| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #include <grpc/support/port_platform.h> |
| |
| #ifdef GPR_CPU_POSIX |
| |
| #include <errno.h> |
| #include <string.h> |
| #include <unistd.h> |
| |
| #include <grpc/support/log.h> |
| #include <grpc/support/sync.h> |
| #include <grpc/support/useful.h> |
| |
| static __thread char magic_thread_local; |
| |
| static long ncpus = 0; |
| |
| static void init_ncpus() { |
| ncpus = sysconf(_SC_NPROCESSORS_ONLN); |
| if (ncpus < 1 || ncpus > INT32_MAX) { |
| gpr_log(GPR_ERROR, "Cannot determine number of CPUs: assuming 1"); |
| ncpus = 1; |
| } |
| } |
| |
| unsigned gpr_cpu_num_cores(void) { |
| static gpr_once once = GPR_ONCE_INIT; |
| gpr_once_init(&once, init_ncpus); |
| return (unsigned)ncpus; |
| } |
| |
| unsigned gpr_cpu_current_cpu(void) { |
| /* NOTE: there's no way I know to return the actual cpu index portably... |
| most code that's using this is using it to shard across work queues though, |
| so here we use thread identity instead to achieve a similar though not |
| identical effect */ |
| return (unsigned)GPR_HASH_POINTER(&magic_thread_local, gpr_cpu_num_cores()); |
| } |
| |
| #endif /* GPR_CPU_POSIX */ |