-- --
-- S p e c --
-- --
--- Copyright (C) 1992-2005, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2009, 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- --
--- ware Foundation; either version 2, or (at your option) any later ver- --
--- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
+-- ware Foundation; either version 3, or (at your option) any later ver- --
+-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
--- 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. --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
--- 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 unit does not by itself cause the resulting executable to be --
--- covered by the GNU General Public License. This exception does not --
--- however invalidate any other reasons why the executable file might be --
--- covered by the GNU Public License. --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception, --
+-- version 3.1, as published by the Free Software Foundation. --
+-- --
+-- You should have received a copy of the GNU General Public License and --
+-- a copy of the GCC Runtime Library Exception along with this program; --
+-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
+-- <http://www.gnu.org/licenses/>. --
-- --
-- GNARL was developed by the GNARL team at Florida State University. --
-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- Any changes to this interface may require corresponding compiler changes.
with Ada.Exceptions;
--- Used for: Exception_Id
+with Ada.Unchecked_Conversion;
with System.Parameters;
--- used for Size_Type
-
with System.Task_Info;
--- used for Task_Info_Type
-
with System.Soft_Links;
--- used for TSD
-
with System.Task_Primitives;
--- used for Private_Data
-
-with Unchecked_Conversion;
+with System.Stack_Usage;
package System.Tasking is
+ pragma Preelaborate;
-------------------
-- Locking Rules --
-- Never undefer abort while holding a lock
-- Overlapping critical sections must be properly nested, and locks must
- -- be released in LIFO order. e.g., the following is not allowed:
+ -- be released in LIFO order. E.g., the following is not allowed:
-- Lock (X);
-- ...
type Ada_Task_Control_Block;
type Task_Id is access all Ada_Task_Control_Block;
+ for Task_Id'Size use System.Task_Primitives.Task_Address_Size;
Null_Task : constant Task_Id;
-- This is the compiler interface version of this function. Do not call
-- from the run-time system.
- function To_Task_Id is new Unchecked_Conversion (System.Address, Task_Id);
- function To_Address is new Unchecked_Conversion (Task_Id, System.Address);
+ function To_Task_Id is
+ new Ada.Unchecked_Conversion
+ (System.Task_Primitives.Task_Address, Task_Id);
+ function To_Address is
+ new Ada.Unchecked_Conversion
+ (Task_Id, System.Task_Primitives.Task_Address);
-----------------------
-- Enumeration types --
type Task_States is
(Unactivated,
- -- Task has been created but has not been activated.
+ -- TCB initialized but not task has not been created.
-- It cannot be executing.
+-- Activating,
+-- -- ??? Temporarily at end of list for GDB compatibility
+-- -- Task has been created and is being made Runnable.
+
-- Active states
-- For all states from here down, the task has been activated.
-- For all states from here down, except for Terminated, the task
-- may be executing.
-- Activator = null iff it has not yet completed activating.
- -- For all states from here down,
- -- the task has been activated, and may be executing.
-
Runnable,
-- Task is not blocked for any reason known to Ada.
-- (It may be waiting for a mutex, though.)
-- Task is waiting for created tasks to complete activation
Acceptor_Sleep,
- -- Task is waiting on an accept or selective wait statement
+ -- Task is waiting on an accept or select with terminate
+
+-- Acceptor_Delay_Sleep,
+-- -- ??? Temporarily at end of list for GDB compatibility
+-- -- Task is waiting on an selective wait statement
Entry_Caller_Sleep,
-- Task is waiting on an entry call
Asynchronous_Hold,
-- The task has been held by Asynchronous_Task_Control.Hold_Task
- Interrupt_Server_Blocked_On_Event_Flag
- -- The task has been blocked on a system call waiting for the
- -- completion event.
+ Interrupt_Server_Blocked_On_Event_Flag,
+ -- The task has been blocked on a system call waiting for a
+ -- completion event/signal to occur.
+
+ Activating,
+ -- Task has been created and is being made Runnable
+
+ Acceptor_Delay_Sleep
+ -- Task is waiting on an selective wait statement
);
type Call_Modes is
type Task_Entry_Queue_Array is
array (Task_Entry_Index range <>) of Entry_Queue;
+ -- A data structure which contains the string names of entries and entry
+ -- family members.
