RwLock Class Reference

Overview

A wrapper class for the EtcPal read-write lock type.

Note: The etcpal::RwLock functions are not normally used directly - prefer usage of the RAII types etcpal::ReadGuard and etcpal::WriteGuard to manage locking and unlocking of an etcpal::RwLock.

Example usage:

class ThreadSafeCounter
{
public:
  ThreadSafeCounter() = default;
 
  // Multiple threads/readers can read the counter's value at the same time.
  unsigned int get() const
  {
    etcpal::ReadGuard read_lock(lock_);
    return value_;
  }
 
  // Only one thread/writer can increment/write the counter's value.
  void increment()
  {
    etcpal::WriteGuard write_lock(lock_);
    ++value_;
  }
 
  // Only one thread/writer can reset/write the counter's value.
  void reset()
  {
    etcpal::WriteGuard write_lock(lock_);
    value_ = 0;
  }
 
 private:
  mutable etcpal::RwLock lock_;
  unsigned int value_ = 0;
};
 
int main()
{
  ThreadSafeCounter counter;
 
  auto increment_and_print = [&counter]()
  {
    for (int i = 0; i < 3; i++)
    {
      counter.increment();
      std::cout << counter.get() << '\n';
    }
  };
 
  etcpal::Thread thread1(increment_and_print);
  etcpal::Thread thread2(increment_and_print);
 
  thread1.Join();
  thread2.Join();
 
  std::cout << counter.get() << '\n'; // Outputs '6'
 
  return 0;
}

See rwlock (Read-Write Locks) for more information.

Public Member Functions
	RwLock ()
	Create a new read-write lock.
	~RwLock ()
	Destroy the read-write lock.
	RwLock (const RwLock &other)=delete
RwLock &	operator= (const RwLock &other)=delete
	RwLock (RwLock &&other)=delete
RwLock &	operator= (RwLock &&other)=delete
bool	ReadLock ()
	Access the read-write lock for reading. More...
bool	TryReadLock (int timeout_ms=0)
	Try to access the read-write lock for reading. More...
void	ReadUnlock ()
	Release a read lock on the read-write lock. More...
bool	WriteLock ()
	Access the read-write lock for writing. More...
bool	TryWriteLock (int timeout_ms=0)
	Try to access the read-write lock for writing. More...
void	WriteUnlock ()
	Release a write lock on the read-write lock. More...
etcpal_rwlock_t &	get ()
	Get a reference to the underlying etcpal_rwlock_t type.

Member Function Documentation

ReadLock()

bool ReadLock ( )

inline

Access the read-write lock for reading.

Returns

The result of etcpal_rwlock_readlock() on the underlying read-write lock.

ReadUnlock()

void ReadUnlock ( )

inline

Release a read lock on the read-write lock.

See etcpal_rwlock_readunlock().

TryReadLock()

bool TryReadLock ( int  timeout_ms = 0 )

inline

Try to access the read-write lock for reading.

Returns when either the read lock is acquired or the timeout expires. NOTE: Timeout values other than 0 or ETCPAL_WAIT_FOREVER are typically only honored on real-time platforms. See the table in rwlock (Read-Write Locks) for more information. On platforms where timeouts are not honored, passing 0 for timeout_ms executes a poll for the lock returning immediately, while any other value executes the equivalent of ReadLock().

Parameters

timeout_ms

How long to wait to acquire the read lock, in milliseconds. Default is to poll and return immediately.

Returns

The result of etcpal_rwlock_timed_readlock() on the underlying read-write lock.

TryWriteLock()

bool TryWriteLock ( int  timeout_ms = 0 )

inline

Try to access the read-write lock for writing.

Returns when either the read lock is acquired or the timeout expires. NOTE: Timeout values other than 0 or ETCPAL_WAIT_FOREVER are typically only honored on real-time platforms. See the table in rwlock (Read-Write Locks) for more information. On platforms where timeouts are not honored, passing 0 for timeout_ms executes a poll for the lock returning immediately, while any other value executes the equivalent of WriteLock().

Parameters

timeout_ms

How long to wait to acquire the write lock, in milliseconds. Default is to poll and return immediately.

Returns

The result of etcpal_rwlock_timed_writelock() on the underlying read-write lock.

WriteLock()

bool WriteLock ( )

inline

Access the read-write lock for writing.

Returns

The result of etcpal_rwlock_writelock() on the underlying read-write lock.

WriteUnlock()

void WriteUnlock ( )

inline

Release a write lock on the read-write lock.

See etcpal_rwlock_writeunlock().

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

• include/etcpal/cpp/rwlock.h