indexing
	description:
		"Mutex synchronization object, allows threads to access global %
		%data through critical sections."
	status: "See notice at end of class."
	date: "$Date$"
	revision: "$Revision$"

class
	MUTEX

inherit
	MEMORY
		redefine
			dispose,
			default_create
		end

create
	default_create,
	make

feature -- Initialization

	default_create is
			-- Create mutex.
		do
			mutex_pointer := eif_thr_mutex_create
		ensure then
			valid_mutex: mutex_pointer /= default_pointer
		end

	make is
			-- Create mutex
		obsolete
			"Use `default_create'"
		do
			default_create
		ensure
			valid_mutex: mutex_pointer /= default_pointer
		end
		
feature -- Access

	is_set: BOOLEAN is
			-- Is mutex initialized?
		do
			Result := (mutex_pointer /= default_pointer)
		end

feature -- Status setting

	trylock, has_locked: BOOLEAN is
			-- Has client been successful in locking mutex without waiting?
		require
			valid_mutex: is_set
		do
			Result := eif_thr_mutex_trylock (mutex_pointer)
		end

	lock is
			-- Lock mutex, waiting if necessary until that becomes possible.
		require
			valid_mutex: is_set
		do
			eif_thr_mutex_lock (mutex_pointer)
		end

	unlock is
			-- Unlock mutex.
		require
			valid_mutex: is_set
		do
			eif_thr_mutex_unlock (mutex_pointer)
		end

	destroy is
			-- Destroy mutex.
		require
			valid_mutex: is_set
		do
			eif_thr_mutex_destroy (mutex_pointer)
			mutex_pointer := default_pointer
		end


feature {CONDITION_VARIABLE} -- Implementation

	mutex_pointer: POINTER
			-- C reference to the mutex.

feature {NONE} -- Removal

	dispose is
			-- Called by the garbage collector when the mutex is
			-- collected.
		do
			if is_set then
				destroy
			end
		end

feature {NONE} -- Externals

	eif_thr_mutex_create: POINTER is
		external
			"C | %"eif_threads.h%""
		end

	eif_thr_mutex_lock (a_mutex_pointer: POINTER) is
		external
			"C blocking use %"eif_threads.h%""
		end

	eif_thr_mutex_unlock (a_mutex_pointer: POINTER) is
		external
			"C | %"eif_threads.h%""
		end

	eif_thr_mutex_trylock (a_mutex_pointer: POINTER): BOOLEAN is
		external
			"C blocking use %"eif_threads.h%""
		end

	eif_thr_mutex_destroy (a_mutex_pointer: POINTER) is
		external
			"C | %"eif_threads.h%""
		end

end -- class MUTEX


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--| EiffelThread: library of reusable components for ISE Eiffel.
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--| Contact ISE for any other use.
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