Python - Flask - スレッド入門 - 待ち時間を処理する(threadingモジュール(標準ライブラリ)、Threadクラス、startメソッド)

Head First Python 第2版
原著
楽天ブックス(Kobo)

開発環境

• macOS Mojave - Apple
• Emacs (Text Editor)
• Python 3.7 (プログラミング言語)

Head First Python 第2版 ―頭とからだで覚えるPythonの基本 (Paul Barry (著)、嶋田 健志 (監修)、木下 哲也 (翻訳)、オライリージャパン)の11 3/4章(スレッド入門 - 待ち時間を処理する)、自分で考えてみよう(p. 467)を取り組んでみる。

コード(Emacs)

Python 3

from flask import Flask, render_template, request, escape
from threading import Thread
import time

import vsearch
from DBcm import UseDatabase, ConnectionError, CredentialsError, SQLError

app = Flask(__name__)

app.config['dbconfig'] = {'host': '127.0.0.1',
                          'user': 'vsearch',
                          'password': 'vsearchpasswd',
                          'database': 'vsearchlogDB', }


def log_request(req: 'flask_request', res: str) -> None:
    time.sleep(15)
    with UseDatabase(app.config['dbconfig']) as cursor:
        _SQL = '''
create table if not exists log(
id integer primary key auto_increment,
ts timestamp default current_timestamp,
phrase varchar(128) not null,
letters varchar(32) not null,
ip varchar(16) not null,
browser_string varchar(256) not null,
results varchar(64) not null)
'''
        cursor.execute(_SQL)

        _SQL = '''
insert into log
(phrase, letters, ip, browser_string, results)
values
(%s, %s, %s, %s, %s)
'''
        cursor.execute(
            _SQL,
            (req.form['phrase'], req.form['letters'], req.remote_addr,
             req.user_agent.browser, res))


@app.route('/search4', methods=['POST'])
def do_search() -> 'html':
    phrase = request.form['phrase']
    letters = request.form['letters']
    title = '検索結果'
    results = str(vsearch.search4letters(phrase, letters))
    try:
        t = Thread(target=log_request, args=(request, results))
        t.start()
    except Exception as err:
        print(f'ログリクエストが失敗しました: {err}')
    return render_template('results.html',
                           the_title=title,
                           the_phrase=phrase,
                           the_letters=letters,
                           the_results=results)


@app.route('/')
@app.route('/entry')
def entry_page() -> 'html':
    return render_template(
        'entry.html', the_title='Web版のsearch4lettersにようこそ！')


@app.route('/viewlog')
def view_the_log() -> 'html':
    try:
        with UseDatabase(app.config['dbconfig']) as cursor:
            _SQL = '''
select phrase, letters, ip, browser_string, results from log
'''
            cursor.execute(_SQL)
            contents = cursor.fetchall()
        titles = ('フレーズ', '文字', 'リモートアドレス',
                  'ユーザーエージェント', '結果')
        return render_template('viewlog.html',
                               the_title='ログの閲覧',
                               the_row_titles=titles,
                               the_data=contents,)
    except ConnectionError as err:
        print(f'データベースが動作していますか？エラー: {err}')
        return 'Connection Error'
    except CredentialsError as err:
        print(f'ユーザー/パスワード問題。エラー: {err}')
    except SQLError as err:
        print(f'クエリは正しいですか？エラー: {err}')
    except Exception as err:
        print(f'何か問題が発生しました: {err}')
    return 'Error'


if __name__ == '__main__':
    app.run(debug=True)

入出力結果(Terminal, Jupyter(IPython))

$ python3 vsearch4web.py
 * Serving Flask app "vsearch4web" (lazy loading)
 * Environment: production
   WARNING: Do not use the development server in a production environment.
   Use a production WSGI server instead.
 * Debug mode: on
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 178-619-558
127.0.0.1 - - [20/Oct/2018 14:35:34] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [20/Oct/2018 14:35:36] "POST /search4 HTTP/1.1" 200 -
  C-c C-c$