Re: reference counting.. continued..

From: John-Mark Gurney (gurney_j_at_resnet.uoregon.edu)
Date: 06/13/04

  • Next message: Julian Elischer: "Re: reference counting.. continued.." 
    Date: Sat, 12 Jun 2004 17:49:17 -0700
To: Robert Watson <rwatson@freebsd.org>

    Robert Watson wrote this message on Sat, Jun 12, 2004 at 15:33 -0400:
    > > Our reference counts will almost invariably be integral properties of
    > > our objects and therefore has to interact with the remaining object
    > > locking.
    >
    > I don't have a strong feeling about the general need for a refcount API,
    > but I can confirm that many of the interesting objects in the kernel
    > wouldn't lend themselves to such an API. There are many cases where we'll
    > want to protect the reference count using an existing lock, in which case
    > locking built into the reference count API becomes a liability. Socket
    > reference counting is one example of this: in some ways, it's a general
    > purpose reference count, but the GC behavior is specific to sockets and
    > depends on additional uncounted references from file descriptors and the
    > prototocol layer.

    In working on locking down KQ, I came across the same problem. What I
    ended up doing is creating an object that kept a copy of struct mtx *
    in it. When I created the object, you could either pass in a NULL, and
    a fresh mutex would be created, or you could pass in your own object's
    struct mtx *... This makes it more capable of flexibility and only
    requires a lock/unlocked arg...

    Just a thought... 

    -- 
  John-Mark Gurney				Voice: +1 415 225 5579
     "All that I will do, has been done, All that I have, has not."
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  • Next message: Julian Elischer: "Re: reference counting.. continued.."

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