From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Finalization of library level tasks Date: Tue, 17 Apr 2018 14:47:12 +0200 Organization: Aioe.org NNTP Server Message-ID: References: <702e2422-a93f-4200-9749-5122c3d0f899@googlegroups.com> NNTP-Posting-Host: MyFhHs417jM9AgzRpXn7yg.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 X-Notice: Filtered by postfilter v. 0.8.3 Content-Language: en-US Xref: reader02.eternal-september.org comp.lang.ada:51554 Date: 2018-04-17T14:47:12+02:00 List-Id: On 17/04/2018 13:16, J-P. Rosen wrote: > Le 16/04/2018 à 17:26, Dmitry A. Kazakov a écrit : >> The only place RM explains 'Callable is in ARM C.7.1:riddle: >> >> "(10.a.1/1):Ramification: {8652/0115} {AI95-00206-01} These routines can >> be called with an argument identifying the environment task. >> Is_Terminated will always be False for such a call, but Is_Callable >> (usually True) could be False if the environment task is waiting for the >> termination of dependent tasks. Thus, a dependent task can use >> Is_Callable to determine if the main subprogram has completed." >> >> At least for the environment task 'Callable is defined this (reasonable) >> way. It seems that GNAT uses this definition for all task. > > The environment task calls the main subprogram. Therefore, after the > main subprogram has returned, the environment task may be waiting for > other tasks to terminate, and is thus no more callable. But I don't see > how this relates to your example. It is related directly. Environment_Task'Callable becomes False before completion when the task is still running. If 'Callable is same as 'Terminated why there are two of them? Anyway there must be a way to know if a task was requested to terminate, because the terminate alternative is useless for practical cases. > One thing to keep in mind is the meaning of "or terminate": it means > that no task could possibly call an entry of the task, and therefore > that the task is blocked forever. In this case, it is better to > terminate it. It is a circular statement. Yes, if you want to terminate a task you terminate it. You don't derive that from the task's state. That would be nonsense. If a task wants to terminate it does so without asking the master. If the master want to terminate a task it just orders this and waits. > If you had an else part, there is a way to revive it, and > therefore it cannot be terminatable. I don't understand the meaning of "revive". The meaning of select terminate; else null; end select; is crystal clear: continue if no master did request termination else continue. Again, I thought that T'Callable were there to determine if a master wants the task to terminate. RM is silent about that. Even for the environment task it is in a side note. I am puzzled. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de