class: RWLock

[38:7] extends: object

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.

Members

• handleObj
• lib
• retainedCallbacks
• signalHandlerNames
• signalSetterHandlers

Methods

• RWLock (Handle = null)

  Creates a new RWLock by wrapping a native handle or another wrapper.

  • @p Handle is the native handle or another wrapper whose handle to adopt.

• toNativeHandle (Source)

  Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from fn.call(...), another generated wrapper exposing handle(), or null. Returns null when the argument carries no pointer.

  • @p Source is the raw handle, raw buffer, wrapper, or null.
  • @r A raw pointer carrier or null when no pointer is present.

• getLib ()

  Returns the opened native library for this generated wrapper.

  • @r The opened native library.

• handle ()

  Returns the wrapped NativeHandle.

  • @r The wrapped NativeHandle.

• isNull ()

  Returns true when the wrapped handle is null.

  • @r A bool.

• describe ()

  Returns a small string for debugging generated wrappers.

  • @r A string.