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//
//
// 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.
//
//
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif // _GNU_SOURCE
#include <grpc/support/port_platform.h>
#ifdef GPR_CPU_LINUX
#include <errno.h>
#include <sched.h>
#include <string.h>
#include <unistd.h>
#include <grpc/support/cpu.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include "src/core/lib/gprpp/crash.h"
#include "src/core/lib/gprpp/strerror.h"
static int ncpus = 0;
static void init_num_cpus() {
#ifndef GPR_MUSL_LIBC_COMPAT
if (sched_getcpu() < 0) {
gpr_log(GPR_ERROR, "Error determining current CPU: %s\n",
grpc_core::StrError(errno).c_str());
ncpus = 1;
return;
}
#endif
// This must be signed. sysconf returns -1 when the number cannot be
// determined
ncpus = static_cast<int>(sysconf(_SC_NPROCESSORS_CONF));
if (ncpus < 1) {
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_num_cpus);
return static_cast<unsigned>(ncpus);
}
unsigned gpr_cpu_current_cpu(void) {
#ifdef GPR_MUSL_LIBC_COMPAT
// sched_getcpu() is undefined on musl
return 0;
#else
if (gpr_cpu_num_cores() == 1) {
return 0;
}
int cpu = sched_getcpu();
if (cpu < 0) {
gpr_log(GPR_ERROR, "Error determining current CPU: %s\n",
grpc_core::StrError(errno).c_str());
return 0;
}
if (static_cast<unsigned>(cpu) >= gpr_cpu_num_cores()) {
gpr_log(GPR_DEBUG, "Cannot handle hot-plugged CPUs");
return 0;
}
return static_cast<unsigned>(cpu);
#endif
}
#endif // GPR_CPU_LINUX
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