note
	description: "Class defining an Eiffel thread."
	legal: "See notice at end of class."
	status: "See notice at end of class."
	date: "$Date: 2018-01-22 11:15:04 +0000 (Mon, 22 Jan 2018) $"
	revision: "$Revision: 101252 $"

deferred class 
	THREAD

feature {NONE} -- Initialization

	default_create
			-- Process instances of classes with no creation clause.
			-- (Default: do nothing.)
			-- (from ANY)
		do
		end

	make
			-- Initialize Current.
		do
			create launch_mutex.make
		end
	
feature -- Access

	current_thread_id: POINTER
			-- Thread identifier of the Current thread
			-- (from THREAD_ENVIRONMENT)
		external
			"C inline use <eif_threads.h>"
		alias
			"return eif_thr_thread_id();"
		end

	generating_type: TYPE [detachable THREAD]
			-- Type of current object
			-- (type of which it is a direct instance)
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			generating_type_not_void: Result /= Void
		end

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			generator_not_void: Result /= Void
			generator_not_empty: not Result.is_empty
		end

	get_current_id: POINTER
		obsolete "Use `current_thread_id' instead. [2017-05-31]"
			-- Returns a pointer to the thread-id of the thread.
			-- (from THREAD_ENVIRONMENT)
		do
			Result := current_thread_id
		end

	terminated: BOOLEAN
			-- True if the thread has terminated.

	thread_id: POINTER
			-- Thread-id of the current thread object.
	
feature -- Comparison

	frozen deep_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.is_deep_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			shallow_implies_deep: standard_equal (a, b) implies Result
			both_or_none_void: (a = Void) implies (Result = (b = Void))
			same_type: (Result and (a /= Void)) implies (b /= Void and then a.same_type (b))
			symmetric: Result implies deep_equal (b, a)
		end

	frozen equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.is_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.is_equal (b))
		end

	frozen is_deep_equal alias "≡≡≡" (other: THREAD): BOOLEAN
			-- Are Current and other attached to isomorphic object structures?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			shallow_implies_deep: standard_is_equal (other) implies Result
			same_type: Result implies same_type (other)
			symmetric: Result implies other.is_deep_equal (Current)
		end

	is_equal (other: THREAD): BOOLEAN
			-- Is other attached to an object considered
			-- equal to current object?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			symmetric: Result implies other ~ Current
			consistent: standard_is_equal (other) implies Result
		end

	frozen standard_equal (a: detachable ANY; b: like arg #1): BOOLEAN
			-- Are a and b either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		do
			if a = Void then
				Result := b = Void
			else
				Result := b /= Void and then a.standard_is_equal (b)
			end
		ensure -- from ANY
			instance_free: class
			definition: Result = (a = Void and b = Void) or else ((a /= Void and b /= Void) and then a.standard_is_equal (b))
		end

	frozen standard_is_equal alias "≜" (other: THREAD): BOOLEAN
			-- Is other attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
		end
	
feature -- Status report

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of other (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		end

	is_exit_supported: BOOLEAN
			-- Can exit be called?
		do
			Result := True
		ensure
			is_class: class
		end

	is_last_launch_successful: BOOLEAN
			-- Was the last call to launch or launch_with_attributes in current thread
			-- of execution successful?
		do
			Result := Is_last_launch_successful_cell.item
		end

	is_launchable: BOOLEAN
			-- Can we launch a new thread?
		do
			Result := launch_mutex.is_set and thread_id = default_pointer and not terminated
		end

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of other?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		external
			"built_in"
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))
		end
	
feature -- Duplication

	frozen clone (other: detachable ANY): like other
		obsolete "Use `twin' instead. [2017-05-31]"
			-- Void if other is void; otherwise new object
			-- equal to other
			--
			-- For non-void other, clone calls copy;
			-- to change copying/cloning semantics, redefine copy.
			-- (from ANY)
		do
			if other /= Void then
				Result := other.twin
			end
		ensure -- from ANY
			instance_free: class
			equal: Result ~ other
		end

	copy (other: THREAD)
			-- Update current object using fields of object attached
			-- to other, so as to yield equal objects.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		external
			"built_in"
		ensure -- from ANY
			is_equal: Current ~ other
		end

	frozen deep_clone (other: detachable ANY): like other
		obsolete "Use `deep_twin' instead. [2017-05-31]"
			-- Void if other is void: otherwise, new object structure
			-- recursively duplicated from the one attached to other
			-- (from ANY)
		do
			if other /= Void then
				Result := other.deep_twin
			end
		ensure -- from ANY
			instance_free: class
			deep_equal: deep_equal (other, Result)
		end

	frozen deep_copy (other: THREAD)
			-- Effect equivalent to that of:
			--		copy (other . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		do
			copy (other.deep_twin)
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)
		end

