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backend/overlay: implement sync + close on OverlayFile
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@bpowers
bpowers committed Jul 12, 2016
1 parent d88658f commit 887add8
Showing 1 changed file with 97 additions and 46 deletions.
143 changes: 97 additions & 46 deletions src/backend/OverlayFS.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,11 @@ let deletionLogPath = '/.deletedFiles.log';
* Given a read-only mode, makes it writable.
*/
function makeModeWritable(mode: number): number {
return 0x92 | mode;
return 0o222 | mode;
}

function getFlag(f: string): FileFlag {
return FileFlag.getFileFlag(f);
}

/**
Expand All @@ -23,13 +27,29 @@ class OverlayFile extends preload_file.PreloadFile<OverlayFS> implements file.Fi
super(fs, path, flag, stats, data);
}

public sync(cb: (e?: ApiError) => void): void {
if (!this.isDirty()) {
cb(null);
return;
}

this._fs._syncAsync(this, (err: ApiError) => {
this.resetDirty();
cb(err);
});
}

public syncSync(): void {
if (this.isDirty()) {
this._fs._syncSync(this);
this.resetDirty();
}
}

public close(cb: (e?: ApiError) => void): void {
this.sync(cb);
}

public closeSync(): void {
this.syncSync();
}
Expand All @@ -39,8 +59,6 @@ class OverlayFile extends preload_file.PreloadFile<OverlayFS> implements file.Fi
* OverlayFS makes a read-only filesystem writable by storing writes on a second,
* writable file system. Deletes are persisted via metadata stored on the writable
* file system.
*
* Currently only works for two synchronous file systems.
*/
export default class OverlayFS extends file_system.SynchronousFileSystem implements file_system.FileSystem {
private _writable: file_system.FileSystem;
Expand All @@ -49,6 +67,7 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
private _initializeCallbacks: ((e?: ApiError) => void)[] = [];
private _deletedFiles: {[path: string]: boolean} = {};
private _deleteLog: file.File = null;
private _isAsync: boolean;

constructor(writable: file_system.FileSystem, readable: file_system.FileSystem) {
super();
Expand All @@ -57,9 +76,7 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
if (this._writable.isReadOnly()) {
throw new ApiError(ErrorCode.EINVAL, "Writable file system must be writable.");
}
if (!this._writable.supportsSynch() || !this._readable.supportsSynch()) {
throw new ApiError(ErrorCode.EINVAL, "OverlayFS currently only operates on synchronous file systems.");
}
this._isAsync = !this._writable.supportsSynch() || !this._readable.supportsSynch();
}

private checkInitialized(): void {
Expand All @@ -75,6 +92,38 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
};
}

private createParentDirectoriesAsync(p: string, cb: ()=>void): void {
let parent = path.dirname(p)
let toCreate: string[] = [];
let _this = this;

this._writable.stat(parent, false, statDone);
function statDone(err: ApiError, stat?: Stats): void {
if (err) {
toCreate.push(parent);
parent = path.dirname(parent);
_this._writable.stat(parent, false, statDone);
} else {
createParents();
}
}

function createParents(): void {
if (!toCreate.length) {
cb();
return;
}
let dir = toCreate.pop();
// FIXME: get correct permissions
_this._writable.mkdir(dir, 0o777, (err?: ApiError) => {
// FIXME: better error handling
if (err)
throw err;
createParents();
});
}
}

/**
* With the given path, create the needed parent directories on the writable storage
* should they not exist. Use modes from the read-only storage.
Expand All @@ -96,9 +145,15 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
return true;
}

public _syncSync(file: preload_file.PreloadFile<any>): void {
public _syncAsync(file: preload_file.PreloadFile<OverlayFS>, cb: (err: ApiError)=>void): void {
this.createParentDirectoriesAsync(file.getPath(), () => {
this._writable.writeFile(file.getPath(), file.getBuffer(), null, getFlag('w'), file.getStats().mode, cb);
});
}

public _syncSync(file: preload_file.PreloadFile<OverlayFS>): void {
this.createParentDirectories(file.getPath());
this._writable.writeFileSync(file.getPath(), file.getBuffer(), null, FileFlag.getFileFlag('w'), file.getStats().mode);
this._writable.writeFileSync(file.getPath(), file.getBuffer(), null, getFlag('w'), file.getStats().mode);
}