+
+ type String_Access is access all String;
+
+ type Entry_Names_Array is
+ array (Entry_Index range <>) of String_Access;
+
+ type Entry_Names_Array_Access is access all Entry_Names_Array;
+
+ procedure Free_Entry_Names_Array (Obj : in out Entry_Names_Array);
+ -- Deallocate all string names contained in an entry names array
+
----------------------------------
-- Entry_Call_Record definition --
----------------------------------
end record;
pragma Suppress_Initialization (Restricted_Entry_Call_Record);
+ -------------------------------------------
+ -- Task termination procedure definition --
+ -------------------------------------------
+
+ -- We need to redefine here these types (already defined in
+ -- Ada.Task_Termination) for avoiding circular dependencies.
+
+ type Cause_Of_Termination is (Normal, Abnormal, Unhandled_Exception);
+ -- Possible causes for task termination:
+ --
+ -- Normal means that the task terminates due to completing the
+ -- last sentence of its body, or as a result of waiting on a
+ -- terminate alternative.
+
+ -- Abnormal means that the task terminates because it is being aborted
+
+ -- handled_Exception means that the task terminates because of exception
+ -- raised by the execution of its task_body.
+
+ type Termination_Handler is access protected procedure
+ (Cause : Cause_Of_Termination;
+ T : Task_Id;
+ X : Ada.Exceptions.Exception_Occurrence);
+ -- Used to represent protected procedures to be executed when task
+ -- terminates.
+
------------------------------------
-- Task related other definitions --
------------------------------------
type Activation_Chain is limited private;
- -- Comment required ???
+ -- Linked list of to-be-activated tasks, linked through
+ -- Activation_Link. The order of tasks on the list is irrelevant, because
+ -- the priority rules will ensure that they actually start activating in
+ -- priority order.
type Activation_Chain_Access is access all Activation_Chain;
- -- Comment required ???
type Task_Procedure_Access is access procedure (Arg : System.Address);
type Access_Boolean is access all Boolean;
- Detect_Blocking : constant Boolean;
- -- Boolean constant set True iff Detect_Blocking is active
+ function Detect_Blocking return Boolean;
+ pragma Inline (Detect_Blocking);
+ -- Return whether the Detect_Blocking pragma is enabled
+
+ function Storage_Size (T : Task_Id) return System.Parameters.Size_Type;
+ -- Retrieve from the TCB of the task the allocated size of its stack,
+ -- either the system default or the size specified by a pragma. This
+ -- is in general a non-static value that can depend on discriminants
+ -- of the task.
+
+ type Bit_Array is array (Integer range <>) of Boolean;
+ pragma Pack (Bit_Array);
+
+ subtype Debug_Event_Array is Bit_Array (1 .. 16);
+
+ Global_Task_Debug_Event_Set : Boolean := False;
+ -- Set True when running under debugger control and a task debug
+ -- event signal has been requested.
----------------------------------------------
-- Ada_Task_Control_Block (ATCB) definition --
-- and rendezvous.
--
-- Ada 95 notes: In Ada 95, this field will be transferred to the
- -- Priority field of an Entry_Calls component when an entry call
- -- is initiated. The Priority of the Entry_Calls component will not
- -- change for the duration of the call. The accepting task can
- -- use it to boost its own priority without fear of its changing in
- -- the meantime.
+ -- Priority field of an Entry_Calls component when an entry call is
+ -- initiated. The Priority of the Entry_Calls component will not change
+ -- for the duration of the call. The accepting task can use it to boost
+ -- its own priority without fear of its changing in the meantime.
--
- -- This can safely be used in the priority ordering
- -- of entry queues. Once a call is queued, its priority does not
- -- change.
+ -- This can safely be used in the priority ordering of entry queues.
+ -- Once a call is queued, its priority does not change.
--
- -- Since an entry call cannot be made while executing
- -- a protected action, the priority of a task will never reflect a
- -- priority ceiling change at the point of an entry call.
