| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- |
| -- -- |
| -- SYSTEM.TASKING.PROTECTED_OBJECTS.SINGLE_ENTRY -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 1998-2013, 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 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. -- |
| -- -- |
| -- 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. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| pragma Style_Checks (All_Checks); |
| -- Turn off subprogram ordering check, since restricted GNARLI subprograms are |
| -- gathered together at end. |
| |
| -- This package provides an optimized version of Protected_Objects.Operations |
| -- and Protected_Objects.Entries making the following assumptions: |
| |
| -- PO has only one entry |
| -- There is only one caller at a time (No_Entry_Queue) |
| -- There is no dynamic priority support (No_Dynamic_Priorities) |
| -- No Abort Statements |
| -- (No_Abort_Statements, Max_Asynchronous_Select_Nesting => 0) |
| -- PO are at library level |
| -- No Requeue |
| -- None of the tasks will terminate (no need for finalization) |
| |
| -- This interface is intended to be used in the ravenscar and restricted |
| -- profiles, the compiler is responsible for ensuring that the conditions |
| -- mentioned above are respected, except for the No_Entry_Queue restriction |
| -- that is checked dynamically in this package, since the check cannot be |
| -- performed at compile time, and is relatively cheap (see PO_Do_Or_Queue, |
| -- Service_Entry). |
| |
| pragma Polling (Off); |
| -- Turn off polling, we do not want polling to take place during tasking |
| -- operations. It can cause infinite loops and other problems. |
| |
| pragma Suppress (All_Checks); |
| -- Why is this required ??? |
| |
| with Ada.Exceptions; |
| |
| with System.Task_Primitives.Operations; |
| with System.Parameters; |
| |
| package body System.Tasking.Protected_Objects.Single_Entry is |
| |
| package STPO renames System.Task_Primitives.Operations; |
| |
| use Parameters; |
| |
| ----------------------- |
| -- Local Subprograms -- |
| ----------------------- |
| |
| procedure Send_Program_Error (Entry_Call : Entry_Call_Link); |
| pragma Inline (Send_Program_Error); |
| -- Raise Program_Error in the caller of the specified entry call |
| |
| -------------------------- |
| -- Entry Calls Handling -- |
| -------------------------- |
| |
| procedure Wakeup_Entry_Caller (Entry_Call : Entry_Call_Link); |
| pragma Inline (Wakeup_Entry_Caller); |
| -- This is called at the end of service of an entry call, to abort the |
| -- caller if he is in an abortable part, and to wake up the caller if he |
| -- is on Entry_Caller_Sleep. Call it holding the lock of Entry_Call.Self. |
| |
| procedure Wait_For_Completion (Entry_Call : Entry_Call_Link); |
| pragma Inline (Wait_For_Completion); |
| -- This procedure suspends the calling task until the specified entry call |
| -- has either been completed or cancelled. On exit, the call will not be |
| -- queued. This waits for calls on protected entries. |
| -- Call this only when holding Self_ID locked. |
| |
| procedure Check_Exception |
| (Self_ID : Task_Id; |
| Entry_Call : Entry_Call_Link); |
| pragma Inline (Check_Exception); |
| -- Raise any pending exception from the Entry_Call. This should be called |
| -- at the end of every compiler interface procedure that implements an |
| -- entry call. The caller should not be holding any locks, or there will |
| -- be deadlock. |
| |
| procedure PO_Do_Or_Queue |
| (Object : Protection_Entry_Access; |
| Entry_Call : Entry_Call_Link); |
| -- This procedure executes or queues an entry call, depending on the status |
| -- of the corresponding barrier. The specified object is assumed locked. |
| |
| --------------------- |
| -- Check_Exception -- |
| --------------------- |
| |
| procedure Check_Exception |
| (Self_ID : Task_Id; |
| Entry_Call : Entry_Call_Link) |
| is |
| pragma Warnings (Off, Self_ID); |
| |
| procedure Internal_Raise (X : Ada.Exceptions.Exception_Id); |
| pragma Import (C, Internal_Raise, "__gnat_raise_with_msg"); |
| |
| use type Ada.Exceptions.Exception_Id; |
| |
| E : constant Ada.Exceptions.Exception_Id := |
| Entry_Call.Exception_To_Raise; |
| |
| begin |
| if E /= Ada.Exceptions.Null_Id then |
| Internal_Raise (E); |
| end if; |
| end Check_Exception; |
| |
| ------------------------ |
