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Ensure CpuInfo::DetectNumberOfCores is > 0 and thread safe.

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This CL adds error handling for sysconf, which can return -1 and
adds an RTC_CHECK_GT to ensure the value returned is always greater
than 0.

On top of that CpuInfo::DetectNumberOfCores is made thread safe because
the static local variable is initialized with the right values istead
of 0.

Bug: None
Change-Id: I294684e7380b12cda55ec8d6c7a90e132dc3af85
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/138210
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28057}
This commit is contained in:
Mirko Bonadei 2019-05-24 13:47:23 +02:00 committed by Commit Bot
parent fadb1811a8
commit a8cf3b7cbd
1 changed files with 9 additions and 5 deletions
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14
system_wrappers/source/cpu_info.cc
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@ -24,8 +24,7 @@
namespace internal {
static int DetectNumberOfCores() {
// We fall back on assuming a single core in case of errors.
int number_of_cores = 1;
int number_of_cores;
#if defined(WEBRTC_WIN)
SYSTEM_INFO si;
@ -33,6 +32,10 @@ static int DetectNumberOfCores() {
number_of_cores = static_cast<int>(si.dwNumberOfProcessors);
#elif defined(WEBRTC_LINUX) || defined(WEBRTC_ANDROID)
number_of_cores = static_cast<int>(sysconf(_SC_NPROCESSORS_ONLN));
if (number_of_cores < 0) {
RTC_LOG(LS_ERROR) << "Failed to get number of cores";
number_of_cores = 1;
}
#elif defined(WEBRTC_MAC) || defined(WEBRTC_IOS)
int name[] = {CTL_HW, HW_AVAILCPU};
size_t size = sizeof(number_of_cores);
@ -44,10 +47,12 @@ static int DetectNumberOfCores() {
number_of_cores = zx_system_get_num_cpus();
#else
RTC_LOG(LS_ERROR) << "No function to get number of cores";
number_of_cores = 1;
#endif
RTC_LOG(LS_INFO) << "Available number of cores: " << number_of_cores;
RTC_CHECK_GT(number_of_cores, 0);
return number_of_cores;
}
} // namespace internal
@ -59,9 +64,8 @@ uint32_t CpuInfo::DetectNumberOfCores() {
// is running in a sandbox, we may only be able to read the value once (before
// the sandbox is initialized) and not thereafter.
// For more information see crbug.com/176522.
static uint32_t logical_cpus = 0;
if (!logical_cpus)
logical_cpus = static_cast<uint32_t>(internal::DetectNumberOfCores());
static const uint32_t logical_cpus =
static_cast<uint32_t>(internal::DetectNumberOfCores());
return logical_cpus;
}