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Diffstat (limited to 'gcc-4.4.3/gcc/ada/s-shasto.ads')
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diff --git a/gcc-4.4.3/gcc/ada/s-shasto.ads b/gcc-4.4.3/gcc/ada/s-shasto.ads deleted file mode 100644 index 0ef65cc59..000000000 --- a/gcc-4.4.3/gcc/ada/s-shasto.ads +++ /dev/null @@ -1,183 +0,0 @@ ------------------------------------------------------------------------------- --- -- --- GNAT COMPILER COMPONENTS -- --- -- --- S Y S T E M . S H A R E D _ S T O R A G E -- --- -- --- S p e c -- --- -- --- Copyright (C) 1998-2009, Free Software Foundation, Inc. -- --- -- --- GNAT 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/>. -- --- -- --- GNAT was originally developed by the GNAT team at New York University. -- --- Extensive contributions were provided by Ada Core Technologies Inc. -- --- -- ------------------------------------------------------------------------------- - --- This package manages the shared/persistent storage required for --- full implementation of variables in Shared_Passive packages, more --- precisely variables whose enclosing dynamic scope is a shared --- passive package. This implementation is specific to GNAT and GLADE --- provides a more general implementation not dedicated to file --- storage. - --- This unit (and shared passive partitions) are supported on all --- GNAT implementations except on OpenVMS (where problems arise from --- trying to share files, and with version numbers of files) - --- -------------------------- --- -- Shared Storage Model -- --- -------------------------- - --- The basic model used is that each partition that references the --- Shared_Passive package has a local copy of the package data that --- is initialized in accordance with the declarations of the package --- in the normal manner. The routines in System.Shared_Storage are --- then used to ensure that the values in these separate copies are --- properly synchronized with the state of the overall system. - --- In the GNAT implementation, this synchronization is ensured by --- maintaining a set of files, in a designated directory. The --- directory is designated by setting the environment variable --- SHARED_MEMORY_DIRECTORY. This variable must be set for all --- partitions. If the environment variable is not defined, then the --- current directory is used. - --- There is one storage for each variable. The name is the fully --- qualified name of the variable with all letters forced to lower --- case. For example, the variable Var in the shared passive package --- Pkg results in the storage name pkg.var. - --- If the storage does not exist, it indicates that no partition has --- assigned a new value, so that the initial value is the correct --- one. This is the critical component of the model. It means that --- there is no system-wide synchronization required for initializing --- the package, since the shared storages need not (and do not) --- reflect the initial state. There is therefore no issue of --- synchronizing initialization and read/write access. - --- ----------------------- --- -- Read/Write Access -- --- ----------------------- - --- The approach is as follows: - --- For each shared variable, var, an instantiation of the below generic --- package is created which provides Read and Write supporting procedures. - --- The routine Read in package System.Shared_Storage.Shared_Var_Procs --- ensures to assign variable V to the last written value among processes --- referencing it. A call to this procedure is generated by the expander --- before each read access to the shared variable. - --- The routine Write in package System.Shared_Storage.Shared_Var_Proc --- set a new value to the shared variable and, according to the used --- implementation, propagate this value among processes referencing it. --- A call to this procedure is generated by the expander after each --- assignment of the shared variable. - --- Note: a special circuit allows the use of stream attributes Read and --- Write for limited types (using the corresponding attribute for the --- full type), but there are limitations on the data that can be placed --- in shared passive partitions. See sem_smem.ads/adb for details. - --- ---------------------------------------------------------------- --- -- Handling of Protected Objects in Shared Passive Partitions -- --- ---------------------------------------------------------------- - --- In the context of GNAT, during the execution of a protected --- subprogram call, access is locked out using a locking mechanism --- per protected object, as provided by the GNAT.Lock_Files --- capability in the specific case of GNAT. This package contains the --- lock and unlock calls, and the expander generates a call to the --- lock routine before the protected call and a call to the unlock --- routine after the protected call. - --- Within the code of the protected subprogram, the access to the --- protected object itself uses the local copy, without any special --- synchronization. Since global access is locked out, no other task --- or partition can attempt to read or write this data as long as the --- lock is held. - --- The data in the local copy does however need synchronizing with --- the global values in the shared storage. This is achieved as --- follows: - --- The protected object generates a read and assignment routine as --- described for other shared passive variables. The code for the --- 'Read and 'Write attributes (not normally allowed, but allowed --- in this special case) simply reads or writes the values of the --- components in the protected record. - --- The lock call is followed by a call to the shared read routine to --- synchronize the local copy to contain the proper global value. - --- The unlock call in the procedure case only is preceded by a call --- to the shared assign routine to synchronize the global shared --- storages with the (possibly modified) local copy. - --- These calls to the read and assign routines, as well as the lock --- and unlock routines, are inserted by the expander (see exp_smem.adb). - -package System.Shared_Storage is - - procedure Shared_Var_Lock (Var : String); - -- This procedure claims the shared storage lock. It is used for - -- protected types in shared passive packages. A call to this - -- locking routine is generated as the first operation in the code - -- for the body of a protected subprogram, and it busy waits if - -- the lock is busy. - - procedure Shared_Var_Unlock (Var : String); - -- This procedure releases the shared storage lock obtained by a - -- prior call to the Shared_Var_Lock procedure, and is to be - -- generated as the last operation in the body of a protected - -- subprogram. - - -- This generic package is instantiated for each shared passive - -- variable. It provides supporting procedures called upon each - -- read or write access by the expanded code. - - generic - - type Typ is limited private; - -- Shared passive variable type - - V : in out Typ; - -- Shared passive variable - - Full_Name : String; - -- Shared passive variable storage name - - package Shared_Var_Procs is - - procedure Read; - -- Shared passive variable access routine. Each reference to the - -- shared variable, V, is preceded by a call to the corresponding - -- Read procedure, which either leaves the initial value unchanged - -- if the storage does not exist, or reads the current value from - -- the shared storage. - - procedure Write; - -- Shared passive variable assignment routine. Each assignment to - -- the shared variable, V, is followed by a call to the corresponding - -- Write procedure, which writes the new value to the shared storage. - - end Shared_Var_Procs; - -end System.Shared_Storage; |