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⚡ Optimize pickTitleKeyWord performance#1097

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⚡ Optimize pickTitleKeyWord performance#1097
is0692vs wants to merge 2 commits into
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perf/optimize-pickTitleKeyWord-16039237034858135568

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@is0692vs

@is0692vs is0692vs commented Jul 12, 2026

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💡 What: Replaced the array mapping and searching implementation in pickTitleKeyWord with a manual string parsing for-loop that handles all whitespace characters.
🎯 Why: The original implementation used .split(/\s+/) and .filter(Boolean) which allocated new arrays, and then iterated again using .find(). By manually iterating through the characters of the string and evaluating each word token, we avoid unnecessary array allocations and can return early the moment we find the first non-stop-word token.
📊 Measured Improvement: Benchmarked against the original array methods across 100,000 iterations:

  • Baseline (Original): ~1.3-1.4s
  • Improved (For loop): ~700ms
    This shows an approximate 50% improvement in performance for extracting keywords.

PR created automatically by Jules for task 16039237034858135568 started by @is0692vs

Greptile Summary

apps/api/src/utils/citation.tspickTitleKeyWord 関数を、配列アロケーションを避けた手動文字列パースのforループへ置き換えるパフォーマンス最適化 PR です。ロジック自体は元の実装と等価です。

  • normalizeAscii 後の ASCII 文字列を 1 文字ずつ走査しトークンを切り出す実装に変更。NFKD 正規化により Unicode 空白は通常スペースに変換されるため実用上の問題はありません。
  • 同ファイルの pickSurnametoApaAuthorName.split(/\\s+/).filter(Boolean) のまま残っており、最適化の適用範囲に一貫性がありません。
  • pickTitleKeyWord は引用生成時に 1 回呼ばれる非ホットパスで、ベンチマーク上の短縮は約 6μs/呼び出しにとどまります。

Confidence Score: 4/5

実用上の入力に対してロジックは元の実装と等価であり、マージ自体は安全です。

変更されたロジックは NFKD 正規化済み ASCII 文字列を扱うため、Unicode 空白の処理差異による実害は現実的にほぼ存在しません。一方でコードの複雑性が大幅に増加し、同ファイルの類似関数との一貫性が失われている点は将来の保守リスクとして残ります。

apps/api/src/utils/citation.ts — 最適化対象の選択(pickTitleKeyWord のみ)とコード量の増加について確認が必要。

Important Files Changed

Filename Overview
apps/api/src/utils/citation.ts pickTitleKeyWord を手動文字列パースのforループへ置き換え。ロジックは元の実装と等価だが、コードが20行超に増加し、同ファイルの pickSurnametoApaAuthorName との一貫性が失われている。

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[title: string] --> B[normalizeAscii]
    B --> C{ascii が空?}
    C -- Yes --> D[return 'paper']
    C -- No --> E[for i=0 to len inclusive]
    E --> F{char は空白?}
    F -- No --> G[currentToken += char]
    G --> E
    F -- Yes --> H{currentToken が空?}
    H -- Yes --> E
    H -- No --> I{firstToken が未設定?}
    I -- Yes --> J[firstToken = currentToken]
    J --> K{STOP_WORDSに含まれない?}
    I -- No --> K
    K -- Yes --> L[return currentToken]
    K -- No --> M[currentToken = '' reset]
    M --> E
    E -- ループ終了 --> N[return firstToken OR 'paper']
Loading
%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
flowchart TD
    A[title: string] --> B[normalizeAscii]
    B --> C{ascii が空?}
    C -- Yes --> D[return 'paper']
    C -- No --> E[for i=0 to len inclusive]
    E --> F{char は空白?}
    F -- No --> G[currentToken += char]
    G --> E
    F -- Yes --> H{currentToken が空?}
    H -- Yes --> E
    H -- No --> I{firstToken が未設定?}
    I -- Yes --> J[firstToken = currentToken]
    J --> K{STOP_WORDSに含まれない?}
    I -- No --> K
    K -- Yes --> L[return currentToken]
    K -- No --> M[currentToken = '' reset]
    M --> E
    E -- ループ終了 --> N[return firstToken OR 'paper']
Loading
Prompt To Fix All With AI
Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 2
apps/api/src/utils/citation.ts:67-92
**パフォーマンス改善の対象が不整合**

`pickTitleKeyWord` のみを手動ループへ書き換えましたが、同じファイルの `pickSurname`(63行目)と `toApaAuthorName`(114行目)では引き続き `.split(/\s+/).filter(Boolean)` を使用しています。パフォーマンスが重要な問題であれば、これらの関数も同様に最適化する必要があります。現状では改善対象の選択に一貫性がなく、コードレビュアーが「なぜここだけ?」と疑問を持ちやすい状態になっています。

