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go/importer/util.go
Alan Donovan e2921e188a go.tools/importer: make loading/parsing concurrent.
1. ParseFiles (in util.go) parses each file in its own goroutine.

2. (*Importer).LoadPackage asynchronously prefetches the
   import graph by scanning the imports of each loaded package
   and calling LoadPackage on each one.

   LoadPackage is now thread-safe and idempotent: it uses a
   condition variable per package; the first goroutine to
   request a package becomes responsible for loading it and
   broadcasts to the others (waiting) when it becomes ready.

ssadump runs 34% faster when loading the oracle.

Also, refactorings:
- delete SourceLoader mechanism; just expose go/build.Context directly.
- CreateSourcePackage now also returns an error directly,
  rather than via PackageInfo.Err, since every client wants that.

R=crawshaw
CC=golang-dev
https://golang.org/cl/13509045
2013-09-04 13:15:49 -04:00

130 lines
3.1 KiB
Go

// Copyright 2013 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 importer
// This file defines various utility functions exposed by the package
// and used by it.
import (
"errors"
"go/ast"
"go/build"
"go/parser"
"go/token"
"os"
"path/filepath"
"strings"
"sync"
)
// CreatePackageFromArgs builds an initial Package from a list of
// command-line arguments.
// If args is a list of *.go files, they are parsed and type-checked.
// If args is a Go package import path, that package is imported.
// The rest result contains the suffix of args that were not consumed.
//
// This utility is provided to facilitate construction of command-line
// tools with a consistent user interface.
//
func CreatePackageFromArgs(imp *Importer, args []string) (info *PackageInfo, rest []string, err error) {
switch {
case len(args) == 0:
return nil, nil, errors.New("no *.go source files nor package name was specified.")
case strings.HasSuffix(args[0], ".go"):
// % tool a.go b.go ...
// Leading consecutive *.go arguments constitute main package.
i := 1
for ; i < len(args) && strings.HasSuffix(args[i], ".go"); i++ {
}
var files []*ast.File
files, err = ParseFiles(imp.Fset, ".", args[:i]...)
rest = args[i:]
if err == nil {
info, err = imp.CreateSourcePackage("main", files)
}
default:
// % tool my/package ...
// First argument is import path of main package.
pkgname := args[0]
info, err = imp.LoadPackage(pkgname)
rest = args[1:]
}
return
}
var cwd string
func init() {
var err error
cwd, err = os.Getwd()
if err != nil {
panic("getcwd failed: " + err.Error())
}
}
// loadPackage ascertains which files belong to package path, then
// loads, parses and returns them.
func loadPackage(ctxt *build.Context, fset *token.FileSet, path string) (files []*ast.File, err error) {
// TODO(adonovan): fix: Do we need cwd? Shouldn't
// ImportDir(path) / $GOROOT suffice?
bp, err := ctxt.Import(path, cwd, 0)
if _, ok := err.(*build.NoGoError); ok {
return nil, nil // empty directory
}
if err != nil {
return // import failed
}
return ParseFiles(fset, bp.Dir, bp.GoFiles...)
}
// ParseFiles parses the Go source files files within directory dir
// and returns their ASTs, or the first parse error if any.
//
func ParseFiles(fset *token.FileSet, dir string, files ...string) ([]*ast.File, error) {
var wg sync.WaitGroup
n := len(files)
parsed := make([]*ast.File, n, n)
errors := make([]error, n, n)
for i, file := range files {
if !filepath.IsAbs(file) {
file = filepath.Join(dir, file)
}
wg.Add(1)
go func(i int, file string) {
parsed[i], errors[i] = parser.ParseFile(fset, file, nil, parser.DeclarationErrors)
wg.Done()
}(i, file)
}
wg.Wait()
for _, err := range errors {
if err != nil {
return nil, err
}
}
return parsed, nil
}
// ---------- Internal helpers ----------
// unparen returns e with any enclosing parentheses stripped.
func unparen(e ast.Expr) ast.Expr {
for {
p, ok := e.(*ast.ParenExpr)
if !ok {
break
}
e = p.X
}
return e
}
func unreachable() {
panic("unreachable")
}