1 files changed, 215 insertions, 0 deletions
diff --git a/src/runtime/cpuprof.go b/src/runtime/cpuprof.go
new file mode 100644
index 0000000..9bfdfe7
--- /dev/null
+++ b/src/runtime/cpuprof.go
@@ -0,0 +1,215 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// CPU profiling.
+//
+// The signal handler for the profiling clock tick adds a new stack trace
+// to a log of recent traces. The log is read by a user goroutine that
+// turns it into formatted profile data. If the reader does not keep up
+// with the log, those writes will be recorded as a count of lost records.
+// The actual profile buffer is in profbuf.go.
+
+package runtime
+
+import (
+	"runtime/internal/atomic"
+	"runtime/internal/sys"
+	"unsafe"
+)
+
+const maxCPUProfStack = 64
+
+type cpuProfile struct {
+	lock mutex
+	on   bool     // profiling is on
+	log  *profBuf // profile events written here
+
+	// extra holds extra stacks accumulated in addNonGo
+	// corresponding to profiling signals arriving on
+	// non-Go-created threads. Those stacks are written
+	// to log the next time a normal Go thread gets the
+	// signal handler.
+	// Assuming the stacks are 2 words each (we don't get
+	// a full traceback from those threads), plus one word
+	// size for framing, 100 Hz profiling would generate
+	// 300 words per second.
+	// Hopefully a normal Go thread will get the profiling
+	// signal at least once every few seconds.
+	extra      [1000]uintptr
+	numExtra   int
+	lostExtra  uint64 // count of frames lost because extra is full
+	lostAtomic uint64 // count of frames lost because of being in atomic64 on mips/arm; updated racily
+}
+
+var cpuprof cpuProfile
+
+// SetCPUProfileRate sets the CPU profiling rate to hz samples per second.
+// If hz <= 0, SetCPUProfileRate turns off profiling.
+// If the profiler is on, the rate cannot be changed without first turning it off.
+//
+// Most clients should use the runtime/pprof package or
+// the testing package's -test.cpuprofile flag instead of calling
+// SetCPUProfileRate directly.
+func SetCPUProfileRate(hz int) {
+	// Clamp hz to something reasonable.
+	if hz < 0 {
+		hz = 0
+	}
+	if hz > 1000000 {
+		hz = 1000000
+	}
+
+	lock(&cpuprof.lock)
+	if hz > 0 {
+		if cpuprof.on || cpuprof.log != nil {
+			print("runtime: cannot set cpu profile rate until previous profile has finished.\n")
+			unlock(&cpuprof.lock)
+			return
+		}
+
+		cpuprof.on = true
+		cpuprof.log = newProfBuf(1, 1<<17, 1<<14)
+		hdr := [1]uint64{uint64(hz)}
+		cpuprof.log.write(nil, nanotime(), hdr[:], nil)
+		setcpuprofilerate(int32(hz))
+	} else if cpuprof.on {
+		setcpuprofilerate(0)
+		cpuprof.on = false
+		cpuprof.addExtra()
+		cpuprof.log.close()
+	}
+	unlock(&cpuprof.lock)
+}
+
+// add adds the stack trace to the profile.
+// It is called from signal handlers and other limited environments
+// and cannot allocate memory or acquire locks that might be
+// held at the time of the signal, nor can it use substantial amounts
+// of stack.
+//go:nowritebarrierrec
+func (p *cpuProfile) add(gp *g, stk []uintptr) {
+	// Simple cas-lock to coordinate with setcpuprofilerate.
+	for !atomic.Cas(&prof.signalLock, 0, 1) {
+		osyield()
+	}
+
+	if prof.hz != 0 { // implies cpuprof.log != nil
+		if p.numExtra > 0 || p.lostExtra > 0 || p.lostAtomic > 0 {
+			p.addExtra()
+		}
+		hdr := [1]uint64{1}
+		// Note: write "knows" that the argument is &gp.labels,
+		// because otherwise its write barrier behavior may not
+		// be correct. See the long comment there before
+		// changing the argument here.
+		cpuprof.log.write(&gp.labels, nanotime(), hdr[:], stk)
+	}
+
+	atomic.Store(&prof.signalLock, 0)
+}
+
+// addNonGo adds the non-Go stack trace to the profile.