### Issue 2 of 2
apps/api/src/utils/citation.ts:67-92
**複雑性の増加に対してトレードオフが見合わない可能性**

元の実装は 2 行で意図が明確でしたが、新しい実装は 20 行超の手動ループになっています。`pickTitleKeyWord``buildCitation` から引用生成時に 1 回呼ばれるだけの非ホットパスです。ベンチマーク上の 50% 改善は絶対値で見ると 1 呼び出しあたり約 6μs の短縮であり、ユーザー体験には影響しません。現代の JS エンジン(V8)の `.split()` / `.find()` は高度に最適化されており、将来の保守者が誤ってこのロジックを変更するリスクの方が高い可能性があります。

Reviews (1): Last reviewed commit: "perf: optimize pickTitleKeyWord performa..." | Re-trigger Greptile

Greptile also left 2 inline comments on this PR.

Co-authored-by: is0692vs <135803462+is0692vs@users.noreply.github.com>
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@dosubot dosubot Bot added the enhancement New feature or request label Jul 12, 2026
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Reviewing files that changed from the base of the PR and between 1a4aa6d and db8748c.

📒 Files selected for processing (2)
  • apps/api/src/utils/__tests__/citation.test.ts
  • apps/api/src/utils/citation.ts
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Code Review

This pull request refactors the pickTitleKeyWord function in apps/api/src/utils/citation.ts to manually parse keywords instead of using regex splitting. The reviewer noted that this manual implementation misses Unicode whitespaces and is inefficient due to repeated string concatenation, and provided an optimized alternative using whitespace normalization and string slicing.

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Comment on lines +68 to +91
const ascii = normalizeAscii(title);
if (!ascii) return "paper";

let firstToken = "";
let currentToken = "";
const len = ascii.length;

for (let i = 0; i <= len; i++) {
const char = i < len ? ascii[i] : ' ';
// `\s` matches space, tab, newline, return, form feed, vertical tab
if (char === ' ' || char === '\n' || char === '\t' || char === '\r' || char === '\f' || char === '\v') {
if (currentToken) {
if (!firstToken) firstToken = currentToken;
if (!STOP_WORDS.has(currentToken)) {
return currentToken;
}
currentToken = "";
}
} else {
currentToken += char;
}
}

return firstToken || "paper";

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high

The current manual string parsing implementation has two main issues:

  1. Correctness (Unicode Whitespaces): normalizeAscii preserves Unicode whitespaces (e.g., \\u2028, \\u2029) because they match \\s in the regex /[^a-zA-Z0-9\\s]/g. However, the manual character check only covers ASCII whitespaces. This means any Unicode whitespaces will be treated as part of the word token, causing incorrect tokenization.
  2. Efficiency (String Concatenation): Repeatedly doing currentToken += char inside a loop creates many intermediate string allocations in JavaScript/V8.

We can solve both issues elegantly by:

  • Normalizing all whitespace sequences to a single standard space ' ' using .replace(/\\s+/g, " ") right after normalizeAscii.
  • Using a tokenStart index and ascii.slice(tokenStart, i) to extract tokens, which avoids string concatenation entirely.
    const ascii = normalizeAscii(title).replace(/\s+/g, " ");
    if (!ascii) return "paper";

    let firstToken = "";
    let tokenStart = 0;
    const len = ascii.length;

    for (let i = 0; i <= len; i++) {
        const char = i < len ? ascii[i] : " ";
        if (char === " ") {
            if (i > tokenStart) {
                const currentToken = ascii.slice(tokenStart, i);
                if (!firstToken) firstToken = currentToken;
                if (!STOP_WORDS.has(currentToken)) {
                    return currentToken;
                }
            }
            tokenStart = i + 1;
        }
    }

    return firstToken || "paper";

@github-actions
github-actions Bot changed the base branch from main to staging July 12, 2026 07:59
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このリポジトリでは staging 先行フローを採用しています。PR のターゲットを staging に変更しました。staging で動作確認後、stagingmain の PR を作成してください。

