObject::ListHeadType &wlist, IWaitObject *wobj)
	Called by kernel when a new task starts waiting on this event.
static void	RemoveWaitObject (IWaitObject::ListHeadType &wlist, IWaitObject *wobj)
	Called by kernel when a waiting task is being removed (timeout expired, wait aborted, task terminated etc.).
static void	WakeOne (IWaitObject::ListHeadType &wlist)
	Wake the first task in the wait list (FIFO order).
static void	WakeAll (IWaitObject::ListHeadType &wlist)
	Wake all tasks currently in the wait list.

Private Attributes
TId	m_owner_tid
	thread id of the current owner
uint16_t	m_recursion_count
	recursion depth
IWaitObject::ListHeadType	m_wait_list
	Tasks blocked on this object.
DLHeadType *	m_head
	Owning list head, or NULL when the entry is not linked.
DLEntryType *	m_next
	Next entry in the list, or NULL (open list boundary) / first entry (closed loop).
DLEntryType *	m_prev
	Previous entry in the list, or NULL (open list boundary) / last entry (closed loop).

Static Private Attributes
static const uint16_t	RECURSION_MAX = 0xFFFEU
	maximum nesting depth

Detailed Description

Recursive mutex primitive that allows the same thread to acquire the lock multiple times.

Recursive mutex tracks ownership and a recursion count. If the owning thread calls Lock() again, the count is incremented and the call returns immediately without blocking. The lock is only fully released when Unlock() has been called an equal number of times.

// Example: Recursive locking in nested methods
stk::sync::Mutex g_ResourceMtx;
 
void Method_Internal() {
    // second acquisition (recursion count = 2)
    g_ResourceMtx.Lock();
    // ... perform internal logic ...
    g_ResourceMtx.Unlock();
}
 
void Method_Public() {
    // first acquisition (recursion count = 1)
    if (g_ResourceMtx.TimedLock(100)) {
        // safe to call: same thread already owns the lock
        Method_Internal();
        g_ResourceMtx.Unlock();
    }
}

Note

Only available when kernel is compiled with KERNEL_SYNC mode enabled.

See also

ISyncObject, IWaitObject, IKernelService::Wait

Definition at line 54 of file stk_sync_mutex.h.

Member Typedef Documentation

DLEntryType

typedef DListEntry<ISyncObject, TClosedLoop> stk::util::DListEntry< ISyncObject, TClosedLoop >::DLEntryType

inherited

Convenience alias for this entry type. Used to avoid repeating the full template spelling.

Definition at line 75 of file stk_linked_list.h.

DLHeadType

typedef DListHead<ISyncObject, TClosedLoop> stk::util::DListEntry< ISyncObject, TClosedLoop >::DLHeadType

inherited

Convenience alias for the corresponding list head type.

Definition at line 80 of file stk_linked_list.h.

ListEntryType

typedef DLEntryType stk::ISyncObject::ListEntryType

inherited

List entry type of ISyncObject elements.

Definition at line 557 of file stk_common.h.

ListHeadType

typedef DLHeadType stk::ISyncObject::ListHeadType

inherited

List head type for ISyncObject elements.

Definition at line 552 of file stk_common.h.

Member Enumeration Documentation

anonymous enum

anonymous enum

inherited

A tag for type-safe casts done by CastListEntryToParent.

See also

CastListEntryToParent.

Definition at line 70 of file stk_linked_list.h.

{ DLEntryTag = 1 };

Constructor & Destructor Documentation

Mutex() [1/2]

stk::sync::Mutex::Mutex ( )

inlineexplicit

Constructor.

Definition at line 59 of file stk_sync_mutex.h.

                     : m_owner_tid(TID_NONE), m_recursion_count(0U)
    {}

References m_owner_tid, m_recursion_count, and stk::TID_NONE.

Referenced by Mutex().

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~Mutex()

stk::sync::Mutex::~Mutex ( )

inline

Destructor.

Note

If tasks are still waiting at destruction time it is considered a logical error (dangling waiters). An assertion is triggered in debug builds.

MISRA deviation: [STK-DEV-005] Rule 10-3-2.

Definition at line 67 of file stk_sync_mutex.h.

    {
        STK_ASSERT(m_wait_list.IsEmpty()); // API contract: must not be destroyed with waiting tasks
    }

References stk::SyncObjectBase::m_wait_list, STK_ASSERT, and STK_VIRT_DTOR.