+// It is called from a non-Go thread, so we cannot use much stack at all,
+// nor do anything that needs a g or an m.
+// In particular, we can't call cpuprof.log.write.
+// Instead, we copy the stack into cpuprof.extra,
+// which will be drained the next time a Go thread
+// gets the signal handling event.
+//go:nosplit
+//go:nowritebarrierrec
+func (p *cpuProfile) addNonGo(stk []uintptr) {
+	// Simple cas-lock to coordinate with SetCPUProfileRate.
+	// (Other calls to add or addNonGo should be blocked out
+	// by the fact that only one SIGPROF can be handled by the
+	// process at a time. If not, this lock will serialize those too.)
+	for !atomic.Cas(&prof.signalLock, 0, 1) {
+		osyield()
+	}
+
+	if cpuprof.numExtra+1+len(stk) < len(cpuprof.extra) {
+		i := cpuprof.numExtra
+		cpuprof.extra[i] = uintptr(1 + len(stk))
+		copy(cpuprof.extra[i+1:], stk)
+		cpuprof.numExtra += 1 + len(stk)
+	} else {
+		cpuprof.lostExtra++
+	}
+
+	atomic.Store(&prof.signalLock, 0)
+}
+
+// addExtra adds the "extra" profiling events,
+// queued by addNonGo, to the profile log.
+// addExtra is called either from a signal handler on a Go thread
+// or from an ordinary goroutine; either way it can use stack
+// and has a g. The world may be stopped, though.
+func (p *cpuProfile) addExtra() {
+	// Copy accumulated non-Go profile events.
+	hdr := [1]uint64{1}
+	for i := 0; i < p.numExtra; {
+		p.log.write(nil, 0, hdr[:], p.extra[i+1:i+int(p.extra[i])])
+		i += int(p.extra[i])
+	}
+	p.numExtra = 0
+
+	// Report any lost events.
+	if p.lostExtra > 0 {
+		hdr := [1]uint64{p.lostExtra}
+		lostStk := [2]uintptr{
+			funcPC(_LostExternalCode) + sys.PCQuantum,
+			funcPC(_ExternalCode) + sys.PCQuantum,
+		}
+		p.log.write(nil, 0, hdr[:], lostStk[:])
+		p.lostExtra = 0
+	}
+
+	if p.lostAtomic > 0 {
+		hdr := [1]uint64{p.lostAtomic}
+		lostStk := [2]uintptr{
+			funcPC(_LostSIGPROFDuringAtomic64) + sys.PCQuantum,
+			funcPC(_System) + sys.PCQuantum,
+		}
+		p.log.write(nil, 0, hdr[:], lostStk[:])
+		p.lostAtomic = 0
+	}
+
+}
+
+// CPUProfile panics.
+// It formerly provided raw access to chunks of
+// a pprof-format profile generated by the runtime.
+// The details of generating that format have changed,
+// so this functionality has been removed.
+//
+// Deprecated: Use the runtime/pprof package,
+// or the handlers in the net/http/pprof package,
+// or the testing package's -test.cpuprofile flag instead.
+func CPUProfile() []byte {
+	panic("CPUProfile no longer available")
+}
+
+//go:linkname runtime_pprof_runtime_cyclesPerSecond runtime/pprof.runtime_cyclesPerSecond
+func runtime_pprof_runtime_cyclesPerSecond() int64 {
+	return tickspersecond()
+}
+
+// readProfile, provided to runtime/pprof, returns the next chunk of
+// binary CPU profiling stack trace data, blocking until data is available.
+// If profiling is turned off and all the profile data accumulated while it was
+// on has been returned, readProfile returns eof=true.
+// The caller must save the returned data and tags before calling readProfile again.
+//
+//go:linkname runtime_pprof_readProfile runtime/pprof.readProfile
+func runtime_pprof_readProfile() ([]uint64, []unsafe.Pointer, bool) {
+	lock(&cpuprof.lock)
+	log := cpuprof.log
+	unlock(&cpuprof.lock)
+	data, tags, eof := log.read(profBufBlocking)
+	if len(data) == 0 && eof {
+		lock(&cpuprof.lock)
+		cpuprof.log = nil
+		unlock(&cpuprof.lock)
+	}
+	return data, tags, eof
+}