build: move package sources from src/pkg to src

Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.

1 files changed, 644 insertions, 0 deletions

diff --git a/src/runtime/chan.go b/src/runtime/chan.go
new file mode 100644
index 000000000..91ade4d37
--- /dev/null
+++ b/src/runtime/chan.go
@@ -0,0 +1,644 @@
+// Copyright 2014 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.
+
+package runtime
+
+// This file contains the implementation of Go channels.
+
+import "unsafe"
+
+const (
+	maxAlign  = 8
+	hchanSize = unsafe.Sizeof(hchan{}) + uintptr(-int(unsafe.Sizeof(hchan{}))&(maxAlign-1))
+	debugChan = false
+)
+
+// TODO(khr): make hchan.buf an unsafe.Pointer, not a *uint8
+
+func makechan(t *chantype, size int64) *hchan {
+	elem := t.elem
+
+	// compiler checks this but be safe.
+	if elem.size >= 1<<16 {
+		gothrow("makechan: invalid channel element type")
+	}
+	if hchanSize%maxAlign != 0 || elem.align > maxAlign {
+		gothrow("makechan: bad alignment")
+	}
+	if size < 0 || int64(uintptr(size)) != size || (elem.size > 0 && uintptr(size) > (maxMem-hchanSize)/uintptr(elem.size)) {
+		panic("makechan: size out of range")
+	}
+
+	var c *hchan
+	if elem.kind&kindNoPointers != 0 || size == 0 {
+		// Allocate memory in one call.
+		// Hchan does not contain pointers interesting for GC in this case:
+		// buf points into the same allocation, elemtype is persistent.
+		// SudoG's are referenced from their owning thread so they can't be collected.
+		// TODO(dvyukov,rlh): Rethink when collector can move allocated objects.
+		c = (*hchan)(gomallocgc(hchanSize+uintptr(size)*uintptr(elem.size), nil, flagNoScan))
+		if size > 0 && elem.size != 0 {
+			c.buf = (*uint8)(add(unsafe.Pointer(c), hchanSize))
+		} else {
+			c.buf = (*uint8)(unsafe.Pointer(c)) // race detector uses this location for synchronization
+		}
+	} else {
+		c = new(hchan)
+		c.buf = (*uint8)(newarray(elem, uintptr(size)))
+	}
+	c.elemsize = uint16(elem.size)
+	c.elemtype = elem
+	c.dataqsiz = uint(size)
+
+	if debugChan {
+		print("makechan: chan=", c, "; elemsize=", elem.size, "; elemalg=", elem.alg, "; dataqsiz=", size, "\n")
+	}
+	return c
+}
+
+// chanbuf(c, i) is pointer to the i'th slot in the buffer.
+func chanbuf(c *hchan, i uint) unsafe.Pointer {
+	return add(unsafe.Pointer(c.buf), uintptr(i)*uintptr(c.elemsize))
+}
+
+// entry point for c <- x from compiled code
+//go:nosplit
+func chansend1(t *chantype, c *hchan, elem unsafe.Pointer) {
+	chansend(t, c, elem, true, getcallerpc(unsafe.Pointer(&t)))
+}
+
+/*
+ * generic single channel send/recv
+ * If block is not nil,
+ * then the protocol will not
+ * sleep but return if it could
+ * not complete.
+ *
+ * sleep can wake up with g.param == nil
+ * when a channel involved in the sleep has
+ * been closed.  it is easiest to loop and re-run
+ * the operation; we'll see that it's now closed.
+ */
+func chansend(t *chantype, c *hchan, ep unsafe.Pointer, block bool, callerpc uintptr) bool {
+	if raceenabled {
+		raceReadObjectPC(t.elem, ep, callerpc, funcPC(chansend))
+	}
+
+	if c == nil {
+		if !block {
+			return false
+		}
+		gopark(nil, nil, "chan send (nil chan)")
+		gothrow("unreachable")
+	}
+
+	if debugChan {
+		print("chansend: chan=", c, "\n")
+	}
+
+	if raceenabled {
+		racereadpc(unsafe.Pointer(c), callerpc, funcPC(chansend))
+	}
+
+	// Fast path: check for failed non-blocking operation without acquiring the lock.
