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------------------------------------------------------------------------------ -- -- -- 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 . O P E R A T I O N S -- -- -- -- B o d y -- -- -- -- 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 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. -- -- -- ------------------------------------------------------------------------------ -- This is a Solaris (native) version of this package -- This package contains all the GNULL primitives that interface directly with -- the underlying OS. 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. with Ada.Unchecked_Deallocation; with Interfaces.C; with System.Tasking.Debug; with System.Interrupt_Management; with System.OS_Primitives; with System.Task_Info; pragma Warnings (Off); with System.OS_Lib; pragma Warnings (On); with System.Soft_Links; -- We use System.Soft_Links instead of System.Tasking.Initialization -- because the later is a higher level package that we shouldn't depend on. -- For example when using the restricted run time, it is replaced by -- System.Tasking.Restricted.Stages. package body System.Task_Primitives.Operations is package SSL renames System.Soft_Links; use System.Tasking.Debug; use System.Tasking; use Interfaces.C; use System.OS_Interface; use System.Parameters; use System.OS_Primitives; ---------------- -- Local Data -- ---------------- -- The following are logically constants, but need to be initialized -- at run time. Environment_Task_Id : Task_Id; -- A variable to hold Task_Id for the environment task. -- If we use this variable to get the Task_Id, we need the following -- ATCB_Key only for non-Ada threads. Unblocked_Signal_Mask : aliased sigset_t; -- The set of signals that should unblocked in all tasks ATCB_Key : aliased thread_key_t; -- Key used to find the Ada Task_Id associated with a thread, -- at least for C threads unknown to the Ada run-time system. Single_RTS_Lock : aliased RTS_Lock; -- This is a lock to allow only one thread of control in the RTS at -- a time; it is used to execute in mutual exclusion from all other tasks. -- Used mainly in Single_Lock mode, but also to protect All_Tasks_List Next_Serial_Number : Task_Serial_Number := 100; -- We start at 100, to reserve some special values for -- using in error checking. -- The following are internal configuration constants needed. Abort_Handler_Installed : Boolean := False; -- True if a handler for the abort signal is installed ---------------------- -- Priority Support -- ---------------------- Priority_Ceiling_Emulation : constant Boolean := True; -- controls whether we emulate priority ceiling locking -- To get a scheduling close to annex D requirements, we use the real-time -- class provided for LWPs and map each task/thread to a specific and -- unique LWP (there is 1 thread per LWP, and 1 LWP per thread). -- The real time class can only be set when the process has root -- privileges, so in the other cases, we use the normal thread scheduling -- and priority handling. Using_Real_Time_Class : Boolean := False; -- indicates whether the real time class is being used (i.e. the process -- has root privileges). Prio_Param : aliased struct_pcparms; -- Hold priority info (Real_Time) initialized during the package -- elaboration. ----------------------------------- -- External Configuration Values -- ----------------------------------- Time_Slice_Val : Integer; pragma Import (C, Time_Slice_Val, "__gl_time_slice_val"); Locking_Policy : Character; pragma Import (C, Locking_Policy, "__gl_locking_policy"); Dispatching_Policy : Character; pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy"); Foreign_Task_Elaborated : aliased Boolean := True; -- Used to identified fake tasks (i.e., non-Ada Threads) ----------------------- -- Local Subprograms -- ----------------------- function sysconf (name : System.OS_Interface.int) return processorid_t; pragma Import (C, sysconf, "sysconf"); SC_NPROCESSORS_CONF : constant System.OS_Interface.int := 14; function Num_Procs (name : System.OS_Interface.int := SC_NPROCESSORS_CONF) return processorid_t renames sysconf; procedure Abort_Handler (Sig : Signal; Code : not null access siginfo_t; Context : not null access ucontext_t); -- Target-dependent binding of inter-thread Abort signal to -- the raising of the Abort_Signal exception. -- See also comments in 7staprop.adb ------------ -- Checks -- ------------ function Check_Initialize_Lock (L : Lock_Ptr; Level : Lock_Level) return Boolean; pragma Inline (Check_Initialize_Lock); function Check_Lock (L : Lock_Ptr) return Boolean; pragma Inline (Check_Lock); function Record_Lock (L : Lock_Ptr) return Boolean; pragma Inline (Record_Lock); function Check_Sleep (Reason : Task_States) return Boolean; pragma Inline (Check_Sleep); function Record_Wakeup (L : Lock_Ptr; Reason : Task_States) return Boolean; pragma Inline (Record_Wakeup); function Check_Wakeup (T : Task_Id; Reason : Task_States) return Boolean; pragma Inline (Check_Wakeup); function Check_Unlock (L : Lock_Ptr) return Boolean; pragma Inline (Check_Unlock); function Check_Finalize_Lock (L : Lock_Ptr) return Boolean; pragma Inline (Check_Finalize_Lock); -------------------- -- Local Packages -- -------------------- package Specific is procedure Initialize (Environment_Task : Task_Id); pragma Inline (Initialize); -- Initialize various data needed by this package function Is_Valid_Task return Boolean; pragma Inline (Is_Valid_Task); -- Does executing thread have a TCB? procedure Set (Self_Id : Task_Id); pragma Inline (Set); -- Set the self id for the current task function Self return Task_Id; pragma Inline (Self); -- Return a pointer to the Ada Task Control Block of the calling task end Specific; package body Specific is separate; -- The body of this package is target specific --------------------------------- -- Support for foreign threads -- --------------------------------- function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id; -- Allocate and Initialize a new ATCB for the current Thread function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id is separate; ------------ -- Checks -- ------------ Check_Count : Integer := 0; Lock_Count : Integer := 0; Unlock_Count : Integer := 0; ------------------- -- Abort_Handler -- ------------------- procedure Abort_Handler (Sig : Signal; Code : not null access siginfo_t; Context : not null access ucontext_t) is pragma Unreferenced (Sig); pragma Unreferenced (Code); pragma Unreferenced (Context); Self_ID : constant Task_Id := Self; Old_Set : aliased sigset_t; Result : Interfaces.C.int; pragma Warnings (Off, Result); begin -- It's not safe to raise an exception when using GCC ZCX mechanism. -- Note that we still need to install a signal handler, since in some -- cases (e.g. shutdown of the Server_Task in System.Interrupts) we -- need to send the Abort signal to a task. if ZCX_By_Default and then GCC_ZCX_Support then return; end if; if Self_ID.Deferral_Level = 0 and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level and then not Self_ID.Aborting then Self_ID.Aborting := True; -- Make sure signals used for RTS internal purpose are unmasked Result := thr_sigsetmask (SIG_UNBLOCK, Unblocked_Signal_Mask'Unchecked_Access, Old_Set'Unchecked_Access); pragma Assert (Result = 0); raise Standard'Abort_Signal; end if; end Abort_Handler; ----------------- -- Stack_Guard -- ----------------- -- The underlying thread system sets a guard page at the -- bottom of a thread stack, so nothing is needed. procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is pragma Unreferenced (T); pragma Unreferenced (On); begin null; end Stack_Guard; ------------------- -- Get_Thread_Id -- ------------------- function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is begin return T.Common.LL.Thread; end Get_Thread_Id; ---------------- -- Initialize -- ---------------- procedure Initialize (Environment_Task : ST.Task_Id) is act : aliased struct_sigaction; old_act : aliased struct_sigaction; Tmp_Set : aliased sigset_t; Result : Interfaces.C.int; procedure Configure_Processors; -- Processors configuration -- The user can specify a processor which the program should run -- on to emulate a single-processor system. This can be easily -- done by setting environment variable GNAT_PROCESSOR to one of -- the following : -- -- -2 : use the default configuration (run the program on all -- available processors) - this is the same as having -- GNAT_PROCESSOR unset -- -1 : let the RTS choose one processor and run the program on -- that processor -- 0 .. Last_Proc : run the program on the specified processor -- -- Last_Proc is equal to the value of the system variable -- _SC_NPROCESSORS_CONF, minus one. procedure Configure_Processors is Proc_Acc : constant System.OS_Lib.String_Access := System.OS_Lib.Getenv ("GNAT_PROCESSOR"); Proc : aliased processorid_t; -- User processor # Last_Proc : processorid_t; -- Last processor # begin if Proc_Acc.all'Length /= 0 then -- Environment variable is defined Last_Proc := Num_Procs - 1; if Last_Proc /= -1 then Proc := processorid_t'Value (Proc_Acc.all); if Proc <= -2 or else Proc > Last_Proc then -- Use the default configuration null; elsif Proc = -1 then -- Choose a processor Result := 0; while Proc < Last_Proc loop Proc := Proc + 1; Result := p_online (Proc, PR_STATUS); exit when Result = PR_ONLINE; end loop; pragma Assert (Result = PR_ONLINE); Result := processor_bind (P_PID, P_MYID, Proc, null); pragma Assert (Result = 0); else -- Use user processor Result := processor_bind (P_PID, P_MYID, Proc, null); pragma Assert (Result = 0); end if; end if; end if; exception when Constraint_Error => -- Illegal environment variable GNAT_PROCESSOR - ignored null; end Configure_Processors; function State (Int : System.Interrupt_Management.Interrupt_ID) return Character; pragma Import (C, State, "__gnat_get_interrupt_state"); -- Get interrupt state. Defined in a-init.c -- The input argument is the interrupt number, -- and the result is one of the following: Default : constant Character := 's'; -- 'n' this interrupt not set by any Interrupt_State pragma -- 'u' Interrupt_State pragma set state to User -- 'r' Interrupt_State pragma set state to Runtime -- 's' Interrupt_State pragma set state to System (use "default" -- system handler) -- Start of processing for Initialize begin Environment_Task_Id := Environment_Task; Interrupt_Management.Initialize; -- Prepare the set of signals that should unblocked in all tasks Result := sigemptyset (Unblocked_Signal_Mask'Access); pragma Assert (Result = 0); for J in Interrupt_Management.Interrupt_ID loop if System.Interrupt_Management.Keep_Unmasked (J) then Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J)); pragma Assert (Result = 0); end if; end loop; if Dispatching_Policy = 'F' then declare Result : Interfaces.C.long; Class_Info : aliased struct_pcinfo; Secs, Nsecs : Interfaces.C.long; begin -- If a pragma Time_Slice is specified, takes the value in account if Time_Slice_Val > 0 then -- Convert Time_Slice_Val (microseconds) to seconds/nanosecs