// license that can be found in the LICENSE file.

package runtime

// This file contains the implementation of Go select statements.

import (
	"internal/abi"
	"unsafe"
)

const debugSelect = false

// Select case descriptor.
// Known to compiler.
// Changes here must also be made in src/cmd/compile/internal/walk/select.go's scasetype.
type scase struct {
	c    *hchan         // chan
	elem unsafe.Pointer // data element
}

//  At least one of c.sendq and c.recvq is empty,
//  except for the case of an unbuffered channel with a single goroutine
//  blocked on it for both sending and receiving using a select statement,
//  in which case the length of c.sendq and c.recvq is limited only by the
//  size of the select statement.
//
// For buffered channels, also:
//  c.qcount > 0 implies that c.recvq is empty.
//  c.qcount < c.dataqsiz implies that c.sendq is empty.

import (

	// are only accessed when holding a semaRoot lock.

	acquiretime int64
	releasetime int64
	ticket      uint32

	// isSelect indicates g is participating in a select, so
	// g.selectDone must be CAS'd to win the wake-up race.
	isSelect bool

	// success indicates whether communication over channel c
	// succeeded. It is true if the goroutine was awoken because a

package clause

// Select select attrs when querying, updating, creating
type Select struct {
	Distinct   bool
	Columns    []Column
	Expression Expression
}

func (s Select) Name() string {
	return "SELECT"
}

func (s Select) Build(builder Builder) {
	if len(s.Columns) > 0 {
		if s.Distinct {
			builder.WriteString("DISTINCT ")
		}

		for idx, column := range s.Columns {
			if idx > 0 {
				builder.WriteByte(',')

	// optimization: zero-case select
	if ncas == 0 {
		return []ir.Node{mkcallstmt("block")}
	}

	// optimization: one-case select: single op.
	if ncas == 1 {
		cas := cases[0]
		ir.SetPos(cas)
		l := cas.Init()
		if cas.Comm != nil { // not default:
			n := cas.Comm
			l = append(l, ir.TakeInit(n)...)
			switch n.Op() {
			default:
				base.Fatalf("select %v", n.Op())

			case ir.OSEND:

// license that can be found in the LICENSE file.

package codegen

func f() {
	ch1 := make(chan int)
	ch2 := make(chan int)
	for {
		// amd64:-`MOVQ\t[$]0, command-line-arguments..autotmp_3`
		select {
		case <-ch1:
		case <-ch2:
		default:
		}
	}

var counterErrorsInvalidToolchainInFile = telemetry.NewCounter("go/errors:invalid-toolchain-in-file")

// Select invokes a different Go toolchain if directed by
// the GOTOOLCHAIN environment variable or the user's configuration
// or go.mod file.
// It must be called early in startup.
// See https://go.dev/doc/toolchain#select.
func Select() {
	log.SetPrefix("go: ")
	defer log.SetPrefix("")

	if !modload.WillBeEnabled() {
		return
	}

		return nil
	}

	panic(fmt.Errorf("unknown output format '%v'", s3Select.Output.format))
}

// Evaluate - filters and sends records read from opened reader as per select statement to http response writer.
func (s3Select *S3Select) Evaluate(w http.ResponseWriter) {
	getProgressFunc := s3Select.getProgress
	if !s3Select.Progress.Enabled {
		getProgressFunc = nil
	}

	}
	releasem(mp)
	return s
}

//go:nosplit
func releaseSudog(s *sudog) {
	if s.elem != nil {
		throw("runtime: sudog with non-nil elem")
	}
	if s.isSelect {
		throw("runtime: sudog with non-false isSelect")
	}
	if s.next != nil {
		throw("runtime: sudog with non-nil next")
	}
	if s.prev != nil {
		throw("runtime: sudog with non-nil prev")
	}
	if s.waitlink != nil {

Matthew Dempsky <******@****.***> 1646087539 -0800