FastBuffer implementation. API needs migration

tim-smart · ry · commit 746d487da860 · 2010-09-09T11:03:47.000-07:00
diff --git a/lib/buffer.js b/lib/buffer.js
@@ -1,7 +1,5 @@
 var Buffer = process.binding('buffer').Buffer;
 
-exports.Buffer = Buffer;
-
 function toHex (n) {
   if (n < 16) return "0" + n.toString(16);
   return n.toString(16);
@@ -87,3 +85,166 @@ Buffer.prototype.get = function (index) {
 Buffer.prototype.set = function (index, value) {
   return this[index] = value;
 };
+
+// FastBuffer
+var POOLSIZE = 8*1024;
+var pool;
+
+function allocPool () {
+  pool      = new Buffer(POOLSIZE);
+  pool.used = 0;
+}
+
+function FastBuffer (subject, encoding, legacy, slice_legacy) {
+  var length, type;
+
+  // Are we slicing?
+  if (typeof legacy === 'number') {
+    this.parent = subject;
+    this.length = encoding;
+    this.offset = legacy;
+    legacy      = slice_legacy;
+  } else {
+    // Find the length
+    switch (type = typeof subject) {
+      case 'number':
+        length = subject;
+        break;
+
+      case 'string':
+      case 'object': // Assume object is an array
+        length = subject.length;
+        break;
+
+      default:
+        throw new Error("First argument need to be an number, array or string.");
+    }
+
+    this.length = length;
+
+    if (length > POOLSIZE) {
+      // Big buffer, just alloc one.
+      this.parent = new Buffer(subject, encoding);
+      this.offset = 0;
+    } else {
+      // Small buffer.
+      if (!pool || pool.length - pool.used < length) allocPool();
+      this.parent =  pool;
+      this.offset =  pool.used;
+      pool.used   += length;
+
+      // Do we need to write stuff?
+      if (type !== 'number') {
+        // Assume object is an array
+        if (type === 'object') {
+          for (var i = 0; i < length; i++) {
+            this.parent[i + this.offset] = subject[i];
+          }
+        } else {
+          // We are a string
+          this.write(subject, 0, encoding);
+        }
+      }
+    }
+  }
+
+  // Make sure the api is equivilent to old buffers, unless user doesn't
+  // want overhead
+  if (legacy !== false) {
+    Buffer.makeFastBuffer(this.parent, this, this.offset, this.length);
+  }
+}
+
+exports.FastBuffer = FastBuffer;
+exports.Buffer     = FastBuffer;
+
+// Static methods
+FastBuffer.isBuffer = function isBuffer(b) {
+  return b instanceof FastBuffer;
+};
+
+// Inspect
+FastBuffer.prototype.inspect = function inspect() {
+  var out = [],
+      len = this.length;
+  for (var i = 0; i < len; i++) {
+    out[i] = toHex(this.parent[i + this.offset]);
+  }
+  return "<Buffer " + out.join(" ") + ">";
+};
+
+FastBuffer.prototype.get = function (i) {
+  if (i < 0 || i >= this.length) throw new Error("oob");
+  return this.parent[this.offset + i];
+};
+
+FastBuffer.prototype.set = function (i, v) {
+  if (i < 0 || i >= this.length) throw new Error("oob");
+  return this.parent[this.offset + i] = v;
+};
+
+// TODO define slice, toString, write, etc.
+// slice should not use c++
+
+// write(string, offset = 0, encoding = 'uft8')
+FastBuffer.prototype.write = function write (string, offset, encoding) {
+  if (!isFinite(offset)) {
+    var swap = encoding;
+    encoding = offset;
+    offset = swap;
+  }
+
+  var max_length;
+  offset   || (offset   = 0);
+  encoding || (encoding = 'uft8');
+
+  // Make sure we are not going to overflow
+  max_length = this.length - offset;
+  if (string.length > max_length) {
+    string = string.slice(0, max_length);
+  }
+
+  return this.parent.write(string, this.offset + offset, encoding);
+}
+
+// toString(encoding, start=0, end=buffer.length)
+FastBuffer.prototype.toString = function toSting (encoding, start, end) {
+  encoding || (encoding = 'utf8');
+  start    || (start    = 0);
+  end      || (end      = this.length);
+
+  // Make sure we aren't oob
+  if (end > this.length) {
+    end = this.length;
+  }
+
+  return this.parent.toString(encoding, start + this.offset, end + this.offset);
+};
+
+// byteLength
+FastBuffer.byteLength = Buffer.byteLength;
+
+// copy(targetBuffer, targetStart, sourceStart, sourceEnd=buffer.length)
+FastBuffer.prototype.copy = function copy (target_buffer, target_start, start, end) {
+  start || (start = 0);
+  end   || (end   = this.length);
+
+  // Are we oob?
+  if (end > this.length) {
+    end = this.length;
+  }
+
+  return this.parent.copy(target_buffer, target_start, start + this.offset, end + this.offset);
+};
+
+// slice(start, end)
+FastBuffer.prototype.slice = function slice (start, end, legacy) {
+  if (end > this.length) {
+    throw new Error("oob");
+  }
+  if (start > end) {
+    throw new Error("oob");
+  }
+
+  return new FastBuffer(this.parent, end - start, +start + this.offset, legacy);
+};
diff --git a/src/node_buffer.cc b/src/node_buffer.cc
@@ -264,6 +264,21 @@ Buffer::~Buffer() {
 }
 
 
+Handle<Value> Buffer::MakeFastBuffer(const Arguments &args) {
+  HandleScope scope;
+
+  Buffer *buffer = ObjectWrap::Unwrap<Buffer>(args[0]->ToObject());
+  Local<Object> fast_buffer = args[1]->ToObject();;
+  uint32_t offset = args[2]->Uint32Value();
+  uint32_t length = args[3]->Uint32Value();
+
+  fast_buffer->SetIndexedPropertiesToPixelData((uint8_t*)buffer->data() + offset,
+                                               length);
+
+  return Undefined();
+}
+
+
 char* Buffer::data() {
   return blob_->data + off_;
 }
diff --git a/src/node_buffer.h b/src/node_buffer.h
@@ -51,6 +51,7 @@ class Buffer : public ObjectWrap {
   static v8::Persistent<v8::FunctionTemplate> constructor_template;
 
   static v8::Handle<v8::Value> New(const v8::Arguments &args);
+  static v8::Handle<v8::Value> MakeFastBuffer(const v8::Arguments &args);
   static v8::Handle<v8::Value> Slice(const v8::Arguments &args);
   static v8::Handle<v8::Value> BinarySlice(const v8::Arguments &args);
   static v8::Handle<v8::Value> AsciiSlice(const v8::Arguments &args);
