extract KeyDecoder interface

gfx · gfx · commit bc71d5cf8b40 · 2020-09-06T14:15:33.000+09:00
diff --git a/.eslintrc.js b/.eslintrc.js
@@ -45,7 +45,7 @@ module.exports = {
     "@typescript-eslint/no-throw-literal": "warn",
     "@typescript-eslint/no-extra-semi": "warn",
     "@typescript-eslint/no-extra-non-null-assertion": "warn",
-    "@typescript-eslint/no-unused-vars": "warn",
+    "@typescript-eslint/no-unused-vars": ["warn", { "argsIgnorePattern": "^_" }],
     "@typescript-eslint/no-use-before-define": "warn",
     "@typescript-eslint/no-for-in-array": "warn",
     "@typescript-eslint/no-unnecessary-condition": ["warn", { "allowConstantLoopConditions": true }],
diff --git a/benchmark/benchmark-from-msgpack-lite.ts b/benchmark/benchmark-from-msgpack-lite.ts
@@ -69,6 +69,11 @@ if (msgpack_msgpack) {
   buf = bench('buf = /* @msgpack/msgpack */ encoder.encode(obj);', (data) => encoder.encode(data), data);
   obj = bench('obj = /* @msgpack/msgpack */ decoder.decodeSync(buf);', (buf) => decoder.decodeSync(buf), buf);
   runTest(obj);
+
+  if (process.env.CACHE_HIT_RATE) {
+    const {hit, miss} = decoder.keyDecoder;
+    console.log(`CACHE_HIT_RATE: cache hit rate in CachedKeyDecoder: hit=${hit}, hiss=${miss}, hit rate=${hit / (hit + miss)}`);
+  }
 }
 
 if (msgpack_js_v5) {
diff --git a/src/CachedKeyDecoder.ts b/src/CachedKeyDecoder.ts
@@ -8,7 +8,14 @@ interface KeyCacheRecord {
 const DEFAULT_MAX_KEY_LENGTH = 16;
 const DEFAULT_MAX_LENGTH_PER_KEY = 16;
 
-export class CachedKeyDecoder {
+export interface KeyDecoder {
+  canBeCached(byteLength: number): boolean;
+  decode(bytes: Uint8Array, inputOffset: number, byteLength: number): string;
+}
+
+export class CachedKeyDecoder implements KeyDecoder {
+  hit = 0;
+  miss = 0;
   private readonly caches: Array<Array<KeyCacheRecord>>;
 
   constructor(readonly maxKeyLength = DEFAULT_MAX_KEY_LENGTH, readonly maxLengthPerKey = DEFAULT_MAX_LENGTH_PER_KEY) {
@@ -57,8 +64,10 @@ export class CachedKeyDecoder {
   public decode(bytes: Uint8Array, inputOffset: number, byteLength: number): string {
     const cachedValue = this.get(bytes, inputOffset, byteLength);
     if (cachedValue != null) {
+      this.hit++;
       return cachedValue;
     }
+    this.miss++;
 
     const value = utf8DecodeJs(bytes, inputOffset, byteLength);
     // Ensure to copy a slice of bytes because the byte may be NodeJS Buffer and Buffer#slice() returns a reference to its internal ArrayBuffer.
diff --git a/src/Decoder.ts b/src/Decoder.ts
@@ -3,7 +3,7 @@ import { ExtensionCodec, ExtensionCodecType } from "./ExtensionCodec";
 import { getInt64, getUint64 } from "./utils/int";
 import { utf8DecodeJs, TEXT_ENCODING_AVAILABLE, TEXT_DECODER_THRESHOLD, utf8DecodeTD } from "./utils/utf8";
 import { createDataView, ensureUint8Array } from "./utils/typedArrays";
-import { CachedKeyDecoder } from "./CachedKeyDecoder";
+import { CachedKeyDecoder, KeyDecoder } from "./CachedKeyDecoder";
 
 const enum State {
   ARRAY,
@@ -77,7 +77,7 @@ export class Decoder<ContextType> {
     readonly maxArrayLength = DEFAULT_MAX_LENGTH,
     readonly maxMapLength = DEFAULT_MAX_LENGTH,
     readonly maxExtLength = DEFAULT_MAX_LENGTH,
-    readonly cachedKeyDecoder: CachedKeyDecoder | null = sharedCachedKeyDecoder,
+    readonly keyDecoder: KeyDecoder | null = sharedCachedKeyDecoder,
   ) {}
 
   private reinitializeState() {
@@ -494,8 +494,8 @@ export class Decoder<ContextType> {
 
     const offset = this.pos + headerOffset;
     let object: string;
-    if (this.stateIsMapKey() && this.cachedKeyDecoder?.canBeCached(byteLength)) {
-      object = this.cachedKeyDecoder.decode(this.bytes, offset, byteLength);
+    if (this.stateIsMapKey() && this.keyDecoder?.canBeCached(byteLength)) {
+      object = this.keyDecoder.decode(this.bytes, offset, byteLength);
     } else if (TEXT_ENCODING_AVAILABLE && byteLength > TEXT_DECODER_THRESHOLD) {
       object = utf8DecodeTD(this.bytes, offset, byteLength);
     } else {
