[telemetry] Implement per-pixel algorithms in Bitmap as a C++ extension.

tools/telemetry/telemetry/core/bitmaptools/__init__.py

Index: tools/telemetry/telemetry/core/bitmaptools/__init__.py
diff --git a/tools/telemetry/telemetry/core/bitmaptools/__init__.py b/tools/telemetry/telemetry/core/bitmaptools/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..8bf7958123d4b0e2d1d6ab34375ffe71e35ea447
--- /dev/null
+++ b/tools/telemetry/telemetry/core/bitmaptools/__init__.py
@@ -0,0 +1,39 @@
+""" Bitmap processing routines.

[tonyg, 2013/12/12 22:17:48]

Please add the standard copyright.

[szym, 2013/12/12 22:54:12]

Done.

+
+All functions accept a tuple of (pixels, width, channels) as the first argument.
+Bounding box is a tuple (left, right, width, height).
+"""
+
+def _BuildExtension():
+  """Builds the extension library in place."""

[tonyg, 2013/12/12 22:17:48]

Clever!

+  import os
+  from distutils import log
+  from distutils.core import Distribution, Extension
+
+  dirname = os.path.dirname(__file__)
+  # Source file paths must be relative to current path.
+  relpath = os.path.relpath(dirname, os.getcwd())
+  src_files = [
+    os.path.join(relpath, 'bitmaptools.cc')
+  ]
+  dist = Distribution({
+    'ext_modules': [ Extension('bitmaptools', src_files) ]
+  })
+  dist.script_args = ['build_ext', '--build-temp', 'build',
+                      '--build-lib', dirname]
+  dist.parse_command_line()
+  log.set_threshold(log.ERROR)
+  dist.run_commands()
+  dist.script_args = ['clean', '--all']
+  dist.parse_command_line()
+  log.set_threshold(log.ERROR)
+  dist.run_commands()

[tonyg, 2013/12/12 22:17:48]

I don't follow exactly how this works. Does this routine avoid building every
time once the user has built once?

[szym, 2013/12/12 22:54:12]

This _BuildExtension() is equivalent to running make. If the sources are older
than the .so, no action is taken.

[tonyg, 2013/12/12 23:19:02]

Even with 'clean' in script_args?

[szym, 2013/12/12 23:30:36]

'clean' removes the build-temp directory, not the build-dir. But now I realized
that I didn't set build-temp for clean, and doing it in tools/telemetry/build is
a bad idea.

Fixed it to use a temporary directory.

+
+try:
+  _BuildExtension()
+except:
+  # TODO(tonyg): fetch from cloudstorage
+  raise

[tonyg, 2013/12/12 22:17:48]

In practice, when will we hit this?

[szym, 2013/12/12 22:54:12]

On Ubuntu, no python-dev or build-essential.

[tonyg, 2013/12/12 23:19:02]

The GPU tests do rely on the Bitmap class on all platforms. We can't land
anything that would temporarily break win, mac or linux.

If that is going to be a problem, one possible approach would be to split this
CL and check in the bitmaptools directory first. Then I could build on each
platform and do the cloud storage uploads.

[szym, 2013/12/12 23:30:36]

How can we check if it works on all platforms?

+
+# pylint: disable=W0401
+from .bitmaptools import *