GM: fix --mismatchPath option

GM: fix --mismatchPath option
(currently, it doesn't actually write any files!)

TBR=rmistry

Committed: https://code.google.com/p/skia/source/detail?r=8963

[epoger, 2013-05-02 15:58:49]

https://codereview.chromium.org/14855005/diff/1/gm/tests/outputs/compared-aga...
File
gm/tests/outputs/compared-against-different-pixels-images/output-expected/command_line
(right):

https://codereview.chromium.org/14855005/diff/1/gm/tests/outputs/compared-aga...
gm/tests/outputs/compared-against-different-pixels-images/output-expected/command_line:1:
out/Debug/gm --verbose --hierarchy --match selftest1 --config 8888 565 -r
gm/tests/inputs/images/different-pixels --writeJsonSummaryPath
gm/tests/outputs/compared-against-different-pixels-images/output-actual/json-summary.txt
--writePath
gm/tests/outputs/compared-against-different-pixels-images/output-actual/writePath
--mismatchPath
gm/tests/outputs/compared-against-different-pixels-images/output-actual/mismatchPath
patchset 1 just changes the self-test to add --writePath and --mismatchPath
flags, and then updates the expected results to match what we get.

https://codereview.chromium.org/14855005/diff/1/gm/tests/outputs/compared-aga...
File
gm/tests/outputs/compared-against-different-pixels-images/output-expected/stdout
(right):

https://codereview.chromium.org/14855005/diff/1/gm/tests/outputs/compared-aga...
gm/tests/outputs/compared-against-different-pixels-images/output-expected/stdout:13:
GM: [*] 2 ExpectationsMismatch: 8888/selftest1 565/selftest1
This indicates that GM should write its actual results for these two tests into
mismatchPath... but it doesn't!  That's the error I want to fix in this CL.

https://codereview.chromium.org/14855005/diff/1/gm/tests/outputs/compared-aga...
File
gm/tests/outputs/compared-against-different-pixels-images/output-expected/writePath/565/selftest1.png
(right):

https://codereview.chromium.org/14855005/diff/1/gm/tests/outputs/compared-aga...
gm/tests/outputs/compared-against-different-pixels-images/output-expected/writePath/565/selftest1.png:2:
62050 1
all 565/selftest1.png files were written out by gm with this checksum (62050 1);
replacing the actual PNG file with the checksum description works around
https://code.google.com/p/chromium/issues/detail?id=169600 ('gcl/upload.py fail
to upload binary files to rietveld')

https://codereview.chromium.org/14855005/diff/1/gm/tests/outputs/compared-aga...
File
gm/tests/outputs/compared-against-different-pixels-images/output-expected/writePath/8888/selftest1.png
(right):

https://codereview.chromium.org/14855005/diff/1/gm/tests/outputs/compared-aga...
gm/tests/outputs/compared-against-different-pixels-images/output-expected/writePath/8888/selftest1.png:2:
26853 1
all 8888/selftest1.png files were written out by gm with this checksum (26853 1)

[epoger, 2013-05-02 16:23:30]

https://codereview.chromium.org/14855005/diff/9001/gm/gmmain.cpp
File gm/gmmain.cpp (right):

https://codereview.chromium.org/14855005/diff/9001/gm/gmmain.cpp#newcode1643
gm/gmmain.cpp:1643: bool prepare_subdirectories(const char *root, bool
useFileHierarchy,
All patchset 2 does is extract prepare_subdirectories() into its own function. 
No behavioral changes yet, as demonstrated by unchanged self-test results.

[epoger, 2013-05-02 16:34:34]

https://codereview.chromium.org/14855005/diff/5002/gm/gmmain.cpp
File gm/gmmain.cpp (right):

https://codereview.chromium.org/14855005/diff/5002/gm/gmmain.cpp#newcode1903
gm/gmmain.cpp:1903: if (!prepare_subdirectories(gmmain.fMismatchPath,
gmmain.fUseFileHierarchy, configs)) {
Patchset 3 creates subdirectories for mismatchPath like it does for writePath,
and now the results confirm that this allows mismatches to be written out.

The problem, though, is that the mismatchPath subdirectories are created even if
there are no mismatches!  This can be misleading ("hey, I see that the directory
mismatchPath/8888 exists, that must mean that there are some 8888 mismatches").

I'm going to see if there is some relatively simple way to only create the
directory structures when they are needed to write out a file.

[epoger, 2013-05-02 16:49:07]

On 2013/05/02 16:34:34, epoger wrote:
> The problem, though, is that the mismatchPath subdirectories are created even
if
> there are no mismatches!  This can be misleading ("hey, I see that the
directory
> mismatchPath/8888 exists, that must mean that there are some 8888
mismatches").
> 
> I'm going to see if there is some relatively simple way to only create the
> directory structures when they are needed to write out a file.

I looked into this, and it seems like it would be pretty tricky...

I was gonna add code to the write_bitmap() method that would create the
intermediate directories on the fly if they hadn't been created yet.  But
SkOSFile.h provides only mkdir(), not mkdirs(), so I would have to add logic to
iterate over all directories within the path, and create directories at all
levels.

A better long-term solution, IMHO, is for SkOSFile to provide these two
functions:
1. bool mkdirs(dirpath) : create all levels of directories needed for dirpath to
exist
2. char *dirname(filepath) : get the name of the directory containing the file
specified in this path

Then, we could add this simple call to write_bitmap(), before writing out each
file:
mkdirs(dirname(path.c_str()))

In the meanwhile, I'm going to let GM create the mismatchPath directory trees
whether they are needed or not.  At least then, the mismatches will be written
out!

[epoger, 2013-05-02 17:03:40]

Ready for review at patchset 4.

If you look at the intermediate patchsets, you'll see where I temporarily
modified the self-tests to exercise this before and after the change.

Unfortunately, the gm self-tests cannot exercise this in production, for a
couple of reasons that are described within those interim patchsets.  So in
patchset 4, I had to pull them out.

[epoger, 2013-05-02 18:24:06]

Committed patchset #4 manually as r8963 (presubmit successful).