internal/gocommand/invoke.go - tools - Git at Google

 // Copyright 2020 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 gocommand is a helper for calling the go command.
 package gocommand

 import (
 	"bytes"
 	"context"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
 	"regexp"
 	"strings"
 	"sync"
 	"time"

 	"golang.org/x/tools/internal/event"
 )

 // An Runner will run go command invocations and serialize
 // them if it sees a concurrency error.
 type Runner struct {
 	// once guards the runner initialization.
 	once sync.Once

 	// inFlight tracks available workers.
 	inFlight chan struct{}

 	// serialized guards the ability to run a go command serially,
 	// to avoid deadlocks when claiming workers.
 	serialized chan struct{}
 }

 const maxInFlight = 10

 func (runner *Runner) initialize() {
 	runner.once.Do(func() {
 		runner.inFlight = make(chan struct{}, maxInFlight)
 		runner.serialized = make(chan struct{}, 1)
 	})
 }

 // 1.13: go: updates to go.mod needed, but contents have changed
 // 1.14: go: updating go.mod: existing contents have changed since last read
 var modConcurrencyError = regexp.MustCompile(`go:.*go.mod.*contents have changed`)

 // Run is a convenience wrapper around RunRaw.
 // It returns only stdout and a "friendly" error.
 func (runner *Runner) Run(ctx context.Context, inv Invocation) (*bytes.Buffer, error) {
 	stdout, _, friendly, _ := runner.RunRaw(ctx, inv)
 	return stdout, friendly
 }

 // RunPiped runs the invocation serially, always waiting for any concurrent
 // invocations to complete first.
 func (runner *Runner) RunPiped(ctx context.Context, inv Invocation, stdout, stderr io.Writer) error {
 	_, err := runner.runPiped(ctx, inv, stdout, stderr)
 	return err
 }

 // RunRaw runs the invocation, serializing requests only if they fight over
 // go.mod changes.
 func (runner *Runner) RunRaw(ctx context.Context, inv Invocation) (*bytes.Buffer, *bytes.Buffer, error, error) {
 	// Make sure the runner is always initialized.
 	runner.initialize()

 	// First, try to run the go command concurrently.
 	stdout, stderr, friendlyErr, err := runner.runConcurrent(ctx, inv)

 	// If we encounter a load concurrency error, we need to retry serially.
 	if friendlyErr == nil || !modConcurrencyError.MatchString(friendlyErr.Error()) {
 		return stdout, stderr, friendlyErr, err
 	}
 	event.Error(ctx, "Load concurrency error, will retry serially", err)

 	// Run serially by calling runPiped.
 	stdout.Reset()
 	stderr.Reset()
 	friendlyErr, err = runner.runPiped(ctx, inv, stdout, stderr)
 	return stdout, stderr, friendlyErr, err
 }

 func (runner *Runner) runConcurrent(ctx context.Context, inv Invocation) (*bytes.Buffer, *bytes.Buffer, error, error) {
 	// Wait for 1 worker to become available.
 	select {
 	case <-ctx.Done():
 		return nil, nil, nil, ctx.Err()
 	case runner.inFlight <- struct{}{}:
 		defer func() { <-runner.inFlight }()
 	}

 	stdout, stderr := &bytes.Buffer{}, &bytes.Buffer{}
 	friendlyErr, err := inv.runWithFriendlyError(ctx, stdout, stderr)
 	return stdout, stderr, friendlyErr, err
 }

 func (runner *Runner) runPiped(ctx context.Context, inv Invocation, stdout, stderr io.Writer) (error, error) {
 	// Make sure the runner is always initialized.
 	runner.initialize()

 	// Acquire the serialization lock. This avoids deadlocks between two
 	// runPiped commands.
 	select {
 	case <-ctx.Done():
 		return nil, ctx.Err()
 	case runner.serialized <- struct{}{}:
 		defer func() { <-runner.serialized }()
 	}

