Read/Write Lock control. More...

#include <ReadWrite.h>

Inheritance diagram for FreeRTOScpp::ReadWriteLock:

Collaboration diagram for FreeRTOScpp::ReadWriteLock:

Public Member Functions
	ReadWriteLock ()

	~ReadWriteLock ()

bool	give () override

bool	give () override

bool	readLock (TickType_t wait=portMAX_DELAY)
	ReadLock. More...

bool	readLock (Time_ms delay_ms)

bool	readUnlock ()
	Remove our lock. More...

bool	releaseReserved ()
	If we have a reserved lock, down grade to just a read lock. More...

bool	requestReserved ()
	Task with a Read Lock request upgrade to a reserved lock. More...

bool	reservedLock (TickType_t wait=portMAX_DELAY)
	Get an upgradable Read Lock. More...

bool	reservedLock (Time_ms delay_ms)

Reader &	rlock ()
	Get Read Lockable. More...

bool	take (TickType_t wait) override

bool	take (Time_ms ms)

bool	take (Time_ms ms)

bool	take (TickType_t wait) override

Writer &	wlock ()
	Get Write Lockable. More...

bool	writeLock (TickType_t wait=portMAX_DELAY)
	Take the write lock, requires readCount to be 0, or 1 if we reserved the upgrade. More...

bool	writeLock (Time_ms delay_ms)

bool	writeUnlock ()
	Release the write lock. More...

Protected Attributes
EventGroup	event

int	readCount = 0
	Count of Read Locks. More...

TaskHandle_t	reserved = nullptr
	Reserved Lock indicator. More...

int	writeReq = -1
	Write Request Pending Priority. More...

Detailed Description

Read/Write Lock control.

States:

Free: readCount == 0
Read: readCount > 0, reserved == 0
Reserved: readCount > 0, reserved != 0
Write: readCount == -1, reserved == 0
Upgraded: readCount == -1, reserved != 0

Warning: This is a fairly new module, and may not be fully tested

Constructor & Destructor Documentation

◆ ReadWriteLock()

FreeRTOScpp::ReadWriteLock::ReadWriteLock ( )

◆ ~ReadWriteLock()

FreeRTOScpp::ReadWriteLock::~ReadWriteLock ( )

Member Function Documentation

◆ give() [1/2]

bool FreeRTOScpp::Reader::give ( )

overridevirtualinherited

Implements FreeRTOScpp::Lockable.

Referenced by FreeRTOScpp::Reader::Reader(), and FreeRTOScpp::Writer::Writer().

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◆ give() [2/2]

bool FreeRTOScpp::Writer::give ( )

overridevirtualinherited

Implements FreeRTOScpp::Lockable.

◆ readLock() [1/2]

bool FreeRTOScpp::ReadWriteLock::readLock ( TickType_t wait = portMAX_DELAY )

ReadLock.

Get a read lock.

Parameters

wait	The maximum number of ticks to wait to get the lock

Returns: true if the read lock has been granted

Algorithm:

Loop
- If readCount >=0 and our priority > writeReq
  - Increment readCount
  - return true
- if Time has expired:
  - return false
- else wait a tick for read_bit event.

◆ readLock() [2/2]

bool FreeRTOScpp::ReadWriteLock::readLock ( Time_ms delay_ms )

inline

References FreeRTOScpp::ms2ticks(), and readLock().

Referenced by readLock().

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◆ readUnlock()

bool FreeRTOScpp::ReadWriteLock::readUnlock ( )

Remove our lock.

If we reserved the upgrade, release that.

◆ releaseReserved()

bool FreeRTOScpp::ReadWriteLock::releaseReserved ( )

If we have a reserved lock, down grade to just a read lock.

◆ requestReserved()

bool FreeRTOScpp::ReadWriteLock::requestReserved ( )

Task with a Read Lock request upgrade to a reserved lock.

If no reservation current, will be granted, if reservation present, will be rejected.

Does not check if this task has a read lock, but that is assumed.

◆ reservedLock() [1/2]

bool FreeRTOScpp::ReadWriteLock::reservedLock ( TickType_t wait = portMAX_DELAY )

Get an upgradable Read Lock.

like readLock, but add reserved == nullptr to the conditions. On success will set reserved to our task handle.

