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Add "/file.js" buffered disk I/O object.
This is similar to the class node.File which was removed in 82cb1b5. Needs documentation.
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‎lib/file.js‎

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exports.debugLevel = 0; // Increase to get more verbose debug output
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function debugMessage (msg) {
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if (exports.debugLevel > 0) {
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node.error(__filename + ": " + msg.toString());
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}
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}
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function debugObject (obj) {
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if (exports.debugLevel > 0) {
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node.error(__filename + ": " + JSON.stringify(obj));
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}
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}
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exports.File = function (filename, mode, options) {
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var self = this;
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options = options || {};
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self.encoding = options.encoding || "utf8";
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self.filename = filename;
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self.actionQueue = [];
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self.currentAction = null;
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switch (mode) {
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case "r":
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self.flags = node.O_RDONLY;
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break;
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case "r+":
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self.flags = node.O_RDWR;
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break;
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case "w":
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self.flags = node.O_CREAT | node.O_TRUNC | node.O_WRONLY;
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break;
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case "w+":
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self.flags = node.O_CREAT | node.O_TRUNC | node.O_RDWR;
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break;
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case "a":
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self.flags = node.O_APPEND | node.O_CREAT | node.O_WRONLY;
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break;
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case "a+":
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self.flags = node.O_APPEND | node.O_CREAT | node.O_RDWR;
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break;
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default:
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throw new Error("Unknown mode");
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}
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self.open(self.filename, self.flags, 0666).addCallback(function (fd) {
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debugMessage(self.filename + " opened. fd = " + fd);
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self.fd = fd;
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}).addErrback(function () {
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self.emit("error", ["open"]);
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});
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};
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var proto = exports.File.prototype;
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proto._maybeDispatch = function () {
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var self = this;
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if (self.currentAction) return;
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self.currentAction = self.actionQueue.shift();
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if (!self.currentAction) return;
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debugObject(self.currentAction);
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var args = self.currentAction.args || [];
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if (self.currentAction.method != "open") {
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args.unshift(self.fd);
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}
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var method = self.currentAction.method;
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if (!args[3] && (method == "read" || method == "write")) {
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args[3] = self.encoding;
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}
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var promise = node.fs[method].apply(self, args);
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var userPromise = self.currentAction.promise;
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promise.addCallback(function () {
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node.assert(self.currentAction.promise == userPromise);
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userPromise.emitSuccess.apply(userPromise, arguments);
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self.currentAction = null;
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self._maybeDispatch();
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}).addErrback(function () {
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debugMessage("Error in method " + method);
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node.assert(self.currentAction.promise == userPromise);
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userPromise.emitError.apply(userPromise, arguments);
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self.currentAction = null;
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self._maybeDispatch();
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});
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};
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proto._queueAction = function (method, args) {
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var userPromise = new node.Promise;
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this.actionQueue.push({ method: method, args: args, promise: userPromise });
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this._maybeDispatch();
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return userPromise;
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};
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// FIXME the following can probably be DRY'd up with some fancy getter
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// stuff.
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proto.open = function (filename, flags, mode) {
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return this._queueAction("open", [filename, flags, mode]);
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};
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proto.write = function (data, pos, encoding) {
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return this._queueAction("write", [data, pos, encoding]);
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};
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proto.read = function (length, pos, encoding) {
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return this._queueAction("read", [length, pos, encoding]);
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};
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proto.close = function () {
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return this._queueAction("close");
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};

‎test/mjsunit/test-buffered-file.js‎

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include("common.js");
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var testTxt = node.path.join(fixturesDir, "test.txt");
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var libDir = node.path.join(testDir, "../../lib");
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node.libraryPaths.unshift(libDir);
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include("/file.js");
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var fileUnlinked = false;
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var file = new File(testTxt, "w+");
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file.write("hello\n");
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file.write("world\n");
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setTimeout(function () {
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file.write("hello\n");
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file.write("world\n");
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file.close().addCallback(function () {
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node.error("file closed...");
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var out = node.fs.cat(testTxt).wait();
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print("the file contains: ");
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p(out);
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assertEquals("hello\nworld\nhello\nworld\n", out);
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var file2 = new File(testTxt, "r");
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file2.read(5).addCallback(function (data) {
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puts("read(5): " + JSON.stringify(data));
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assertEquals("hello", data);
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node.fs.unlink(testTxt).addCallback(function () {
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fileUnlinked = true;
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});
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});
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file2.close();
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});
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}, 10);
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process.addListener("exit", function () {
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assertTrue(fileUnlinked);
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puts("done");
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});

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