Only HistogramBase is used outside of base/metrics

Only HistogramBase is used outside of base/metrics.
So client code of histogram will see a simpler interface. This also makes adding SparseHistogram to existing metrics framework possible.

This CL depends on https://codereview.chromium.org/11682003/
So please review that one first.

[email protected],[email protected]
BUG=139612
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=178242

[kaiwang, 2013-01-11 22:52:26]

Hi Ilya and Jim, please start to review this CL (as the one it depends on was
submitted :-)

[Ilya Sherman, 2013-01-12 00:48:01]

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_ba...
File base/metrics/histogram_base.h (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_ba...
base/metrics/histogram_base.h:96: void AddBoolean(bool value);
IMO these should be virtual functions with default implementations that are
NOTREACHED(), overridden by subclasses where appropriate.

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_un...
File base/metrics/histogram_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_un...
base/metrics/histogram_unittest.cc:182: Histogram* histogram =
static_cast<Histogram*>(
The need for a static_cast<> here makes me think the return type from FactoryGet
isn't quite right...

https://codereview.chromium.org/11615008/diff/25001/base/metrics/statistics_r...
File base/metrics/statistics_recorder_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/statistics_r...
base/metrics/statistics_recorder_unittest.cc:63: DeleteHistogram(histogram);
Why is it safe to delete the histogram here?  Isn't it the case that the
StatisticsRecorder might be holding a reference to it?

[kaiwang, 2013-01-16 02:07:34]

Sorry for late response. Busy with other tasks...

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_ba...
File base/metrics/histogram_base.h (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_ba...
base/metrics/histogram_base.h:96: void AddBoolean(bool value);
Take AddTime for example, there's no TimeHistogram. The function is just
converting TimeDelta to int. I don't see why it can not be applied to all kinds
of histograms?

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_un...
File base/metrics/histogram_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_un...
base/metrics/histogram_unittest.cc:182: Histogram* histogram =
static_cast<Histogram*>(
But last time you mentioned it's fine to use static_cast in some situation?

I can get around of static_cast by directly create any kind of histograms.
(Friend test is needed). Just don't see the necessarity.

https://codereview.chromium.org/11615008/diff/25001/base/metrics/statistics_r...
File base/metrics/statistics_recorder_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/statistics_r...
base/metrics/statistics_recorder_unittest.cc:63: DeleteHistogram(histogram);
This one tests the situation that StatisticsRecorder was not initialized. See
line 50

[Ilya Sherman, 2013-01-16 04:34:34]

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_ba...
File base/metrics/histogram_base.h (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_ba...
base/metrics/histogram_base.h:96: void AddBoolean(bool value);
On 2013/01/16 02:07:34, kaiwang wrote:
> Take AddTime for example, there's no TimeHistogram. The function is just
> converting TimeDelta to int. I don't see why it can not be applied to all
kinds
> of histograms?

It doesn't make much sense for a boolean histogram, for example.  What types of
histograms do people actually use this method with?

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_un...
File base/metrics/histogram_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/histogram_un...
base/metrics/histogram_unittest.cc:182: Histogram* histogram =
static_cast<Histogram*>(
On 2013/01/16 02:07:34, kaiwang wrote:
> But last time you mentioned it's fine to use static_cast in some situation?

For deserializing, you mean?  In that case, there's not much choice.

> I can get around of static_cast by directly create any kind of histograms.
> (Friend test is needed). Just don't see the necessarity.

If it's only an issue for test code, then ok, it's probably fine.

https://codereview.chromium.org/11615008/diff/25001/base/metrics/statistics_r...
File base/metrics/statistics_recorder_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/statistics_r...
base/metrics/statistics_recorder_unittest.cc:63: DeleteHistogram(histogram);
On 2013/01/16 02:07:34, kaiwang wrote:
> This one tests the situation that StatisticsRecorder was not initialized. See
> line 50

Ah, I see.  IMO it would be helpful to add a comment here briefly mentioning why
this is safe.

[kaiwang, 2013-01-16 07:38:23]

Only for first comment:

In current code, AddTime is an inline function in Histogram. So all types of
histograms can call it.
AddBoolean is DCHECKed in all histograms except BooleanHistogram. But please
note, BooleanHistogram is not a type of histogram only records or accepts true
or false, it's just a specialized LinearHistogram (so a linear histogram with 0
buckets: 0~1, 1~max). It still has function Add to add any int sample.

[kaiwang, 2013-01-16 07:39:11]

On 2013/01/16 07:38:23, kaiwang wrote:
> Only for first comment:
> 
> In current code, AddTime is an inline function in Histogram. So all types of
> histograms can call it.
> AddBoolean is DCHECKed in all histograms except BooleanHistogram. But please
> note, BooleanHistogram is not a type of histogram only records or accepts true
> or false, it's just a specialized LinearHistogram (so a linear histogram with
0

typo: 2 buckets

> buckets: 0~1, 1~max). It still has function Add to add any int sample.

