glib/org.gtkkn.bindings.glib/RwLock

RwLock

class RwLock(pointer: <Error class: unknown class><<Error class: unknown class>>, cleaner: <Error class: unknown class>? = null) : ProxyInstance

The GRWLock struct is an opaque data structure to represent a reader-writer lock. It is similar to a #GMutex in that it allows multiple threads to coordinate access to a shared resource.

The difference to a mutex is that a reader-writer lock discriminates between read-only ('reader') and full ('writer') access. While only one thread at a time is allowed write access (by holding the 'writer' lock via g_rw_lock_writer_lock()), multiple threads can gain simultaneous read-only access (by holding the 'reader' lock via g_rw_lock_reader_lock()).

It is unspecified whether readers or writers have priority in acquiring the lock when a reader already holds the lock and a writer is queued to acquire it.

Here is an example for an array with access functions: |[ GRWLock lock; GPtrArray *array;

gpointer my_array_get (guint index) { gpointer retval = NULL;

if (!array)
  return NULL;

g_rw_lock_reader_lock (&lock);
if (index < array->len)
  retval = g_ptr_array_index (array, index);
g_rw_lock_reader_unlock (&lock);

return retval;

}

void my_array_set (guint index, gpointer data) { g_rw_lock_writer_lock (&lock);

if (!array)
  array = g_ptr_array_new ();

if (index >= array->len)
  g_ptr_array_set_size (array, index+1);
g_ptr_array_index (array, index) = data;

g_rw_lock_writer_unlock (&lock);

} ]| This example shows an array which can be accessed by many readers (the my_array_get() function) simultaneously, whereas the writers (the my_array_set() function) will only be allowed one at a time and only if no readers currently access the array. This is because of the potentially dangerous resizing of the array. Using these functions is fully multi-thread safe now.

If a #GRWLock is allocated in static storage then it can be used without initialisation. Otherwise, you should call g_rw_lock_init() on it and g_rw_lock_clear() when done.

A GRWLock should only be accessed with the g_rw_lock_ functions.

Since

2.32

Constructors

RwLock

constructor()

Allocate a new RwLock.

constructor(scope: <Error class: unknown class>)

Allocate a new RwLock using the provided AutofreeScope.

constructor(pointer: <Error class: unknown class><<Error class: unknown class>>, cleaner: <Error class: unknown class>? = null)

Properties

glibRWLockPointer

val glibRWLockPointer: <Error class: unknown class><<Error class: unknown class>>

handle

open override val handle: <Error class: unknown class>?

Functions

clear

fun clear()

Frees the resources allocated to a lock with g_rw_lock_init().

equals

open operator override fun equals(other: Any?): Boolean

Compare two proxy instances for equality. This will compare both the type of the instances, and their memory addresses.

hashCode

open override fun hashCode(): Int

init

fun init()

Initializes a #GRWLock so that it can be used.

readerLock

fun readerLock()

Obtain a read lock on @rw_lock. If another thread currently holds the write lock on @rw_lock, the current thread will block until the write lock was (held and) released. If another thread does not hold the write lock, but is waiting for it, it is implementation defined whether the reader or writer will block. Read locks can be taken recursively.

readerTrylock

fun readerTrylock(): Boolean

Tries to obtain a read lock on @rw_lock and returns true if the read lock was successfully obtained. Otherwise it returns false.

readerUnlock

fun readerUnlock()

Release a read lock on @rw_lock.

writerLock

fun writerLock()

Obtain a write lock on @rw_lock. If another thread currently holds a read or write lock on @rw_lock, the current thread will block until all other threads have dropped their locks on @rw_lock.

writerTrylock

fun writerTrylock(): Boolean

Tries to obtain a write lock on @rw_lock. If another thread currently holds a read or write lock on @rw_lock, it immediately returns false. Otherwise it locks @rw_lock and returns true.

writerUnlock

fun writerUnlock()

Release a write lock on @rw_lock.