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#pragma once
namespace NYT {
////////////////////////////////////////////////////////////////////////////////
/*!
* Index of the CPU the calling thread currently runs on, in [0, NumberOfCpus).
* On Linux/x86-64 and Linux/arm64 the fast path is a single thread-local read of
* the kernel's rseq area; the first call per thread lazily registers rseq, and
* reads fall back to sched_getcpu() when rseq is unavailable. On other platforms
* it is sched_getcpu() (Linux) or 0.
* It is a hint (the thread may migrate right after) -- for sharding, not correctness.
*
* The rseq backend lives in library/cpp/yt/rseq, with no third-party dependency.
*
* Fiber-TLS: the fast path is inlined and reads the thread pointer, so it must be
* reached only through a non-inlinable, fiber-switch-free frame (a virtual call or
* YT_PREVENT_TLS_CACHING; see library/cpp/yt/misc/tls.h). Otherwise the thread base
* may be cached and reused after the fiber resumes on another OS thread, reading a
* different -- possibly already-freed -- thread's area.
*/
int GetCurrentCpuId();
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT
#define CPU_ID_INL_H_
#include "cpu_id-inl.h"
#undef CPU_ID_INL_H_
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