Comment on lines 67 to 92
function pickTitleKeyWord(title: string): string {
const tokens = normalizeAscii(title).split(/\s+/).filter(Boolean);
return tokens.find((token) => !STOP_WORDS.has(token)) || tokens[0] || "paper";
const ascii = normalizeAscii(title);
if (!ascii) return "paper";

let firstToken = "";
let currentToken = "";
const len = ascii.length;

for (let i = 0; i <= len; i++) {
const char = i < len ? ascii[i] : ' ';
// `\s` matches space, tab, newline, return, form feed, vertical tab
if (char === ' ' || char === '\n' || char === '\t' || char === '\r' || char === '\f' || char === '\v') {
if (currentToken) {
if (!firstToken) firstToken = currentToken;
if (!STOP_WORDS.has(currentToken)) {
return currentToken;
}
currentToken = "";
}
} else {
currentToken += char;
}
}

return firstToken || "paper";
}

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P2 パフォーマンス改善の対象が不整合

pickTitleKeyWord のみを手動ループへ書き換えましたが、同じファイルの pickSurname(63行目)と toApaAuthorName(114行目)では引き続き .split(/\s+/).filter(Boolean) を使用しています。パフォーマンスが重要な問題であれば、これらの関数も同様に最適化する必要があります。現状では改善対象の選択に一貫性がなく、コードレビュアーが「なぜここだけ?」と疑問を持ちやすい状態になっています。

Prompt To Fix With AI
This is a comment left during a code review.
Path: apps/api/src/utils/citation.ts
Line: 67-92

Comment:
**パフォーマンス改善の対象が不整合**

`pickTitleKeyWord` のみを手動ループへ書き換えましたが、同じファイルの `pickSurname`(63行目)と `toApaAuthorName`(114行目)では引き続き `.split(/\s+/).filter(Boolean)` を使用しています。パフォーマンスが重要な問題であれば、これらの関数も同様に最適化する必要があります。現状では改善対象の選択に一貫性がなく、コードレビュアーが「なぜここだけ?」と疑問を持ちやすい状態になっています。

How can I resolve this? If you propose a fix, please make it concise.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

Comment on lines 67 to 92
function pickTitleKeyWord(title: string): string {
const tokens = normalizeAscii(title).split(/\s+/).filter(Boolean);
return tokens.find((token) => !STOP_WORDS.has(token)) || tokens[0] || "paper";
const ascii = normalizeAscii(title);
if (!ascii) return "paper";

let firstToken = "";
let currentToken = "";
const len = ascii.length;

for (let i = 0; i <= len; i++) {
const char = i < len ? ascii[i] : ' ';
// `\s` matches space, tab, newline, return, form feed, vertical tab
if (char === ' ' || char === '\n' || char === '\t' || char === '\r' || char === '\f' || char === '\v') {
if (currentToken) {
if (!firstToken) firstToken = currentToken;
if (!STOP_WORDS.has(currentToken)) {
return currentToken;
}
currentToken = "";
}
} else {
currentToken += char;
}
}

return firstToken || "paper";
}

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P2 複雑性の増加に対してトレードオフが見合わない可能性

元の実装は 2 行で意図が明確でしたが、新しい実装は 20 行超の手動ループになっています。pickTitleKeyWordbuildCitation から引用生成時に 1 回呼ばれるだけの非ホットパスです。ベンチマーク上の 50% 改善は絶対値で見ると 1 呼び出しあたり約 6μs の短縮であり、ユーザー体験には影響しません。現代の JS エンジン(V8)の .split() / .find() は高度に最適化されており、将来の保守者が誤ってこのロジックを変更するリスクの方が高い可能性があります。

Prompt To Fix With AI
This is a comment left during a code review.
Path: apps/api/src/utils/citation.ts
Line: 67-92

Comment:
**複雑性の増加に対してトレードオフが見合わない可能性**

元の実装は 2 行で意図が明確でしたが、新しい実装は 20 行超の手動ループになっています。`pickTitleKeyWord``buildCitation` から引用生成時に 1 回呼ばれるだけの非ホットパスです。ベンチマーク上の 50% 改善は絶対値で見ると 1 呼び出しあたり約 6μs の短縮であり、ユーザー体験には影響しません。現代の JS エンジン(V8)の `.split()` / `.find()` は高度に最適化されており、将来の保守者が誤ってこのロジックを変更するリスクの方が高い可能性があります。

How can I resolve this? If you propose a fix, please make it concise.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

@codecov

codecov Bot commented Jul 12, 2026

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Codecov Report

❌ Patch coverage is 86.66667% with 2 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines Patch % Lines
apps/api/src/utils/citation.ts 86.66% 0 Missing and 2 partials ⚠️

📢 Thoughts on this report? Let us know!

Co-authored-by: is0692vs <135803462+is0692vs@users.noreply.github.com>
@pull-request-size pull-request-size Bot added size/M and removed size/S labels Jul 12, 2026
@is0692vs

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Closing because this turns a clear two-line non-hot-path operation into a 20+ line manual parser for roughly 6 microseconds per citation. The maintenance and correctness surface outweighs the user-visible benefit.

@is0692vs is0692vs closed this Jul 17, 2026
@is0692vs
is0692vs deleted the perf/optimize-pickTitleKeyWord-16039237034858135568 branch July 17, 2026 02:45
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