Mutex() [2/2]

stk::sync::Mutex::Mutex ( const Mutex & )

privatedelete

References Mutex().

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Member Function Documentation

AddWaitObject() [1/2]

void stk::ISyncObject::AddWaitObject ( IWaitObject::ListHeadType & wlist, IWaitObject * wobj )

inlinestaticinherited

Called by kernel when a new task starts waiting on this event.

Parameters

[in]

wobj

Wait object representing blocked task.

Note

Utility for AddWaitObject and ARM TrustZone support.

Definition at line 563 of file stk_common.h.

    {
        STK_ASSERT(wobj->GetHead() == nullptr);
        wlist.LinkBack(wobj);
    }

References stk::util::DListEntry< T, TClosedLoop >::GetHead(), stk::util::DListHead< T, TClosedLoop >::LinkBack(), and STK_ASSERT.

Referenced by stk::SyncObjectBase::AddWaitObject(), and stk::Kernel< TMode, TSize, TStrategy, TPlatform >::KernelTask::WaitObject::SetupWait().

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AddWaitObject() [2/2]

void stk::SyncObjectBase::AddWaitObject ( IWaitObject * wobj )

inlineoverridevirtualinherited

Called by kernel when a new task starts waiting on this event.

Parameters

[in]

wobj

Wait object representing blocked task.

Note

Must be called inside the critical section (see hw::CriticalSection, sync::ScopedCrticalSection).

Implements stk::ISyncObject.

Definition at line 253 of file stk_helper.h.

    {
        ISyncObject::AddWaitObject(m_wait_list, wobj);
    }

References stk::ISyncObject::AddWaitObject(), and m_wait_list.

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FindWeightHigherThan()

Weight stk::ISyncObject::FindWeightHigherThan ( Weight comp ) const

inlineinherited

Find higher weight within linked wait objects.

Implementation of ISyncObject::Tick, see ISyncObject. Placed here as it depends on GetUserTaskFromTid.

Parameters

[in]

comp

Weight to compare with.

Returns

Higher weight value than comp, or NO_WEIGHT if there is no object with a higher weight.

Note

Must be called inside the critical section (see hw::CriticalSection, sync::ScopedCrticalSection).

Definition at line 334 of file stk_helper.h.

{
    Weight max_weight = NO_WEIGHT;
    const IWaitObject *itr = util::DListCast::ListEntryToParent<const IWaitObject>(GetWaitList().GetFirst());
 
    while (itr != nullptr)
    {
        const Weight w = GetUserTaskFromTid(itr->GetTid())->GetWeight();
        if (w > max_weight)
        {
            max_weight = w;
        }
            
        itr = util::DListCast::ListEntryToParent<const IWaitObject>(itr->GetNext());
    }
 
    return ((max_weight > comp) ? max_weight : NO_WEIGHT);
}

References stk::util::DListEntry< T, TClosedLoop >::GetNext(), stk::IWaitObject::GetTid(), stk::GetUserTaskFromTid(), GetWaitList(), stk::ITask::GetWeight(), stk::util::DListCast::ListEntryToParent(), and stk::NO_WEIGHT.

Referenced by stk::Kernel< stk::KERNEL_DYNAMIC|stk::KERNEL_SYNC|stk::KERNEL_TICKLESS,(16U), stk::SwitchStrategyFP32, stk::PlatformDefault >::OnRestoreWeight(), and stk::sync::Mutex::Unlock().

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GetHead()

DLHeadType * stk::util::DListEntry< ISyncObject, TClosedLoop >::GetHead ( )

inlineinherited

Get the list head this entry currently belongs to.

Returns

Pointer to the owning DListHead, or NULL if the entry is not linked.

Definition at line 85 of file stk_linked_list.h.

{ return m_head; }

GetNext()

DLEntryType * stk::util::DListEntry< ISyncObject, TClosedLoop >::GetNext ( )

inlineinherited

Get the next entry in the list.

Returns

Pointer to the next DListEntry, or NULL if this is the last entry (open list) or the first entry (closed loop, where next wraps to first).

Note

In a closed loop (TClosedLoop == true) this pointer is never NULL when the entry is linked.

Definition at line 98 of file stk_linked_list.h.

{ return m_next; }

GetOwner()

TId stk::sync::Mutex::GetOwner ( ) const

inline

Get owner of the mutex.

Warning

ISR-safe.

