unix,win: add uv_available_parallelism()

[bnoordhuis]

Replacement for the usage pattern where people use uv_cpu_info() as an
imperfect heuristic for determining the amount of parallelism that is
available to their programs.

Fixes #3493.

---

You can test the linux behavior with:

$ taskset 3 ./build/uv_run_tests_a platform_output platform_output | grep uv_available_parallelism
uv_available_parallelism: 2

$ taskset 0xffffffff ./build/uv_run_tests_a platform_output platform_output | grep uv_available_parallelism
uv_available_parallelism: 12

[vtjnash]

@tkf replaces JuliaLang/julia#42340

[saghul]

Nice, I just needed this the other day and used the naive CPU count!

[vtjnash]

This broke zOS (in jenkins CI):

/u/iojs/build/workspace/libuv-test-commit-zos-cmake/BUILDTYPE/Release/nodes/zos-s390x/src/unix/core.c:1677:16: error: use of undeclared identifier '_SC_NPROCESSORS_ONLN'

[bnoordhuis]

Fix(ish) in #3513.

[nappy]

This change is causing the following build error for nodejs 18.14.1 on Android:

/home/nappy/ndks/android-ndk-r25c/toolchains/llvm/prebuilt/linux-x86_64/bin/armv7a-linux-androideabi23-clang -o /home/nappy/node/out/Release/obj.target/libuv/deps/uv/src/unix/getnameinfo.o ../deps/uv/src/unix/getnameinfo.c '-DV8_DEPRECATION_WARNINGS' '-DV8_IMMINENT_DEPRECATION_WARNINGS' '-D_GLIBCXX_USE_CXX11_ABI=1' '-DNODE_OPENSSL_CONF_NAME=nodejs_conf' '-DICU_NO_USER_DATA_OVERRIDE' '-D__STDC_FORMAT_MACROS' '-D_LARGEFILE_SOURCE' '-D_FILE_OFFSET_BITS=64' '-D_GLIBCXX_USE_C99_MATH' -I../deps/uv/include -I../deps/uv/src  -Wall -Wextra -Wno-unused-parameter -fvisibility=hidden -g --std=gnu89 -Wall -Wextra -Wno-unused-parameter -Wstrict-prototypes -fno-strict-aliasing -O3 -fno-omit-frame-pointer -fPIC  -MMD -MF /home/nappy/node/out/Release/.deps//home/nappy/node/out/Release/obj.target/libuv/deps/uv/src/unix/getnameinfo.o.d.raw -I/home/nappy/openssl/include -fPIE -fPIC -c    
In file included from <built-in>:385:
../deps/uv/src/unix/core.c:1632:3: error: use of undeclared identifier 'cpu_set_t'
  cpu_set_t set;
  ^
../deps/uv/src/unix/core.c:1635:26: error: use of undeclared identifier 'set'
  memset(&set, 0, sizeof(set));
                         ^
../deps/uv/src/unix/core.c:1635:11: error: use of undeclared identifier 'set'
  memset(&set, 0, sizeof(set));
          ^
../deps/uv/src/unix/core.c:1641:12: warning: implicit declaration of function 'sched_getaffinity' [-Wimplicit-function-declaration]
  if (0 == sched_getaffinity(0, sizeof(set), &set))
           ^
../deps/uv/src/unix/core.c:1641:40: error: use of undeclared identifier 'set'
  if (0 == sched_getaffinity(0, sizeof(set), &set))
                                       ^
../deps/uv/src/unix/core.c:1641:47: error: use of undeclared identifier 'set'
  if (0 == sched_getaffinity(0, sizeof(set), &set))
                                              ^
../deps/uv/src/unix/core.c:1642:10: warning: implicit declaration of function 'CPU_COUNT' [-Wimplicit-function-declaration]
    rc = CPU_COUNT(&set);
         ^
../deps/uv/src/unix/core.c:1642:21: error: use of undeclared identifier 'set'
    rc = CPU_COUNT(&set);
                    ^
1 warning generated.
3 warnings and 6 errors generated

[bnoordhuis]

@nappy No, it's because of how node compiles libuv. It looks like it's missing a -D_GNU_SOURCE.

[nappy]

@bnoordhuis Thanks for the heads up. Adding the flag indeed helped. I opened a node issue on that.
off-topic: Could you maybe also hint me into the right direction on the follow up error: make[1]: *** No rule to make target '/home/nappy/node/out/Release/obj.target/libuv/deps/uv/src/unix/android-ifaddrs.o', needed by '/home/nappy/node/out/Release/obj.target/deps/uv/libuv.a'. Stop. Do I need to extend the gyp files or sth along those lines? Seems also be cause by new libuv version.

[bnoordhuis]

I know you figured it out already but for posterity: yeah, that file went away in the latest release.