Secs := Interfaces.C.long (Time_Slice_Val / 1_000_000); Nsecs := Interfaces.C.long ((Time_Slice_Val rem 1_000_000) * 1_000); -- Otherwise, default to no time slicing (i.e run until blocked) else Secs := RT_TQINF; Nsecs := RT_TQINF; end if; -- Get the real time class id Class_Info.pc_clname (1) := 'R'; Class_Info.pc_clname (2) := 'T'; Class_Info.pc_clname (3) := ASCII.NUL; Result := priocntl (PC_VERSION, P_LWPID, P_MYID, PC_GETCID, Class_Info'Address); -- Request the real time class Prio_Param.pc_cid := Class_Info.pc_cid; Prio_Param.rt_pri := pri_t (Class_Info.rt_maxpri); Prio_Param.rt_tqsecs := Secs; Prio_Param.rt_tqnsecs := Nsecs; Result := priocntl (PC_VERSION, P_LWPID, P_MYID, PC_SETPARMS, Prio_Param'Address); Using_Real_Time_Class := Result /= -1; end; end if; Specific.Initialize (Environment_Task); -- The following is done in Enter_Task, but this is too late for the -- Environment Task, since we need to call Self in Check_Locks when -- the run time is compiled with assertions on. Specific.Set (Environment_Task); -- Initialize the lock used to synchronize chain of all ATCBs Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level); -- Make environment task known here because it doesn't go through -- Activate_Tasks, which does it for all other tasks. Known_Tasks (Known_Tasks'First) := Environment_Task; Environment_Task.Known_Tasks_Index := Known_Tasks'First; Enter_Task (Environment_Task); Configure_Processors; if State (System.Interrupt_Management.Abort_Task_Interrupt) /= Default then -- Set sa_flags to SA_NODEFER so that during the handler execution -- we do not change the Signal_Mask to be masked for the Abort_Signal -- This is a temporary fix to the problem that the Signal_Mask is -- not restored after the exception (longjmp) from the handler. -- The right fix should be made in sigsetjmp so that we save -- the Signal_Set and restore it after a longjmp. -- In that case, this field should be changed back to 0. ??? act.sa_flags := 16; act.sa_handler := Abort_Handler'Address; Result := sigemptyset (Tmp_Set'Access); pragma Assert (Result = 0); act.sa_mask := Tmp_Set; Result := sigaction (Signal (System.Interrupt_Management.Abort_Task_Interrupt), act'Unchecked_Access, old_act'Unchecked_Access); pragma Assert (Result = 0); Abort_Handler_Installed := True; end if; end Initialize; --------------------- -- Initialize_Lock -- --------------------- -- Note: mutexes and cond_variables needed per-task basis are initialized -- in Initialize_TCB and the Storage_Error is handled. Other mutexes (such -- as RTS_Lock, Memory_Lock...) used in RTS is initialized before any -- status change of RTS. Therefore raising Storage_Error in the following -- routines should be able to be handled safely. procedure Initialize_Lock (Prio : System.Any_Priority; L : not null access Lock) is Result : Interfaces.C.int; begin pragma Assert (Check_Initialize_Lock (Lock_Ptr (L), PO_Level)); if Priority_Ceiling_Emulation then L.Ceiling := Prio; end if; Result := mutex_init (L.L'Access, USYNC_THREAD, System.Null_Address); pragma Assert (Result = 0 or else Result = ENOMEM); if Result = ENOMEM then raise Storage_Error with "Failed to allocate a lock"; end if; end Initialize_Lock; procedure Initialize_Lock (L : not null access RTS_Lock; Level : Lock_Level) is Result : Interfaces.C.int; begin pragma Assert (Check_Initialize_Lock (To_Lock_Ptr (RTS_Lock_Ptr (L)), Level)); Result := mutex_init (L.L'Access, USYNC_THREAD, System.Null_Address); pragma Assert (Result = 0 or else Result = ENOMEM); if Result = ENOMEM then raise Storage_Error with "Failed to allocate a lock"; end if; end Initialize_Lock; ------------------- -- Finalize_Lock -- ------------------- procedure Finalize_Lock (L : not null access Lock) is Result : Interfaces.C.int; begin pragma Assert (Check_Finalize_Lock (Lock_Ptr (L))); Result := mutex_destroy (L.L'Access); pragma Assert (Result = 0); end Finalize_Lock; procedure Finalize_Lock (L : not null access RTS_Lock) is Result : Interfaces.C.int; begin pragma Assert (Check_Finalize_Lock (To_Lock_Ptr (RTS_Lock_Ptr (L)))); Result := mutex_destroy (L.L'Access); pragma Assert (Result = 0); end Finalize_Lock; ---------------- -- Write_Lock -- ---------------- procedure Write_Lock (L : not null access Lock; Ceiling_Violation : out Boolean) is Result : Interfaces.C.int; begin pragma Assert (Check_Lock (Lock_Ptr (L))); if Priority_Ceiling_Emulation and then Locking_Policy = 'C' then declare Self_Id : constant Task_Id := Self; Saved_Priority : System.Any_Priority; begin if Self_Id.Common.LL.Active_Priority > L.Ceiling then Ceiling_Violation := True; return; end if; Saved_Priority := Self_Id.Common.LL.Active_Priority; if Self_Id.Common.LL.Active_Priority < L.Ceiling then Set_Priority (Self_Id, L.Ceiling); end if; Result := mutex_lock (L.L'Access); pragma Assert (Result = 0); Ceiling_Violation := False; L.Saved_Priority := Saved_Priority; end; else Result := mutex_lock (L.L'Access); pragma Assert (Result = 0); Ceiling_Violation := False; end if; pragma Assert (Record_Lock (Lock_Ptr (L))); end Write_Lock; procedure Write_Lock (L : not null access RTS_Lock; Global_Lock : Boolean := False) is Result : Interfaces.C.int; begin if not Single_Lock or else Global_Lock then pragma Assert (Check_Lock (To_Lock_Ptr (RTS_Lock_Ptr (L)))); Result := mutex_lock (L.L'Access); pragma Assert (Result = 0); pragma Assert (Record_Lock (To_Lock_Ptr (RTS_Lock_Ptr (L)))); end if; end Write_Lock; procedure Write_Lock (T : Task_Id) is Result : Interfaces.C.int; begin if not Single_Lock then pragma Assert (Check_Lock (To_Lock_Ptr (T.Common.LL.L'Access))); Result := mutex_lock (T.Common.LL.L.L'Access); pragma Assert (Result = 0); pragma Assert (Record_Lock (To_Lock_Ptr (T.Common.LL.L'Access))); end if; end Write_Lock; --------------- -- Read_Lock -- --------------- procedure Read_Lock (L : not null access Lock; Ceiling_Violation : out Boolean) is begin Write_Lock (L, Ceiling_Violation); end Read_Lock; ------------ -- Unlock -- ------------ procedure Unlock (L : not null access Lock) is Result : Interfaces.C.int; begin pragma Assert (Check_Unlock (Lock_Ptr (L))); if Priority_Ceiling_Emulation and then Locking_Policy = 'C' then declare Self_Id : constant Task_Id := Self; begin Result := mutex_unlock (L.L'Access); pragma Assert (Result = 0); if Self_Id.Common.LL.Active_Priority > L.Saved_Priority then Set_Priority (Self_Id, L.Saved_Priority); end if; end; else Result := mutex_unlock (L.L'Access); pragma Assert (Result = 0); end if; end Unlock; procedure Unlock (L : not null access RTS_Lock; Global_Lock : Boolean := False) is Result : Interfaces.C.int; begin if not Single_Lock or else Global_Lock then pragma Assert (Check_Unlock (To_Lock_Ptr (RTS_Lock_Ptr (L)))); Result := mutex_unlock (L.L'Access); pragma Assert (Result = 0); end if; end Unlock; procedure Unlock (T : Task_Id) is Result : Interfaces.C.int; begin if not Single_Lock then pragma Assert (Check_Unlock (To_Lock_Ptr (T.Common.LL.L'Access))); Result := mutex_unlock (T.Common.LL.L.L'Access); pragma Assert (Result = 0); end if; end Unlock; ----------------- -- Set_Ceiling -- ----------------- -- Dynamic priority ceilings are not supported by the underlying system procedure Set_Ceiling (L : not null access Lock; Prio : System.Any_Priority) is pragma Unreferenced (L, Prio); begin null; end Set_Ceiling; -- For the time delay implementation, we need to make sure we -- achieve following criteria: -- 1) We have to delay at least for the amount requested. -- 2) We have to give up CPU even though the actual delay does not -- result in blocking. -- 3) Except for restricted run-time systems that do not support -- ATC or task abort, the delay must be interrupted by the -- abort_task operation. -- 4) The implementation has to be efficient so that the delay overhead -- is relatively cheap. -- (1)-(3) are Ada requirements. Even though (2) is an Annex-D -- requirement we still want to provide the effect in all cases. -- The reason is that users may want to use short delays to implement -- their own scheduling effect in the absence of language provided -- scheduling policies. --------------------- -- Monotonic_Clock -- --------------------- function Monotonic_Clock return Duration is TS : aliased timespec; Result : Interfaces.C.int; begin Result := clock_gettime (CLOCK_REALTIME, TS'Unchecked_Access); pragma Assert (Result = 0); return To_Duration (TS); end Monotonic_Clock; ------------------- -- RT_Resolution -- ------------------- function RT_Resolution return Duration is begin return 10#1.0#E-6; end RT_Resolution; ----------- -- Yield -- ----------- procedure Yield (Do_Yield : Boolean := True) is begin if Do_Yield then System.OS_Interface.thr_yield; end if; end Yield; ----------- -- Self --- ----------- function Self return Task_Id renames Specific.Self; ------------------ -- Set_Priority -- ------------------ procedure Set_Priority (T : Task_Id; Prio : System.Any_Priority; Loss_Of_Inheritance : Boolean := False) is pragma Unreferenced (Loss_Of_Inheritance); Result : Interfaces.C.int; pragma Unreferenced (Result); Param : aliased struct_pcparms; use Task_Info; begin T.Common.Current_Priority := Prio; if Priority_Ceiling_Emulation then T.Common.LL.Active_Priority := Prio; end if; if Using_Real_Time_Class then Param.pc_cid := Prio_Param.pc_cid; Param.rt_pri := pri_t (Prio); Param.rt_tqsecs := Prio_Param.rt_tqsecs; Param.rt_tqnsecs := Prio_Param.rt_tqnsecs; Result := Interfaces.C.int ( priocntl (PC_VERSION, P_LWPID, T.Common.LL.LWP, PC_SETPARMS, Param'Address)); else if T.Common.Task_Info /= null and then not T.Common.Task_Info.Bound_To_LWP then -- The task is not bound to a LWP, so use thr_setprio Result := thr_setprio (T.Common.LL.Thread, Interfaces.C.int (Prio)); else -- The task is bound to a LWP, use priocntl -- ??? TBD null; end if; end if; end Set_Priority; ------------------ -- Get_Priority -- ------------------ function Get_Priority (T : Task_Id) return System.Any_Priority is begin return T.Common.Current_Priority; end Get_Priority; ---------------- -- Enter_Task -- ---------------- procedure Enter_Task (Self_ID : Task_Id) is Result : Interfaces.C.int; Proc : processorid_t; -- User processor # Last_Proc : processorid_t; -- Last processor # use System.Task_Info; begin Self_ID.Common.LL.Thread := thr_self; Self_ID.Common.LL.LWP := lwp_self; if Self_ID.Common.Task_Info /= null then if Self_ID.Common.Task_Info.New_LWP and then Self_ID.Common.Task_Info.CPU /= CPU_UNCHANGED then Last_Proc := Num_Procs - 1; if Self_ID.Common.Task_Info.CPU = ANY_CPU then Result := 0; Proc := 0; while Proc < Last_Proc loop Result := p_online (Proc, PR_STATUS); exit when Result = PR_ONLINE; Proc := Proc + 1; end loop; Result := processor_bind (P_LWPID, P_MYID, Proc, null); pragma Assert (Result = 0); else -- Use specified processor if Self_ID.Common.Task_Info.CPU < 0 or else Self_ID.Common.Task_Info.CPU > Last_Proc then raise Invalid_CPU_Number; end if; Result := processor_bind (P_LWPID, P_MYID, Self_ID.Common.Task_Info.CPU, null); pragma Assert (Result = 0); end if; end if; end if; Specific.Set (Self_ID); -- We need the above code even if we do