+	//
+	// After observing that the channel is not closed, we observe that the channel is
+	// not ready for sending. Each of these observations is a single word-sized read
+	// (first c.closed and second c.recvq.first or c.qcount depending on kind of channel).
+	// Because a closed channel cannot transition from 'ready for sending' to
+	// 'not ready for sending', even if the channel is closed between the two observations,
+	// they imply a moment between the two when the channel was both not yet closed
+	// and not ready for sending. We behave as if we observed the channel at that moment,
+	// and report that the send cannot proceed.
+	//
+	// It is okay if the reads are reordered here: if we observe that the channel is not
+	// ready for sending and then observe that it is not closed, that implies that the
+	// channel wasn't closed during the first observation.
+	if !block && c.closed == 0 && ((c.dataqsiz == 0 && c.recvq.first == nil) ||
+		(c.dataqsiz > 0 && c.qcount == c.dataqsiz)) {
+		return false
+	}
+
+	var t0 int64
+	if blockprofilerate > 0 {
+		t0 = cputicks()
+	}
+
+	lock(&c.lock)
+	if c.closed != 0 {
+		unlock(&c.lock)
+		panic("send on closed channel")
+	}
+
+	if c.dataqsiz == 0 { // synchronous channel
+		sg := c.recvq.dequeue()
+		if sg != nil { // found a waiting receiver
+			if raceenabled {
+				racesync(c, sg)
+			}
+			unlock(&c.lock)
+
+			recvg := sg.g
+			recvg.param = unsafe.Pointer(sg)
+			if sg.elem != nil {
+				memmove(unsafe.Pointer(sg.elem), ep, uintptr(c.elemsize))
+			}
+			if sg.releasetime != 0 {
+				sg.releasetime = cputicks()
+			}
+			goready(recvg)
+			return true
+		}
+
+		if !block {
+			unlock(&c.lock)
+			return false
+		}
+
+		// no receiver available: block on this channel.
+		gp := getg()
+		mysg := acquireSudog()
+		mysg.releasetime = 0
+		if t0 != 0 {
+			mysg.releasetime = -1
+		}
+		mysg.elem = ep
+		mysg.waitlink = nil
+		gp.waiting = mysg
+		mysg.g = gp
+		mysg.selectdone = nil
+		gp.param = nil
+		c.sendq.enqueue(mysg)
+		goparkunlock(&c.lock, "chan send")
+
+		// someone woke us up.
+		if gp.param == nil {
+			if c.closed == 0 {
+				gothrow("chansend: spurious wakeup")
+			}
+			panic("send on closed channel")
+		}
+		if mysg.releasetime > 0 {
+			blockevent(int64(mysg.releasetime)-t0, 2)
+		}
+		if mysg != gp.waiting {
+			gothrow("G waiting list is corrupted!")
