------------------------------------------------------------------------------
-- --
--- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
+-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . T A S K _ P R I M I T I V E S --
-- --
-- S p e c --
-- --
--- Copyright (C) 1991-2000 Free Software Foundation, Inc. --
+-- Copyright (C) 1991-2008, Free Software Foundation, Inc. --
-- --
-- GNARL is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNARL; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- --
------------------------------------------------------------------------------
--- This is the DEC Unix 4.0 version of this package.
+-- This is the DEC Unix 4.0 version of this package
--- This package provides low-level support for most tasking features.
+-- This package provides low-level support for most tasking features
pragma Polling (Off);
--- Turn off polling, we do not want ATC polling to take place during
--- tasking operations. It causes infinite loops and other problems.
+-- Turn off polling, we do not want ATC polling to take place during tasking
+-- operations. It causes infinite loops and other problems.
with Interfaces.C;
--- used for int
--- size_t
with System.OS_Interface;
--- used for pthread_mutex_t
--- pthread_cond_t
--- pthread_t
package System.Task_Primitives is
+ pragma Preelaborate;
type Lock is limited private;
- -- Should be used for implementation of protected objects.
+ -- Should be used for implementation of protected objects
type RTS_Lock is limited private;
- -- Should be used inside the runtime system.
- -- The difference between Lock and the RTS_Lock is that the later
- -- one serves only as a semaphore so that do not check for
- -- ceiling violations.
+ -- Should be used inside the runtime system. The difference between Lock
+ -- and the RTS_Lock is that the later one serves only as a semaphore so
+ -- that do not check for ceiling violations.
+
+ type Suspension_Object is limited private;
+ -- Should be used for the implementation of Ada.Synchronous_Task_Control
type Task_Body_Access is access procedure;
-- Pointer to the task body's entry point (or possibly a wrapper
-- declared local to the GNARL).
type Private_Data is limited private;
- -- Any information that the GNULLI needs maintained on a per-task
- -- basis. A component of this type is guaranteed to be included
- -- in the Ada_Task_Control_Block.
+ -- Any information that the GNULLI needs maintained on a per-task basis.
+ -- A component of this type is guaranteed to be included
+
+ subtype Task_Address is System.Address;
+ -- In some versions of Task_Primitives, notably for VMS, Task_Address is
+ -- the short version of address defined in System.Aux_DEC. To avoid
+ -- dragging Aux_DEC into tasking packages a tasking specific subtype is
+ -- defined here.
+
+ Task_Address_Size : constant := Standard'Address_Size;
+ -- The size of Task_Address
+
+ Alternate_Stack_Size : constant := 0;
+ -- No alternate signal stack is used on this platform
private
type Lock is record
- L : aliased System.OS_Interface.pthread_mutex_t;
- Ceiling : Interfaces.C.int;
+ L : aliased System.OS_Interface.pthread_mutex_t;
+ Ceiling : Interfaces.C.int;
end record;
type RTS_Lock is new System.OS_Interface.pthread_mutex_t;
+
+ type Suspension_Object is record
+ State : Boolean;
+ pragma Atomic (State);
+ -- Boolean that indicates whether the object is open. This field is
+ -- marked Atomic to ensure that we can read its value without locking
+ -- the access to the Suspension_Object.
+
+ Waiting : Boolean;
+ -- Flag showing if there is a task already suspended on this object
+
+ L : aliased System.OS_Interface.pthread_mutex_t;
+ -- Protection for ensuring mutual exclusion on the Suspension_Object
+
+ CV : aliased System.OS_Interface.pthread_cond_t;
+ -- Condition variable used to queue threads until the is signaled
+ end record;
+
type Private_Data is record
- Thread : aliased System.OS_Interface.pthread_t;
+ Thread : aliased System.OS_Interface.pthread_t;
pragma Atomic (Thread);
-- Thread field may be updated by two different threads of control.
- -- (See, Enter_Task and Create_Task in s-taprop.adb).
- -- They put the same value (thr_self value). We do not want to
- -- use lock on those operations and the only thing we have to
- -- make sure is that they are updated in atomic fashion.
-
- CV : aliased System.OS_Interface.pthread_cond_t;
- L : aliased RTS_Lock;
- -- protection for all components is lock L
+ -- (See, Enter_Task and Create_Task in s-taprop.adb). They put the same
+ -- value (thr_self value). We do not want to use lock on those
+ -- operations and the only thing we have to make sure is that they are
+ -- updated in atomic fashion.
+
+ CV : aliased System.OS_Interface.pthread_cond_t;
+
+ L : aliased RTS_Lock;
+ -- Protection for all components is lock L
end record;
end System.Task_Primitives;
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