93 lines
2.3 KiB
Go
93 lines
2.3 KiB
Go
// Copyright 2015 Google Inc. All Rights Reserved.
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// Author: jacobsa@google.com (Aaron Jacobs)
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package memfs
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import (
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"sync"
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"github.com/jacobsa/fuse"
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"github.com/jacobsa/fuse/fuseutil"
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"github.com/jacobsa/gcloud/syncutil"
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"github.com/jacobsa/gcsfuse/timeutil"
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)
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// Create a file system that stores data and metadata in memory.
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func NewMemFS(
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clock timeutil.Clock) fuse.FileSystem
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type memFS struct {
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fuseutil.NotImplementedFileSystem
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/////////////////////////
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// Dependencies
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/////////////////////////
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clock timeutil.Clock
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/////////////////////////
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// Mutable state
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/////////////////////////
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mu syncutil.InvariantMutex
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// The next inode to issue.
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//
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// INVARIANT: nextInode > 0
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nextInode fuse.InodeID // GUARDED_BY(mu)
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// A map from inode number to file or directory with that inode.
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//
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// INVARIANT: inodeIndex[fuse.RootInodeID != nil
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// INVARIANT: For all keys k, k > 0
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// INVARIANT: For all keys k, k < nextInode
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// INVARIANT: For all keys k, inodeIndex[k] is *memFile or *memDir
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// INVARIANT: For all keys k, inodeIndex[k].inode == k
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// INVARIANT: For all dirs d, all of d's children are in the map.
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inodeIndex map[fuse.InodeID]interface{} // GUARDED_BY(mu)
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}
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type memFile struct {
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/////////////////////////
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// Constant data
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/////////////////////////
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inode fuse.InodeID
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/////////////////////////
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// Mutable state
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/////////////////////////
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mu sync.RWMutex
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// The current contents of the file.
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contents []byte // GUARDED_BY(mu)
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}
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// TODO(jacobsa): Add a test that various WriteAt calls with a real on-disk
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// file to verify what the behavior should be here, particularly when starting
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// a write well beyond EOF. Leave the test around for documentation purposes.
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func (f *memFile) WriteAt(p []byte, off int64) (n int, err error)
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type memDir struct {
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/////////////////////////
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// Constant data
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/////////////////////////
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inode fuse.InodeID
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/////////////////////////
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// Mutable state
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/////////////////////////
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mu syncutil.InvariantMutex
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// The contents of the directory. An entry with inode zero is unused.
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//
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// This array can never be shortened, nor can its elements be moved, because
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// we use its indices for Dirent.Offset, which is exposed to the user who
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// might be calling readdir in a loop while concurrently modifying the
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// directory. Unused entries can, however, be reused.
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entries []fuseutil.Dirent
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}
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