+		}
+		gp.waiting = nil
+		releaseSudog(mysg)
+		return true
+	}
+
+	// asynchronous channel
+	// wait for some space to write our data
+	var t1 int64
+	for c.qcount >= c.dataqsiz {
+		if !block {
+			unlock(&c.lock)
+			return false
+		}
+		gp := getg()
+		mysg := acquireSudog()
+		mysg.releasetime = 0
+		if t0 != 0 {
+			mysg.releasetime = -1
+		}
+		mysg.g = gp
+		mysg.elem = nil
+		mysg.selectdone = nil
+		c.sendq.enqueue(mysg)
+		goparkunlock(&c.lock, "chan send")
+
+		// someone woke us up - try again
+		if mysg.releasetime > 0 {
+			t1 = mysg.releasetime
+		}
+		releaseSudog(mysg)
+		lock(&c.lock)
+		if c.closed != 0 {
+			unlock(&c.lock)
+			panic("send on closed channel")
+		}
+	}
+
+	// write our data into the channel buffer
+	if raceenabled {
+		raceacquire(chanbuf(c, c.sendx))
+		racerelease(chanbuf(c, c.sendx))
+	}
+	memmove(chanbuf(c, c.sendx), ep, uintptr(c.elemsize))
+	c.sendx++
+	if c.sendx == c.dataqsiz {
+		c.sendx = 0
+	}
+	c.qcount++
+
+	// wake up a waiting receiver
+	sg := c.recvq.dequeue()
+	if sg != nil {
+		recvg := sg.g
+		unlock(&c.lock)
+		if sg.releasetime != 0 {
+			sg.releasetime = cputicks()
+		}
+		goready(recvg)
+	} else {
+		unlock(&c.lock)
+	}
+	if t1 > 0 {
+		blockevent(t1-t0, 2)
+	}
+	return true
+}
+
+func closechan(c *hchan) {
+	if c == nil {
+		panic("close of nil channel")
+	}
+
+	lock(&c.lock)
+	if c.closed != 0 {
+		unlock(&c.lock)
+		panic("close of closed channel")
+	}
+
+	if raceenabled {
+		callerpc := getcallerpc(unsafe.Pointer(&c))
+		racewritepc(unsafe.Pointer(c), callerpc, funcPC(closechan))
+		racerelease(unsafe.Pointer(c))
+	}
+
+	c.closed = 1
+
+	// release all readers
+	for {
+		sg := c.recvq.dequeue()
+		if sg == nil {
+			break
+		}
+		gp := sg.g
+		gp.param = nil
+		if sg.releasetime != 0 {
+			sg.releasetime = cputicks()
+		}
+		goready(gp)
+	}
+
+	// release all writers
+	for {
+		sg := c.sendq.dequeue()
+		if sg == nil {
+			break
+		}
+		gp := sg.g
+		gp.param = nil
+		if sg.releasetime != 0 {
+			sg.releasetime = cputicks()
+		}
+		goready(gp)
+	}
+	unlock(&c.lock)
+}
+
+// entry points for <- c from compiled code
+//go:nosplit
+func chanrecv1(t *chantype, c *hchan, elem unsafe.Pointer) {
+	chanrecv(t, c, elem, true)
+}
+
+//go:nosplit
+func chanrecv2(t *chantype, c *hchan, elem unsafe.Pointer) (received bool) {
+	_, received = chanrecv(t, c, elem, true)
+	return
+}
+
+// chanrecv receives on channel c and writes the received data to ep.
+// ep may be nil, in which case received data is ignored.
+// If block == false and no elements are available, returns (false, false).
+// Otherwise, if c is closed, zeros *ep and returns (true, false).
+// Otherwise, fills in *ep with an element and returns (true, true).
+func chanrecv(t *chantype, c *hchan, ep unsafe.Pointer, block bool) (selected, received bool) {
+	// raceenabled: don't need to check ep, as it is always on the stack.
+
+	if debugChan {
+		print("chanrecv: chan=", c, "\n")
+	}
+
+	if c == nil {
+		if !block {
+			return
+		}
+		gopark(nil, nil, "chan receive (nil chan)")
+		gothrow("unreachable")
+	}
+
+	// Fast path: check for failed non-blocking operation without acquiring the lock.
+	//
+	// After observing that the channel is not ready for receiving, we observe that the
+	// channel is not closed. Each of these observations is a single word-sized read
+	// (first c.sendq.first or c.qcount, and second c.closed).
+	// Because a channel cannot be reopened, the later observation of the channel
+	// being not closed implies that it was also not closed at the moment of the
+	// first observation. We behave as if we observed the channel at that moment
+	// and report that the receive cannot proceed.
+	//
+	// The order of operations is important here: reversing the operations can lead to
+	// incorrect behavior when racing with a close.
