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// Copyright 2018 Google LLC
//
// 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.
package time
import (
"syscall"
"unsafe"
)
// syscallTSCReferenceClocks is the standard referenceClocks, collecting
// samples using CLOCK_GETTIME and RDTSC.
type syscallTSCReferenceClocks struct {
tscCycleClock
}
// Sample implements sampler.Sample.
func (syscallTSCReferenceClocks) Sample(c ClockID) (sample, error) {
var s sample
s.before = Rdtsc()
// Don't call clockGettime to avoid a call which may call morestack.
var ts syscall.Timespec
_, _, e := syscall.RawSyscall(syscall.SYS_CLOCK_GETTIME, uintptr(c), uintptr(unsafe.Pointer(&ts)), 0)
if e != 0 {
return sample{}, e
}
s.after = Rdtsc()
s.ref = ReferenceNS(ts.Nano())
return s, nil
}
// clockGettime calls SYS_CLOCK_GETTIME, returning time in nanoseconds.
func clockGettime(c ClockID) (ReferenceNS, error) {
var ts syscall.Timespec
_, _, e := syscall.RawSyscall(syscall.SYS_CLOCK_GETTIME, uintptr(c), uintptr(unsafe.Pointer(&ts)), 0)
if e != 0 {
return 0, e
}
return ReferenceNS(ts.Nano()), nil
}
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