Replace buffer.slice in text search with buffer.toString(undefined, start, end).

roblourens · roblourens · commit 740457e881bf · 2016-11-23T11:24:30.000-08:00
This is much faster although it's not totally obvious why. But it's run for every line of every file in the workspace so it's very sensitive. See microsoft#15384.
diff --git a/src/vs/workbench/services/search/node/textSearch.ts b/src/vs/workbench/services/search/node/textSearch.ts
@@ -166,16 +166,16 @@ export class Engine implements ISearchEngine<ISerializedFileMatch> {
 
 			const outer = this;
 
-			function decodeBuffer(buffer: NodeBuffer): string {
+			function decodeBuffer(buffer: NodeBuffer, start: number, end: number): string {
 				if (options.encoding === UTF8 || options.encoding === UTF8_with_bom) {
-					return buffer.toString(); // much faster to use built in toString() when encoding is default
+					return buffer.toString(undefined, start, end); // much faster to use built in toString() when encoding is default
 				}
 
-				return decode(buffer, options.encoding);
+				return decode(buffer.slice(start, end), options.encoding);
 			}
 
 			function lineFinished(offset: number): void {
-				line += decodeBuffer(buffer.slice(pos, i + offset));
+				line += decodeBuffer(buffer, pos, i + offset);
 				perLineCallback(line, lineNumber);
 				line = '';
 				lineNumber++;
@@ -245,7 +245,7 @@ export class Engine implements ISearchEngine<ISerializedFileMatch> {
 						}
 					}
 
-					line += decodeBuffer(buffer.slice(pos, bytesRead));
+					line += decodeBuffer(buffer, pos, bytesRead);
 
 					readFile(false /* isFirstRead */, clb); // Continue reading
 				});

Original file line number	Diff line number	Diff line change
`@@ -166,16 +166,16 @@ export class Engine implements ISearchEngine<ISerializedFileMatch> {`
`166`	`166`
`167`	`167`	`const outer = this;`
`168`	`168`
`169`		`- function decodeBuffer(buffer: NodeBuffer): string {`
	`169`	`+ function decodeBuffer(buffer: NodeBuffer, start: number, end: number): string {`
`170`	`170`	`if (options.encoding === UTF8 \|\| options.encoding === UTF8_with_bom) {`
`171`		`- return buffer.toString(); // much faster to use built in toString() when encoding is default`
	`171`	`+ return buffer.toString(undefined, start, end); // much faster to use built in toString() when encoding is default`
`172`	`172`	`}`
`173`	`173`
`174`		`- return decode(buffer, options.encoding);`
	`174`	`+ return decode(buffer.slice(start, end), options.encoding);`
`175`	`175`	`}`
`176`	`176`
`177`	`177`	`function lineFinished(offset: number): void {`
`178`		`- line += decodeBuffer(buffer.slice(pos, i + offset));`
	`178`	`+ line += decodeBuffer(buffer, pos, i + offset);`
`179`	`179`	`perLineCallback(line, lineNumber);`
`180`	`180`	`line = '';`
`181`	`181`	`lineNumber++;`
`@@ -245,7 +245,7 @@ export class Engine implements ISearchEngine<ISerializedFileMatch> {`
`245`	`245`	`}`
`246`	`246`	`}`
`247`	`247`
`248`		`- line += decodeBuffer(buffer.slice(pos, bytesRead));`
	`248`	`+ line += decodeBuffer(buffer, pos, bytesRead);`
`249`	`249`
`250`	`250`	`readFile(false /* isFirstRead */, clb); // Continue reading`
`251`	`251`	`});`