reduce new Uint8Array in Encoder

Author: gfx

Makefile

@@ -1,9 +1,13 @@
+
 test:
+	npm run test
+
+test-all:
 	npm ci
 	npm run test:browser
 	npm run test:cover
 
-publish: validate-git-status test
+publish: validate-git-status test-all
 	npm publish
 	git push origin master
 	git push origin master --tags

src/Encoder.ts

@@ -11,6 +11,7 @@ export const DEFAULT_INITIAL_BUFFER_SIZE = 1024;
 export class Encoder {
   private pos = 0;
   private view = new DataView(new ArrayBuffer(this.initialBufferSize));
+  private bytes = new Uint8Array(this.view.buffer);
 
   constructor(
     readonly extensionCodec = ExtensionCodec.defaultCodec,
@@ -37,7 +38,7 @@ export class Encoder {
   }
 
   getUint8Array(): Uint8Array {
-    return new Uint8Array(this.view.buffer, this.view.byteOffset, this.pos);
+    return this.bytes.subarray(0, this.pos);
   }
 
   ensureBufferSizeToWrite(sizeToWrite: number) {
@@ -50,11 +51,13 @@ export class Encoder {
 
   resizeBuffer(newSize: number) {
     const newBuffer = new ArrayBuffer(newSize);
+    const newBytes = new Uint8Array(newBuffer);
+    const newView = new DataView(newBuffer);
 
-    new Uint8Array(newBuffer).set(new Uint8Array(this.view.buffer));
+    newBytes.set(this.bytes);
 
-    const newView = new DataView(newBuffer);
     this.view = newView;
+    this.bytes = newBytes;
   }
 
   encodeNil() {
@@ -148,8 +151,7 @@ export class Encoder {
       const maxSize = maxHeaderSize + strLength * 4;
       this.ensureBufferSizeToWrite(maxSize);
 
-      const output = new Uint8Array(this.view.buffer, this.view.byteOffset + this.pos);
-      const consumedLength = utf8EncodeWasm(object, output);
+      const consumedLength = utf8EncodeWasm(object, this.bytes, this.pos);
       this.pos += consumedLength;
       return;
     } else {

src/wasmFunctions.ts

@@ -45,7 +45,7 @@ function setMemoryStr(destPtr: pointer, destByteLength: number, str: string, str
  * It encodes string to MessagePack str family (headByte/size + utf8 bytes).
  * @returns The whole byte length including headByte/size.
  */
-export function utf8EncodeWasm(str: string, output: Uint8Array): number {
+export function utf8EncodeWasm(str: string, output: Uint8Array, outputOffset: number): number {
   const strLength = str.length;
   const inputByteLength = strLength * 2;
   const inputU16BePtr: pointer = wm.malloc(inputByteLength);
@@ -55,7 +55,7 @@ export function utf8EncodeWasm(str: string, output: Uint8Array): number {
   const outputPtr: pointer = wm.malloc(maxOutputHeaderSize + strLength * 4);
   try {
     const outputLength = wm.utf8EncodeUint16Array(outputPtr, inputU16BePtr, strLength);
-    output.set(new Uint8Array(wm.memory.buffer, outputPtr, outputLength));
+    output.set(new Uint8Array(wm.memory.buffer, outputPtr, outputLength), outputOffset);
     return outputLength;
   } finally {
     wm.free(inputU16BePtr);