gatefs.go

Documentation: golang.org/x/tools/godoc/vfs/gatefs

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package gatefs provides an implementation of the FileSystem
     6  // interface that wraps another FileSystem and limits its concurrency.
     7  package gatefs // import "golang.org/x/tools/godoc/vfs/gatefs"
     8  
     9  import (
    10  	"fmt"
    11  	"os"
    12  
    13  	"golang.org/x/tools/godoc/vfs"
    14  )
    15  
    16  // New returns a new FileSystem that delegates to fs.
    17  // If gateCh is non-nil and buffered, it's used as a gate
    18  // to limit concurrency on calls to fs.
    19  func New(fs vfs.FileSystem, gateCh chan bool) vfs.FileSystem {
    20  	if cap(gateCh) == 0 {
    21  		return fs
    22  	}
    23  	return gatefs{fs, gate(gateCh)}
    24  }
    25  
    26  type gate chan bool
    27  
    28  func (g gate) enter() { g <- true }
    29  func (g gate) leave() { <-g }
    30  
    31  type gatefs struct {
    32  	fs vfs.FileSystem
    33  	gate
    34  }
    35  
    36  func (fs gatefs) String() string {
    37  	return fmt.Sprintf("gated(%s, %d)", fs.fs.String(), cap(fs.gate))
    38  }
    39  
    40  func (fs gatefs) RootType(path string) vfs.RootType {
    41  	return fs.fs.RootType(path)
    42  }
    43  
    44  func (fs gatefs) Open(p string) (vfs.ReadSeekCloser, error) {
    45  	fs.enter()
    46  	defer fs.leave()
    47  	rsc, err := fs.fs.Open(p)
    48  	if err != nil {
    49  		return nil, err
    50  	}
    51  	return gatef{rsc, fs.gate}, nil
    52  }
    53  
    54  func (fs gatefs) Lstat(p string) (os.FileInfo, error) {
    55  	fs.enter()
    56  	defer fs.leave()
    57  	return fs.fs.Lstat(p)
    58  }
    59  
    60  func (fs gatefs) Stat(p string) (os.FileInfo, error) {
    61  	fs.enter()
    62  	defer fs.leave()
    63  	return fs.fs.Stat(p)
    64  }
    65  
    66  func (fs gatefs) ReadDir(p string) ([]os.FileInfo, error) {
    67  	fs.enter()
    68  	defer fs.leave()
    69  	return fs.fs.ReadDir(p)
    70  }
    71  
    72  type gatef struct {
    73  	rsc vfs.ReadSeekCloser
    74  	gate
    75  }
    76  
    77  func (f gatef) Read(p []byte) (n int, err error) {
    78  	f.enter()
    79  	defer f.leave()
    80  	return f.rsc.Read(p)
    81  }
    82  
    83  func (f gatef) Seek(offset int64, whence int) (ret int64, err error) {
    84  	f.enter()
    85  	defer f.leave()
    86  	return f.rsc.Seek(offset, whence)
    87  }
    88  
    89  func (f gatef) Close() error {
    90  	f.enter()
    91  	defer f.leave()
    92  	return f.rsc.Close()
    93  }
    94
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