| -- Send_Program_Error -- |
| ------------------------ |
| |
| procedure Send_Program_Error (Entry_Call : Entry_Call_Link) is |
| Caller : constant Task_Id := Entry_Call.Self; |
| |
| begin |
| Entry_Call.Exception_To_Raise := Program_Error'Identity; |
| |
| if Single_Lock then |
| STPO.Lock_RTS; |
| end if; |
| |
| STPO.Write_Lock (Caller); |
| Wakeup_Entry_Caller (Entry_Call); |
| STPO.Unlock (Caller); |
| |
| if Single_Lock then |
| STPO.Unlock_RTS; |
| end if; |
| end Send_Program_Error; |
| |
| ------------------------- |
| -- Wait_For_Completion -- |
| ------------------------- |
| |
| procedure Wait_For_Completion (Entry_Call : Entry_Call_Link) is |
| Self_Id : constant Task_Id := Entry_Call.Self; |
| begin |
| Self_Id.Common.State := Entry_Caller_Sleep; |
| STPO.Sleep (Self_Id, Entry_Caller_Sleep); |
| Self_Id.Common.State := Runnable; |
| end Wait_For_Completion; |
| |
| ------------------------- |
| -- Wakeup_Entry_Caller -- |
| ------------------------- |
| |
| -- This is called at the end of service of an entry call, to abort the |
| -- caller if he is in an abortable part, and to wake up the caller if it |
| -- is on Entry_Caller_Sleep. It assumes that the call is already off-queue. |
| |
| -- (This enforces the rule that a task must be off-queue if its state is |
| -- Done or Cancelled.) Call it holding the lock of Entry_Call.Self. |
| |
| -- The caller is waiting on Entry_Caller_Sleep, in Wait_For_Completion. |
| |
| procedure Wakeup_Entry_Caller |
| (Entry_Call : Entry_Call_Link) |
| is |
| Caller : constant Task_Id := Entry_Call.Self; |
| begin |
| pragma Assert |
| (Caller.Common.State /= Terminated and then |
| Caller.Common.State /= Unactivated); |
| Entry_Call.State := Done; |
| STPO.Wakeup (Caller, Entry_Caller_Sleep); |
| end Wakeup_Entry_Caller; |
| |
| ----------------------- |
| -- Restricted GNARLI -- |
| ----------------------- |
| |
| -------------------------------------------- |
| -- Exceptional_Complete_Single_Entry_Body -- |
| -------------------------------------------- |
| |
| procedure Exceptional_Complete_Single_Entry_Body |
| (Object : Protection_Entry_Access; |
| Ex : Ada.Exceptions.Exception_Id) |
| is |
| begin |
| Object.Call_In_Progress.Exception_To_Raise := Ex; |
| end Exceptional_Complete_Single_Entry_Body; |
| |
| --------------------------------- |
| -- Initialize_Protection_Entry -- |
| --------------------------------- |
| |
| procedure Initialize_Protection_Entry |
| (Object : Protection_Entry_Access; |
| Ceiling_Priority : Integer; |
| Compiler_Info : System.Address; |
| Entry_Body : Entry_Body_Access) |
| is |
| begin |
| Initialize_Protection (Object.Common'Access, Ceiling_Priority); |
| |
| Object.Compiler_Info := Compiler_Info; |
| Object.Call_In_Progress := null; |
| Object.Entry_Body := Entry_Body; |
| Object.Entry_Queue := null; |
| end Initialize_Protection_Entry; |
| |
| ---------------- |
| -- Lock_Entry -- |
| ---------------- |
| |
| -- Compiler interface only |
| |
| -- Do not call this procedure from within the run-time system. |
| |
| procedure Lock_Entry (Object : Protection_Entry_Access) is |
| begin |
| Lock (Object.Common'Access); |
| end Lock_Entry; |
| |
| -------------------------- |
| -- Lock_Read_Only_Entry -- |
| -------------------------- |
| |
| -- Compiler interface only |
| |
| -- Do not call this procedure from within the runtime system |
| |
| procedure Lock_Read_Only_Entry (Object : Protection_Entry_Access) is |
| begin |
| Lock_Read_Only (Object.Common'Access); |
| end Lock_Read_Only_Entry; |
| |
| -------------------- |
| -- PO_Do_Or_Queue -- |
| -------------------- |
| |
| procedure PO_Do_Or_Queue |
| (Object : Protection_Entry_Access; |
| Entry_Call : Entry_Call_Link) |
| is |
| Barrier_Value : Boolean; |
| |
| begin |
| -- When the Action procedure for an entry body returns, it must be |
| -- completed (having called [Exceptional_]Complete_Entry_Body). |
| |
| Barrier_Value := Object.Entry_Body.Barrier (Object.Compiler_Info, 1); |
| |
| if Barrier_Value then |
| if Object.Call_In_Progress /= null then |
| |
| -- This violates the No_Entry_Queue restriction, send |
| -- Program_Error to the caller. |
| |
| Send_Program_Error (Entry_Call); |
| return; |
| end if; |
| |
| Object.Call_In_Progress := Entry_Call; |
| Object.Entry_Body.Action |
| (Object.Compiler_Info, Entry_Call.Uninterpreted_Data, 1); |
