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Dart - make vTable deduplication optional (#6734)

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This commit is contained in:
Ivan Dlugos
2021-07-16 00:50:12 +02:00
committed by GitHub
parent e8423da1b7
commit dd5bb55cad
13 changed files with 54 additions and 47 deletions
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37
dart/lib/flat_buffers.dart
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@@ -108,8 +108,9 @@ class Builder {
final int initialSize;
/// The list of existing VTable(s).
final List<int> _vTables = List<int>.filled(16, 0, growable: true)
..length = 0;
final List<int> _vTables;
final bool deduplicateTables;
ByteData _buf;
@@ -146,8 +147,10 @@ class Builder {
this.initialSize: 1024,
bool internStrings = false,
Allocator allocator = const DefaultAllocator(),
this.deduplicateTables = true,
}) : _allocator = allocator,
_buf = allocator.allocate(initialSize) {
_buf = allocator.allocate(initialSize),
_vTables = deduplicateTables ? [] : const [] {
if (internStrings) {
_strings = new Map<String, int>();
}
@@ -309,26 +312,30 @@ class Builder {
int? vTableTail;
{
currentVTable.computeFieldOffsets(tableTail);
// Try to find an existing compatible VTable.
// Search backward - more likely to have recently used one
for (int i = _vTables.length - 1; i >= 0; i--) {
final int vt2Offset = _vTables[i];
final int vt2Start = _buf.lengthInBytes - vt2Offset;
final int vt2Size = _buf.getUint16(vt2Start, Endian.little);
if (currentVTable._vTableSize == vt2Size &&
currentVTable._offsetsMatch(vt2Start, _buf)) {
vTableTail = vt2Offset;
break;
// Try to find an existing compatible VTable.
if (deduplicateTables) {
// Search backward - more likely to have recently used one
for (int i = _vTables.length - 1; i >= 0; i--) {
final int vt2Offset = _vTables[i];
final int vt2Start = _buf.lengthInBytes - vt2Offset;
final int vt2Size = _buf.getUint16(vt2Start, Endian.little);
if (currentVTable._vTableSize == vt2Size &&
currentVTable._offsetsMatch(vt2Start, _buf)) {
vTableTail = vt2Offset;
break;
}
}
}
// Write a new VTable.
if (vTableTail == null) {
_prepare(_sizeofUint16, _currentVTable!.numOfUint16);
vTableTail = _tail;
currentVTable.tail = vTableTail;
currentVTable.output(_buf, _buf.lengthInBytes - _tail);
_vTables.add(currentVTable.tail);
if (deduplicateTables) _vTables.add(currentVTable.tail);
}
}
// Set the VTable offset.
@@ -459,7 +466,7 @@ class Builder {
_maxAlign = 1;
_tail = 0;
_currentVTable = null;
_vTables.length = 0;
if (deduplicateTables) _vTables.clear();
if (_strings != null) {
_strings = new Map<String, int>();
}