Definition at line 99 of file stk_sync_mutex.h.

{ return m_owner_tid; }

References m_owner_tid.

Referenced by uxSemaphoreGetCount(), xSemaphoreGetMutexHolder(), and xSemaphoreGetMutexHolderFromISR().

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GetPrev()

DLEntryType * stk::util::DListEntry< ISyncObject, TClosedLoop >::GetPrev ( )

inlineinherited

Get the previous entry in the list.

Returns

Pointer to the previous DListEntry, or NULL if this is the first entry (open list) or the last entry (closed loop, where prev wraps to last).

Note

In a closed loop (TClosedLoop == true) this pointer is never NULL when the entry is linked.

Definition at line 114 of file stk_linked_list.h.

{ return m_prev; }

GetTraceName()

const char * stk::ITraceable::GetTraceName ( ) const

inlineinherited

Get name.

Returns

Name string, or NULL if not set or if STK_SYNC_DEBUG_NAMES is 0.

Definition at line 515 of file stk_common.h.

    {
    #if STK_SYNC_DEBUG_NAMES
        return m_trace_name;
    #else
        return nullptr;
    #endif
    }

GetWaitList() [1/2]

const IWaitObject::ListHeadType & stk::SyncObjectBase::GetWaitList ( ) const

inlineoverridevirtualinherited

Get list of tasks blocked on this object.

Note

Read-only access for diagnostics / telemetry.

Implements stk::ISyncObject.

Definition at line 263 of file stk_helper.h.

    {
        return m_wait_list;
    }

References m_wait_list.

GetWaitList() [2/2]

IWaitObject::ListHeadType & stk::SyncObjectBase::GetWaitList ( )

inlineoverrideprotectedvirtualinherited

Get list of tasks blocked on this object.

Implements stk::ISyncObject.

Definition at line 290 of file stk_helper.h.

    {
        return m_wait_list;
    }

References m_wait_list.

IsLinked()

bool stk::util::DListEntry< ISyncObject, TClosedLoop >::IsLinked ( ) const

inlineinherited

Check whether this entry is currently a member of any list.

Returns

true if linked (m_head != NULL); false otherwise.

Definition at line 127 of file stk_linked_list.h.

{ return (GetHead() != nullptr); }

Link()

void stk::util::DListEntry< ISyncObject, TClosedLoop >::Link ( DLHeadType * head, DLEntryType * next, DLEntryType * prev )

inlineprivateinherited

Wire this entry into a list between prev and next.

Parameters

[in]	head	The owning DListHead. Stored as a back-pointer for IsLinked() and ownership checks.
[in]	next	The entry that will follow this one, or NULL if this becomes the last entry.
[in]	prev	The entry that will precede this one, or NULL if this becomes the first entry.

Note

Called exclusively by DListHead::Link(). Assumes the entry is not currently linked. Updates the neighbours' forward/back pointers to splice this entry in.

Definition at line 162 of file stk_linked_list.h.

    {
        m_head = head;
        m_next = next;
        m_prev = prev;
 
        if (m_prev != nullptr)
        {
            m_prev->m_next = this;
        }
 
        if (m_next != nullptr)
        {
            m_next->m_prev = this;
        }
    }

Lock()

void stk::sync::Mutex::Lock ( )

inlineoverridevirtual

Acquire lock.

Warning

ISR-unsafe.

Implements stk::IMutex.

Definition at line 83 of file stk_sync_mutex.h.

{ STK_UNUSED(TimedLock(WAIT_INFINITE)); }

References STK_UNUSED, TimedLock(), and stk::WAIT_INFINITE.

Referenced by stk_mutex_lock().

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operator const ISyncObject *()

stk::util::DListEntry< ISyncObject, TClosedLoop >::operator const ISyncObject * ( ) const

inlineinherited

Implicit conversion to a const pointer to the host object (T).

Note

Safe because T must derive from DListEntry<T, TClosedLoop>. Eliminates the need for explicit static_cast at call sites.

MISRA deviation: [STK-DEV-004] Rule 5-2-x.

Definition at line 141 of file stk_linked_list.h.

{ return static_cast<const T *>(this); }

operator ISyncObject *()

stk::util::DListEntry< ISyncObject, TClosedLoop >::operator ISyncObject* ( )

inlineinherited

Implicit conversion to a mutable pointer to the host object (T).

Note

Safe because T must derive from DListEntry<T, TClosedLoop>. Eliminates the need for explicit static_cast at call sites.

