Hi, It may be wrong but you may need to add -DNDEBUG flag to C compiler.
Thanks, -- kou In <CANapY_LzahViR9e7e90H=wq3j0tnbZJe1Vm=j7=vvyqawnc...@mail.gmail.com> "Re: Using Plasma with xnd" on Tue, 27 Mar 2018 13:41:49 +0000, Saul Shanabrook <s.shanabr...@gmail.com> wrote: > Ah, I see I can use garrow_buffer_get_mutable_data from c_glib. > > On Tue, Mar 27, 2018 at 9:29 AM Saul Shanabrook <s.shanabr...@gmail.com> > wrote: > >> I am in the process of changing over my C wrapper to work with Arrow >> 0.9.0. One change is that the plasma APIs now use arrow::Buffer instead of >> of raw pointers, in Create and Get. >> >> In my C wrapper for Create, I need to get the mutable data pointer from >> the arrow::Buffer, after it is created. Here is my current implementation: >> https://github.com/plures/pxnd/blob/84e9403ef3811e0893e12076455d7cbc49c39358/libplasma/plasma.cc#L56-L75 >> I do something similar to the Python wrapper around plasma: >> https://github.com/apache/arrow/blob/f9f8320339692d4134d1ef42c32cb7c8d547593e/python/pyarrow/plasma.pyx#L300-L307 >> >> >> However, this fails to link, I think because the mutable_data method is >> defined in the class and so is inline. So it doesn't show up in the >> libarrow.dylib/libarrow.a archive. Let me know if I am missing something >> obvious, this is just my hypothesis for why it isn't working. >> >> Is there a way for a third party library to get the pointer to the data >> from a arrow::Buffer? >> >> On Wed, Mar 7, 2018 at 10:59 AM Wes McKinney <wesmck...@gmail.com> wrote: >> >>> Where are you going to make Plasma requests, in Python or in C? >>> >>> * If in Python, use the buffer protocol to access the memory in C >>> https://docs.python.org/3/c-api/buffer.html#bufferobjects >>> * If in C, then I would suggest adding extern "C" APIs directly in >>> libplasma.so so you can connect to the Plasma store and make requests >>> directly in C. >>> >>> I want to make 100% sure that you need to interact with the Plasma >>> client in C before I send you down that path. Here's an example of a C >>> API embedded in an otherwise C++ library >>> https://github.com/wesm/feather/blob/master/cpp/src/feather/feather-c.h. >>> >>> - Wes >>> >>> On Wed, Mar 7, 2018 at 10:53 AM, Saul Shanabrook <s.shanabr...@gmail.com> >>> wrote: >>> > Hey Wes, >>> > >>> > Since all our logic for writing and reading the data is written in C, we >>> > need to be get access to the memory in C as well. I think it makes sense >>> > then for me to work on creating a C++ wrapper around Plasma that exports >>> > what is necessary in C. Should that be in Arrow GLib? >>> > >>> > Best, >>> > Saul >>> > >>> > On Tue, Mar 6, 2018 at 11:49 PM Wes McKinney <wesmck...@gmail.com> >>> wrote: >>> > >>> >> hi Saul -- I think the easiest solution here is the buffer/memoryview >>> >> protocol. You won't have to touch the Cython or C++ API from pyarrow >>> >> if you do this. >>> >> >>> >> You can interact with a Buffer object like any other Python object >>> >> implementing the buffer protocol. See numpy.frombuffer as an example >>> >> of a function that interacts with such objects. I would suggest adding >>> >> a method to xnd method for this. >>> >> >>> >> If you need to interact with Plasma from C then things will be more >>> >> complicated -- Robert or Philipp should be able to advise in this >>> >> case. >>> >> >>> >> - Wes >>> >> >>> >> On Tue, Mar 6, 2018 at 4:55 PM, Saul Shanabrook < >>> s.shanabr...@gmail.com> >>> >> wrote: >>> >> > Hey Wes, >>> >> > >>> >> > I don't have much experience doing C + Python + Cython development, >>> so I >>> >> am >>> >> > probably missing something obvious, but reading the Cython docs, >>> >> > < >>> >> >>> https://cython.readthedocs.io/en/latest/src/userguide/external_C_code.html#public-declarations >>> >> > >>> >> > it >>> >> > seems like I can only access types marked as public from C code. >>> When I >>> >> > compile arrow locally, I do get some C++ headers for the plasma code, >>> >> but I >>> >> > don't think I can use them from C code either. >>> >> > >>> >> > Best, >>> >> > Saul >>> >> > >>> >> > >>> >> > >>> >> > On Tue, Mar 6, 2018 at 3:12 PM Wes McKinney <wesmck...@gmail.com> >>> wrote: >>> >> > >>> >> >> hi Saul, >>> >> >> >>> >> >> Are you able to use the buffer/memoryview protocol? Instances of >>> >> >> pyarrow.Buffer, like PlasmaBuffer, support this >>> >> >> >>> >> >> >>> >> >>> https://github.com/apache/arrow/blob/master/python/pyarrow/plasma.pyx#L182 >>> >> >> >>> >> >> - Wes >>> >> >> >>> >> >> On Tue, Mar 6, 2018 at 3:09 PM, Saul Shanabrook < >>> s.shanabr...@gmail.com >>> >> > >>> >> >> wrote: >>> >> >> > I am trying to use the Plasma store to back xnd objects. Xnd ( >>> >> >> > https://xnd.readthedocs.io/en/latest/xnd/index.html) is a >>> container >>> >> >> library >>> >> >> > in C that has Python bindings. I would like to get a pointer to >>> the >>> >> >> > allocated memory after creating or get an object in Plasma. I see >>> that >>> >> >> this >>> >> >> > is supported in the C++ API ( >>> >> >> > >>> >> >> >>> >> >>> https://arrow.apache.org/docs/cpp/classplasma_1_1_plasma_client.html#ac18ab9cc792c620a97a3dcb165e0ecd7 >>> >> >> ) >>> >> >> > but not in the python API (as far as I can tell). Is it possible >>> to >>> >> use >>> >> >> the >>> >> >> > C++ Plasma API from a C project? If not, would it make sense to >>> expose >>> >> >> > pointer access on the Python API using capsules >>> >> >> > https://docs.python.org/3.6/c-api/capsule.html >>> >> >> > <https://docs.python.org/3.6/c-api/capsule.html#capsules>? >>> >> >> >>> >> >>> >>
