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Message-ID: <4BA7BEB3.9040105@davidnewall.com> Date: Tue, 23 Mar 2010 05:32:11 +1030 From: David Newall <davidn@...idnewall.com> To: Kyle Hubert <khubert@...il.com> CC: linux-kernel@...r.kernel.org Subject: Re: SysV IPC message queues Kyle, Processes do not open nor close message queues, rather they place messages on and fetch them from queues. Let me say this again: you do not open a queue like you must for a file, but go directly to the equivalent of read and write. There is no refcount to indicate how many processes are "using" a queue, although there may be one indicating how many are actively waiting to receive a message. Removing a queue when that count reaches zero would be quite wrong because a process stops waiting as soon as it receives a message; so the count would be zero more often than not. Do not allow IPC_PRIVATE to lead you into false understanding of what a message queue is. IPC_PRIVATE does not cause creation of a private queue, as indicated in msgget(2): "The name choice IPC_PRIVATE was perhaps unfortunate, IPC_NEW would more clearly show its function." Queues are not accessed by key but by id. You do not need to know the key for a queue to access it, neither do you need to use msgget(2) to find a queue's id. So, no, sorry, but your idea must be rejected. David -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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