Add a new class to take care of out-of-order execution.

Add new class ExecutionQueue to take care of out-of-order execution.

ExecutionQueue takes care of reordering execution depending on each Dependency
requirements. There is no need to sort anymore.

ExecutionQueue also manages the Progress instance and is multithread safe, in preparation to parallel checkout.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=55882

[M-A Ruel, 2010-08-10 19:44:06]

Dependent on http://codereview.chromium.org/3159002

Still doesn't fix the duplicate execution, will be done in a subsequent change
since this is not as urgent.

This change should make parallel execution much more doable, especially that
I've intentionally make the scheduler multi thread safe.

[M-A Ruel, 2010-08-10 19:55:00]

I forgot to say it also fixed pagespeed checkout.

[M-A Ruel, 2010-08-12 00:27:52]

ping

[bradn, 2010-08-12 00:40:36]

http://codereview.chromium.org/3112002/diff/6001/7001
File gclient.py (right):

http://codereview.chromium.org/3112002/diff/6001/7001#newcode98
gclient.py:98: Methods of this class are multithread safe."""
""" on the next line.

http://codereview.chromium.org/3112002/diff/6001/7001#newcode98
gclient.py:98: Methods of this class are multithread safe."""
Why go to all the trouble with locks, it appears to only end up doing one at a
time. Or are you building up to allowing the queue to have some number of
workers?

http://codereview.chromium.org/3112002/diff/6001/7001#newcode99
gclient.py:99: def __init__(self, pm):
pm seems a little opaque, maybe a comment or a more verbose name? Base class?

http://codereview.chromium.org/3112002/diff/6001/7001#newcode104
gclient.py:104: self.ran = []
This grows without bound, no?

http://codereview.chromium.org/3112002/diff/6001/7001#newcode163
gclient.py:163: return False
This ends up returning False both if your out of work, or if there are cycles.
Is that what you intended?

[M-A Ruel, 2010-08-12 00:53:08]

ptal

http://codereview.chromium.org/3112002/diff/6001/7001
File gclient.py (right):

http://codereview.chromium.org/3112002/diff/6001/7001#newcode98
gclient.py:98: Methods of this class are multithread safe."""
On 2010/08/12 00:40:36, bradn wrote:
> Why go to all the trouble with locks, it appears to only end up doing one at a
> time. Or are you building up to allowing the queue to have some number of
> workers?

I assumed you didn't want a bazillion changes in one review.

http://codereview.chromium.org/3112002/diff/6001/7001#newcode99
gclient.py:99: def __init__(self, pm):
On 2010/08/12 00:40:36, bradn wrote:
> pm seems a little opaque, maybe a comment or a more verbose name? Base class?

renamed to progress.

http://codereview.chromium.org/3112002/diff/6001/7001#newcode104
gclient.py:104: self.ran = []
On 2010/08/12 00:40:36, bradn wrote:
> This grows without bound, no?

only if self.enqueue() is called without bound?

http://codereview.chromium.org/3112002/diff/6001/7001#newcode163
gclient.py:163: return False
On 2010/08/12 00:40:36, bradn wrote:
> This ends up returning False both if your out of work, or if there are cycles.
> Is that what you intended?

Yes. I'll change it only if needed.

[bradn, 2010-08-12 00:55:37]

LGTM