[dart:io] Remove collisions from IO Service port dispatch

[dart:io] Remove collisions from IO Service port dispatch

This change prevents IO Service requests from colliding on the same
IO Service port. If requests can collide, a request that could otherwise
be serviced immediately can become blocked on a request that is blocked.

To avoid collisions, this change maintains a free list of IO Service
ports. If the free list is empty, we allocate a new IO Service port.

R=bkonyi@google.com

Committed: https://github.com/dart-lang/sdk/commit/3310e0cebd9c95cd508fdb5ef061b73422c72f85

[zra, 2017-05-23 22:30:52]

Description was changed from

==========
[dart:io] Remove collisions from IO Service port dispatch
==========

to

==========
[dart:io] Remove collisions from IO Service port dispatch

This change prevents IO Service requests from colliding on the same
IO Service port. If requests can collide, a request that could otherwise
be serviced immediately can become blocked on a request that is blocked.

To avoid collisions, this change maintains a free list of IO Service
ports. If the free list is empty, we allocate a new IO Service port.
==========

[zra, 2017-05-23 22:31:34]

zra@google.com changed reviewers:
+ asiva@google.com, bkonyi@google.com

[zra, 2017-05-23 22:31:35]

John, could you try patching this in to see if it fixes your
problem? It should patch cleanly against 1.23.

[bkonyi, 2017-05-23 22:40:18]

LGTM

[codefu, 2017-05-23 22:47:10]

On 2017/05/23 22:31:35, zra wrote:
> John, could you try patching this in to see if it fixes your
> problem? It should patch cleanly against 1.23.

building and testing now.

[codefu, 2017-05-23 22:58:27]

On 2017/05/23 22:47:10, codefu wrote:
> On 2017/05/23 22:31:35, zra wrote:
> > John, could you try patching this in to see if it fixes your
> > problem? It should patch cleanly against 1.23.
> 
> building and testing now.

Verified working on our embedded device:
1) Tested with two joysticks; experienced lockup of one joystick doing all the
input.
2) Compiled / uploaded / re-ran #1 - cannot block.

LGTM

[zra, 2017-05-24 06:58:17]

Description was changed from

==========
[dart:io] Remove collisions from IO Service port dispatch

This change prevents IO Service requests from colliding on the same
IO Service port. If requests can collide, a request that could otherwise
be serviced immediately can become blocked on a request that is blocked.

To avoid collisions, this change maintains a free list of IO Service
ports. If the free list is empty, we allocate a new IO Service port.
==========

to

==========
[dart:io] Remove collisions from IO Service port dispatch

This change prevents IO Service requests from colliding on the same
IO Service port. If requests can collide, a request that could otherwise
be serviced immediately can become blocked on a request that is blocked.

To avoid collisions, this change maintains a free list of IO Service
ports. If the free list is empty, we allocate a new IO Service port.

R=bkonyi@google.com

Committed:
https://github.com/dart-lang/sdk/commit/3310e0cebd9c95cd508fdb5ef061b73422c72f85
==========

[zra, 2017-05-24 06:58:18]

Committed patchset #1 (id:1) manually as
3310e0cebd9c95cd508fdb5ef061b73422c72f85 (presubmit successful).