optimize cache size according to the benchmark results

benchmark/key-decoder.ts

@@ -14,14 +14,25 @@ type InputType = {
 const keys: Array<InputType> = Object.keys(require("./benchmark-from-msgpack-lite-data.json")).map((str) => {
   const byteLength = utf8Count(str);
   const bytes = new Uint8Array(new ArrayBuffer(byteLength));
-
   utf8EncodeJs(str, bytes, 0);
-
   return { bytes, byteLength, str };
 });
 
 for (const dataSet of [keys]) {
   const keyDecoder = new CachedKeyDecoder();
+  // make cache storage full
+  for (let i = 0; i < keyDecoder.maxKeyLength; i++) {
+    for (let j = 0; j < keyDecoder.maxLengthPerKey; j++) {
+      const str = `${j.toString().padStart(i + 1, "0")}`;
+      const byteLength = utf8Count(str);
+      const bytes = new Uint8Array(new ArrayBuffer(byteLength));
+      utf8EncodeJs(str, bytes, 0);
+      keyDecoder.decode(bytes, 0, byteLength); // fill
+    }
+  }
+
+  // console.dir(keyDecoder, { depth: 100 });
+  console.log("## When the cache storage is full.");
 
   const suite = new Benchmark.Suite();
 

src/CachedKeyDecoder.ts

@@ -6,15 +6,12 @@ interface KeyCacheRecord {
 }
 
 const DEFAULT_MAX_KEY_LENGTH = 16;
-const DEFAULT_MAX_LENGTH_PER_KEY = 32;
+const DEFAULT_MAX_LENGTH_PER_KEY = 16;
 
 export class CachedKeyDecoder {
   private readonly caches: Array<Array<KeyCacheRecord>>;
 
-  constructor(
-    private readonly maxKeyLength = DEFAULT_MAX_KEY_LENGTH,
-    private readonly maxLengthPerKey = DEFAULT_MAX_LENGTH_PER_KEY,
-  ) {
+  constructor(readonly maxKeyLength = DEFAULT_MAX_KEY_LENGTH, readonly maxLengthPerKey = DEFAULT_MAX_LENGTH_PER_KEY) {
     // avoid `new Array(N)` to create a non-sparse array for performance.
     this.caches = [];
     for (let i = 0; i < this.maxKeyLength; i++) {
@@ -32,9 +29,10 @@ export class CachedKeyDecoder {
 
     FIND_CHUNK: for (let i = 0; i < recordsLength; i++) {
       const record = records[i];
+      const recordBytes = record.bytes;
 
       for (let j = 0; j < byteLength; j++) {
-        if (record.bytes[j] !== bytes[inputOffset + j]) {
+        if (recordBytes[j] !== bytes[inputOffset + j]) {
           continue FIND_CHUNK;
         }
       }