Use a pool to force dart2js to run sequentially.

Use a pool to force dart2js to run sequentially.

R=nweiz@google.com

Committed: https://code.google.com/p/dart/source/detail?r=32836

[Bob Nystrom, 2014-02-19 21:57:40]

This is cleaner than the previous code and also fixes a dumb bug on my part.
Right now, it logs *before* acquiring the "lock" which means it will spew
logging for the same entrypoint multiple times.

In my "50 copies of TodoMVC" package, running pub build before this change
produces 250k lines of output (!). This change gets it down to 2,274.

[nweiz, 2014-02-19 23:15:52]

lgtm

https://codereview.chromium.org/172793004/diff/1/sdk/lib/_internal/pub/lib/sr...
File sdk/lib/_internal/pub/lib/src/barback/dart2js_transformer.dart (right):

https://codereview.chromium.org/172793004/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/barback/dart2js_transformer.dart:36: /// Dart2js
uses lots of memory, so if we try to actually run compiles in
One-sentence paragraph.

https://codereview.chromium.org/172793004/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/barback/dart2js_transformer.dart:40: static final
_pool = new Pool(1);
Yay code re-use!

[Bob Nystrom, 2014-02-20 00:32:04]

https://codereview.chromium.org/172793004/diff/1/sdk/lib/_internal/pub/lib/sr...
File sdk/lib/_internal/pub/lib/src/barback/dart2js_transformer.dart (right):

https://codereview.chromium.org/172793004/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/barback/dart2js_transformer.dart:36: /// Dart2js
uses lots of memory, so if we try to actually run compiles in
On 2014/02/19 23:15:52, nweiz wrote:
> One-sentence paragraph.

Done.

https://codereview.chromium.org/172793004/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/barback/dart2js_transformer.dart:40: static final
_pool = new Pool(1);
On 2014/02/19 23:15:52, nweiz wrote:
> Yay code re-use!

Yeah, this is much cleaner. Works like a charm.

[Bob Nystrom, 2014-02-20 00:35:10]

Committed patchset #2 manually as r32836 (presubmit successful).