MISRA deviation: [STK-DEV-004] Rule 5-2-x.

Definition at line 134 of file stk_linked_list.h.

{ return static_cast<T *>(this); }

operator=()

Mutex & stk::sync::Mutex::operator= ( const Mutex & )

privatedelete

RemoveWaitObject() [1/2]

void stk::ISyncObject::RemoveWaitObject ( IWaitObject::ListHeadType & wlist, IWaitObject * wobj )

inlinestaticinherited

Called by kernel when a waiting task is being removed (timeout expired, wait aborted, task terminated etc.).

Parameters

[in]

wobj

Wait object to remove from the wait list.

Note

Utility for AddWaitObject and ARM TrustZone support.

Definition at line 579 of file stk_common.h.

    {
        STK_ASSERT(wobj->GetHead() == &wlist);
        wlist.Unlink(wobj);
    }

References stk::util::DListEntry< T, TClosedLoop >::GetHead(), STK_ASSERT, and stk::util::DListHead< T, TClosedLoop >::Unlink().

Referenced by stk::SyncObjectBase::RemoveWaitObject().

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RemoveWaitObject() [2/2]

void stk::SyncObjectBase::RemoveWaitObject ( IWaitObject * wobj )

inlineoverridevirtualinherited

Called by kernel when a waiting task is being removed (timeout expired, wait aborted, task terminated etc.).

Parameters

[in]

wobj

Wait object to remove from the wait list.

Note

Must be called inside the critical section (see hw::CriticalSection, sync::ScopedCrticalSection).

Implements stk::ISyncObject.

Definition at line 258 of file stk_helper.h.

    {
        ISyncObject::RemoveWaitObject(m_wait_list, wobj);
    }

References m_wait_list, and stk::ISyncObject::RemoveWaitObject().

Referenced by stk::sync::Event::RemoveWaitObject().

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SetTraceName()

void stk::ITraceable::SetTraceName ( const char * name )

inlineinherited

Set name.

Parameters

[in]

name

Null-terminated string or NULL.

Note

If STK_SYNC_DEBUG_NAMES is 0 then calling this function has no effect.

Definition at line 503 of file stk_common.h.

    {
    #if STK_SYNC_DEBUG_NAMES
        m_trace_name = name;
    #else
        STK_UNUSED(name);
    #endif
    }

References STK_UNUSED.

Referenced by stk::memory::BlockMemoryPool::BlockMemoryPool(), and stk::memory::BlockMemoryPool::BlockMemoryPool().

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Tick()

bool stk::ISyncObject::Tick ( Timeout elapsed_ticks )

inlinevirtualinherited

Called by kernel on every system tick to handle timeout logic of waiting tasks.

Implementation of ISyncObject::Tick, see ISyncObject. Placed here as it depends on hw namespace.

Parameters

[in]

elapsed_ticks

Number of ticks elapsed between this and previous calls, in case of KERNEL_TICKLESS mode this value can be >1, for non-tickless mode it is always 1.

Returns

true if this synchronization object still has waiters with a finite timeout and requires further tick calls. false if the wait list is empty or all remaining waiters have infinite timeouts, signaling to the kernel that it may stop calling Tick() for this object until a new waiter is added.

Note

When this method returns false, the kernel unlinks this object from its active sync list. It will be re-linked automatically when the next waiter is added via AddWaitObject().

Does not need to be called inside critical section.

Definition at line 299 of file stk_helper.h.

{
    IWaitObject::ListHeadType &wlist = GetWaitList();
 
    // note: ScopedCriticalSection usage
    //
    // Single-core: no critical section needed - Tick() runs inside the
    // SysTick ISR which already executes with interrupts disabled, making
    // re-entrancy impossible on the local core.
    //
    // Multi-core: critical section is required because the tick handler on
    // each core may call Tick() concurrently for the same Semaphore instance,
    // and ISyncObject::Tick() is not re-entrant.
#if (STK_ARCH_CPU_COUNT > 1)
    const hw::CriticalSection::ScopedLock cs_;
#endif
 
    IWaitObject *itr = util::DListCast::ListEntryToParent<IWaitObject>(wlist.GetFirst());
 
    while (itr != nullptr)
    {
        IWaitObject *const next = util::DListCast::ListEntryToParent<IWaitObject>(itr->GetNext());
 
        if (!itr->Tick(elapsed_ticks))
        {
            itr->Wake(true);
        }
 
        itr = next;
    }
 
    return !wlist.IsEmpty();
}

References stk::util::DListHead< T, TClosedLoop >::GetFirst(), stk::util::DListEntry< T, TClosedLoop >::GetNext(), GetWaitList(), stk::util::DListHead< T, TClosedLoop >::IsEmpty(), stk::util::DListCast::ListEntryToParent(), stk::IWaitObject::Tick(), and stk::IWaitObject::Wake().

