perf(codec): improve bytify and hexify perf (#580)

Author: homura

.changeset/big-ears-allow.md

@@ -0,0 +1,5 @@
+---
+"@ckb-lumos/codec": patch
+---
+
+improving `hexify` and `bytify` performance

package.json

@@ -23,6 +23,7 @@
     "@typescript-eslint/eslint-plugin": "^5.59.2",
     "@typescript-eslint/parser": "^5.59.2",
     "ava": "^3.8.2",
+    "benchmark": "^2.1.4",
     "c8": "^7.10.0",
     "eslint": "^8.40.0",
     "eslint-import-resolver-typescript": "^2.7.0",

packages/codec/src/bytes.ts

@@ -14,22 +14,39 @@ export function bytifyRawString(rawString: string): Uint8Array {
   return new Uint8Array(buffer);
 }
 
+const CHAR_0 = "0".charCodeAt(0); // 48
+const CHAR_9 = "9".charCodeAt(0); // 57
+const CHAR_A = "A".charCodeAt(0); // 65
+const CHAR_F = "F".charCodeAt(0); // 70
+const CHAR_a = "a".charCodeAt(0); // 97
+// const CHAR_f = "f".charCodeAt(0); // 102
+
 function bytifyHex(hex: string): Uint8Array {
   assertHexString(hex);
 
-  hex = hex.slice(2);
-  const uint8s = [];
-  for (let i = 0; i < hex.length; i += 2) {
-    uint8s.push(parseInt(hex.substr(i, 2), 16));
+  const u8a = Uint8Array.from({ length: hex.length / 2 - 1 });
+
+  for (let i = 2, j = 0; i < hex.length; i = i + 2, j++) {
+    const c1 = hex.charCodeAt(i);
+    const c2 = hex.charCodeAt(i + 1);
+
+    // prettier-ignore
+    const n1 = c1 <= CHAR_9 ? c1 - CHAR_0 : c1 <= CHAR_F ? c1 - CHAR_A + 10 : c1 - CHAR_a + 10
+    // prettier-ignore
+    const n2 = c2 <= CHAR_9 ? c2 - CHAR_0 : c2 <= CHAR_F ? c2 - CHAR_A + 10 : c2 - CHAR_a + 10
+
+    u8a[j] = (n1 << 4) | n2;
   }
 
-  return Uint8Array.from(uint8s);
+  return u8a;
 }
 
 function bytifyArrayLike(xs: ArrayLike<number>): Uint8Array {
-  const isValidU8Vec = Array.from(xs).every((v) => v >= 0 && v <= 255);
-  if (!isValidU8Vec) {
-    throw new Error("invalid ArrayLike, all elements must be 0-255");
+  for (let i = 0; i < xs.length; i++) {
+    const v = xs[i];
+    if (v < 0 || v > 255 || !Number.isInteger(v)) {
+      throw new Error("invalid ArrayLike, all elements must be 0-255");
+    }
   }
 
   return Uint8Array.from(xs);
@@ -61,6 +78,10 @@ function equalUint8Array(a: Uint8Array, b: Uint8Array): boolean {
   }
   return true;
 }
+
+const HEX_CACHE = Array.from({ length: 256 }).map((_, i) =>
+  i.toString(16).padStart(2, "0")
+);
 /**
  * convert a {@link BytesLike} to an even length hex string prefixed with "0x"
  * @param buf
@@ -69,9 +90,13 @@ function equalUint8Array(a: Uint8Array, b: Uint8Array): boolean {
  * hexify(Buffer.from([1, 2, 3])) // "0x010203"
  */
 export function hexify(buf: BytesLike): string {
-  const hex = Array.from(bytify(buf))
-    .map((b) => b.toString(16).padStart(2, "0"))
-    .join("");
+  let hex = "";
+
+  const u8a = bytify(buf);
+  for (let i = 0; i < u8a.length; i++) {
+    hex += HEX_CACHE[u8a[i]];
+  }
+
   return "0x" + hex;
 }
 

packages/codec/src/utils.ts

@@ -4,48 +4,76 @@ import {
   isCodecExecuteError,
 } from "./error";
 
