Only write .in outputs if they have changed.

Only write .in outputs if they have changed.

This reduces the number of targets that have to be built when changing the
status of a runtime-enabled feature dramatically (for content_shell, from
1229 to 44), because these changes only affect the source file and not the
header.

In such cases, ninja notices when the modification time is left alone, and
it can propagate this "clean" (not changed) state to dependent targets.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=185134

[jbroman, 2014-11-10 21:12:55]

jbroman@chromium.org changed reviewers:
+ dpranke@chromium.org

[jbroman, 2014-11-10 21:12:55]

Seems like a straightforward enough change; I'd been getting annoyed that REF.in
changes always triggered large incremental builds.

WDYT?

[Dirk Pranke, 2014-11-10 22:04:56]

lgtm w/ nit, below ...

https://codereview.chromium.org/688443007/diff/1/Source/build/scripts/in_gene...
File Source/build/scripts/in_generator.py (right):

https://codereview.chromium.org/688443007/diff/1/Source/build/scripts/in_gene...
Source/build/scripts/in_generator.py:58: def _write_file(self, output_dir,
contents, file_name):
I'd probably rename this to _write_file_if_changed.

[jbroman, 2014-11-11 15:23:46]

The CQ bit was checked by jbroman@chromium.org

[commit-bot: I haz the power, 2014-11-11 15:24:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/688443007/20001

[jbroman, 2014-11-11 15:30:54]

https://codereview.chromium.org/688443007/diff/1/Source/build/scripts/in_gene...
File Source/build/scripts/in_generator.py (right):

https://codereview.chromium.org/688443007/diff/1/Source/build/scripts/in_gene...
Source/build/scripts/in_generator.py:58: def _write_file(self, output_dir,
contents, file_name):
On 2014/11/10 22:04:56, Dirk Pranke wrote:
> I'd probably rename this to _write_file_if_changed.

Done.

[commit-bot: I haz the power, 2014-11-11 17:09:47]

Committed patchset #2 (id:20001) as 185134