direct fetch of Task_Id in Self -- for the main task on Sun, x86 Solaris and for gcc 2.7.2. end Enter_Task; -------------- -- New_ATCB -- -------------- function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is begin return new Ada_Task_Control_Block (Entry_Num); end New_ATCB; ------------------- -- Is_Valid_Task -- ------------------- function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task; ----------------------------- -- Register_Foreign_Thread -- ----------------------------- function Register_Foreign_Thread return Task_Id is begin if Is_Valid_Task then return Self; else return Register_Foreign_Thread (thr_self); end if; end Register_Foreign_Thread; -------------------- -- Initialize_TCB -- -------------------- procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is Result : Interfaces.C.int := 0; begin -- Give the task a unique serial number Self_ID.Serial_Number := Next_Serial_Number; Next_Serial_Number := Next_Serial_Number + 1; pragma Assert (Next_Serial_Number /= 0); Self_ID.Common.LL.Thread := To_thread_t (-1); if not Single_Lock then Result := mutex_init (Self_ID.Common.LL.L.L'Access, USYNC_THREAD, System.Null_Address); Self_ID.Common.LL.L.Level := Private_Task_Serial_Number (Self_ID.Serial_Number); pragma Assert (Result = 0 or else Result = ENOMEM); end if; if Result = 0 then Result := cond_init (Self_ID.Common.LL.CV'Access, USYNC_THREAD, 0); pragma Assert (Result = 0 or else Result = ENOMEM); end if; if Result = 0 then Succeeded := True; else if not Single_Lock then Result := mutex_destroy (Self_ID.Common.LL.L.L'Access); pragma Assert (Result = 0); end if; Succeeded := False; end if; end Initialize_TCB; ----------------- -- Create_Task -- ----------------- procedure Create_Task (T : Task_Id; Wrapper : System.Address; Stack_Size : System.Parameters.Size_Type; Priority : System.Any_Priority; Succeeded : out Boolean) is pragma Unreferenced (Priority); Result : Interfaces.C.int; Adjusted_Stack_Size : Interfaces.C.size_t; Opts : Interfaces.C.int := THR_DETACHED; Page_Size : constant System.Parameters.Size_Type := 4096; -- This constant is for reserving extra space at the -- end of the stack, which can be used by the stack -- checking as guard page. The idea is that we need -- to have at least Stack_Size bytes available for -- actual use. use System.Task_Info; begin Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size + Page_Size); -- Since the initial signal mask of a thread is inherited from the -- creator, and the Environment task has all its signals masked, we -- do not need to manipulate caller's signal mask at this point. -- All tasks in RTS will have All_Tasks_Mask initially. if T.Common.Task_Info /= null then if T.Common.Task_Info.New_LWP then Opts := Opts + THR_NEW_LWP; end if; if T.Common.Task_Info.Bound_To_LWP then Opts := Opts + THR_BOUND; end if; else Opts := THR_DETACHED + THR_BOUND; end if; Result := thr_create (System.Null_Address, Adjusted_Stack_Size, Thread_Body_Access (Wrapper), To_Address (T), Opts, T.Common.LL.Thread'Access); Succeeded := Result = 0; pragma Assert (Result = 0 or else Result = ENOMEM or else Result = EAGAIN); end Create_Task; ------------------ -- Finalize_TCB -- ------------------ procedure Finalize_TCB (T : Task_Id) is Result : Interfaces.C.int; Tmp : Task_Id := T; Is_Self : constant Boolean := T = Self; procedure Free is new Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id); begin T.Common.LL.Thread := To_thread_t (0); if not Single_Lock then Result := mutex_destroy (T.Common.LL.L.L'Access); pragma Assert (Result = 0); end if; Result := cond_destroy (T.Common.LL.CV'Access); pragma Assert (Result = 0); if T.Known_Tasks_Index /= -1 then Known_Tasks (T.Known_Tasks_Index) := null; end if; Free (Tmp); if Is_Self then Specific.Set (null); end if; end Finalize_TCB; --------------- -- Exit_Task -- --------------- -- This procedure must be called with abort deferred. It can no longer -- call Self or access the current task's ATCB, since the ATCB has been -- deallocated. procedure Exit_Task is begin Specific.Set (null); end Exit_Task; ---------------- -- Abort_Task -- ---------------- procedure Abort_Task (T : Task_Id) is Result : Interfaces.C.int; begin if Abort_Handler_Installed then pragma Assert (T /= Self); Result := thr_kill (T.Common.LL.Thread, Signal (System.Interrupt_Management.Abort_Task_Interrupt)); pragma Assert (Result = 0); end if; end Abort_Task; ----------- -- Sleep -- ----------- procedure Sleep (Self_ID : Task_Id; Reason : Task_States) is Result : Interfaces.C.int; begin pragma Assert (Check_Sleep (Reason)); if Single_Lock then Result := cond_wait (Self_ID.Common.LL.CV'Access, Single_RTS_Lock.L'Access); else Result := cond_wait (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L.L'Access); end if; pragma Assert (Record_Wakeup (To_Lock_Ptr (Self_ID.Common.LL.L'Access), Reason)); pragma Assert (Result = 0 or else Result = EINTR); end Sleep; -- Note that we are relying heavily here on GNAT representing -- Calendar.Time, System.Real_Time.Time, Duration, -- System.Real_Time.Time_Span in the same way, i.e., as a 64-bit count of -- nanoseconds. -- This allows us to always pass the timeout value as a Duration -- ??? -- We are taking liberties here with the semantics of the delays. That is, -- we make no distinction between delays on the Calendar clock and delays -- on the Real_Time clock. That is technically incorrect, if the Calendar -- clock happens to be reset or adjusted. To solve this defect will require -- modification to the compiler interface, so that it can pass