1"""Custom rules for gRPC Python"""
2
3
4# Adapted with modifications from
5# tensorflow/tensorflow/core/platform/default/build_config.bzl
6# Native Bazel rules don't exist yet to compile Cython code, but rules have
7# been written at cython/cython and tensorflow/tensorflow. We branch from
8# Tensorflow's version as it is more actively maintained and works for gRPC
9# Python's needs.
10def pyx_library(name, deps=[], py_deps=[], srcs=[], **kwargs):
11    """Compiles a group of .pyx / .pxd / .py files.
12
13    First runs Cython to create .cpp files for each input .pyx or .py + .pxd
14    pair. Then builds a shared object for each, passing "deps" to each cc_binary
15    rule (includes Python headers by default). Finally, creates a py_library rule
16    with the shared objects and any pure Python "srcs", with py_deps as its
17    dependencies; the shared objects can be imported like normal Python files.
18
19    Args:
20        name: Name for the rule.
21        deps: C/C++ dependencies of the Cython (e.g. Numpy headers).
22        py_deps: Pure Python dependencies of the final library.
23        srcs: .py, .pyx, or .pxd files to either compile or pass through.
24        **kwargs: Extra keyword arguments passed to the py_library.
25    """
26    # First filter out files that should be run compiled vs. passed through.
27    py_srcs = []
28    pyx_srcs = []
29    pxd_srcs = []
30    for src in srcs:
31        if src.endswith(".pyx") or (src.endswith(".py") and
32                                    src[:-3] + ".pxd" in srcs):
33            pyx_srcs.append(src)
34        elif src.endswith(".py"):
35            py_srcs.append(src)
36        else:
37            pxd_srcs.append(src)
38        if src.endswith("__init__.py"):
39            pxd_srcs.append(src)
40
41    # Invoke cython to produce the shared object libraries.
42    for filename in pyx_srcs:
43        native.genrule(
44            name=filename + "_cython_translation",
45            srcs=[filename],
46            outs=[filename.split(".")[0] + ".cpp"],
47            # Optionally use PYTHON_BIN_PATH on Linux platforms so that python 3
48            # works. Windows has issues with cython_binary so skip PYTHON_BIN_PATH.
49            cmd=
50            "PYTHONHASHSEED=0 $(location @cython//:cython_binary) --cplus $(SRCS) --output-file $(OUTS)",
51            tools=["@cython//:cython_binary"] + pxd_srcs,
52        )
53
54    shared_objects = []
55    for src in pyx_srcs:
56        stem = src.split(".")[0]
57        shared_object_name = stem + ".so"
58        native.cc_binary(
59            name=shared_object_name,
60            srcs=[stem + ".cpp"],
61            deps=deps + ["@local_config_python//:python_headers"],
62            linkshared=1,
63        )
64        shared_objects.append(shared_object_name)
65
66    # Now create a py_library with these shared objects as data.
67    native.py_library(
68        name=name,
69        srcs=py_srcs,
70        deps=py_deps,
71        srcs_version="PY2AND3",
72        data=shared_objects,
73        **kwargs)
74
75