+	if !block && (c.dataqsiz == 0 && c.sendq.first == nil ||
+		c.dataqsiz > 0 && atomicloaduint(&c.qcount) == 0) &&
+		atomicload(&c.closed) == 0 {
+		return
+	}
+
+	var t0 int64
+	if blockprofilerate > 0 {
+		t0 = cputicks()
+	}
+
+	lock(&c.lock)
+	if c.dataqsiz == 0 { // synchronous channel
+		if c.closed != 0 {
+			return recvclosed(c, ep)
+		}
+
+		sg := c.sendq.dequeue()
+		if sg != nil {
+			if raceenabled {
+				racesync(c, sg)
+			}
+			unlock(&c.lock)
+
+			if ep != nil {
+				memmove(ep, sg.elem, uintptr(c.elemsize))
+			}
+			gp := sg.g
+			gp.param = unsafe.Pointer(sg)
+			if sg.releasetime != 0 {
+				sg.releasetime = cputicks()
+			}
+			goready(gp)
+			selected = true
+			received = true
+			return
+		}
+
+		if !block {
+			unlock(&c.lock)
+			return
+		}
+
+		// no sender available: block on this channel.
+		gp := getg()
+		mysg := acquireSudog()
+		mysg.releasetime = 0
+		if t0 != 0 {
+			mysg.releasetime = -1
+		}
+		mysg.elem = ep
+		mysg.waitlink = nil
+		gp.waiting = mysg
+		mysg.g = gp
+		mysg.selectdone = nil
+		gp.param = nil
+		c.recvq.enqueue(mysg)
+		goparkunlock(&c.lock, "chan receive")
+
+		// someone woke us up
+		gp.waiting = nil
+		if mysg.releasetime > 0 {
+			blockevent(mysg.releasetime-t0, 2)
+		}
+		releaseSudog(mysg)
+
+		if gp.param != nil {
+			// a sender sent us some data. It already wrote to ep.
+			selected = true
+			received = true
+			return
+		}
+
+		lock(&c.lock)
+		if c.closed == 0 {
+			gothrow("chanrecv: spurious wakeup")
+		}
+		return recvclosed(c, ep)
+	}
+
+	// asynchronous channel
+	// wait for some data to appear
+	var t1 int64
+	for c.qcount <= 0 {
+		if c.closed != 0 {
+			selected, received = recvclosed(c, ep)
+			if t1 > 0 {
+				blockevent(t1-t0, 2)
+			}
+			return
+		}
+
+		if !block {
+			unlock(&c.lock)
+			return
+		}
+
+		// wait for someone to send an element
+		gp := getg()
+		mysg := acquireSudog()
+		mysg.releasetime = 0
+		if t0 != 0 {
+			mysg.releasetime = -1
+		}
+		mysg.elem = nil
+		mysg.g = gp
+		mysg.selectdone = nil
+
+		c.recvq.enqueue(mysg)
+		goparkunlock(&c.lock, "chan receive")
+
+		// someone woke us up - try again
+		if mysg.releasetime > 0 {
+			t1 = mysg.releasetime
+		}
+		releaseSudog(mysg)
+		lock(&c.lock)
+	}
+
+	if raceenabled {
+		raceacquire(chanbuf(c, c.recvx))
+		racerelease(chanbuf(c, c.recvx))
+	}
+	if ep != nil {
+		memmove(ep, chanbuf(c, c.recvx), uintptr(c.elemsize))
+	}
+	memclr(chanbuf(c, c.recvx), uintptr(c.elemsize))
+
+	c.recvx++
+	if c.recvx == c.dataqsiz {
+		c.recvx = 0
+	}
+	c.qcount--
+
+	// ping a sender now that there is space
+	sg := c.sendq.dequeue()
+	if sg != nil {
+		gp := sg.g
+		unlock(&c.lock)
+		if sg.releasetime != 0 {
+			sg.releasetime = cputicks()
+		}
+		goready(gp)
+	} else {
+		unlock(&c.lock)
+	}
+
+	if t1 > 0 {
+		blockevent(t1-t0, 2)
+	}
+	selected = true
+	received = true
+	return
+}
+
+// recvclosed is a helper function for chanrecv.  Handles cleanup
+// when the receiver encounters a closed channel.