	frozen deep_twin: THREAD
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			deep_twin_not_void: Result /= Void
			deep_equal: deep_equal (Current, Result)
		end

	frozen standard_clone (other: detachable ANY): like other
		obsolete "Use `standard_twin' instead. [2017-05-31]"
			-- Void if other is void; otherwise new object
			-- field-by-field identical to other.
			-- Always uses default copying semantics.
			-- (from ANY)
		do
			if other /= Void then
				Result := other.standard_twin
			end
		ensure -- from ANY
			instance_free: class
			equal: standard_equal (Result, other)
		end

	frozen standard_copy (other: THREAD)
			-- Copy every field of other onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		external
			"built_in"
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)
		end

	frozen standard_twin: THREAD
			-- New object field-by-field identical to other.
			-- Always uses default copying semantics.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)
		end

	frozen twin: THREAD
			-- New object equal to Current
			-- twin calls copy; to change copying/twinning semantics, redefine copy.
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result ~ Current
		end
	
feature -- Basic operations

	frozen as_attached: attached THREAD
		obsolete "Remove calls to this feature. [2017-05-31]"
			-- Attached version of Current.
			-- (Can be used during transitional period to convert
			-- non-void-safe classes to void-safe ones.)
			-- (from ANY)
		do
			Result := Current
		end

	frozen default: detachable THREAD
			-- Default value of object's type
			-- (from ANY)
		do
		end

	frozen default_pointer: POINTER
			-- Default value of type POINTER
			-- (Avoid the need to write p.default for
			-- some p of type POINTER.)
			-- (from ANY)
		do
		ensure -- from ANY
			instance_free: class
		end

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)
		do
		end

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
		do
		ensure -- from ANY
			instance_free: class
		end

	execute
			-- Routine executed when thread is launched.
		deferred
		end

	exit
			-- Exit calling thread. Must be called from the thread itself.
		require
			is_exit_supported: is_exit_supported
			self: current_thread_id = thread_id
		do
			c_exit
		end

	frozen launch
			-- Initialize a new thread running execute.
			-- Set is_last_launch_successful to True if successful, False otherwise.			
		require
			thread_capable: {PLATFORM}.is_thread_capable
			is_launchable: is_launchable
		do
			launch_with_attributes (create {THREAD_ATTRIBUTES}.make)
		end

	frozen launch_with_attributes (attr: THREAD_ATTRIBUTES)
			-- Initialize a new thread running execute, using attributes.
			-- Set is_last_launch_successful to True if successful, False otherwise.
		require
			thread_capable: {PLATFORM}.is_thread_capable
			is_launchable: is_launchable
		do
			launch_mutex.lock
			if not is_launchable then
				Is_last_launch_successful_cell.put (False)
			else
				create_thread_with_attr (Current, $thr_main, $thr_set_terminated, attr.item)
				thread_id := last_created_thread;
				Is_last_launch_successful_cell.put (True)
			end;
			launch_mutex.unlock
		rescue
			Is_last_launch_successful_cell.put (False);
			launch_mutex.unlock
		end

	sleep (nanoseconds: INTEGER_64)
			-- Suspend thread execution for interval specified in
			-- nanoseconds (1 nanosecond = 10^(-9) second).
		require
			self: current_thread_id = thread_id
			non_negative_nanoseconds: nanoseconds >= 0
		do
			(create {EXECUTION_ENVIRONMENT}).sleep (nanoseconds)
		end
	
feature {NONE} -- Basic operations

	c_exit
			-- Implementation of exit.
		require
			is_exit_supported: is_exit_supported
			self: 
		external
			"C use %"eif_threads.h%""
		alias
			"eif_thr_exit"
		end
	
feature {NONE} -- Implementation

	Is_last_launch_successful_cell: CELL [BOOLEAN]
			-- Internal storage for is_last_launch_successful.
			-- It is a once per thread and not an attribute because if you have multiple threads
			-- calling launch on the same object, one will set it to True, and the other will
			-- override the value with False.
		once
			create Result.put (False)
		end

	launch_mutex: MUTEX
			-- Mutex used to ensure that no two threads call launch or launch_with_attributes
			-- on the same object. This ensures the validity of querying thread_id from
			-- the launch routines.