through more -- information, to tell us here which clock to use! -- cond_timedwait will return if any of the following happens: -- 1) some other task did cond_signal on this condition variable -- In this case, the return value is 0 -- 2) the call just returned, for no good reason -- This is called a "spurious wakeup". -- In this case, the return value may also be 0. -- 3) the time delay expires -- In this case, the return value is ETIME -- 4) this task received a signal, which was handled by some -- handler procedure, and now the thread is resuming execution -- UNIX calls this an "interrupted" system call. -- In this case, the return value is EINTR -- If the cond_timedwait returns 0 or EINTR, it is still possible that the -- time has actually expired, and by chance a signal or cond_signal -- occurred at around the same time. -- We have also observed that on some OS's the value ETIME will be -- returned, but the clock will show that the full delay has not yet -- expired. -- For these reasons, we need to check the clock after return from -- cond_timedwait. If the time has expired, we will set Timedout = True. -- This check might be omitted for systems on which the cond_timedwait() -- never returns early or wakes up spuriously. -- Annex D requires that completion of a delay cause the task to go to the -- end of its priority queue, regardless of whether the task actually was -- suspended by the delay. Since cond_timedwait does not do this on -- Solaris, we add a call to thr_yield at the end. We might do this at the -- beginning, instead, but then the round-robin effect would not be the -- same; the delayed task would be ahead of other tasks of the same -- priority that awoke while it was sleeping. -- For Timed_Sleep, we are expecting possible cond_signals to indicate -- other events (e.g., completion of a RV or completion of the abortable -- part of an async. select), we want to always return if interrupted. The -- caller will be responsible for checking the task state to see whether -- the wakeup was spurious, and to go back to sleep again in that case. We -- don't need to check for pending abort or priority change on the way in -- our out; that is the caller's responsibility. -- For Timed_Delay, we are not expecting any cond_signals or other -- interruptions, except for priority changes and aborts. Therefore, we -- don't want to return unless the delay has actually expired, or the call -- has been aborted. In this case, since we want to implement the entire -- delay statement semantics, we do need to check for pending abort and -- priority changes. We can quietly handle priority changes inside the -- procedure, since there is no entry-queue reordering involved. ----------------- -- Timed_Sleep -- ----------------- procedure Timed_Sleep (Self_ID : Task_Id; Time : Duration; Mode : ST.Delay_Modes; Reason : System.Tasking.Task_States; Timedout : out Boolean; Yielded : out Boolean) is Base_Time : constant Duration := Monotonic_Clock; Check_Time : Duration := Base_Time; Abs_Time : Duration; Request : aliased timespec; Result : Interfaces.C.int; begin pragma Assert (Check_Sleep (Reason)); Timedout := True; Yielded := False; Abs_Time := (if Mode = Relative then Duration'Min (Time, Max_Sensible_Delay) + Check_Time else Duration'Min (Check_Time + Max_Sensible_Delay, Time)); if Abs_Time > Check_Time then Request := To_Timespec (Abs_Time); loop exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level; if Single_Lock then Result := cond_timedwait (Self_ID.Common.LL.CV'Access, Single_RTS_Lock.L'Access, Request'Access); else Result := cond_timedwait (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L.L'Access, Request'Access); end if; Yielded := True; Check_Time := Monotonic_Clock; exit when Abs_Time <= Check_Time or else Check_Time < Base_Time; if Result = 0 or Result = EINTR then -- Somebody may have called Wakeup for us Timedout := False; exit; end if; pragma Assert (Result = ETIME); end loop; end if; pragma Assert (Record_Wakeup (To_Lock_Ptr (Self_ID.Common.LL.L'Access), Reason)); end Timed_Sleep; ----------------- -- Timed_Delay -- ----------------- procedure Timed_Delay (Self_ID : Task_Id; Time : Duration; Mode : ST.Delay_Modes) is Base_Time : constant Duration := Monotonic_Clock; Check_Time : Duration := Base_Time; Abs_Time : Duration; Request : aliased timespec; Result : Interfaces.C.int; Yielded : Boolean := False; begin if Single_Lock then Lock_RTS; end if; Write_Lock (Self_ID); Abs_Time := (if Mode = Relative then Time + Check_Time else Duration'Min (Check_Time + Max_Sensible_Delay, Time)); if Abs_Time > Check_Time then Request := To_Timespec (Abs_Time); Self_ID.Common.State := Delay_Sleep; pragma Assert (Check_Sleep (Delay_Sleep)); loop exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level; if Single_Lock then Result := cond_timedwait (Self_ID.Common.LL.CV'Access, Single_RTS_Lock.L'Access, Request'Access); else Result := cond_timedwait (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L.L'Access, Request'Access); end if; Yielded := True; Check_Time := Monotonic_Clock; exit when Abs_Time <= Check_Time or else Check_Time < Base_Time; pragma Assert (Result = 0 or else Result = ETIME or else Result = EINTR); end loop; pragma Assert (Record_Wakeup (To_Lock_Ptr (Self_ID.Common.LL.L'Access), Delay_Sleep)); Self_ID.Common.State := Runnable; end if; Unlock (Self_ID); if Single_Lock then Unlock_RTS; end if; if not Yielded then thr_yield; end if; end Timed_Delay; ------------ -- Wakeup -- ------------ procedure Wakeup (T : Task_Id; Reason : Task_States) is Result : Interfaces.C.int; begin pragma Assert (Check_Wakeup (T, Reason)); Result := cond_signal (T.Common.LL.CV'Access); pragma Assert (Result = 0); end Wakeup; --------------------------- -- Check_Initialize_Lock -- --------------------------- -- The following code is intended to check some of the invariant assertions -- related to lock usage, on which we depend. function Check_Initialize_Lock (L : Lock_Ptr; Level : Lock_Level) return Boolean is Self_ID : constant Task_Id := Self; begin -- Check that caller is abort-deferred if Self_ID.Deferral_Level = 0 then return False; end if; -- Check that the lock is not yet initialized if L.Level /= 0 then return False; end if; L.Level := Lock_Level'Pos (Level) + 1; return True; end Check_Initialize_Lock; ---------------- -- Check_Lock -- ---------------- function Check_Lock (L : Lock_Ptr) return Boolean is Self_ID : constant Task_Id := Self; P : Lock_Ptr; begin -- Check that the argument is not null if L = null then return False; end if; -- Check that L is not frozen if L.Frozen then return False; end if; -- Check that caller is abort-deferred if Self_ID.Deferral_Level = 0 then return False; end if; -- Check that caller is not holding this lock already if L.Owner = To_Owner_ID (To_Address (Self_ID)) then return False; end if; if Single_Lock then return True; end if; -- Check that TCB lock order rules are satisfied P := Self_ID.Common.LL.Locks; if P /= null then if P.Level >= L.Level and then (P.Level > 2 or else L.Level > 2) then return False; end if; end if; return True; end Check_Lock; ----------------- -- Record_Lock -- ----------------- function Record_Lock (L : Lock_Ptr) return Boolean is Self_ID : constant Task_Id := Self; P : Lock_Ptr; begin Lock_Count := Lock_Count + 1; -- There should be no owner for this lock at this point if L.Owner /= null then return False; end if; -- Record new owner L.Owner := To_Owner_ID (To_Address (Self_ID)); if Single_Lock then return True; end if; -- Check that TCB lock order rules are satisfied P := Self_ID.Common.LL.Locks; if P /= null then L.Next := P; end if; Self_ID.Common.LL.Locking := null; Self_ID.Common.LL.Locks := L; return True; end Record_Lock; ----------------- -- Check_Sleep -- ----------------- function Check_Sleep (Reason : Task_States) return Boolean is pragma Unreferenced (Reason); Self_ID : constant Task_Id := Self; P : Lock_Ptr; begin -- Check that caller is abort-deferred if Self_ID.Deferral_Level = 0 then return False; end if; if Single_Lock then return True; end if; -- Check that caller is holding own lock, on top of list if Self_ID.Common.LL.Locks /= To_Lock_Ptr (Self_ID.Common.LL.L'Access) then return False; end if; -- Check that TCB lock order rules are satisfied if Self_ID.Common.LL.Locks.Next /= null then return False; end if; Self_ID.Common.LL.L.Owner := null; P := Self_ID.Common.LL.Locks; Self_ID.Common.LL.Locks := Self_ID.Common.LL.Locks.Next; P.Next := null; return True; end Check_Sleep; ------------------- -- Record_Wakeup -- ------------------- function Record_Wakeup (L : Lock_Ptr; Reason : Task_States) return Boolean is pragma Unreferenced (Reason); Self_ID : constant Task_Id := Self; P : Lock_Ptr; begin -- Record new owner L.Owner := To_Owner_ID (To_Address (Self_ID)); if Single_Lock then return True; end if; -- Check that TCB lock order rules are satisfied P := Self_ID.Common.LL.Locks; if P /= null then L.Next := P; end if; Self_ID.Common.LL.Locking := null; Self_ID.Common.LL.Locks := L; return True; end Record_Wakeup; ------------------ -- Check_Wakeup -- ------------------ function Check_Wakeup (T : Task_Id; Reason : Task_States) return Boolean is Self_ID : constant Task_Id := Self; begin -- Is caller holding T's lock? if T.Common.LL.L.Owner /= To_Owner_ID (To_Address (Self_ID)) then return False; end if; -- Are reasons for wakeup and sleep consistent? if T.Common.State /= Reason then return False; end if; return True; end Check_Wakeup; ------------------ -- Check_Unlock -- ------------------ function Check_Unlock (L : Lock_Ptr) return Boolean is Self_ID : constant Task_Id := Self; P : Lock_Ptr; begin Unlock_Count := Unlock_Count + 1; if L = null then return False; end if; if L.Buddy /= null then return False; end if; -- Magic constant 4??? if L.Level = 4 then Check_Count := Unlock_Count; end if; -- Magic constant 1000??? if Unlock_Count - Check_Count > 1000 then Check_Count := Unlock_Count; end if; -- Check that caller is abort-deferred if Self_ID.Deferral_Level = 0 then return False; end if; -- Check that caller is holding this lock, on top of list if Self_ID.Common.LL.Locks /= L then return False; end if; -- Record there is no owner now L.Owner := null; P := Self_ID.Common.LL.Locks; Self_ID.Common.LL.Locks := Self_ID.Common.LL.Locks.Next; P.Next := null; return True; end Check_Unlock; -------------------- -- Check_Finalize -- -------------------- function Check_Finalize_Lock (L : Lock_Ptr) return Boolean is Self_ID : constant Task_Id := Self; begin -- Check that caller is abort-deferred if Self_ID.Deferral_Level = 0 then return False; end if; -- Check that no one is holding this lock if L.Owner /= null then return False; end if; L.Frozen := True; return True; end Check_Finalize_Lock; ---------------- -- Initialize -- ---------------- procedure Initialize (S : in out Suspension_Object) is Result : Interfaces.C.int; begin -- Initialize internal state (always to zero (RM D.10(6))) S.State := False; S.Waiting := False; -- Initialize internal mutex Result := mutex_init (S.L'Access, USYNC_THREAD, System.Null_Address); pragma