+// Caller must hold c.lock, recvclosed will release the lock.
+func recvclosed(c *hchan, ep unsafe.Pointer) (selected, recevied bool) {
+	if raceenabled {
+		raceacquire(unsafe.Pointer(c))
+	}
+	unlock(&c.lock)
+	if ep != nil {
+		memclr(ep, uintptr(c.elemsize))
+	}
+	return true, false
+}
+
+// compiler implements
+//
+//	select {
+//	case c <- v:
+//		... foo
+//	default:
+//		... bar
+//	}
+//
+// as
+//
+//	if selectnbsend(c, v) {
+//		... foo
+//	} else {
+//		... bar
+//	}
+//
+func selectnbsend(t *chantype, c *hchan, elem unsafe.Pointer) (selected bool) {
+	return chansend(t, c, elem, false, getcallerpc(unsafe.Pointer(&t)))
+}
+
+// compiler implements
+//
+//	select {
+//	case v = <-c:
+//		... foo
+//	default:
+//		... bar
+//	}
+//
+// as
+//
+//	if selectnbrecv(&v, c) {
+//		... foo
+//	} else {
+//		... bar
+//	}
+//
+func selectnbrecv(t *chantype, elem unsafe.Pointer, c *hchan) (selected bool) {
+	selected, _ = chanrecv(t, c, elem, false)
+	return
+}
+
+// compiler implements
+//
+//	select {
+//	case v, ok = <-c:
+//		... foo
+//	default:
+//		... bar
+//	}
+//
+// as
+//
+//	if c != nil && selectnbrecv2(&v, &ok, c) {
+//		... foo
+//	} else {
+//		... bar
+//	}
+//
+func selectnbrecv2(t *chantype, elem unsafe.Pointer, received *bool, c *hchan) (selected bool) {
+	// TODO(khr): just return 2 values from this function, now that it is in Go.
+	selected, *received = chanrecv(t, c, elem, false)
+	return
+}
+
+func reflect_chansend(t *chantype, c *hchan, elem unsafe.Pointer, nb bool) (selected bool) {
+	return chansend(t, c, elem, !nb, getcallerpc(unsafe.Pointer(&t)))
+}
+
+func reflect_chanrecv(t *chantype, c *hchan, nb bool, elem unsafe.Pointer) (selected bool, received bool) {
+	return chanrecv(t, c, elem, !nb)
+}
+
+func reflect_chanlen(c *hchan) int {
+	if c == nil {
+		return 0
+	}
+	return int(c.qcount)
+}
+
+func reflect_chancap(c *hchan) int {
+	if c == nil {
+		return 0
+	}
+	return int(c.dataqsiz)
+}
+
+func (q *waitq) enqueue(sgp *sudog) {
+	sgp.next = nil
+	if q.first == nil {
+		q.first = sgp
+		q.last = sgp
+		return
+	}
+	q.last.next = sgp
+	q.last = sgp
+}
+
+func (q *waitq) dequeue() *sudog {
+	for {
+		sgp := q.first
+		if sgp == nil {
+			return nil
+		}
+		q.first = sgp.next
+		if q.last == sgp {
+			q.last = nil
+		}
+
+		// if sgp participates in a select and is already signaled, ignore it
+		if sgp.selectdone != nil {
+			// claim the right to signal
+			if *sgp.selectdone != 0 || !cas(sgp.selectdone, 0, 1) {
+				continue
+			}
+		}
+
+		return sgp
+	}
+}
+
+func racesync(c *hchan, sg *sudog) {
+	racerelease(chanbuf(c, 0))
+	raceacquireg(sg.g, chanbuf(c, 0))
+	racereleaseg(sg.g, chanbuf(c, 0))
+	raceacquire(chanbuf(c, 0))
+}