+ -- Since an entry call cannot be made while executing a protected
+ -- action, the priority of a task will never reflect a priority ceiling
+ -- change at the point of an entry call.
--
-- Protection: Only written by Self, and only accessed when Acceptor
-- accepts an entry or when Created activates, at which points Self is
-- are invoked from protected actions. pragma Atomic is used because it
-- can be read/written from protected interrupt handlers.
- Task_Image : String (1 .. 32);
- -- Hold a string that provides a readable id for task,
- -- built from the variable of which it is a value or component.
+ Task_Image : String (1 .. System.Parameters.Max_Task_Image_Length);
+ -- Hold a string that provides a readable id for task, built from the
+ -- variable of which it is a value or component.
Task_Image_Len : Natural;
-- Actual length of Task_Image
Task_Arg : System.Address;
-- The argument to task procedure. Provide a handle for discriminant
- -- information
+ -- information.
--
-- Protection: Part of the synchronization between Self and Activator.
-- Activator writes it, once, before Self starts executing. Thereafter,
-- Self only reads it.
+ Task_Alternate_Stack : System.Address;
+ -- The address of the alternate signal stack for this task, if any
+ --
+ -- Protection: Only accessed by Self
+
Task_Entry_Point : Task_Procedure_Access;
-- Information needed to call the procedure containing the code for
-- the body of this task.
Task_Info : System.Task_Info.Task_Info_Type;
-- System-specific attributes of the task as specified by the
-- Task_Info pragma.
+
+ Analyzer : System.Stack_Usage.Stack_Analyzer;
+ -- For storing informations used to measure the stack usage
+
+ Global_Task_Lock_Nesting : Natural;
+ -- This is the current nesting level of calls to
+ -- System.Tasking.Initialization.Lock_Task. This allows a task to call
+ -- Lock_Task multiple times without deadlocking. A task only locks
+ -- Global_Task_Lock when its Global_Task_Lock_Nesting goes from 0 to 1,
+ -- and only unlocked when it goes from 1 to 0.
+ --
+ -- Protection: Only accessed by Self
+
+ Fall_Back_Handler : Termination_Handler;
+ -- This is the fall-back handler that applies to the dependent tasks of
+ -- the task.
+ --
+ -- Protection: Self.L
+
+ Specific_Handler : Termination_Handler;
+ -- This is the specific handler that applies only to this task, and not
+ -- any of its dependent tasks.
+ --
+ -- Protection: Self.L
+
+ Debug_Events : Debug_Event_Array;
+ -- Word length array of per task debug events, of which 11 kinds are
+ -- currently defined in System.Tasking.Debugging package.
end record;
---------------------------------------
-- Restricted_Ada_Task_Control_Block --
---------------------------------------
- -- This type should only be used by the restricted GNARLI and by
- -- restricted GNULL implementations to allocate an ATCB (see
- -- System.Task_Primitives.Operations.New_ATCB) that will take
- -- significantly less memory.
+ -- This type should only be used by the restricted GNARLI and by restricted
+ -- GNULL implementations to allocate an ATCB (see System.Task_Primitives.
+ -- Operations.New_ATCB) that will take significantly less memory.
-- Note that the restricted GNARLI should only access fields that are
-- present in the Restricted_Ada_Task_Control_Block structure.
-- Normally, a task starts out with internal master nesting level one
-- larger than external master nesting level. It is incremented to one by
-- Enter_Master, which is called in the task body only if the compiler
- -- thinks the task may have dependent tasks. It is set to for the
+ -- thinks the task may have dependent tasks. It is set to 1 for the
-- environment task, the level 2 is reserved for server tasks of the
-- run-time system (the so called "independent tasks"), and the level 3 is
- -- for the library level tasks.
+ -- for the library level tasks. Foreign threads which are detected by
+ -- the run-time have a level of 0, allowing these tasks to be easily
+ -- distinguished if needed.
+ Foreign_Task_Level : constant Master_Level := 0;
Environment_Task_Level : constant Master_Level := 1;
Independent_Task_Level : constant Master_Level := 2;
Library_Task_Level : constant Master_Level := 3;
-- Cancellation of the call has been attempted.
-- Consider merging this into State???
