diff options
Diffstat (limited to 'vendor/golang.org/x/tools/internal/fastwalk')
5 files changed, 370 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/internal/fastwalk/fastwalk.go b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk.go new file mode 100644 index 00000000..5cc7df53 --- /dev/null +++ b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk.go @@ -0,0 +1,191 @@ +// Copyright 2016 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 fastwalk provides a faster version of filepath.Walk for file system +// scanning tools. +package fastwalk + +import ( + "errors" + "os" + "path/filepath" + "runtime" + "sync" +) + +// TraverseLink is used as a return value from WalkFuncs to indicate that the +// symlink named in the call may be traversed. +var TraverseLink = errors.New("fastwalk: traverse symlink, assuming target is a directory") + +// Walk is a faster implementation of filepath.Walk. +// +// filepath.Walk's design necessarily calls os.Lstat on each file, +// even if the caller needs less info. +// Many tools need only the type of each file. +// On some platforms, this information is provided directly by the readdir +// system call, avoiding the need to stat each file individually. +// fastwalk_unix.go contains a fork of the syscall routines. +// +// See golang.org/issue/16399 +// +// Walk walks the file tree rooted at root, calling walkFn for +// each file or directory in the tree, including root. +// +// If fastWalk returns filepath.SkipDir, the directory is skipped. +// +// Unlike filepath.Walk: +// * file stat calls must be done by the user. +// The only provided metadata is the file type, which does not include +// any permission bits. +// * multiple goroutines stat the filesystem concurrently. The provided +// walkFn must be safe for concurrent use. +// * fastWalk can follow symlinks if walkFn returns the TraverseLink +// sentinel error. It is the walkFn's responsibility to prevent +// fastWalk from going into symlink cycles. +func Walk(root string, walkFn func(path string, typ os.FileMode) error) error { + // TODO(bradfitz): make numWorkers configurable? We used a + // minimum of 4 to give the kernel more info about multiple + // things we want, in hopes its I/O scheduling can take + // advantage of that. Hopefully most are in cache. Maybe 4 is + // even too low of a minimum. Profile more. + numWorkers := 4 + if n := runtime.NumCPU(); n > numWorkers { + numWorkers = n + } + + // Make sure to wait for all workers to finish, otherwise + // walkFn could still be called after returning. This Wait call + // runs after close(e.donec) below. + var wg sync.WaitGroup + defer wg.Wait() + + w := &walker{ + fn: walkFn, + enqueuec: make(chan walkItem, numWorkers), // buffered for performance + workc: make(chan walkItem, numWorkers), // buffered for performance + donec: make(chan struct{}), + + // buffered for correctness & not leaking goroutines: + resc: make(chan error, numWorkers), + } + defer close(w.donec) + + for i := 0; i < numWorkers; i++ { + wg.Add(1) + go w.doWork(&wg) + } + todo := []walkItem{{dir: root}} + out := 0 + for { + workc := w.workc + var workItem walkItem + if len(todo) == 0 { + workc = nil + } else { + workItem = todo[len(todo)-1] + } + select { + case workc <- workItem: + todo = todo[:len(todo)-1] + out++ + case it := <-w.enqueuec: + todo = append(todo, it) + case err := <-w.resc: + out-- + if err != nil { + return err + } + if out == 0 && len(todo) == 0 { + // It's safe to quit here, as long as the buffered + // enqueue channel isn't also readable, which might + // happen if the worker sends both another unit of + // work and its result before the other select was + // scheduled and both w.resc and w.enqueuec were + // readable. + select { + case it := <-w.enqueuec: + todo = append(todo, it) + default: + return nil + } + } + } + } +} + +// doWork reads directories as instructed (via workc) and runs the +// user's callback function. +func (w *walker) doWork(wg *sync.WaitGroup) { + defer wg.Done() + for { + select { + case <-w.donec: + return + case it := <-w.workc: + select { + case <-w.donec: + return + case w.resc <- w.walk(it.dir, !it.callbackDone): + } + } + } +} + +type walker struct { + fn func(path string, typ os.FileMode) error + + donec chan struct{} // closed on fastWalk's return + workc chan walkItem // to workers + enqueuec chan walkItem // from workers + resc chan error // from workers +} + +type walkItem struct { + dir string + callbackDone bool // callback already called; don't do it again +} + +func (w *walker) enqueue(it walkItem) { + select { + case w.enqueuec <- it: + case <-w.donec: + } +} + +func (w *walker) onDirEnt(dirName, baseName string, typ os.FileMode) error { + joined := dirName + string(os.PathSeparator) + baseName + if typ == os.ModeDir { + w.enqueue(walkItem{dir: joined}) + return nil + } + + err := w.fn(joined, typ) + if typ == os.ModeSymlink { + if err == TraverseLink { + // Set callbackDone so we don't call it twice for both the + // symlink-as-symlink and the symlink-as-directory later: + w.enqueue(walkItem{dir: joined, callbackDone: true}) + return nil + } + if err == filepath.SkipDir { + // Permit SkipDir on symlinks too. + return nil + } + } + return err +} + +func (w *walker) walk(root string, runUserCallback bool) error { + if runUserCallback { + err := w.fn(root, os.ModeDir) + if err == filepath.SkipDir { + return nil + } + if err != nil { + return err + } + } + + return readDir(root, w.onDirEnt) +} diff --git a/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_dirent_fileno.go