1------------------------------------------------------------------------------ 2-- -- 3-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- 4-- -- 5-- SYSTEM.TASKING.PROTECTED_OBJECTS.ENTRIES -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2012, Free Software Foundation, Inc. -- 10-- -- 11-- GNARL is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. -- 17-- -- 18-- As a special exception under Section 7 of GPL version 3, you are granted -- 19-- additional permissions described in the GCC Runtime Library Exception, -- 20-- version 3.1, as published by the Free Software Foundation. -- 21-- -- 22-- You should have received a copy of the GNU General Public License and -- 23-- a copy of the GCC Runtime Library Exception along with this program; -- 24-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 25-- <http://www.gnu.org/licenses/>. -- 26-- -- 27-- GNARL was developed by the GNARL team at Florida State University. -- 28-- Extensive contributions were provided by Ada Core Technologies, Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32-- This package contains all simple primitives related to Protected_Objects 33-- with entries (i.e init, lock, unlock). 34 35-- The handling of protected objects with no entries is done in 36-- System.Tasking.Protected_Objects, the complex routines for protected 37-- objects with entries in System.Tasking.Protected_Objects.Operations. 38 39-- The split between Entries and Operations is needed to break circular 40-- dependencies inside the run time. 41 42-- Note: the compiler generates direct calls to this interface, via Rtsfind. 43-- Any changes to this interface may require corresponding compiler changes. 44 45with Ada.Finalization; 46with Ada.Unchecked_Conversion; 47 48package System.Tasking.Protected_Objects.Entries is 49 pragma Elaborate_Body; 50 51 subtype Positive_Protected_Entry_Index is 52 Protected_Entry_Index range 1 .. Protected_Entry_Index'Last; 53 54 type Find_Body_Index_Access is access 55 function 56 (O : System.Address; 57 E : Protected_Entry_Index) 58 return Protected_Entry_Index; 59 60 type Protected_Entry_Body_Array is 61 array (Positive_Protected_Entry_Index range <>) of Entry_Body; 62 -- Contains executable code for all entry bodies of a protected type 63 64 type Protected_Entry_Body_Access is access all Protected_Entry_Body_Array; 65 66 type Protected_Entry_Queue_Array is 67 array (Protected_Entry_Index range <>) of Entry_Queue; 68 69 -- The following declarations define an array that contains the string 70 -- names of entries and entry family members, together with an associated 71 -- access type. 72 73 type Protected_Entry_Names_Array is 74 array (Entry_Index range <>) of String_Access; 75 76 type Protected_Entry_Names_Access is access all Protected_Entry_Names_Array; 77 78 -- The following type contains the GNARL state of a protected object. 79 -- The application-defined portion of the state (i.e. private objects) 80 -- is maintained by the compiler-generated code. Note that there is a 81 -- simplified version of this type declared in System.Tasking.PO_Simple 82 -- that handle the simple case (no entries). 83 84 type Protection_Entries (Num_Entries : Protected_Entry_Index) is new 85 Ada.Finalization.Limited_Controlled 86 with record 87 L : aliased Task_Primitives.Lock; 88 -- The underlying lock associated with a Protection_Entries. Note 89 -- that you should never (un)lock Object.L directly, but instead 90 -- use Lock_Entries/Unlock_Entries. 91 92 Compiler_Info : System.Address; 93 -- Pointer to compiler-generated record representing protected object 94 95 Call_In_Progress : Entry_Call_Link; 96 -- Pointer to the entry call being executed (if any) 97 98 Ceiling : System.Any_Priority; 99 -- Ceiling priority associated with the protected object 100 101 New_Ceiling : System.Any_Priority; 102 -- New ceiling priority associated to the protected object. In case 103 -- of assignment of a new ceiling priority to the protected object the 104 -- frontend generates a call to set_ceiling to save the new value in 105 -- this field. After such assignment this value can be read by means 106 -- of the 'Priority attribute, which generates a call to get_ceiling. 107 -- However, the ceiling of the protected object will not be changed 108 -- until completion of the protected action in which the assignment 109 -- has been executed (AARM D.5.2 (10/2)). 110 111 Owner : Task_Id; 112 -- This field contains the protected object's owner. Null_Task 113 -- indicates that the protected object is not currently being used. 114 -- This information is used for detecting the type of potentially 115 -- blocking operations described in the ARM 9.5.1, par. 15 (external 116 -- calls on a protected subprogram with the same target object as that 117 -- of the protected action). 