[python-dtcwt] 201/497: memoize any to-host copies in OpenCL transform result

[Ghislain Vaillant]

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ghisvail-guest pushed a commit to branch debian/sid
in repository python-dtcwt.

commit a708eb9a0a769ab0d81196d456e969253fb532f4
Author: Rich Wareham <rjw57 at cam.ac.uk>
Date:   Wed Nov 13 11:35:46 2013 +0000

    memoize any to-host copies in OpenCL transform result
---
 dtcwt/backend/backend_opencl/transform2d.py | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/dtcwt/backend/backend_opencl/transform2d.py b/dtcwt/backend/backend_opencl/transform2d.py
index e19744f..9be3f9c 100644
--- a/dtcwt/backend/backend_opencl/transform2d.py
+++ b/dtcwt/backend/backend_opencl/transform2d.py
@@ -6,7 +6,7 @@ from six.moves import xrange
 
 from dtcwt import biort as _biort, qshift as _qshift
 from dtcwt.defaults import DEFAULT_BIORT, DEFAULT_QSHIFT
-from dtcwt.utils import appropriate_complex_type_for, asfarray
+from dtcwt.utils import appropriate_complex_type_for, asfarray, memoize
 from dtcwt.backend.backend_opencl.lowlevel import colfilter, coldfilt, colifilt
 from dtcwt.backend.backend_opencl.lowlevel import axis_convolve, axis_convolve_dfilter, q2c
 from dtcwt.backend.backend_opencl.lowlevel import to_device, to_queue, to_array, empty
@@ -38,6 +38,15 @@ class TransformDomainSignalOpenCL(object):
     are implemented via properties. The original OpenCL arrays may be accessed
     via the ``cl_...`` attributes.
 
+    .. note::
+    
+        The copy from device to host is performed *once* and then memoized.
+        This makes repeated access to the host-side attributes efficient but
+        will mean that any changes to the device-side arrays will not be
+        reflected in the host-side attributes after their first access. You
+        should not be modifying the arrays once you return an instance of this
+        class anyway but if you do, beware!
+
     .. py:attribute:: cl_lowpass
 
         The CL array containing the lowpass image.
@@ -58,14 +67,17 @@ class TransformDomainSignalOpenCL(object):
         self.cl_scales = scales
 
     @property
+    @memoize
     def lowpass(self):
         return to_array(self.cl_lowpass) if self.cl_lowpass is not None else None
 
     @property
+    @memoize
     def subbands(self):
         return tuple(to_array(x) for x in self.cl_subbands) if self.cl_subbands is not None else None
 
     @property
+    @memoize
     def scales(self):
         return tuple(to_array(x) for x in self.cl_scales) if self.cl_scales is not None else None
 

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