Assert (Result = 0 or else Result = ENOMEM); if Result = ENOMEM then raise Storage_Error with "Failed to allocate a lock"; end if; -- Initialize internal condition variable Result := cond_init (S.CV'Access, USYNC_THREAD, 0); pragma Assert (Result = 0 or else Result = ENOMEM); if Result /= 0 then Result := mutex_destroy (S.L'Access); pragma Assert (Result = 0); if Result = ENOMEM then raise Storage_Error; end if; end if; end Initialize; -------------- -- Finalize -- -------------- procedure Finalize (S : in out Suspension_Object) is Result : Interfaces.C.int; begin -- Destroy internal mutex Result := mutex_destroy (S.L'Access); pragma Assert (Result = 0); -- Destroy internal condition variable Result := cond_destroy (S.CV'Access); pragma Assert (Result = 0); end Finalize; ------------------- -- Current_State -- ------------------- function Current_State (S : Suspension_Object) return Boolean is begin -- We do not want to use lock on this read operation. State is marked -- as Atomic so that we ensure that the value retrieved is correct. return S.State; end Current_State; --------------- -- Set_False -- --------------- procedure Set_False (S : in out Suspension_Object) is Result : Interfaces.C.int; begin SSL.Abort_Defer.all; Result := mutex_lock (S.L'Access); pragma Assert (Result = 0); S.State := False; Result := mutex_unlock (S.L'Access); pragma Assert (Result = 0); SSL.Abort_Undefer.all; end Set_False; -------------- -- Set_True -- -------------- procedure Set_True (S : in out Suspension_Object) is Result : Interfaces.C.int; begin SSL.Abort_Defer.all; Result := mutex_lock (S.L'Access); pragma Assert (Result = 0); -- If there is already a task waiting on this suspension object then -- we resume it, leaving the state of the suspension object to False, -- as it is specified in ARM D.10 par. 9. Otherwise, it just leaves -- the state to True. if S.Waiting then S.Waiting := False; S.State := False; Result := cond_signal (S.CV'Access); pragma Assert (Result = 0); else S.State := True; end if; Result := mutex_unlock (S.L'Access); pragma Assert (Result = 0); SSL.Abort_Undefer.all; end Set_True; ------------------------ -- Suspend_Until_True -- ------------------------ procedure Suspend_Until_True (S : in out Suspension_Object) is Result : Interfaces.C.int; begin SSL.Abort_Defer.all; Result := mutex_lock (S.L'Access); pragma Assert (Result = 0); if S.Waiting then -- Program_Error must be raised upon calling Suspend_Until_True -- if another task is already waiting on that suspension object -- (RM D.10(10)). Result := mutex_unlock (S.L'Access); pragma Assert (Result = 0); SSL.Abort_Undefer.all; raise Program_Error; else -- Suspend the task if the state is False. Otherwise, the task -- continues its execution, and the state of the suspension object -- is set to False (ARM D.10 par. 9). if S.State then S.State := False; else S.Waiting := True; loop -- Loop in case pthread_cond_wait returns earlier than expected -- (e.g. in case of EINTR caused by a signal). Result := cond_wait (S.CV'Access, S.L'Access); pragma Assert (Result = 0 or else Result = EINTR); exit when not S.Waiting; end loop; end if; Result := mutex_unlock (S.L'Access); pragma Assert (Result = 0); SSL.Abort_Undefer.all; end if; end Suspend_Until_True; ---------------- -- Check_Exit -- ---------------- function Check_Exit (Self_ID : Task_Id) return Boolean is begin -- Check that caller is just holding Global_Task_Lock and no other locks if Self_ID.Common.LL.Locks = null then return False; end if; -- 2 = Global_Task_Level if Self_ID.Common.LL.Locks.Level /= 2 then return False; end if; if Self_ID.Common.LL.Locks.Next /= null then return False; end if; -- Check that caller is abort-deferred if Self_ID.Deferral_Level = 0 then return False; end if; return True; end Check_Exit; -------------------- -- Check_No_Locks -- -------------------- function Check_No_Locks (Self_ID : Task_Id) return Boolean is begin return Self_ID.Common.LL.Locks = null; end Check_No_Locks; ---------------------- -- Environment_Task -- ---------------------- function Environment_Task return Task_Id is begin return Environment_Task_Id; end Environment_Task; -------------- -- Lock_RTS -- -------------- procedure Lock_RTS is begin Write_Lock (Single_RTS_Lock'Access, Global_Lock => True); end Lock_RTS; ---------------- -- Unlock_RTS -- ---------------- procedure Unlock_RTS is begin Unlock (Single_RTS_Lock'Access, Global_Lock => True); end Unlock_RTS; ------------------ -- Suspend_Task -- ------------------ function Suspend_Task (T : ST.Task_Id; Thread_Self : Thread_Id) return Boolean is begin if T.Common.LL.Thread /= Thread_Self then return thr_suspend (T.Common.LL.Thread) = 0; else return True; end if; end Suspend_Task; ----------------- -- Resume_Task -- ----------------- function Resume_Task (T : ST.Task_Id; Thread_Self : Thread_Id) return Boolean is begin if T.Common.LL.Thread /= Thread_Self then return thr_continue (T.Common.LL.Thread) = 0; else return True; end if; end Resume_Task; -------------------- -- Stop_All_Tasks -- -------------------- procedure Stop_All_Tasks is begin null; end Stop_All_Tasks; --------------- -- Stop_Task -- --------------- function Stop_Task (T : ST.Task_Id) return Boolean is pragma Unreferenced (T); begin return False; end Stop_Task; ------------------- -- Continue_Task -- ------------------- function Continue_Task (T : ST.Task_Id) return Boolean is pragma Unreferenced (T); begin return False; end Continue_Task; end System.Task_Primitives.Operations;
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