File : posix-mutexes.ads
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-- --
-- FLORIST (FSU Implementation of POSIX.5) COMPONENTS --
-- --
-- P O S I X . M U T E X E S --
-- --
-- S p e c --
-- --
-- --
-- This file is a component of FLORIST, an implementation of the POSIX --
-- Ada bindings for use with the GNAT Ada compiler and the FSU Gnu Ada --
-- Runtime Library (GNARL). --
-- --
-- This package specification contains some text extracted from IEEE STD --
-- 1003.5: 1990, Information Technology -- POSIX Ada Language Interfaces --
-- Part 1: Binding for System Application Program Interface, as amended --
-- by IEEE STD 1003.5b: 1996, Amendment 1: Realtime Extensions, copyright --
-- 1996 by the Institute of Electrical and Electronics Engineers, Inc. --
-- --
-- The package specifications in the IEEE standards cited above represent --
-- only a portion of the documents and are not to be interpreteted --
-- outside the context of the documents. The standards must be used in --
-- conjunction with the package specifications in order to claim --
-- conformance. The IEEE takes no responsibility for and will assume no --
-- liability for damages resulting from the reader's misinterpretation of --
-- said information resulting from its out-of-context nature. To order --
-- copies of the IEEE standards, please contact the IEEE Service Center --
-- at 445 Hoes Lane, PO Box 1331, Piscataway, NJ 08855-1331; via phone at --
-- 1-800-678-IEEE, 908-981-1393; or via fax at 908-981-9667. --
-- --
-- These package specifications are distributed in the hope that they --
-- will be useful, but WITHOUT ANY WARRANTY; without even the implied --
-- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
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-- [$Revision: 1.1.1.1 $]
with POSIX.C;
package POSIX.Mutexes is
-- ========== --
-- WARNINGS --
-- ========== --
-- This package is for mixed-language programming, in which
-- an Ada task needs to synchronize with a C thread.
-- Do NOT use POSIX mutexes to synchronize between Ada tasks.
-- Instead, use Ada protected objects.
-- Protected objects are implemented using mutexes.
-- The difference is that they are safer.
-- In particular protected operations are abort-deferred,
-- and have cleanup code to ensure mutexes are always released,
-- even if a protected operation completes abnormally due to an exception.
-- If you use one of these "raw" mutexes, you risk undefined
-- behavior if you violate any of the POSIX.1c rules about mutexes,
-- or if you attempt to abort (including ATC) a task that is performing
-- a mutex or CV operation.
type Mutex is limited private;
type Mutex_Descriptor is private;
type Attributes is private;
procedure Initialize (Attr : in out Attributes);
procedure Finalize (Attr : in out Attributes);
function Get_Process_Shared (Attr : Attributes)
return Boolean;
procedure Set_Process_Shared
(Attr : in out Attributes;
Is_Shared : in Boolean := False);
subtype Ceiling_Priority is Integer;
type Locking_Policy is range 0 .. 2;
No_Priority_Inheritance : constant Locking_Policy := 0;
Highest_Blocked_Task : constant Locking_Policy := 1;
Highest_Ceiling_Priority : constant Locking_Policy := 2;
procedure Set_Locking_Policy
(Attr : in out Attributes;
Locking : in Locking_Policy);
function Get_Locking_Policy
(Attr : Attributes)
return Locking_Policy;
procedure Set_Ceiling_Priority
(Attr : in out Attributes;
New_Ceiling : in Ceiling_Priority);
function Get_Ceiling_Priority (Attr : Attributes)
return Ceiling_Priority;
procedure Initialize
(M : in out Mutex;
Attr : in Attributes);
procedure Initialize (M : in out Mutex);
function Descriptor_Of (M : Mutex) return Mutex_Descriptor;
procedure Finalize (M : in out Mutex);
procedure Set_Ceiling_Priority
(M : in Mutex_Descriptor;
New_Ceiling : in Ceiling_Priority;
Old_Ceiling : out Ceiling_Priority);
function Get_Ceiling_Priority (M : Mutex_Descriptor)
return Ceiling_Priority;
procedure Lock (M : in Mutex_Descriptor);
function Try_Lock (M : Mutex_Descriptor) return Boolean;
procedure Unlock (M : in Mutex_Descriptor);
private
type Dummy is tagged null record;
type Attributes is record
Attr : aliased POSIX.C.pthread_mutexattr_t;
-- to force by-reference parameter mode:
D : Dummy;
end record;
type Mutex is record
Mutex : aliased POSIX.C.pthread_mutex_t;
-- to force by-reference parameter mode:
D : Dummy;
end record;
-- The "access constant" is sometimes a lie, but it allows
-- us to emulate the POSIX C-language interface without violating
-- Ada rules about pointers to variables vs. pointers to constants.
type Mutex_Descriptor is access constant POSIX.C.pthread_mutex_t;
pragma Convention (C, Mutex_Descriptor);
end POSIX.Mutexes;