code review 12663043: net: separate unix pollster initialization from network...

net: separate unix pollster initialization from network file descriptor allocation

Unlike the existing net package own pollster, runtime-integrated
network pollster on BSD variants, actually kqueue, requires a socket
that has beed passed to syscall.Listen previously for a stream
listener.

This CL separates pollDesc.Init of Unix network pollster from newFD
to avoid any breakages in the transition from Unix network pollster
to runtime-integrated pollster. Upcoming CLs will rearrange the call
order of pollster and syscall functions like the following;

- For dialers that open active connections, pollDesc.Init will be
  called in between syscall.Bind and syscall.Connect.

- For stream listeners that open passive stream connections,
  pollDesc.Init will be called just after syscall.Listen.

- For datagram listeners that open datagram connections,
  pollDesc.Init will be called just after syscall.Bind.

This is in preparation for runtime-integrated network pollster for BSD
variants.

Update issue 5199

[mikio, 2013-08-08 20:49:24]

Hello dvyukov@google.com (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://go.googlecode.com/hg/

[bradfitz, 2013-08-08 21:27:48]

Who is calling these methods when they don't have pollServers?



On Thu, Aug 8, 2013 at 1:49 PM, <mikioh.mikioh@gmail.com> wrote:

> Reviewers: dvyukov,
>
> Message:
> Hello dvyukov@google.com (cc: golang-dev@googlegroups.com),
>
> I'd like you to review this change to
> https://go.googlecode.com/hg/
>
>
> Description:
> net: separate unix pollster initialization from network file descriptor
> allocation
>
> This is in preparation for runtime-integrated network pollster for BSD
> variants.
>
> Update issue 5199
>
> Please review this at
https://codereview.appspot.**com/12663043/<https://codereview.appspot.com/126...
>
> Affected files:
>   M src/pkg/net/fd_poll_unix.go
>
>
> Index: src/pkg/net/fd_poll_unix.go
> ==============================**==============================**=======
> --- a/src/pkg/net/fd_poll_unix.go
> +++ b/src/pkg/net/fd_poll_unix.go
> @@ -252,14 +252,23 @@
>  }
>
>  func (pd *pollDesc) Lock() {
> +       if pd.pollServer == nil {
> +               return
> +       }
>         pd.pollServer.Lock()
>  }
>
>  func (pd *pollDesc) Unlock() {
> +       if pd.pollServer == nil {
> +               return
> +       }
>         pd.pollServer.Unlock()
>  }
>
>  func (pd *pollDesc) Wakeup() {
> +       if pd.pollServer == nil {
> +               return
> +       }
>         pd.pollServer.Wakeup()
>  }
>
> @@ -294,6 +303,9 @@
>  }
>
>  func (pd *pollDesc) Evict() bool {
> +       if pd.pollServer == nil {
> +               return false
> +       }
>         return pd.pollServer.Evict(pd)
>  }
>
>
>
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>
>

[dvyukov, 2013-08-08 21:41:50]

When you switch to runtime netpoll, you will delete fd_poll_unix.go. So why do
we need to modify it now?

[mikio, 2013-08-08 22:01:08]

On Fri, Aug 9, 2013 at 6:41 AM,  <dvyukov@google.com> wrote:

> When you switch to runtime netpoll, you will delete fd_poll_unix.go. So
> why do we need to modify it now?

I don't think it will happen at the same time.

- rearranging the call order of pollster and syscall functions w/ old
unix pollster
- switching from unix pollster to runtime-integrated pollster

[mikio, 2013-08-08 22:09:23]

On Fri, Aug 9, 2013 at 6:27 AM, Brad Fitzpatrick <bradfitz@golang.org> wrote:

> Who is calling these methods when they don't have pollServers?

After rearranging the call oder of pollster and syscall functions it
will happen.
Updated the CL description.

[dvyukov, 2013-08-08 22:28:43]

LGTM
I think I understand what happens

[mikio, 2013-08-09 00:03:00]

*** Submitted as https://code.google.com/p/go/source/detail?r=333a1fab08e7 ***

net: separate unix pollster initialization from network file descriptor
allocation

Unlike the existing net package own pollster, runtime-integrated
network pollster on BSD variants, actually kqueue, requires a socket
that has beed passed to syscall.Listen previously for a stream
listener.

This CL separates pollDesc.Init of Unix network pollster from newFD
to avoid any breakages in the transition from Unix network pollster
to runtime-integrated pollster. Upcoming CLs will rearrange the call
order of pollster and syscall functions like the following;

- For dialers that open active connections, pollDesc.Init will be
  called in between syscall.Bind and syscall.Connect.

- For stream listeners that open passive stream connections,
  pollDesc.Init will be called just after syscall.Listen.

- For datagram listeners that open datagram connections,
  pollDesc.Init will be called just after syscall.Bind.

This is in preparation for runtime-integrated network pollster for BSD
variants.

Update issue 5199

R=dvyukov, bradfitz
CC=golang-dev
https://codereview.appspot.com/12663043