 	// Wait for all in-progress go commands to return before proceeding,
 	// to avoid load concurrency errors.
 	for i := 0; i < maxInFlight; i++ {
 		select {
 		case <-ctx.Done():
 			return nil, ctx.Err()
 		case runner.inFlight <- struct{}{}:
 			// Make sure we always "return" any workers we took.
 			defer func() { <-runner.inFlight }()
 		}
 	}

 	return inv.runWithFriendlyError(ctx, stdout, stderr)
 }

 // An Invocation represents a call to the go command.
 type Invocation struct {
 	Verb       string
 	Args       []string
 	BuildFlags []string
 	Env        []string
 	WorkingDir string
 	Logf       func(format string, args ...interface{})
 }

 func (i *Invocation) runWithFriendlyError(ctx context.Context, stdout, stderr io.Writer) (friendlyError error, rawError error) {
 	rawError = i.run(ctx, stdout, stderr)
 	if rawError != nil {
 		friendlyError = rawError
 		// Check for 'go' executable not being found.
 		if ee, ok := rawError.(*exec.Error); ok && ee.Err == exec.ErrNotFound {
 			friendlyError = fmt.Errorf("go command required, not found: %v", ee)
 		}
 		if ctx.Err() != nil {
 			friendlyError = ctx.Err()
 		}
 		friendlyError = fmt.Errorf("err: %v: stderr: %s", friendlyError, stderr)
 	}
 	return
 }

 func (i *Invocation) run(ctx context.Context, stdout, stderr io.Writer) error {
 	log := i.Logf
 	if log == nil {
 		log = func(string, ...interface{}) {}
 	}

 	goArgs := []string{i.Verb}
 	switch i.Verb {
 	case "mod":
 		// mod needs the sub-verb before build flags.
 		goArgs = append(goArgs, i.Args[0])
 		goArgs = append(goArgs, i.BuildFlags...)
 		goArgs = append(goArgs, i.Args[1:]...)
 	case "env":
 		// env doesn't take build flags.
 		goArgs = append(goArgs, i.Args...)
 	default:
 		goArgs = append(goArgs, i.BuildFlags...)
 		goArgs = append(goArgs, i.Args...)
 	}
 	cmd := exec.Command("go", goArgs...)
 	cmd.Stdout = stdout
 	cmd.Stderr = stderr
 	// On darwin the cwd gets resolved to the real path, which breaks anything that
 	// expects the working directory to keep the original path, including the
 	// go command when dealing with modules.
 	// The Go stdlib has a special feature where if the cwd and the PWD are the
 	// same node then it trusts the PWD, so by setting it in the env for the child
 	// process we fix up all the paths returned by the go command.
 	cmd.Env = append(os.Environ(), i.Env...)
 	if i.WorkingDir != "" {
 		cmd.Env = append(cmd.Env, "PWD="+i.WorkingDir)
 		cmd.Dir = i.WorkingDir
 	}
 	defer func(start time.Time) { log("%s for %v", time.Since(start), cmdDebugStr(cmd)) }(time.Now())

 	return runCmdContext(ctx, cmd)
 }

 // runCmdContext is like exec.CommandContext except it sends os.Interrupt
 // before os.Kill.
 func runCmdContext(ctx context.Context, cmd *exec.Cmd) error {
 	if err := cmd.Start(); err != nil {
 		return err
 	}
 	resChan := make(chan error, 1)
 	go func() {
 		resChan <- cmd.Wait()
 	}()

 	select {
 	case err := <-resChan:
 		return err
 	case <-ctx.Done():
 	}
 	// Cancelled. Interrupt and see if it ends voluntarily.
 	cmd.Process.Signal(os.Interrupt)
 	select {
 	case err := <-resChan:
 		return err
 	case <-time.After(time.Second):
 	}
 	// Didn't shut down in response to interrupt. Kill it hard.
 	cmd.Process.Kill()
 	return <-resChan
 }

 func cmdDebugStr(cmd *exec.Cmd) string {
 	env := make(map[string]string)
 	for _, kv := range cmd.Env {
 		split := strings.Split(kv, "=")
 		k, v := split[0], split[1]
 		env[k] = v
 	}

 	return fmt.Sprintf("GOROOT=%v GOPATH=%v GO111MODULE=%v GOPROXY=%v PWD=%v go %v", env["GOROOT"], env["GOPATH"], env["GO111MODULE"], env["GOPROXY"], env["PWD"], cmd.Args)
 }
	// Copyright 2020 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 gocommand is a helper for calling the go command.
	package gocommand

	import (
	"bytes"
	"context"
	"fmt"
	"io"
	"os"
	"os/exec"
	"regexp"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/internal/event"
	)