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TimedLock()

bool stk::sync::Mutex::TimedLock ( Timeout timeout_ticks )

inline

Acquire lock.

Parameters

[in]

timeout_ticks

Maximum time to wait (ticks).

Note

Maximum number of recursive locks must not exceed 0xFFFEU.

Warning

ISR-safe only with timeout_ticks = NO_WAIT, ISR-unsafe otherwise.

Returns

True if lock acquired, false if timeout occurred.

Definition at line 114 of file stk_sync_mutex.h.

{
    IKernelService *const svc = IKernelService::GetInstance();
    const TId current_tid = svc->GetTid();
 
    ScopedCriticalSection cs_;
 
    const TId owner_tid = m_owner_tid;
    bool success = false;
 
    // recursive path: already owned by the calling thread
    if ((m_recursion_count != 0U) && (owner_tid == current_tid))
    {
        STK_ASSERT(m_recursion_count < RECURSION_MAX); // API contract: caller must not exceed max recursion depth
 
        m_recursion_count = static_cast<uint16_t>(m_recursion_count + 1U);
        success = true;
    }
    // fast path: mutex is free
    else if (m_recursion_count == 0U)
    {
        // kernel invariant: counter is zero so owner must be TID_NONE
        if (owner_tid != TID_NONE)
        {
            STK_KERNEL_PANIC(KERNEL_PANIC_ASSERT);
        }
 
        m_recursion_count = 1U;
        m_owner_tid       = current_tid;
        __stk_full_memfence();
 
        success = true;
    }
    // slow path: block until available or timeout expires
    else if (timeout_ticks != NO_WAIT)
    {
        STK_ASSERT(!hw::IsInsideISR()); // API contract: caller must not be in ISR for a blocking call
 
        // boost priority of the owner to avoid priority inversion (in case of SwitchStrategyFixedPriority,
        // otherwise ignored by the kernel), noop if ISwitchStrategy::PRIORITY_INHERITANCE_API = 0
        svc->InheritWeight(owner_tid, GetUserTaskFromTid(current_tid)->GetWeight());
 
        // mutex owned by another thread (slow path/blocking)
        if (svc->Wait(this, &cs_, timeout_ticks) == WAIT_RESULT_TIMEOUT)
        {
            // if owner did not change, undo priority boost to avoid stuck elevated priority: lookup for a
            // higher weight within existing wait objects, noop if ISwitchStrategy::PRIORITY_INHERITANCE_API = 0
            if (owner_tid == m_owner_tid)
            {
                svc->RestoreWeight(owner_tid, this);
            }
 
            success = false;
        }
        else
        {
            // kernel invariant: if either condition is false, the low-level lock and the
            // recursion counter are out of sync, this is an internal defect, not a caller error
            if ((m_owner_tid != current_tid) || (m_recursion_count != 1U))
            {
                STK_KERNEL_PANIC(KERNEL_PANIC_ASSERT);
            }
 
            success = true;
        }
    }
    // try-lock variant: owned by someone else, but no-wait requested
    else
    {
        // success is false already, noop
    }
 
    return success;
}    

References stk::IKernelService::GetInstance(), stk::IKernelService::GetTid(), stk::GetUserTaskFromTid(), stk::SyncObjectBase::IKernelService, stk::IKernelService::InheritWeight(), stk::hw::IsInsideISR(), stk::KERNEL_PANIC_ASSERT, m_owner_tid, m_recursion_count, stk::NO_WAIT, RECURSION_MAX, stk::IKernelService::RestoreWeight(), STK_ASSERT, stk::STK_KERNEL_PANIC(), stk::TID_NONE, stk::IKernelService::Wait(), and stk::WAIT_RESULT_TIMEOUT.

Referenced by Lock(), osMutexAcquire(), stk_mutex_timed_lock(), TryLock(), and xSemaphoreTake().

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TryLock()

bool stk::sync::Mutex::TryLock ( )

inline

Acquire the lock.

