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In RenderBatchWriter, deduplicate strings only when safe to do so (#1340) 

We allow deduplication of HTML element and attribute names, plus whitespace text nodes / attribute values.
This commit is contained in:
Steve Sanderson 2018-08-22 14:52:35 +01:00 committed by GitHub
parent 3a2606a636
commit 1089eecbfc
2 changed files with 94 additions and 23 deletions
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38
src/Microsoft.AspNetCore.Blazor.Server/Circuits/RenderBatchWriter.cs
View File

@ -34,11 +34,13 @@ namespace Microsoft.AspNetCore.Blazor.Server.Circuits
internal class RenderBatchWriter : IDisposable
{
private readonly List<string> _strings;
private readonly Dictionary<string, int> _deduplicatedStringIndices;
private readonly BinaryWriter _binaryWriter;
public RenderBatchWriter(Stream output, bool leaveOpen)
{
_strings = new List<string>();
_deduplicatedStringIndices = new Dictionary<string, int>();
_binaryWriter = new BinaryWriter(output, Encoding.UTF8, leaveOpen);
}
@ -104,7 +106,7 @@ namespace Microsoft.AspNetCore.Blazor.Server.Circuits
_binaryWriter.Write((int)edit.Type);
_binaryWriter.Write(edit.SiblingIndex);
_binaryWriter.Write(edit.ReferenceFrameIndex);
WriteString(edit.RemovedAttributeName);
WriteString(edit.RemovedAttributeName, allowDeduplication: true);
}
int Write(in ArrayRange<RenderTreeFrame> frames)
@ -137,7 +139,7 @@ namespace Microsoft.AspNetCore.Blazor.Server.Circuits
switch (frame.FrameType)
{
case RenderTreeFrameType.Attribute:
WriteString(frame.AttributeName);
WriteString(frame.AttributeName, allowDeduplication: true);
if (frame.AttributeValue is bool boolValue)
{
// Encoding the bool as either "" or null is pretty odd, but avoids
@ -147,11 +149,12 @@ namespace Microsoft.AspNetCore.Blazor.Server.Circuits
// or something else, we'll need a different encoding mechanism. Since there
// would never be more than (say) 2^28 (268 million) distinct string table
// entries, we could use the first 4 bits to encode the value type.
WriteString(boolValue ? string.Empty : null);
WriteString(boolValue ? string.Empty : null, allowDeduplication: true);
}
else
{
WriteString(frame.AttributeValue as string);
var attributeValueString = frame.AttributeValue as string;
WriteString(attributeValueString, allowDeduplication: string.IsNullOrEmpty(attributeValueString));
}
_binaryWriter.Write(frame.AttributeEventHandlerId);
break;
@ -168,11 +171,11 @@ namespace Microsoft.AspNetCore.Blazor.Server.Circuits
break;
case RenderTreeFrameType.Element:
_binaryWriter.Write(frame.ElementSubtreeLength);
WriteString(frame.ElementName);
WriteString(frame.ElementName, allowDeduplication: true);
WritePadding(_binaryWriter, 4);
break;
case RenderTreeFrameType.ElementReferenceCapture:
WriteString(frame.ElementReferenceCaptureId);
WriteString(frame.ElementReferenceCaptureId, allowDeduplication: false);
WritePadding(_binaryWriter, 8);
break;
case RenderTreeFrameType.Region:
@ -180,11 +183,13 @@ namespace Microsoft.AspNetCore.Blazor.Server.Circuits
WritePadding(_binaryWriter, 8);
break;
case RenderTreeFrameType.Text:
WriteString(frame.TextContent);
WriteString(
frame.TextContent,
allowDeduplication: string.IsNullOrWhiteSpace(frame.TextContent));
WritePadding(_binaryWriter, 8);
break;
case RenderTreeFrameType.Markup:
WriteString(frame.MarkupContent);
WriteString(frame.MarkupContent, allowDeduplication: false);
WritePadding(_binaryWriter, 8);
break;
default:
@ -207,7 +212,7 @@ namespace Microsoft.AspNetCore.Blazor.Server.Circuits
return startPos;
}
void WriteString(string value)
void WriteString(string value, bool allowDeduplication)
{
if (value == null)
{
@ -215,9 +220,20 @@ namespace Microsoft.AspNetCore.Blazor.Server.Circuits
}
else
{
var stringIndex = _strings.Count;
int stringIndex;
if (!allowDeduplication || !_deduplicatedStringIndices.TryGetValue(value, out stringIndex))
{
stringIndex = _strings.Count;
_strings.Add(value);
if (allowDeduplication)
{
_deduplicatedStringIndices.Add(value, stringIndex);
}
}
_binaryWriter.Write(stringIndex);
_strings.Add(value);
}
}

79
test/Microsoft.AspnetCore.Blazor.Server.Test/Circuits/RenderBatchWriterTest.cs
View File