	// An Runner will run go command invocations and serialize
	// them if it sees a concurrency error.
	type Runner struct {
	// once guards the runner initialization.
	once sync.Once

	// inFlight tracks available workers.
	inFlight chan struct{}

	// serialized guards the ability to run a go command serially,
	// to avoid deadlocks when claiming workers.
	serialized chan struct{}
	}

	const maxInFlight = 10

	func (runner *Runner) initialize() {
	runner.once.Do(func() {
	runner.inFlight = make(chan struct{}, maxInFlight)
	runner.serialized = make(chan struct{}, 1)
	})
	}

	// 1.13: go: updates to go.mod needed, but contents have changed
	// 1.14: go: updating go.mod: existing contents have changed since last read
	var modConcurrencyError = regexp.MustCompile(`go:.go.mod.contents have changed`)

	// Run is a convenience wrapper around RunRaw.
	// It returns only stdout and a "friendly" error.
	func (runner Runner) Run(ctx context.Context, inv Invocation) (bytes.Buffer, error) {
	stdout, _, friendly, _ := runner.RunRaw(ctx, inv)
	return stdout, friendly
	}

	// RunPiped runs the invocation serially, always waiting for any concurrent
	// invocations to complete first.
	func (runner *Runner) RunPiped(ctx context.Context, inv Invocation, stdout, stderr io.Writer) error {
	_, err := runner.runPiped(ctx, inv, stdout, stderr)
	return err
	}

	// RunRaw runs the invocation, serializing requests only if they fight over
	// go.mod changes.
	func (runner Runner) RunRaw(ctx context.Context, inv Invocation) (bytes.Buffer, *bytes.Buffer, error, error) {
	// Make sure the runner is always initialized.
	runner.initialize()

	// First, try to run the go command concurrently.
	stdout, stderr, friendlyErr, err := runner.runConcurrent(ctx, inv)

	// If we encounter a load concurrency error, we need to retry serially.
	if friendlyErr == nil \|\| !modConcurrencyError.MatchString(friendlyErr.Error()) {
	return stdout, stderr, friendlyErr, err
	}
	event.Error(ctx, "Load concurrency error, will retry serially", err)

	// Run serially by calling runPiped.
	stdout.Reset()
	stderr.Reset()
	friendlyErr, err = runner.runPiped(ctx, inv, stdout, stderr)
	return stdout, stderr, friendlyErr, err
	}

	func (runner Runner) runConcurrent(ctx context.Context, inv Invocation) (bytes.Buffer, *bytes.Buffer, error, error) {
	// Wait for 1 worker to become available.
	select {
	case <-ctx.Done():
	return nil, nil, nil, ctx.Err()
	case runner.inFlight <- struct{}{}:
	defer func() { <-runner.inFlight }()
	}

	stdout, stderr := &bytes.Buffer{}, &bytes.Buffer{}
	friendlyErr, err := inv.runWithFriendlyError(ctx, stdout, stderr)
	return stdout, stderr, friendlyErr, err
	}

	func (runner *Runner) runPiped(ctx context.Context, inv Invocation, stdout, stderr io.Writer) (error, error) {
	// Make sure the runner is always initialized.
	runner.initialize()

	// Acquire the serialization lock. This avoids deadlocks between two
	// runPiped commands.
	select {
	case <-ctx.Done():
	return nil, ctx.Err()
	case runner.serialized <- struct{}{}:
	defer func() { <-runner.serialized }()
	}