[kaiwang, 2013-01-16 19:08:05]

https://codereview.chromium.org/11615008/diff/25001/base/metrics/statistics_r...
File base/metrics/statistics_recorder_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/25001/base/metrics/statistics_r...
base/metrics/statistics_recorder_unittest.cc:63: DeleteHistogram(histogram);
On 2013/01/16 04:34:34, Ilya Sherman wrote:
> On 2013/01/16 02:07:34, kaiwang wrote:
> > This one tests the situation that StatisticsRecorder was not initialized.
See
> > line 50
> 
> Ah, I see.  IMO it would be helpful to add a comment here briefly mentioning
why
> this is safe.

Done.

[Ilya Sherman, 2013-01-18 01:49:10]

lgtm

https://codereview.chromium.org/11615008/diff/34001/base/metrics/histogram_ba...
File base/metrics/histogram_base.cc (right):

https://codereview.chromium.org/11615008/diff/34001/base/metrics/histogram_ba...
base/metrics/histogram_base.cc:89: void HistogramBase::AddTime(TimeDelta time) {
nit: Pass by const-reference.

https://codereview.chromium.org/11615008/diff/34001/base/metrics/histogram_ba...
base/metrics/histogram_base.cc:94: Add(value? 1 : 0);
nit: Please add a space before the question mark.

[kaiwang, 2013-01-18 02:33:19]

https://codereview.chromium.org/11615008/diff/34001/base/metrics/histogram_ba...
File base/metrics/histogram_base.cc (right):

https://codereview.chromium.org/11615008/diff/34001/base/metrics/histogram_ba...
base/metrics/histogram_base.cc:89: void HistogramBase::AddTime(TimeDelta time) {
On 2013/01/18 01:49:10, Ilya Sherman wrote:
> nit: Pass by const-reference.

Done.

https://codereview.chromium.org/11615008/diff/34001/base/metrics/histogram_ba...
base/metrics/histogram_base.cc:94: Add(value? 1 : 0);
On 2013/01/18 01:49:10, Ilya Sherman wrote:
> nit: Please add a space before the question mark.

Done.

[kaiwang, 2013-01-18 02:37:04]

Owners, please review this CL. Thanks a lot!

jar: base/ and net/
brettw: chrome/ , content/ and webkit/

[jar (doing other things), 2013-01-18 03:01:58]

https://codereview.chromium.org/11615008/diff/38002/base/metrics/histogram_un...
File base/metrics/histogram_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/38002/base/metrics/histogram_un...
base/metrics/histogram_unittest.cc:104: Histogram::FactoryGet("Histogram", 1,
64, 8, HistogramBase::kNoFlags));
What was the advantage of having FactoryGet return a HistogramBase, and then
have to use static_cast here?

The upcast seems to be more safely done inside the class, where there is
effective type information.

[kaiwang, 2013-01-18 03:33:03]

https://codereview.chromium.org/11615008/diff/38002/base/metrics/histogram_un...
File base/metrics/histogram_unittest.cc (right):

https://codereview.chromium.org/11615008/diff/38002/base/metrics/histogram_un...
base/metrics/histogram_unittest.cc:104: Histogram::FactoryGet("Histogram", 1,
64, 8, HistogramBase::kNoFlags));
FactoryGet usually get the histogram from StatisticsRecorder, which keeps
pointers to Histogram class (the originally most base class of histograms). Now
we want to store SparseHistograms too, so need to have a base class.

Also limiting the interface is also helpful for code maintaining.

The static_cast only happens in tests. This is to prevent too many "friend"
declarations, since histogram constructors are all private

[kaiwang, 2013-01-22 01:49:06]

ping...

[jar (doing other things), 2013-01-22 17:09:39]

Patch set 9 base LGTM

[brettw, 2013-01-22 18:26:00]

chrome, content, webkit lgtm

[jar (doing other things), 2013-01-22 18:30:37]

Patch set 9.  net/* LGTM

[commit-bot: I haz the power, 2013-01-22 18:31:23]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/[email protected]/11615008/38002

[commit-bot: I haz the power, 2013-01-22 18:35:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/[email protected]/11615008/38002

[commit-bot: I haz the power, 2013-01-22 18:47:02]

Sorry for I got bad news for ya.
Compile failed with a clobber build on linux_aura.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_aura...
Your code is likely broken or HEAD is junk. Please ensure your
code is not broken then alert the build sheriffs.
Look at the try server FAQ for more details.

[kaiwang, 2013-01-23 01:49:25]

TBR sky and erikwright for one line changes under ui and sql

[commit-bot: I haz the power, 2013-01-23 01:51:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/[email protected]/11615008/45025

[commit-bot: I haz the power, 2013-01-23 04:12:22]

Change committed as 178242