public getName() {
Expand All @@ -117,40 +172,37 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
callbackArray.forEach(((cb) => cb(e)));
};

if (!this._isInitialized) {
// The first call to initialize initializes, the rest wait for it to complete.
if (callbackArray.push(cb) === 1) {
// Read deletion log, process into metadata.
this._writable.readFile(deletionLogPath, 'utf8',
FileFlag.getFileFlag('r'), (err: ApiError, data?: string) => {
if (err) {
// ENOENT === Newly-instantiated file system, and thus empty log.
if (err.errno !== ErrorCode.ENOENT) {
return end(err);
}
} else {
data.split('\n').forEach((path: string) => {
// If the log entry begins w/ 'd', it's a deletion. Otherwise, it's
// an undeletion.
// TODO: Clean up log during initialization phase.
this._deletedFiles[path.slice(1)] = path.slice(0, 1) === 'd';
});
}
// Open up the deletion log for appending.
this._writable.open(deletionLogPath, FileFlag.getFileFlag('a'),
0x1a4, (err: ApiError, fd?: file.File) => {
if (err) {
end(err);
} else {
this._deleteLog = fd;
end();
}
});
// if we're already initialized, immediately invoke the callback
if (this._isInitialized)
return cb();

callbackArray.push(cb);
// The first call to initialize initializes, the rest wait for it to complete.
if (callbackArray.length !== 1)
return;

// Read deletion log, process into metadata.
this._writable.readFile(deletionLogPath, 'utf8', getFlag('r'), (err: ApiError, data?: string) => {
if (err) {
// ENOENT === Newly-instantiated file system, and thus empty log.
if (err.errno !== ErrorCode.ENOENT) {
return end(err);
}
} else {
data.split('\n').forEach((path: string) => {
// If the log entry begins w/ 'd', it's a deletion. Otherwise, it's
// an undeletion.
// TODO: Clean up log during initialization phase.
this._deletedFiles[path.slice(1)] = path.slice(0, 1) === 'd';
});
}
} else {
cb();
}
// Open up the deletion log for appending.
this._writable.open(deletionLogPath, getFlag('a'), 0o644, (err: ApiError, fd?: file.File) => {
if (!err)
this._deleteLog = fd;
end(err);
});
});
}

public isReadOnly(): boolean { return false; }
Expand Down Expand Up @@ -184,7 +236,7 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
return;
}

var mode = 0x1ff;
var mode = 0o777;
if (this.existsSync(newPath)) {
var stats = this.statSync(newPath, false),
mode = stats.mode;
Expand Down Expand Up @@ -219,8 +271,7 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
}

this.writeFileSync(newPath,
this.readFileSync(oldPath, null, FileFlag.getFileFlag('r')), null,
FileFlag.getFileFlag('w'), oldStats.mode);
this.readFileSync(oldPath, null, getFlag('r')), null, getFlag('w'), oldStats.mode);
}

if (oldPath !== newPath && this.existsSync(oldPath)) {
Expand Down Expand Up @@ -256,7 +307,7 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
// Create an OverlayFile.
var stats = this._readable.statSync(p, false).clone();
stats.mode = mode;
return new OverlayFile(this, p, flag, stats, this._readable.readFileSync(p, null, FileFlag.getFileFlag('r')));
return new OverlayFile(this, p, flag, stats, this._readable.readFileSync(p, null, getFlag('r')));
}
default:
throw ApiError.EEXIST(p);
Expand Down Expand Up @@ -391,8 +442,8 @@ export default class OverlayFS extends file_system.SynchronousFileSystem impleme
this._writable.mkdirSync(p, pStats.mode);
} else {
this.writeFileSync(p,
this._readable.readFileSync(p, null, FileFlag.getFileFlag('r')), null,
FileFlag.getFileFlag('w'), this.statSync(p, false).mode);
this._readable.readFileSync(p, null, getFlag('r')), null,
getFlag('w'), this.statSync(p, false).mode);
}
}
}

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