@ -6,6 +6,7 @@ using Microsoft.AspNetCore.Blazor.Rendering;
using Microsoft.AspNetCore.Blazor.RenderTree;
using Microsoft.AspNetCore.Blazor.Server.Circuits;
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using Xunit;
@ -147,6 +148,7 @@ namespace Microsoft.AspNetCore.Blazor.Server
RenderTreeEdit.StepIn(107),
RenderTreeEdit.StepOut(),
RenderTreeEdit.UpdateMarkup(108, 109),
RenderTreeEdit.RemoveAttribute(110, "Some removed attribute"), // To test deduplication
};
var bytes = Serialize(new RenderBatch(
new ArrayRange<RenderTreeDiff>(new[]
@ -166,7 +168,7 @@ namespace Microsoft.AspNetCore.Blazor.Server
AssertBinaryContents(bytes, 0,
123, // Component ID for diff 0
8, // diff[0].Edits.Count
9, // diff[0].Edits.Count
RenderTreeEditType.PrependFrame, 456, 789, NullStringMarker,
RenderTreeEditType.RemoveFrame, 101, 0, NullStringMarker,
RenderTreeEditType.SetAttribute, 102, 103, NullStringMarker,
@ -174,8 +176,12 @@ namespace Microsoft.AspNetCore.Blazor.Server
RenderTreeEditType.UpdateText, 105, 106, NullStringMarker,
RenderTreeEditType.StepIn, 107, 0, NullStringMarker,
RenderTreeEditType.StepOut, 0, 0, NullStringMarker,
RenderTreeEditType.UpdateMarkup, 108, 109, NullStringMarker
RenderTreeEditType.UpdateMarkup, 108, 109, NullStringMarker,
RenderTreeEditType.RemoveAttribute, 110, 0, "Some removed attribute"
);
// We can deduplicate attribute names
Assert.Equal(new[] { "Some removed attribute" }, ReadStringTable(bytes));
}
[Fact]
@ -201,14 +207,23 @@ namespace Microsoft.AspNetCore.Blazor.Server
.WithRegionSubtreeLength(1234),
RenderTreeFrame.Text(131, "Some text"),
RenderTreeFrame.Markup(132, "Some markup"),
}, 10),
RenderTreeFrame.Text(133, "\n\t "),
// Testing deduplication
RenderTreeFrame.Attribute(134, "Attribute with string value", "String value"),
RenderTreeFrame.Element(135, "Some element") // Will be dedupliated
.WithElementSubtreeLength(999),
RenderTreeFrame.Text(136, "Some text"), // Will not be deduplicated
RenderTreeFrame.Markup(137, "Some markup"), // Will not be deduplicated
RenderTreeFrame.Text(138, "\n\t "), // Will be deduplicated
}, 16),
default,
default));
// Assert
var referenceFramesStartIndex = ReadInt(bytes, bytes.Length - 16);
AssertBinaryContents(bytes, referenceFramesStartIndex,
10, // Number of frames
16, // Number of frames
RenderTreeFrameType.Attribute, "Attribute with string value", "String value", 0,
RenderTreeFrameType.Attribute, "Attribute with nonstring value", NullStringMarker, 0,
RenderTreeFrameType.Attribute, "Attribute with delegate value", NullStringMarker, 789,
@ -218,8 +233,30 @@ namespace Microsoft.AspNetCore.Blazor.Server
RenderTreeFrameType.ElementReferenceCapture, "my unique ID", 0, 0,
RenderTreeFrameType.Region, 1234, 0, 0,
RenderTreeFrameType.Text, "Some text", 0, 0,
RenderTreeFrameType.Markup, "Some markup", 0, 0
RenderTreeFrameType.Markup, "Some markup", 0, 0,
RenderTreeFrameType.Text, "\n\t ", 0, 0,
RenderTreeFrameType.Attribute, "Attribute with string value", "String value", 0,
RenderTreeFrameType.Element, 999, "Some element", 0,
RenderTreeFrameType.Text, "Some text", 0, 0,
RenderTreeFrameType.Markup, "Some markup", 0, 0,
RenderTreeFrameType.Text, "\n\t ", 0, 0
);
Assert.Equal(new[]
{
"Attribute with string value",
"String value",
"Attribute with nonstring value",
"Attribute with delegate value",
"Some element",
"my unique ID",
"Some text",
"Some markup",
"\n\t ",
"String value",
"Some text",
"Some markup",
}, ReadStringTable(bytes));
}
private Span<byte> Serialize(RenderBatch renderBatch)
@ -232,12 +269,34 @@ namespace Microsoft.AspNetCore.Blazor.Server
}
}
static void AssertBinaryContents(Span<byte> data, int startIndex, params object[] entries)
static string[] ReadStringTable(Span<byte> data)
{
var bytes = data.ToArray();
// The string table position is given by the final int
// The string table position is given by the final int, and continues
// until we get to the final set of top-level indices
var stringTableStartPosition = BitConverter.ToInt32(bytes, bytes.Length - 4);
var stringTableEndPositionExcl = bytes.Length - 20;
var result = new List<string>();
for (var entryPosition = stringTableStartPosition;
entryPosition < stringTableEndPositionExcl;
entryPosition += 4)
{
// The string table entries are all length-prefixed UTF8 blobs
var tableEntryPos = BitConverter.ToInt32(bytes, entryPosition);
var length = (int)ReadUnsignedLEB128(bytes, tableEntryPos, out var numLEB128Bytes);
var value = Encoding.UTF8.GetString(bytes, tableEntryPos + numLEB128Bytes, length);
result.Add(value);
}
return result.ToArray();
}
static void AssertBinaryContents(Span<byte> data, int startIndex, params object[] entries)
{
var bytes = data.ToArray();
var stringTableEntries = ReadStringTable(data);
using (var ms = new MemoryStream(bytes))
using (var reader = new BinaryReader(ms))
@ -267,11 +326,7 @@ namespace Microsoft.AspNetCore.Blazor.Server
}
else
{
// The string table entries are all length-prefixed UTF8 blobs
var tableEntryPos = BitConverter.ToInt32(bytes, stringTableStartPosition + 4 * indexIntoStringTable);
var length = (int)ReadUnsignedLEB128(bytes, tableEntryPos, out var numLEB128Bytes);
var value = Encoding.UTF8.GetString(bytes, tableEntryPos + numLEB128Bytes, length);
Assert.Equal(expectedString, value);
Assert.Equal(expectedString, stringTableEntries[indexIntoStringTable]);
}
}
else