Warning

ISR-safe.

Returns

True if lock acquired, false if lock is already acquired by another task.

Definition at line 89 of file stk_sync_mutex.h.

{ return TimedLock(NO_WAIT); }

References stk::NO_WAIT, and TimedLock().

Referenced by stk_mutex_trylock().

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Unlink()

void stk::util::DListEntry< ISyncObject, TClosedLoop >::Unlink ( )

inlineprivateinherited

Remove this entry from its current list.

Note

Called exclusively by DListHead::Unlink(). Patches the neighbours' pointers to bridge over this entry, then clears m_head, m_next, and m_prev to NULL so the entry is in a clean unlinked state.

Does not update DListHead::m_count or m_first / m_last — those are the responsibility of the calling DListHead::Unlink().

Definition at line 186 of file stk_linked_list.h.

    {
        if (m_prev != nullptr)
        {
            m_prev->m_next = m_next;
        }
 
        if (m_next != nullptr)
        {
            m_next->m_prev = m_prev;
        }
 
        m_head = nullptr;
        m_next = nullptr;
        m_prev = nullptr;
    }

Unlock()

void stk::sync::Mutex::Unlock ( )

inlineoverridevirtual

Release lock.

Warning

ISR-safe.

Implements stk::IMutex.

Definition at line 193 of file stk_sync_mutex.h.

{
    const ScopedCriticalSection cs_;
 
    STK_ASSERT(m_owner_tid == GetTid()); // API contract: caller must own the lock
    STK_ASSERT(m_recursion_count != 0U); // API contract: must have matching Lock()
 
    m_recursion_count = static_cast<uint16_t>(m_recursion_count - 1U);
 
    if (m_recursion_count == 0U)
    {
        IKernelService *const svc = IKernelService::GetInstance();
 
        // restore priority of the owner, noop if ISwitchStrategy::PRIORITY_INHERITANCE_API = 0
        svc->RestoreWeight(m_owner_tid);
 
        if (!m_wait_list.IsEmpty())
        {
            // pass ownership directly to the first waiter (FIFO order)
            IWaitObject *const waiter = util::DListCast::ListEntryToParent<IWaitObject>(m_wait_list.GetFirst());
 
            // transfer ownership to the waiter
            m_recursion_count = 1U;
            m_owner_tid       = waiter->GetTid();
            __stk_full_memfence();
 
            // wake up
            waiter->Wake(false);
 
            // boost priority from the highest-priority task currently in wait list,
            // noop if the list is empty or if ISwitchStrategy::PRIORITY_INHERITANCE_API = 0
            svc->InheritWeight(m_owner_tid,
                FindWeightHigherThan(GetUserTaskFromTid(m_owner_tid)->GetWeight()));
        }
        else
        {
            // free completely if there are no waiters
            m_owner_tid = TID_NONE;
            __stk_full_memfence();
        }
    }
}

References stk::ISyncObject::FindWeightHigherThan(), stk::IKernelService::GetInstance(), stk::GetTid(), stk::IWaitObject::GetTid(), stk::GetUserTaskFromTid(), stk::SyncObjectBase::IKernelService, stk::IKernelService::InheritWeight(), stk::util::DListCast::ListEntryToParent(), m_owner_tid, m_recursion_count, stk::SyncObjectBase::m_wait_list, stk::IKernelService::RestoreWeight(), STK_ASSERT, stk::TID_NONE, and stk::IWaitObject::Wake().

Referenced by stk_mutex_unlock(), and xSemaphoreGive().

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WakeAll() [1/2]

void stk::ISyncObject::WakeAll ( IWaitObject::ListHeadType & wlist )

inlinestaticinherited

Wake all tasks currently in the wait list.

Note

Each woken task is notified with timeout=false, indicating a successful signal (not a timeout expiry).

Does nothing if no tasks are currently waiting.

Utility for AddWaitObject and ARM TrustZone support.

Definition at line 632 of file stk_common.h.

    {
        while (IWaitObject *const obj = util::DListCast::ListEntryToParent<IWaitObject>(wlist.GetFirst()))
        {
            obj->Wake(false);
        }
    }

References stk::util::DListHead< T, TClosedLoop >::GetFirst(), and stk::util::DListCast::ListEntryToParent().

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WakeAll() [2/2]

void stk::SyncObjectBase::WakeAll ( )

inlineoverrideprotectedvirtualinherited

Wake all tasks currently in the wait list.