118 119 Old_Base_Priority : System.Any_Priority; 120 -- Task's base priority when the protected operation was called 121 122 Pending_Action : Boolean; 123 -- Flag indicating that priority has been dipped temporarily in order 124 -- to avoid violating the priority ceiling of the lock associated with 125 -- this protected object, in Lock_Server. The flag tells Unlock_Server 126 -- or Unlock_And_Update_Server to restore the old priority to 127 -- Old_Base_Priority. This is needed because of situations (bad 128 -- language design?) where one needs to lock a PO but to do so would 129 -- violate the priority ceiling. For example, this can happen when an 130 -- entry call has been requeued to a lower-priority object, and the 131 -- caller then tries to cancel the call while its own priority is 132 -- higher than the ceiling of the new PO. 133 134 Finalized : Boolean := False; 135 -- Set to True by Finalize to make this routine idempotent 136 137 Entry_Bodies : Protected_Entry_Body_Access; 138 -- Pointer to an array containing the executable code for all entry 139 -- bodies of a protected type. 140 141 Find_Body_Index : Find_Body_Index_Access; 142 -- A function which maps the entry index in a call (which denotes the 143 -- queue of the proper entry) into the body of the entry. 144 145 Entry_Queues : Protected_Entry_Queue_Array (1 .. Num_Entries); 146 147 Entry_Names : Protected_Entry_Names_Access := null; 148 -- An array of string names which denotes entry [family member] names. 149 -- The structure is indexed by protected entry index and contains Num_ 150 -- Entries components. 151 end record; 152 153 -- No default initial values for this type, since call records will need to 154 -- be re-initialized before every use. 155 156 type Protection_Entries_Access is access all Protection_Entries'Class; 157 -- See comments in s-tassta.adb about the implicit call to Current_Master 158 -- generated by this declaration. 159 160 function To_Address is 161 new Ada.Unchecked_Conversion (Protection_Entries_Access, System.Address); 162 function To_Protection is 163 new Ada.Unchecked_Conversion (System.Address, Protection_Entries_Access); 164 165 function Get_Ceiling 166 (Object : Protection_Entries_Access) return System.Any_Priority; 167 -- Returns the new ceiling priority of the protected object 168 169 function Has_Interrupt_Or_Attach_Handler 170 (Object : Protection_Entries_Access) return Boolean; 171 -- Returns True if an Interrupt_Handler or Attach_Handler pragma applies 172 -- to the protected object. That is to say this primitive returns False for 173 -- Protection, but is overridden to return True when interrupt handlers are 174 -- declared so the check required by C.3.1(11) can be implemented in 175 -- System.Tasking.Protected_Objects.Initialize_Protection. 176 177 procedure Initialize_Protection_Entries 178 (Object : Protection_Entries_Access; 179 Ceiling_Priority : Integer; 180 Compiler_Info : System.Address; 181 Entry_Bodies : Protected_Entry_Body_Access; 182 Find_Body_Index : Find_Body_Index_Access); 183 -- Initialize the Object parameter so that it can be used by the runtime 184 -- to keep track of the runtime state of a protected object. 185 186 procedure Lock_Entries (Object : Protection_Entries_Access); 187 -- Lock a protected object for write access. Upon return, the caller owns 188 -- the lock to this object, and no other call to Lock or Lock_Read_Only 189 -- with the same argument will return until the corresponding call to 190 -- Unlock has been made by the caller. Program_Error is raised in case of 191 -- ceiling violation. 192 193 procedure Lock_Entries_With_Status 194 (Object : Protection_Entries_Access; 195 Ceiling_Violation : out Boolean); 196 -- Same as above, but return the ceiling violation status instead of 197 -- raising Program_Error. 198 199 procedure Lock_Read_Only_Entries (Object : Protection_Entries_Access); 200 -- Lock a protected object for read access. Upon return, the caller owns 201 -- the lock for read access, and no other calls to Lock with the same 202 -- argument will return until the corresponding call to Unlock has been 203 -- made by the caller. Other calls to Lock_Read_Only may (but need not) 204 -- return before the call to Unlock, and the corresponding callers will 205 -- also own the lock for read access. 206 -- 207 -- Note: we are not currently using this interface, it is provided for 208 -- possible future use. At the current time, everyone uses Lock for both 209 -- read and write locks. 210 211 function Number_Of_Entries 212 (Object : Protection_Entries_Access) return Entry_Index; 213 -- Return the number of entries of a protected object 214 215 procedure Set_Ceiling 216 (Object : Protection_Entries_Access; 217 Prio : System.Any_Priority); 218 -- Sets the new ceiling priority of the protected object 219 220 procedure Set_Entry_Names 221 (Object : Protection_Entries_Access; 222 Names : Protected_Entry_Names_Access); 223 -- Associate an array of string that denote entry [family] names with a 224 -- protected object. 225 226 procedure Unlock_Entries (Object : Protection_Entries_Access); 227 -- Relinquish ownership of the lock for the object represented by the 228 -- Object parameter. If this ownership was for write access, or if it was 229 -- for read access where there are no other read access locks outstanding, 230 -- one (or more, in the case of Lock_Read_Only) of the tasks waiting on 231 -- this lock (if any) will be given the lock and allowed to return from 232 -- the Lock or Lock_Read_Only call. 233 234private 235 236 overriding procedure Finalize (Object : in out Protection_Entries); 237 -- Clean up a Protection object; in particular, finalize the associated 238 -- Lock object. 239 240end System.Tasking.Protected_Objects.Entries; 241