-const HEX_DECIMAL_REGEX = /^0x([0-9a-fA-F])+$/;
-const HEX_DECIMAL_WITH_BYTELENGTH_REGEX_MAP = new Map<number, RegExp>();
+const CHAR_0 = "0".charCodeAt(0); // 48
+const CHAR_9 = "9".charCodeAt(0); // 57
+const CHAR_A = "A".charCodeAt(0); // 65
+const CHAR_F = "F".charCodeAt(0); // 70
+const CHAR_a = "a".charCodeAt(0); // 97
+const CHAR_f = "f".charCodeAt(0); // 102
 
-export function assertHexDecimal(str: string, byteLength?: number): void {
-  if (byteLength) {
-    let regex = HEX_DECIMAL_WITH_BYTELENGTH_REGEX_MAP.get(byteLength);
-    if (!regex) {
-      const newRegex = new RegExp(`^0x([0-9a-fA-F]){1,${byteLength * 2}}$`);
-      HEX_DECIMAL_WITH_BYTELENGTH_REGEX_MAP.set(byteLength, newRegex);
-      regex = newRegex;
-    }
-    if (!regex.test(str)) {
-      throw new Error("Invalid hex decimal!");
-    }
-  } else {
-    if (!HEX_DECIMAL_REGEX.test(str)) {
-      throw new Error("Invalid hex decimal!");
+function assertStartsWith0x(str: string): void {
+  if (!str || !str.startsWith("0x")) {
+    throw new Error("Invalid hex string");
+  }
+}
+
+function assertHexChars(str: string): void {
+  const strLen = str.length;
+
+  for (let i = 2; i < strLen; i++) {
+    const char = str[i].charCodeAt(0);
+    if (
+      (char >= CHAR_0 && char <= CHAR_9) ||
+      (char >= CHAR_a && char <= CHAR_f) ||
+      (char >= CHAR_A && char <= CHAR_F)
+    ) {
+      continue;
     }
+
+    throw new Error(`Invalid hex character ${str[i]} in the string ${str}`);
   }
 }
 
-const HEX_STRING_REGEX = /^0x([0-9a-fA-F][0-9a-fA-F])*$/;
-const HEX_STRING_WITH_BYTELENGTH_REGEX_MAP = new Map<number, RegExp>();
+export function assertHexDecimal(str: string, byteLength?: number): void {
+  assertStartsWith0x(str);
+  if (str.length === 2) {
+    throw new Error(
+      "Invalid hex decimal length, should be at least 1 character, the '0x' is incorrect, should be '0x0'"
+    );
+  }
+
+  const strLen = str.length;
 
+  if (typeof byteLength === "number" && strLen > byteLength * 2 + 2) {
+    throw new Error(
+      `Invalid hex decimal length, should be less than ${byteLength} bytes, got ${
+        strLen / 2 - 1
+      } bytes`
+    );
+  }
+
+  assertHexChars(str);
+}
+
+/**
+ * Assert if a string is a valid hex string that is matched with /^0x([0-9a-fA-F][0-9a-fA-F])*$/
+ * @param str
+ * @param byteLength
+ */
 export function assertHexString(str: string, byteLength?: number): void {
-  if (byteLength) {
-    let regex = HEX_STRING_WITH_BYTELENGTH_REGEX_MAP.get(byteLength);
-    if (!regex) {
-      const newRegex = new RegExp(
-        `^0x([0-9a-fA-F][0-9a-fA-F]){${byteLength}}$`
-      );
-      HEX_STRING_WITH_BYTELENGTH_REGEX_MAP.set(byteLength, newRegex);
-      regex = newRegex;
-    }
-    if (!regex.test(str)) {
-      throw new Error("Invalid hex string!");
-    }
-  } else {
-    if (!HEX_STRING_REGEX.test(str)) {
-      throw new Error("Invalid hex string!");
-    }
+  assertStartsWith0x(str);
+
+  const strLen = str.length;
+
+  if (strLen % 2) {
+    throw new Error("Invalid hex string length, must be even!");
   }
+
+  if (typeof byteLength === "number" && strLen !== byteLength * 2 + 2) {
+    throw new Error("Invalid hex string length, not match with byteLength!");
+  }
+
+  assertHexChars(str);
 }
 
 export function assertUtf8String(str: string): void {