Note

Each woken task is notified with timeout=false, indicating a successful signal (not a timeout expiry).

Does nothing if no tasks are currently waiting.

Must be called inside the critical section (see hw::CriticalSection, sync::ScopedCrticalSection).

Implements stk::ISyncObject.

Definition at line 285 of file stk_helper.h.

    {
        IKernelService::GetInstance()->Wake(this, true);
    }

References stk::IKernelService::GetInstance(), and stk::IKernelService::Wake().

Referenced by stk::sync::ConditionVariable::NotifyAll_CS(), stk::sync::Event::Pulse(), and stk::sync::Event::Set().

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WakeOne() [1/2]

void stk::ISyncObject::WakeOne ( IWaitObject::ListHeadType & wlist )

inlinestaticinherited

Wake the first task in the wait list (FIFO order).

Note

The woken task is notified with timeout=false, indicating a successful signal (not a timeout expiry).

Does nothing if no tasks are currently waiting.

Utility for AddWaitObject and ARM TrustZone support.

Definition at line 618 of file stk_common.h.

    {
        if (IWaitObject *const obj = util::DListCast::ListEntryToParent<IWaitObject>(wlist.GetFirst()))
        {
            obj->Wake(false);
        }
    }

References stk::util::DListHead< T, TClosedLoop >::GetFirst(), and stk::util::DListCast::ListEntryToParent().

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WakeOne() [2/2]

void stk::SyncObjectBase::WakeOne ( )

inlineoverrideprotectedvirtualinherited

Wake the first task in the wait list (FIFO order).

Note

The woken task is notified with timeout=false, indicating a successful signal (not a timeout expiry).

Does nothing if no tasks are currently waiting.

Must be called inside the critical section (see hw::CriticalSection, sync::ScopedCrticalSection).

Implements stk::ISyncObject.

Definition at line 280 of file stk_helper.h.

    {
        IKernelService::GetInstance()->Wake(this, false);
    }

References stk::IKernelService::GetInstance(), and stk::IKernelService::Wake().

Referenced by stk::sync::ConditionVariable::NotifyOne_CS(), stk::sync::Event::Pulse(), stk::sync::Event::Set(), and stk::sync::Semaphore::Signal().

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Member Data Documentation

m_head

DLHeadType* stk::util::DListEntry< ISyncObject, TClosedLoop >::m_head

privateinherited

Owning list head, or NULL when the entry is not linked.

Definition at line 203 of file stk_linked_list.h.

m_next

DLEntryType* stk::util::DListEntry< ISyncObject, TClosedLoop >::m_next

privateinherited

Next entry in the list, or NULL (open list boundary) / first entry (closed loop).

Definition at line 204 of file stk_linked_list.h.

m_owner_tid

TId stk::sync::Mutex::m_owner_tid

private

thread id of the current owner

Definition at line 106 of file stk_sync_mutex.h.

Referenced by GetOwner(), Mutex(), TimedLock(), and Unlock().

m_prev

DLEntryType* stk::util::DListEntry< ISyncObject, TClosedLoop >::m_prev

privateinherited

Previous entry in the list, or NULL (open list boundary) / last entry (closed loop).

Definition at line 205 of file stk_linked_list.h.

m_recursion_count

uint16_t stk::sync::Mutex::m_recursion_count

private

recursion depth

Definition at line 107 of file stk_sync_mutex.h.

Referenced by Mutex(), TimedLock(), and Unlock().

m_wait_list

IWaitObject::ListHeadType stk::SyncObjectBase::m_wait_list

protectedinherited

Tasks blocked on this object.

Definition at line 295 of file stk_helper.h.

Referenced by AddWaitObject(), GetWaitList(), GetWaitList(), stk::sync::Event::Pulse(), RemoveWaitObject(), stk::sync::Semaphore::Signal(), SyncObjectBase(), stk::sync::Mutex::Unlock(), stk::sync::ConditionVariable::~ConditionVariable(), stk::sync::Event::~Event(), stk::sync::Mutex::~Mutex(), and stk::sync::Semaphore::~Semaphore().

RECURSION_MAX

const uint16_t stk::sync::Mutex::RECURSION_MAX = 0xFFFEU

staticprivate

maximum nesting depth

Definition at line 104 of file stk_sync_mutex.h.

Referenced by TimedLock().

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

• stk_sync_mutex.h