diff options
Diffstat (limited to 'gcc/ada/g-tasloc.ads')
| -rw-r--r-- | gcc/ada/g-tasloc.ads | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/gcc/ada/g-tasloc.ads b/gcc/ada/g-tasloc.ads index 7b09d45d5d5..f2090b5ceb5 100644 --- a/gcc/ada/g-tasloc.ads +++ b/gcc/ada/g-tasloc.ads @@ -6,8 +6,7 @@ -- -- -- S p e c -- -- -- --- -- --- Copyright (C) 1998-2001 Ada Core Technologies, Inc. -- +-- Copyright (C) 1998-2002 Ada Core Technologies, 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- -- @@ -53,10 +52,10 @@ pragma Elaborate_Body (Task_Lock); pragma Inline (Unlock); -- Releases the global lock, allowing another task to successfully -- complete a Lock operation. Terminates the critical region. - + -- -- The recommended protocol for using these two procedures is as -- follows: - + -- -- Locked_Processing : begin -- Lock; -- ... @@ -67,26 +66,30 @@ pragma Elaborate_Body (Task_Lock); -- Unlock; -- raise; -- end Locked_Processing; - + -- -- This ensures that the lock is not left set if an exception is raised -- explicitly or implicitly during the critical locked region. - + -- -- Note on multiple calls to Lock: It is permissible to call Lock -- more than once with no intervening Unlock from a single task, -- and the lock will not be released until the corresponding number -- of Unlock operations has been performed. For example: - + -- -- GNAT.Task_Lock.Lock; -- acquires lock -- GNAT.Task_Lock.Lock; -- no effect -- GNAT.Task_Lock.Lock; -- no effect -- GNAT.Task_Lock.Unlock; -- no effect -- GNAT.Task_Lock.Unlock; -- no effect -- GNAT.Task_Lock.Unlock; -- releases lock - + -- -- However, as previously noted, the Task_Lock facility should only -- be used for very local locks where the probability of conflict is -- low, so usually this kind of nesting is not a good idea in any case. -- In more complex locking situations, it is more appropriate to define -- an appropriate protected type to provide the required locking. + -- + -- It is an error to call Unlock when there has been no prior call to + -- Lock. The effect of such an erroneous call is undefined, and may + -- result in deadlock, or other malfunction of the run-time system. end GNAT.Task_Lock; |