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#pragma once
#include <library/cpp/yt/cpu_clock/clock.h>
#include <util/generic/bitops.h>
namespace NYT::NProfiling {
////////////////////////////////////////////////////////////////////////////////
//! Timestamp counter + processor id.
struct TTscp
{
//! Defines the range for TTscp::ProcessorId.
//! Always a power of 2.
static constexpr int MaxProcessorId = 64;
static_assert(IsPowerOf2(MaxProcessorId), "MaxProcessorId must be a power of 2.");
//! The moment this TTscp instance was created.
TCpuInstant Instant;
//! "Processor id", always taken modulo #MaxProcessorId.
//! There's no guarantee that same value indicates the same phisycal core.
int ProcessorId;
//! Returns the current timestamp counter and processor id, both obtained from a single serializing rdtscp.
static TTscp Get();
//! A cheaper, lower-precision counterpart of #Get: the processor id comes from the
//! rseq fast path (GetCurrentCpuId) and the instant from a non-serializing rdtsc
//! (GetApproximateCpuInstant), instead of a single serializing rdtscp.
//!
//! WARNING (fiber TLS): inlined and reads the thread pointer (via GetCurrentCpuId),
//! 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).
static TTscp GetApproximate();
};
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT::NProfiling
#define TSCP_INL_H_
#include "tscp-inl.h"
#undef TSCP_INL_H_
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