Only one task can reserve this, as if two are in this state they will deadlock when they both try to upgrade

◆ reservedLock() [2/2]

bool FreeRTOScpp::ReadWriteLock::reservedLock ( Time_ms delay_ms )

inline

References FreeRTOScpp::ms2ticks(), and reservedLock().

Referenced by reservedLock().

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◆ rlock()

Reader& FreeRTOScpp::ReadWriteLock::rlock ( )

inline

Get Read Lockable.

Returns: a lockable object for using with Read Locks.

◆ take() [1/4]

bool FreeRTOScpp::Reader::take ( TickType_t wait )

overridevirtualinherited

Implements FreeRTOScpp::Lockable.

Referenced by FreeRTOScpp::Reader::Reader(), and FreeRTOScpp::Writer::Writer().

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◆ take() [2/4]

bool FreeRTOScpp::Lockable::take ( Time_ms ms )

inlineinherited

References FreeRTOScpp::Lockable::give(), FreeRTOScpp::Lockable::Lockable(), FreeRTOScpp::ms2ticks(), FreeRTOScpp::Lockable::operator=(), and FreeRTOScpp::Lockable::take().

Referenced by FreeRTOScpp::Lockable::take().

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◆ take() [3/4]

bool FreeRTOScpp::Lockable::take ( Time_ms ms )

inlineinherited

References FreeRTOScpp::Lockable::give(), FreeRTOScpp::Lockable::Lockable(), FreeRTOScpp::ms2ticks(), FreeRTOScpp::Lockable::operator=(), and FreeRTOScpp::Lockable::take().

Referenced by FreeRTOScpp::Lockable::take().

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◆ take() [4/4]

bool FreeRTOScpp::Writer::take ( TickType_t wait )

overridevirtualinherited

Implements FreeRTOScpp::Lockable.

◆ wlock()

Writer& FreeRTOScpp::ReadWriteLock::wlock ( )

inline

Get Write Lockable.

Returns: a lockable object for using with Write Locks

◆ writeLock() [1/2]

bool FreeRTOScpp::ReadWriteLock::writeLock ( TickType_t wait = portMAX_DELAY )

Take the write lock, requires readCount to be 0, or 1 if we reserved the upgrade.

◆ writeLock() [2/2]

bool FreeRTOScpp::ReadWriteLock::writeLock ( Time_ms delay_ms )

inline

References FreeRTOScpp::ms2ticks(), and writeLock().

Referenced by writeLock().

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◆ writeUnlock()

bool FreeRTOScpp::ReadWriteLock::writeUnlock ( )

Release the write lock.

If we upgraded go back to a reserved lock which will need to be unlocked.

Member Data Documentation

◆ event

EventGroup FreeRTOScpp::ReadWriteLock::event

protected

◆ readCount

int FreeRTOScpp::ReadWriteLock::readCount = 0

protected

Count of Read Locks.

If 0, then lock is free if >0, lock is in read mode and is the count of the number of read locks granted if <0, loci is in write mode.

◆ reserved

TaskHandle_t FreeRTOScpp::ReadWriteLock::reserved = nullptr

protected

Reserved Lock indicator.

If nullptr, then no reservedLock are currently in existence, so a reservedLock can be granted

Else, TaskHandle of the task that has reserved the right to upgrade to a write lock.

◆ writeReq

int FreeRTOScpp::ReadWriteLock::writeReq = -1

protected

Write Request Pending Priority.

If in Read mode, and a task with priority below writeReq

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

Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ReadWriteLock()

◆ ~ReadWriteLock()

Member Function Documentation

◆ give() [1/2]

◆ give() [2/2]

◆ readLock() [1/2]

◆ readLock() [2/2]

◆ readUnlock()

◆ releaseReserved()

◆ requestReserved()

◆ reservedLock() [1/2]

◆ reservedLock() [2/2]

◆ rlock()

◆ take() [1/4]

◆ take() [2/4]

◆ take() [3/4]

◆ take() [4/4]

◆ wlock()

◆ writeLock() [1/2]

◆ writeLock() [2/2]

◆ writeUnlock()

Member Data Documentation

◆ event

◆ readCount

◆ reserved

◆ writeReq