b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_dirent_fileno.go new file mode 100644 index 00000000..ccffec5a --- /dev/null +++ b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_dirent_fileno.go @@ -0,0 +1,13 @@ +// Copyright 2016 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. + +// +build freebsd openbsd netbsd + +package fastwalk + +import "syscall" + +func direntInode(dirent *syscall.Dirent) uint64 { + return uint64(dirent.Fileno) +} diff --git a/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_dirent_ino.go b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_dirent_ino.go new file mode 100644 index 00000000..ab7fbc0a --- /dev/null +++ b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_dirent_ino.go @@ -0,0 +1,14 @@ +// Copyright 2016 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. + +// +build linux darwin +// +build !appengine + +package fastwalk + +import "syscall" + +func direntInode(dirent *syscall.Dirent) uint64 { + return uint64(dirent.Ino) +} diff --git a/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_portable.go b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_portable.go new file mode 100644 index 00000000..e8ea50d6 --- /dev/null +++ b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_portable.go @@ -0,0 +1,29 @@ +// Copyright 2016 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. + +// +build appengine !linux,!darwin,!freebsd,!openbsd,!netbsd + +package fastwalk + +import ( + "io/ioutil" + "os" +) + +// readDir calls fn for each directory entry in dirName. +// It does not descend into directories or follow symlinks. +// If fn returns a non-nil error, readDir returns with that error +// immediately. +func readDir(dirName string, fn func(dirName, entName string, typ os.FileMode) error) error { + fis, err := ioutil.ReadDir(dirName) + if err != nil { + return err + } + for _, fi := range fis { + if err := fn(dirName, fi.Name(), fi.Mode()&os.ModeType); err != nil { + return err + } + } + return nil +} diff --git a/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_unix.go b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_unix.go new file mode 100644 index 00000000..67db6caf --- /dev/null +++ b/vendor/golang.org/x/tools/internal/fastwalk/fastwalk_unix.go @@ -0,0 +1,123 @@ +// Copyright 2016 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. + +// +build linux darwin freebsd openbsd netbsd +// +build !appengine + +package fastwalk + +import ( + "bytes" + "fmt" + "os" + "syscall" + "unsafe" +) + +const blockSize = 8 << 10 + +// unknownFileMode is a sentinel (and bogus) os.FileMode +// value used to represent a syscall.DT_UNKNOWN Dirent.Type. +const unknownFileMode os.FileMode = os.ModeNamedPipe | os.ModeSocket | os.ModeDevice + +func readDir(dirName string, fn func(dirName, entName string, typ os.FileMode) error) error { + fd, err := syscall.Open(dirName, 0, 0) + if err != nil { + return &os.PathError{Op: "open", Path: dirName, Err: err} + } + defer syscall.Close(fd) + + // The buffer must be at least a block long. + buf := make([]byte, blockSize) // stack-allocated; doesn't escape + bufp := 0 // starting read position in buf + nbuf := 0 // end valid data in buf + for { + if bufp >= nbuf { + bufp = 0 + nbuf, err = syscall.ReadDirent(fd, buf) + if err != nil { + return os.NewSyscallError("readdirent", err) + } + if nbuf <= 0 { + return nil + } + } + consumed, name, typ := parseDirEnt(buf[bufp:nbuf]) + bufp += consumed + if name == "" || name == "." || name == ".." { + continue + } + // Fallback for filesystems (like old XFS) that don't + // support Dirent.Type and have DT_UNKNOWN (0) there + // instead. + if typ == unknownFileMode { + fi, err := os.Lstat(dirName + "/" + name) + if err != nil { + // It got deleted in the meantime. + if os.IsNotExist(err) { + continue + } + return err + } + typ = fi.Mode() & os.ModeType + } + if err := fn(dirName, name, typ); err != nil { + return err + } + } +} + +func parseDirEnt(buf []byte) (consumed int, name string, typ os.FileMode) { + // golang.org/issue/15653 + dirent := (*syscall.Dirent)(unsafe.Pointer(&buf[0])) + if v := unsafe.Offsetof(dirent.Reclen) + unsafe.Sizeof(dirent.Reclen); uintptr(len(buf)) < v { + panic(fmt.Sprintf("buf size of %d smaller than dirent header size %d", len(buf), v)) + } + if len(buf) < int(dirent.Reclen) { + panic(fmt.Sprintf("buf size %d < record length %d", len(buf), dirent.Reclen)) + } + consumed = int(dirent.Reclen) + if direntInode(dirent) == 0 { // File absent in directory. + return + } + switch dirent.Type { + case syscall.DT_REG: + typ = 0 + case syscall.DT_DIR: + typ = os.ModeDir + case syscall.DT_LNK: + typ = os.ModeSymlink + case syscall.DT_BLK: + typ = os.ModeDevice + case syscall.DT_FIFO: + typ = os.ModeNamedPipe + case syscall.DT_SOCK: + typ = os.ModeSocket + case syscall.DT_UNKNOWN: + typ = unknownFileMode + default: + // Skip weird things. + // It's probably a DT_WHT (http://lwn.net/Articles/325369/) + // or something. Revisit if/when this package is moved outside + // of goimports. goimports only cares about regular files, + // symlinks, and directories. + return + } + + nameBuf := (*[unsafe.Sizeof(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0])) + nameLen := bytes.IndexByte(nameBuf[:], 0) + if nameLen < 0 { + panic("failed to find terminating 0 byte in dirent") + } + + // Special cases for common things: + if nameLen == 1 && nameBuf[0] == '.' { + name = "." + } else if nameLen == 2 && nameBuf[0] == '.' && nameBuf[1] == '.' { + name = ".." + } else { + name = string(nameBuf[:nameLen]) + } + return +} |