- Requeue_With_Abort : Boolean := False;
- -- Temporary to tell caller whether requeue is with abort.
- -- Find a better way of doing this ???
+ With_Abort : Boolean := False;
+ -- Tell caller whether the call may be aborted
+ -- ??? consider merging this with Was_Abortable state
Needs_Requeue : Boolean := False;
-- Temporary to tell acceptor of task entry call that
------------------------------------
type Access_Address is access all System.Address;
- -- Comment on what this is used for ???
+ -- Anonymous pointer used to implement task attributes (see s-tataat.adb
+ -- and a-tasatt.adb)
pragma No_Strict_Aliasing (Access_Address);
-- This type is used in contexts where aliasing may be an issue (see
-- associated with protected objects or task entries, and are protected
-- by the protected object lock or Acceptor.L, respectively.
+ Entry_Names : Entry_Names_Array_Access := null;
+ -- An array of string names which denotes entry [family member] names.
+ -- The structure is indexed by task entry index and contains Entry_Num
+ -- components.
+
New_Base_Priority : System.Any_Priority;
-- New value for Base_Priority (for dynamic priorities package)
--
-- Protection: Self.L
- Global_Task_Lock_Nesting : Natural := 0;
- -- This is the current nesting level of calls to
- -- System.Tasking.Stages.Lock_Task_T. This allows a task to call
- -- Lock_Task_T multiple times without deadlocking. A task only locks
- -- All_Task_Lock when its All_Tasks_Nesting goes from 0 to 1, and only
- -- unlocked when it goes from 1 to 0.
- --
- -- Protection: Only accessed by Self
-
Open_Accepts : Accept_List_Access;
-- This points to the Open_Accepts array of accept alternatives passed
-- to the RTS by the compiler-generated code to Selective_Wait. It is
-- this value.
Deferral_Level : Natural := 1;
- -- This is the number of times that Defer_Abortion has been called by
- -- this task without a matching Undefer_Abortion call. Abortion is only
+ -- This is the number of times that Defer_Abort has been called by
+ -- this task without a matching Undefer_Abort call. Abortion is only
-- allowed when this zero. It is initially 1, to protect the task at
-- startup.
-- has exclusive access to this field.
end record;
- ---------------------
- -- Initialize_ATCB --
- ---------------------
+ --------------------
+ -- Initialization --
+ --------------------
+
+ procedure Initialize;
+ -- This procedure constitutes the first part of the initialization of the
+ -- GNARL. This includes creating data structures to make the initial thread
+ -- into the environment task. The last part of the initialization is done
+ -- in System.Tasking.Initialization or System.Tasking.Restricted.Stages.
+ -- All the initializations used to be in Tasking.Initialization, but this
+ -- is no longer possible with the run time simplification (including
+ -- optimized PO and the restricted run time) since one cannot rely on
+ -- System.Tasking.Initialization being present, as was done before.
procedure Initialize_ATCB
(Self_ID : Task_Id;
-- documentation, mention T, and describe Success ???
private
- Null_Task : constant Task_Id := null;
-
- GL_Detect_Blocking : Integer;
- pragma Import (C, GL_Detect_Blocking, "__gl_detect_blocking");
- -- Global variable exported by the binder generated file. A value equal to
- -- 1 indicates that pragma Detect_Blocking is active, while 0 is used for
- -- the pragma not being present.
- Detect_Blocking : constant Boolean := GL_Detect_Blocking = 1;
+ Null_Task : constant Task_Id := null;
- type Activation_Chain is record
+ type Activation_Chain is limited record
T_ID : Task_Id;
end record;
- pragma Volatile (Activation_Chain);
- -- Activation_chain is an in-out parameter of initialization procedures
- -- and it must be passed by reference because the init proc may terminate
+ -- Activation_Chain is an in-out parameter of initialization procedures and
+ -- it must be passed by reference because the init proc may terminate
-- abnormally after creating task components, and these must be properly
- -- registered for removal (Expunge_Unactivated_Tasks).
+ -- registered for removal (Expunge_Unactivated_Tasks). The "limited" forces
+ -- Activation_Chain to be a by-reference type; see RM-6.2(4).
end System.Tasking;
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