	frozen thr_get_terminated: BOOLEAN
			-- Get value of terminated.
		do
			launch_mutex.lock
			Result := terminated;
			launch_mutex.unlock
		end

	frozen thr_main (a_logical_id: INTEGER_32)
			-- Call thread routine.
		do
			launch_mutex.lock;
			launch_mutex.unlock
			execute;
			launch_mutex.lock
			terminated := True
			thread_id := default_pointer;
			launch_mutex.unlock
		rescue
			launch_mutex.lock
			terminated := True
			thread_id := default_pointer;
			launch_mutex.unlock
		end

	frozen thr_set_terminated (b: BOOLEAN)
			-- Set terminated to b.
		do
			launch_mutex.lock
			terminated := b;
			launch_mutex.unlock
		end
	
feature {NONE} -- Externals

	create_thread_with_attr (current_obj: THREAD; init_func, set_terminated_func, attr: POINTER)
			-- Initialize and start thread, after setting its priority
			-- and stack size.
		external
			"C signature (EIF_OBJECT, EIF_PROCEDURE, EIF_PROCEDURE, EIF_POINTER) use %"eif_threads.h%""
		alias
			"eif_thr_create_with_attr"
		end

	last_created_thread: POINTER
			-- Returns a pointer to the thread-id of the last created thread.
		external
			"C use %"eif_threads.h%""
		alias
			"eif_thr_last_thread"
		end

	thread_wait (current_obj: THREAD; get_terminated_func: POINTER)
			-- The calling C thread waits for the current Eiffel thread to
			-- terminate.
		external
			"C signature (EIF_OBJECT, EIF_BOOLEAN_FUNCTION) use %"eif_threads.h%""
		alias
			"eif_thr_wait"
		end

	thread_wait_with_timeout (current_obj: THREAD; get_terminated_func: POINTER; a_timeout_ms: NATURAL_64): BOOLEAN
			-- The calling C thread waits for the current Eiffel thread to
			-- terminate.
		external
			"C signature (EIF_OBJECT, EIF_BOOLEAN_FUNCTION, EIF_NATURAL_64): EIF_BOOLEAN use %"eif_threads.h%""
		alias
			"eif_thr_wait_with_timeout"
		end
	
feature -- Output

	Io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)
		once
			create Result;
			Result.set_output_default
		ensure -- from ANY
			instance_free: class
			io_not_void: Result /= Void
		end

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		do
			Result := tagged_out
		ensure -- from ANY
			out_not_void: Result /= Void
		end

	print (o: detachable ANY)
			-- Write terse external representation of o
			-- on standard output.
			-- (from ANY)
		local
			s: READABLE_STRING_8
		do
			if attached o then
				s := o.out
				if attached {READABLE_STRING_32} s as s32 then
					Io.put_string_32 (s32)
				elseif attached {READABLE_STRING_8} s as s8 then
					Io.put_string (s8)
				else
					Io.put_string_32 (s.as_string_32)
				end
			end
		ensure -- from ANY
			instance_free: class
		end

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- (from ANY)
		external
			"built_in"
		ensure -- from ANY
			tagged_out_not_void: Result /= Void
		end
	
feature -- Platform

	Operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
		once
			create Result
		ensure -- from ANY
			instance_free: class
			operating_environment_not_void: Result /= Void
		end
	
feature {NONE} -- Retrieval

	frozen internal_correct_mismatch
			-- Called from runtime to perform a proper dynamic dispatch on correct_mismatch
			-- from MISMATCH_CORRECTOR.
			-- (from ANY)
		local
			l_msg: STRING_32
			l_exc: EXCEPTIONS
		do
			if attached {MISMATCH_CORRECTOR} Current as l_corrector then
				l_corrector.correct_mismatch
			else
				create l_msg.make_from_string ("Mismatch: ".as_string_32)
				create l_exc;
				l_msg.append (generating_type.name_32);
				l_exc.raise_retrieval_exception (l_msg)
			end
		end
	
feature -- Synchronization

	join
			-- The calling thread waits for the current child thread to terminate.
		do
			if not terminated then
				thread_wait (Current, $thr_get_terminated)
			end
		end

	join_all
			-- The calling thread waits for all other threads to terminate.
			-- (from THREAD_CONTROL)
		external
			"C blocking use %"eif_threads.h%""
		alias
			"eif_thr_join_all"
		end

	join_with_timeout (a_timeout_ms: NATURAL_64): BOOLEAN
			-- The calling thread waits for the current child thread to
			-- terminate for at most a_timeout_ms milliseconds.
			-- True if wait terminates within a_timeout_ms, False otherwise.
		do
			if terminated then
				Result := True
			else
				Result := thread_wait_with_timeout (Current, $thr_get_terminated, a_timeout_ms)
			end
		end

	yield
			-- The calling thread yields its execution in favor of another
			-- thread for an OS specific amount of time.
			-- (from THREAD_CONTROL)
		external
			"C use %"eif_threads.h%""
		alias
			"eif_thr_yield"
		end
	
invariant
		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

note
	copyright: "Copyright (c) 1984-2018, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		5949 Hollister Ave., Goleta, CA 93117 USA
		Telephone 805-685-1006, Fax 805-685-6869
		Website http://www.eiffel.com
		Customer support http://support.eiffel.com
	]"

end -- class THREAD

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