	// Wait for all in-progress go commands to return before proceeding,
	// to avoid load concurrency errors.
	for i := 0; i < maxInFlight; i++ {
	select {
	case <-ctx.Done():
	return nil, ctx.Err()
	case runner.inFlight <- struct{}{}:
	// Make sure we always "return" any workers we took.
	defer func() { <-runner.inFlight }()
	}
	}

	return inv.runWithFriendlyError(ctx, stdout, stderr)
	}

	// An Invocation represents a call to the go command.
	type Invocation struct {
	Verb string
	Args []string
	BuildFlags []string
	Env []string
	WorkingDir string
	Logf func(format string, args ...interface{})
	}

	func (i *Invocation) runWithFriendlyError(ctx context.Context, stdout, stderr io.Writer) (friendlyError error, rawError error) {
	rawError = i.run(ctx, stdout, stderr)
	if rawError != nil {
	friendlyError = rawError
	// Check for 'go' executable not being found.
	if ee, ok := rawError.(*exec.Error); ok && ee.Err == exec.ErrNotFound {
	friendlyError = fmt.Errorf("go command required, not found: %v", ee)
	}
	if ctx.Err() != nil {
	friendlyError = ctx.Err()
	}
	friendlyError = fmt.Errorf("err: %v: stderr: %s", friendlyError, stderr)
	}
	return
	}

	func (i *Invocation) run(ctx context.Context, stdout, stderr io.Writer) error {
	log := i.Logf
	if log == nil {
	log = func(string, ...interface{}) {}
	}

	goArgs := []string{i.Verb}
	switch i.Verb {
	case "mod":
	// mod needs the sub-verb before build flags.
	goArgs = append(goArgs, i.Args[0])
	goArgs = append(goArgs, i.BuildFlags...)
	goArgs = append(goArgs, i.Args[1:]...)
	case "env":
	// env doesn't take build flags.
	goArgs = append(goArgs, i.Args...)
	default:
	goArgs = append(goArgs, i.BuildFlags...)
	goArgs = append(goArgs, i.Args...)
	}
	cmd := exec.Command("go", goArgs...)
	cmd.Stdout = stdout
	cmd.Stderr = stderr
	// On darwin the cwd gets resolved to the real path, which breaks anything that
	// expects the working directory to keep the original path, including the
	// go command when dealing with modules.
	// The Go stdlib has a special feature where if the cwd and the PWD are the
	// same node then it trusts the PWD, so by setting it in the env for the child
	// process we fix up all the paths returned by the go command.
	cmd.Env = append(os.Environ(), i.Env...)
	if i.WorkingDir != "" {
	cmd.Env = append(cmd.Env, "PWD="+i.WorkingDir)
	cmd.Dir = i.WorkingDir
	}
	defer func(start time.Time) { log("%s for %v", time.Since(start), cmdDebugStr(cmd)) }(time.Now())

	return runCmdContext(ctx, cmd)
	}

	// runCmdContext is like exec.CommandContext except it sends os.Interrupt
	// before os.Kill.
	func runCmdContext(ctx context.Context, cmd *exec.Cmd) error {
	if err := cmd.Start(); err != nil {
	return err
	}
	resChan := make(chan error, 1)
	go func() {
	resChan <- cmd.Wait()
	}()

	select {
	case err := <-resChan:
	return err
	case <-ctx.Done():
	}
	// Cancelled. Interrupt and see if it ends voluntarily.
	cmd.Process.Signal(os.Interrupt)
	select {
	case err := <-resChan:
	return err
	case <-time.After(time.Second):
	}
	// Didn't shut down in response to interrupt. Kill it hard.
	cmd.Process.Kill()
	return <-resChan
	}

	func cmdDebugStr(cmd *exec.Cmd) string {
	env := make(map[string]string)
	for _, kv := range cmd.Env {
	split := strings.Split(kv, "=")
	k, v := split[0], split[1]
	env[k] = v
	}

	return fmt.Sprintf("GOROOT=%v GOPATH=%v GO111MODULE=%v GOPROXY=%v PWD=%v go %v", env["GOROOT"], env["GOPATH"], env["GO111MODULE"], env["GOPROXY"], env["PWD"], cmd.Args)
	}