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Merge pull request #1029 from belldon/vtable_reuse

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Update C# FlatBufferBuilder to reuse vtable array
This commit is contained in:
Wouter van Oortmerssen
2015-12-07 14:42:04 -08:00
parent 8e6758d205 d5a113e5bf
commit 8bb45dc0a6
1 changed files with 27 additions and 12 deletions
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39
net/FlatBuffers/FlatBufferBuilder.cs
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@@ -14,9 +14,11 @@
* limitations under the License. * limitations under the License.
*/ */
using System; using System;
using System.Text; using System.Text;
namespace FlatBuffers namespace FlatBuffers
{ {
/// <summary> /// <summary>
@@ -29,8 +31,10 @@ namespace FlatBuffers
private ByteBuffer _bb; private ByteBuffer _bb;
private int _minAlign = 1; private int _minAlign = 1;
// The vtable for the current table, null otherwise. // The vtable for the current table (if _vtableSize >= 0)
private int[] _vtable; private int[] _vtable = new int[16];
// The size of the vtable. -1 indicates no vtable
private int _vtableSize = -1;
// Starting offset of the current struct/table. // Starting offset of the current struct/table.
private int _objectStart; private int _objectStart;
// List of offsets of all vtables. // List of offsets of all vtables.
@@ -54,9 +58,9 @@ namespace FlatBuffers
_space = _bb.Length; _space = _bb.Length;
_bb.Reset(); _bb.Reset();
_minAlign = 1; _minAlign = 1;
_vtable = null; while (_vtableSize > 0) _vtable[--_vtableSize] = 0;
_vtableSize = -1;
_objectStart = 0; _objectStart = 0;
_vtables = new int[16];
_numVtables = 0; _numVtables = 0;
_vectorNumElems = 0; _vectorNumElems = 0;
} }
@@ -226,15 +230,22 @@ namespace FlatBuffers
{ {
// You should not be creating any other objects or strings/vectors // You should not be creating any other objects or strings/vectors
// while an object is being constructed // while an object is being constructed
if (_vtable != null) if (_vtableSize >= 0)
throw new Exception( throw new Exception(
"FlatBuffers: object serialization must not be nested."); "FlatBuffers: object serialization must not be nested.");
} }
public void StartObject(int numfields) public void StartObject(int numfields)
{ {
if (numfields < 0)
throw new ArgumentOutOfRangeException("Flatbuffers: invalid numfields");
NotNested(); NotNested();
_vtable = new int[numfields];
if (_vtable.Length < numfields)
_vtable = new int[numfields];
_vtableSize = numfields;
_objectStart = Offset; _objectStart = Offset;
} }
@@ -243,6 +254,9 @@ namespace FlatBuffers
// buffer. // buffer.
public void Slot(int voffset) public void Slot(int voffset)
{ {
if (voffset >= _vtableSize)
throw new IndexOutOfRangeException("Flatbuffers: invalid voffset");
_vtable[voffset] = Offset; _vtable[voffset] = Offset;
} }
@@ -284,30 +298,31 @@ namespace FlatBuffers
public int EndObject() public int EndObject()
{ {
if (_vtableSize < 0)
if (_vtable == null)
throw new InvalidOperationException( throw new InvalidOperationException(
"Flatbuffers: calling endObject without a startObject"); "Flatbuffers: calling endObject without a startObject");
AddInt((int)0); AddInt((int)0);
var vtableloc = Offset; var vtableloc = Offset;
// Write out the current vtable. // Write out the current vtable.
for (int i = _vtable.Length - 1; i >= 0 ; i--) { for (int i = _vtableSize - 1; i >= 0 ; i--) {
// Offset relative to the start of the table. // Offset relative to the start of the table.
short off = (short)(_vtable[i] != 0 short off = (short)(_vtable[i] != 0
? vtableloc - _vtable[i] ? vtableloc - _vtable[i]
: 0); : 0);
AddShort(off); AddShort(off);
// clear out written entry
_vtable[i] = 0;
} }
const int standardFields = 2; // The fields below: const int standardFields = 2; // The fields below:
AddShort((short)(vtableloc - _objectStart)); AddShort((short)(vtableloc - _objectStart));
AddShort((short)((_vtable.Length + standardFields) * AddShort((short)((_vtableSize + standardFields) *
sizeof(short))); sizeof(short)));
// Search for an existing vtable that matches the current one. // Search for an existing vtable that matches the current one.
int existingVtable = 0; int existingVtable = 0;
for (int i = 0; i < _numVtables; i++) { for (int i = 0; i < _numVtables; i++) {
int vt1 = _bb.Length - _vtables[i]; int vt1 = _bb.Length - _vtables[i];
int vt2 = _space; int vt2 = _space;
@@ -348,7 +363,7 @@ namespace FlatBuffers
_bb.PutInt(_bb.Length - vtableloc, Offset - vtableloc); _bb.PutInt(_bb.Length - vtableloc, Offset - vtableloc);
} }
_vtable = null; _vtableSize = -1;
return vtableloc; return vtableloc;
} }