From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: is there a version of unix written in Ada
Date: Thu, 1 Oct 2020 19:37:01 +0200 [thread overview]
Message-ID: <rl543q$1om5$1@gioia.aioe.org> (raw)
In-Reply-To: htmgbpFihulU1@mid.individual.net
On 01/10/2020 19:01, Niklas Holsti wrote:
> On 2020-10-01 19:06, Dmitry A. Kazakov wrote:
>> On 01/10/2020 17:38, Niklas Holsti wrote:
>>
>>> If the protected procedures belong to different protected objects,
>>> yes it is legal. But not if they belong to the same object, as J-P
>>> noted.
>>
>> But then you have a problem when two independently running protected
>> procedures of *different* objects call a procedure of a third object.
>> You must serialize these calls, and that is effectively blocking.
>
>
> I don't know what you mean by "effectively", here, but yes, one of the
> tasks must wait for the other task to complete the protected operation
> on the third object. So what?
It looks quite complicated to implement, e.g. checking barriers and
doing locking when you are already done that.
Now let's continue the example. What happens when the calling paths are:
O1.P1 --> O3.P3 --> O2.Q
O2.P2 --> O3.P3 --> O2.Q
Let Q1.P1 blocks Q2.P2 on a attempt to enter O3.P3:
O1.P1 --> O3.P3
O2.P2 --> blocked
Then O3.P3 calls O2.Q:
O1.P1 --> O3.P3 --> O2.Q
|
O2.P2 --> blocked V
This will either re-enter O2 or deadlock.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2020-10-01 17:37 UTC|newest]
Thread overview: 105+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <e3c51e65-b71e-4623-bd58-c94cdbcc3ba6o@googlegroups.com>
2020-07-25 7:37 ` is there a version of unix written in Ada mockturtle
2020-07-26 19:45 ` Stéphane Rivière
2020-07-26 22:15 ` Jeffrey R. Carter
2020-07-27 7:40 ` Stéphane Rivière
2020-07-28 13:08 ` DrPi
2020-07-28 16:48 ` Simon Wright
2020-07-28 17:00 ` Fabien Chouteau
2020-07-29 9:21 ` DrPi
2020-07-29 9:28 ` Fabien Chouteau
2020-07-29 15:02 ` DrPi
2020-07-29 15:11 ` Fabien Chouteau
2020-07-29 20:41 ` DrPi
2020-07-29 9:20 ` DrPi
2020-07-29 16:53 ` Simon Wright
2020-07-29 20:42 ` DrPi
2020-07-25 8:47 ` Niklas Holsti
2020-07-25 9:36 ` Stéphane Rivière
2020-07-25 10:41 ` Luke A. Guest
2020-07-25 14:43 ` Jesper Quorning
2020-07-25 19:20 ` Andreas ZEURCHER
2020-07-27 7:40 ` Stéphane Rivière
2020-07-27 15:00 ` nobody in particular
2020-07-27 14:58 ` nobody in particular
2020-07-27 20:28 ` Shark8
2020-07-30 0:57 ` gdotone
2020-07-31 14:01 ` Shark8
2020-09-23 17:39 ` Olivier Henley
2020-09-25 15:06 ` DrPi
2020-09-25 17:31 ` Andreas ZEURCHER
2020-09-26 8:50 ` DrPi
2020-09-27 18:55 ` Luke A. Guest
2020-09-27 19:07 ` Luke A. Guest
2020-09-27 18:53 ` Luke A. Guest
2020-09-27 14:25 ` Shark8
2020-09-27 15:01 ` Dmitry A. Kazakov
2020-09-27 20:59 ` DrPi
2020-09-28 7:41 ` Dmitry A. Kazakov
2020-09-28 13:48 ` Olivier Henley
2020-09-28 14:48 ` Dmitry A. Kazakov
2020-09-28 16:28 ` Olivier Henley
2020-09-28 20:30 ` Dmitry A. Kazakov
2020-09-28 21:06 ` Shark8
2020-09-28 17:47 ` Paul Rubin
2020-09-28 20:27 ` Dmitry A. Kazakov
2020-09-29 23:54 ` Paul Rubin
2020-09-30 8:18 ` Dmitry A. Kazakov
2020-09-30 17:27 ` Paul Rubin
2020-09-30 19:42 ` Dmitry A. Kazakov
2020-09-30 20:33 ` Paul Rubin
2020-09-30 21:03 ` Dmitry A. Kazakov
2020-09-30 22:42 ` Randy Brukardt
2020-10-01 9:28 ` Dmitry A. Kazakov
2020-10-01 9:59 ` J-P. Rosen
2020-10-01 10:21 ` Dmitry A. Kazakov
2020-10-01 11:38 ` Niklas Holsti
2020-10-01 11:52 ` Niklas Holsti
2020-10-01 12:51 ` Dmitry A. Kazakov
2020-10-01 14:18 ` J-P. Rosen
2020-10-01 15:44 ` Dmitry A. Kazakov
2020-10-01 22:10 ` Randy Brukardt
2020-10-02 5:36 ` J-P. Rosen
2020-10-02 6:56 ` Dmitry A. Kazakov
2020-10-02 7:42 ` J-P. Rosen
2020-10-03 3:14 ` Randy Brukardt
2020-10-01 15:38 ` Niklas Holsti
2020-10-01 16:06 ` Dmitry A. Kazakov
2020-10-01 17:01 ` Niklas Holsti
2020-10-01 17:37 ` Dmitry A. Kazakov [this message]
2020-10-01 22:13 ` Randy Brukardt
2020-10-01 11:48 ` J-P. Rosen
2020-10-01 12:54 ` Dmitry A. Kazakov
2020-10-01 7:57 ` Paul Rubin
2020-10-01 9:26 ` Dmitry A. Kazakov
2020-10-01 9:46 ` Paul Rubin
2020-10-01 10:35 ` Dmitry A. Kazakov
2020-10-01 19:02 ` DrPi
2020-10-01 23:12 ` Paul Rubin
2020-10-01 21:54 ` Randy Brukardt
2020-10-01 23:14 ` Paul Rubin
2020-10-01 21:36 ` Brian Drummond
2020-10-02 6:56 ` Dmitry A. Kazakov
2020-10-02 18:34 ` Brian Drummond
2020-10-02 21:24 ` Paul Rubin
2020-10-06 23:54 ` Brian Drummond
2020-10-03 6:54 ` Dmitry A. Kazakov
2020-10-05 14:03 ` Shark8
2020-10-07 11:56 ` Olivier Henley
2020-10-09 12:35 ` Olivier Henley
2020-10-09 14:41 ` Brian Drummond
2020-09-28 18:40 ` Vincent Marciante
2020-09-28 20:28 ` Dmitry A. Kazakov
2020-09-28 17:04 ` DrPi
2020-09-28 17:30 ` Olivier Henley
2020-09-28 18:05 ` Olivier Henley
2020-09-28 19:36 ` Shark8
2020-09-03 10:32 ` c+
2020-09-12 4:30 ` sumde121
2020-09-19 14:09 ` erchetan33
2020-10-01 22:21 Randy Brukardt
2020-10-02 6:55 ` Dmitry A. Kazakov
2020-10-03 3:09 ` Randy Brukardt
2020-10-03 6:42 ` Dmitry A. Kazakov
2020-10-03 7:44 ` Niklas Holsti
2020-10-03 8:16 ` Dmitry A. Kazakov
2020-10-03 10:44 ` Niklas Holsti
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