Faster fs.readFile and fs.readFileSync

lib/fs.js

@@ -103,93 +103,88 @@ fs.readFile = function(path, encoding_) {
   var encoding = typeof(encoding_) === 'string' ? encoding_ : null;
   var callback = arguments[arguments.length - 1];
   if (typeof(callback) !== 'function') callback = noop;
-  var readStream = fs.createReadStream(path);
-  var buffers = [];
-  var nread = 0;
-  var error;
-
-  readStream.on('data', function(chunk) {
-    buffers.push(chunk);
-    nread += chunk.length;
-  });
 
-  readStream.on('error', function(er) {
-    error = er;
-    readStream.destroy();
-    if (!readStream.fd) {
-      readStream.emit('close');
-    }
-  });
+  // first, stat the file, so we know the size.
+  var size;
+  var buffer;
+  var pos = 0;
+  var fd;
+
+  fs.open(path, constants.O_RDONLY, 438 /*=0666*/, function(er, fd_) {
+    if (er) return callback(er);
+    fd = fd_;
 
-  readStream.on('close', function() {
-    if (error) {
-      return callback(error);
+    fs.fstat(fd, function(er, st) {
+      if (er) return callback(er);
+      size = st.size;
+      if (size === 0) {
+        buffer = new Buffer(0);
+        return afterRead(null, 0);
       }
 
-    // copy all the buffers into one
-    var buffer;
-    switch (buffers.length) {
-      case 0: buffer = new Buffer(0); break;
-      case 1: buffer = buffers[0]; break;
-      default: // concat together
-        buffer = new Buffer(nread);
-        var n = 0;
-        buffers.forEach(function(b) {
-          var l = b.length;
-          b.copy(buffer, n, 0, l);
-          n += l;
+      buffer = new Buffer(size);
+      read();
     });
-        break;
+  });
+
+  function read() {
+    fs.read(fd, buffer, pos, size - pos, pos, afterRead);
   }
-    if (encoding) {
-      try {
-        buffer = buffer.toString(encoding);
-      } catch (er) {
+
+  function afterRead(er, bytesRead) {
+    if (er) {
+      return fs.close(fd, function(er2) {
         return callback(er);
+      });
     }
+
+    pos += bytesRead;
+    if (pos === size) close();
+    else read();
   }
-    callback(null, buffer);
+
+  function close() {
+    fs.close(fd, function(er) {
+      if (encoding) buffer = buffer.toString(encoding);
+      return callback(er, buffer);
     });
+  }
 };
 
 fs.readFileSync = function(path, encoding) {
   var fd = fs.openSync(path, constants.O_RDONLY, 438 /*=0666*/);
-  var buffer = new Buffer(4048);
-  var buffers = [];
-  var nread = 0;
-  var lastRead = 0;
 
+  var size;
+  var threw = true;
   try {
-    do {
-      if (lastRead) {
-        buffer._bytesRead = lastRead;
-        nread += lastRead;
-        buffers.push(buffer);
-      }
-      var buffer = new Buffer(4048);
-      lastRead = fs.readSync(fd, buffer, 0, buffer.length, null);
-    } while (lastRead > 0);
+    size = fs.fstatSync(fd).size;
+    threw = false;
   } finally {
+    if (threw) fs.closeSync(fd);
+  }
+
+  if (size === 0) {
     fs.closeSync(fd);
+    return encoding ? '' : new Buffer(0);
   }
 
-  if (buffers.length > 1) {
-    var offset = 0;
-    var i;
-    buffer = new Buffer(nread);
-    buffers.forEach(function(i) {
-      if (!i._bytesRead) return;
-      i.copy(buffer, offset, 0, i._bytesRead);
-      offset += i._bytesRead;
-    });
-  } else if (buffers.length) {
-    // buffers has exactly 1 (possibly zero length) buffer, so this should
-    // be a shortcut
-    buffer = buffers[0].slice(0, buffers[0]._bytesRead);
-  } else {
-    buffer = new Buffer(0);
+  var buffer = new Buffer(size);
+  var pos = 0;
+
+  while (pos < size) {
+    var threw = true;
+    try {
+      var bytesRead = fs.readSync(fd, buffer, pos, size - pos, pos);
+      threw = false;
+    } finally {
+      if (threw) fs.closeSync(fd);
     }
 
+    pos += bytesRead;
+  }
+
+  fs.closeSync(fd);
+
   if (encoding) buffer = buffer.toString(encoding);
   return buffer;
 };

test/simple/test-fs-sync-fd-leak.js

@@ -38,6 +38,10 @@ fs.writeSync = function() {
   throw new Error('BAM');
 };
 
+fs.fstatSync = function() {
+  throw new Error('BAM');
+};
+
 ensureThrows(function() {
   fs.readFileSync('dummy');
 });