The old atomic compare and swap operations (`vtkm::AtomicCompareAndSwap`
and `vtkm::exec::AtomicArrayExecutionObject::CompareAndSwap`) had an
order of arguments that was confusing. The order of the arguments was
shared pointer (or index), desired value, expected value. Most people
probably assume expected value comes before desired value. And this
order conflicts with the order in the `std` methods, GCC atomics, and
Kokkos.
Change the interface of atomic operations to be patterned off the
`std::atomic_compare_exchange` and `std::atomic<T>::compare_exchange`
methods. First, these methods have a more intuitive order of parameters
(shared pointer, expected, desired). Second, rather than take a value
for the expected and return the actual old value, they take a pointer to
the expected value (or reference in `AtomicArrayExecutionObject`) and
modify this value in the case that it does not match the actual value.
This makes it harder to mix up the expected and desired parameters.
Also, because the methods return a bool indicating whether the value was
changed, there is an additional benefit that compare-exchange loops are
implemented easier.
For example, consider you want to apply the function `MyOp` on a
`sharedValue` atomically. With the old interface, you would have to do
something like this.
```cpp
T oldValue;
T newValue;
do
{
oldValue = *sharedValue;
newValue = MyOp(oldValue);
} while (vtkm::AtomicCompareAndSwap(sharedValue, newValue, oldValue) != oldValue);
```
With the new interface, this is simplfied to this.
```cpp
T oldValue = *sharedValue;
while (!vtkm::AtomicCompareExchange(sharedValue, &oldValue, MyOp(oldValue));
```
Virtual methods are being deprecated, so remove their use from the
ColorTable classes. Instead of using a virtual method to look up a value
in the ColorTable, we essentially use a switch statement. This change
also simplified the code quite a bit.
The execution object used to use pointers to handle the virtual objects.
That is no longer necessary, so a simple `vtkm::exec::ColorTable` is
returned for execution objects. (Note that this `ColorTable` contains
pointers that are specific for the particular device.) This is a non-
backward compabible change. However, the only place (outside of the
`ColorTable` implementation itself) was a single worklet for converting
scalars to colors (`vtkm::worklet::colorconversion::TransferFunction`).
This is unlikely to affect anyone.
I also "fixed" some names in enum structs. There has been some
inconsistencies in VTK-m on whether items in an enum struct are
capitolized or camel case. We seem to moving toward camel case, so
deprecate some old names.
The testing helper class provided a method named `GetTestDataBasePath`
that returned the base path to all the data files stored in the VTK-m
repo. This is fine, but it was a little cumbersome to build filenames.
To make things easier, there is now a new method named `DataPath` that
takes a string of the filename (or, rather, subpath) to the file in that
directory and automatically builds the path to it.
We have made several improvements to adding data into an `ArrayHandle`.
## Moving data from an `std::vector`
For numerous reasons, it is convenient to define data in a `std::vector`
and then wrap that into an `ArrayHandle`. It is often the case that an
`std::vector` is filled and then becomes unused once it is converted to an
`ArrayHandle`. In this case, what we really want is to pass the data off to
the `ArrayHandle` so that the `ArrayHandle` is now managing the data and
not the `std::vector`.
C++11 has a mechanism to do this: move semantics. You can now pass
variables to functions as an "rvalue" (right-hand value). When something is
passed as an rvalue, it can pull state out of that variable and move it
somewhere else. `std::vector` implements this movement so that an rvalue
can be moved to another `std::vector` without actually copying the data.
`make_ArrayHandle` now also takes advantage of this feature to move rvalue
`std::vector`s.
There is a special form of `make_ArrayHandle` named `make_ArrayHandleMove`
that takes an rvalue. There is also a special overload of
`make_ArrayHandle` itself that handles an rvalue `vector`. (However, using
the explicit move version is better if you want to make sure the data is
actually moved.)
## Make `ArrayHandle` from initalizer list
A common use case for using `std::vector` (particularly in our unit tests)
is to quickly add an initalizer list into an `ArrayHandle`. Now you can
by simply passing an initializer list to `make_ArrayHandle`.
## Deprecated `make_ArrayHandle` with default shallow copy
For historical reasons, passing an `std::vector` or a pointer to
`make_ArrayHandle` does a shallow copy (i.e. `CopyFlag` defaults to `Off`).
Although more efficient, this mode is inherintly unsafe, and making it the
default is asking for trouble.
To combat this, calling `make_ArrayHandle` without a copy flag is
deprecated. In this way, if you wish to do the faster but more unsafe
creation of an `ArrayHandle` you should explicitly express that.
This requried quite a few changes through the VTK-m source (particularly in
the tests).
## Similar changes to `Field`
`vtkm::cont::Field` has a `make_Field` helper function that is similar to
`make_ArrayHandle`. It also features the ability to create fields from
`std::vector`s and C arrays. It also likewise had the same unsafe behavior
by default of not copying from the source of the arrays.
That behavior has similarly been depreciated. You now have to specify a
copy flag.
The ability to construct a `Field` from an initializer list of values has
also been added.
c689a68c5 Suppress bad deprecation warnings in MSVC
a3f23a03b Do not cast to ArrayHandleVirtual in VariantArrayHandle::CastAndCall
f6b13df51 Support coordinates of both float32 and float64
453e31404 Deprecate ArrayHandleVirtualCoordinates
be7f06bbe CoordinateSystem data is VariantArrayHandle
Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !2177
`CoordinateSystem` differed from `Field` in that its `GetData`
method returned an `ArrayHandleVirtualCoordinates` instead of
a `VariantArrayHandle`. This is probably confusing since
`CoordianteSystem` inherits `Field` and has a pretty dramatic
difference in this behavior.
In preparation to deprecate `ArrayHandleVirtualCoordinates`, this
changes `CoordiantSystem` to be much more like `Field`. (In the
future, we may change the `CoordinateSystem` to point to a `Field`
rather than be a special `Field`.)
A method named `GetDataAsMultiplexer` has been added to
`CoordinateSystem`. This method allows you to get data from
`CoordinateSystem` as a single array type without worrying
about creating functors to handle different types and without
needing virtual methods.
The VS compiler gives a warning when you override a deprecated method.
Changed the StartScene and EndScene methods in Mapper to be non-virtual
with empty implementations. Deleted the corresponding methods from all
subclasses.
Updated the image reader classes to better follow VTK-m naming
convention (i.e. use `ImageReaderPNG` instead of `PNGReader`).
The structure of the image reader class now also better matches
the interface for the VTK reader.
Also put the implementation of the image readers into the `vtkm_io`
library so that it only has to be compiled once.