| Object.Call_In_Progress := null; |
| |
| if Single_Lock then |
| STPO.Lock_RTS; |
| end if; |
| |
| STPO.Write_Lock (Entry_Call.Self); |
| Wakeup_Entry_Caller (Entry_Call); |
| STPO.Unlock (Entry_Call.Self); |
| |
| if Single_Lock then |
| STPO.Unlock_RTS; |
| end if; |
| |
| else |
| pragma Assert (Entry_Call.Mode = Simple_Call); |
| |
| if Object.Entry_Queue /= null then |
| |
| -- This violates the No_Entry_Queue restriction, send |
| -- Program_Error to the caller. |
| |
| Send_Program_Error (Entry_Call); |
| return; |
| else |
| Object.Entry_Queue := Entry_Call; |
| end if; |
| |
| end if; |
| |
| exception |
| when others => |
| Send_Program_Error (Entry_Call); |
| end PO_Do_Or_Queue; |
| |
| ---------------------------- |
| -- Protected_Single_Count -- |
| ---------------------------- |
| |
| function Protected_Count_Entry (Object : Protection_Entry) return Natural is |
| begin |
| if Object.Entry_Queue /= null then |
| return 1; |
| else |
| return 0; |
| end if; |
| end Protected_Count_Entry; |
| |
| --------------------------------- |
| -- Protected_Single_Entry_Call -- |
| --------------------------------- |
| |
| procedure Protected_Single_Entry_Call |
| (Object : Protection_Entry_Access; |
| Uninterpreted_Data : System.Address) |
| is |
| Self_Id : constant Task_Id := STPO.Self; |
| Entry_Call : Entry_Call_Record renames Self_Id.Entry_Calls (1); |
| begin |
| -- If pragma Detect_Blocking is active then Program_Error must be |
| -- raised if this potentially blocking operation is called from a |
| -- protected action. |
| |
| if Detect_Blocking |
| and then Self_Id.Common.Protected_Action_Nesting > 0 |
| then |
| raise Program_Error with "potentially blocking operation"; |
| end if; |
| |
| Lock_Entry (Object); |
| |
| Entry_Call.Mode := Simple_Call; |
| Entry_Call.State := Now_Abortable; |
| Entry_Call.Uninterpreted_Data := Uninterpreted_Data; |
| Entry_Call.Exception_To_Raise := Ada.Exceptions.Null_Id; |
| |
| PO_Do_Or_Queue (Object, Entry_Call'Access); |
| Unlock_Entry (Object); |
| |
| -- The call is either `Done' or not. It cannot be cancelled since there |
| -- is no ATC construct. |
| |
| pragma Assert (Entry_Call.State /= Cancelled); |
| |
| if Entry_Call.State /= Done then |
| if Single_Lock then |
| STPO.Lock_RTS; |
| end if; |
| |
| STPO.Write_Lock (Self_Id); |
| Wait_For_Completion (Entry_Call'Access); |
| STPO.Unlock (Self_Id); |
| |
| if Single_Lock then |
| STPO.Unlock_RTS; |
| end if; |
| end if; |
| |
| Check_Exception (Self_Id, Entry_Call'Access); |
| end Protected_Single_Entry_Call; |
| |
| ----------------------------------- |
| -- Protected_Single_Entry_Caller -- |
| ----------------------------------- |
| |
| function Protected_Single_Entry_Caller |
| (Object : Protection_Entry) return Task_Id |
| is |
| begin |
| return Object.Call_In_Progress.Self; |
| end Protected_Single_Entry_Caller; |
| |
| ------------------- |
| -- Service_Entry -- |
| ------------------- |
| |
| procedure Service_Entry (Object : Protection_Entry_Access) is |
| Entry_Call : constant Entry_Call_Link := Object.Entry_Queue; |
| Caller : Task_Id; |
| |
| begin |
| if Entry_Call /= null |
| and then Object.Entry_Body.Barrier (Object.Compiler_Info, 1) |
| then |
| Object.Entry_Queue := null; |
| |
| if Object.Call_In_Progress /= null then |
| |
| -- Violation of No_Entry_Queue restriction, raise exception |
| |
| Send_Program_Error (Entry_Call); |
| Unlock_Entry (Object); |
| return; |
| end if; |
| |
| Object.Call_In_Progress := Entry_Call; |
| Object.Entry_Body.Action |
| (Object.Compiler_Info, Entry_Call.Uninterpreted_Data, 1); |
| Object.Call_In_Progress := null; |
| Caller := Entry_Call.Self; |
| Unlock_Entry (Object); |
| |
| if Single_Lock then |
| STPO.Lock_RTS; |
| end if; |
| |
| STPO.Write_Lock (Caller); |
| Wakeup_Entry_Caller (Entry_Call); |
| STPO.Unlock (Caller); |
| |
| if Single_Lock then |
| STPO.Unlock_RTS; |
| end if; |
| |
| else |
| -- Just unlock the entry |
| |
| Unlock_Entry (Object); |
| end if; |
| |
| exception |
| when others => |
| Send_Program_Error (Entry_Call); |
| Unlock_Entry (Object); |
| end Service_Entry; |
| |
| ------------------ |
| -- Unlock_Entry -- |
| ------------------ |
| |
| procedure Unlock_Entry (Object : Protection_Entry_Access) is |
| begin |
| Unlock (Object.Common'Access); |
| end Unlock_Entry; |
| |
| end System.Tasking.Protected_Objects.Single_Entry; |
