Index: sdk/lib/io/buffer_list.dart |
diff --git a/sdk/lib/io/buffer_list.dart b/sdk/lib/io/buffer_list.dart |
index 72dc92ff03d07d284b786402aab448d8bfe9c406..c61710f2fd20ca1b75e79e0079d1da6df5f87587 100644 |
--- a/sdk/lib/io/buffer_list.dart |
+++ b/sdk/lib/io/buffer_list.dart |
@@ -5,153 +5,91 @@ |
part of dart.io; |
/** |
- * Utility class that holds a number of byte buffers and can deliver |
- * the bytes either one by one or in chunks. |
+ * Utility class that can fast concatenate [List<int>]s of bytes. Use |
+ * [readBytes] to get the final buffer. |
*/ |
class _BufferList { |
+ const int _INIT_SIZE = 1 * 1024; |
+ |
_BufferList() { |
clear(); |
} |
- /** |
- * Adds a new buffer to the list possibly with an offset of the |
- * first byte of interest. The offset can only be specified if the |
- * buffer list is empty. |
- */ |
- void add(List<int> buffer, [int offset = 0]) { |
- assert(offset == 0 || _buffers.isEmpty); |
- _buffers.addLast(buffer); |
- _length += buffer.length; |
- if (offset != 0) _index = offset; |
- } |
- |
- /** Alias for [add]. */ |
- void write(List<int> buffer, [int offset = 0]) { |
- add(buffer, offset); |
+ int pow2roundup(int x) { |
+ --x; |
+ x |= x >> 1; |
+ x |= x >> 2; |
+ x |= x >> 4; |
+ x |= x >> 8; |
+ x |= x >> 16; |
+ return x + 1; |
} |
/** |
- * Returns the first buffer from the list. This returns the whole |
- * buffer and does not remove the buffer from the list. Use |
- * [index] to determine the index of the first byte in the buffer. |
- */ |
- List<int> get first => _buffers.first; |
- |
- /** |
- * Returns the current index of the next byte. This will always be |
- * an index into the first buffer as when the index is advanced past |
- * the end of a buffer it is removed from the list. |
- */ |
- int get index => _index; |
- |
- /** |
- * Peek at the next available byte. |
- */ |
- int peek() => _buffers.first[_index]; |
- |
- /** |
- * Returns the next available byte removing it from the buffers. |
+ * Adds a new buffer to the list. |
*/ |
- int next() { |
- int value = _buffers.first[_index++]; |
- _length--; |
- if (_index == _buffers.first.length) { |
- _buffers.removeFirst(); |
- _index = 0; |
+ void add(List<int> buffer) { |
+ int bufferLength = buffer.length; |
+ int required = _length + bufferLength; |
+ if (_buffer == null) { |
+ int size = pow2roundup(required); |
+ if (size < _INIT_SIZE) size = _INIT_SIZE; |
+ _buffer = new Uint8List(size); |
+ } else if (_buffer.length < required) { |
+ // This will give is a list in the range of 2-4 times larger than |
+ // required. |
+ int size = pow2roundup(required) * 2; |
+ Uint8List newBuffer = new Uint8List(size); |
+ newBuffer.setRange(0, _buffer.length, _buffer); |
+ _buffer = newBuffer; |
} |
- return value; |
- } |
- |
- /** |
- * Read [count] bytes from the buffer list. If the number of bytes |
- * requested is not available null will be returned. |
- */ |
- List<int> readBytes([int count]) { |
- if (count == null) count = length; |
- List<int> result; |
- if (_length == 0) return new Uint8List(0); |
- if (_length < count) return null; |
- if (_index == 0 && _buffers.first.length == count) { |
- result = _buffers.first; |
- _buffers.removeFirst(); |
- _index = 0; |
- _length -= count; |
- return result; |
+ assert(_buffer.length >= required); |
+ if (buffer is Uint8List) { |
+ _buffer.setRange(_length, required, buffer); |
} else { |
- int firstRemaining = _buffers.first.length - _index; |
- if (firstRemaining >= count) { |
- result = _buffers.first.sublist(_index, _index + count); |
- _index += count; |
- _length -= count; |
- if (_index == _buffers.first.length) { |
- _buffers.removeFirst(); |
- _index = 0; |
- } |
- return result; |
- } else { |
- result = new Uint8List(count); |
- int remaining = count; |
- while (remaining > 0) { |
- int bytesInFirst = _buffers.first.length - _index; |
- if (bytesInFirst <= remaining) { |
- int startIndex = count - remaining; |
- int endIndex = startIndex + bytesInFirst; |
- result.setRange(startIndex, endIndex, _buffers.first, _index); |
- _buffers.removeFirst(); |
- _index = 0; |
- _length -= bytesInFirst; |
- remaining -= bytesInFirst; |
- } else { |
- result.setRange(count - remaining, count, _buffers.first, _index); |
- _index = remaining; |
- _length -= remaining; |
- remaining = 0; |
- assert(_index < _buffers.first.length); |
- } |
- } |
- return result; |
+ for (int i = 0; i < bufferLength; i++) { |
+ _buffer[_length + i] = buffer[i]; |
} |
} |
+ _length = required; |
} |
/** |
- * Remove a number of bytes from the buffer list. Currently the |
- * number of bytes to remove must be confined to the first buffer. |
+ * Same as [add]. |
*/ |
- void removeBytes(int count) { |
- int firstRemaining = first.length - _index; |
- assert(count <= firstRemaining); |
- if (count == firstRemaining) { |
- _buffers.removeFirst(); |
- _index = 0; |
- } else { |
- _index += count; |
- } |
- _length -= count; |
+ void write(List<int> buffer) { |
+ add(buffer); |
} |
+ /** |
+ * Read all the bytes from the buffer list. If it's empty, an empty list |
+ * is returned. A call to [readBytes] will clear the buffer. |
+ */ |
+ List<int> readBytes() { |
+ if (_buffer == null) return new Uint8List(0); |
+ var buffer = new Uint8List.view(_buffer.buffer, 0, _length); |
+ clear(); |
+ return buffer; |
+ } |
/** |
- * Returns the total number of bytes remaining in the buffers. |
+ * Returns the total number of bytes in the buffer. |
*/ |
int get length => _length; |
/** |
- * Returns whether the buffer list is empty that is has no bytes |
- * available. |
+ * Returns whether the buffer list is empty. |
*/ |
- bool get isEmpty => _buffers.isEmpty; |
+ bool get isEmpty => _length == 0; |
/** |
* Clears the content of the buffer list. |
*/ |
void clear() { |
- _index = 0; |
_length = 0; |
- _buffers = new Queue(); |
+ _buffer = null; |
} |
- int _length; // Total number of bytes remaining in the buffers. |
- Queue<List<int>> _buffers; // List of data buffers. |
- int _index; // Index of the next byte in the first buffer. |
+ int _length; // Total number of bytes in the buffer. |
+ Uint8List _buffer; // Internal buffer. |
} |