Python - スレッド入門 - 待ち時間を処理する(Flask、copy_current_requestデコレーター、関数の入れ子)

Head First Python 第2版
原著
楽天ブックス(Kobo) Yahoo!

開発環境

• macOS Mojave - Apple (OS)
• Emacs (Text Editor)
• Windows 10 Pro (OS)
• Visual Studio Code (Text Editor)
• Python 3.7 (プログラミング言語)
• パッケージ
  • psycopg2
  • Flask
• PostgreSQL (ORDBMS(object-relational database management system))

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)、エクササイズ(p. 471)を取り組んでみる。

コード(Emacs)

Python 3

from flask import Flask, render_template, request, escape
from flask import copy_current_request_context
from threading import Thread
import time
import vsearch
import psycopg2 as sql
from DBcm import UseDatabase, ConnectionError

app = Flask(__name__)

dbconfig = {'host': '127.0.0.1',
            'database': 'vsearchlogdb'}


@app.route('/')
@app.route('/entry')
def entry_page() -> str:
    return render_template(
        'entry.html',
        the_title='Welcom to search4letters on the web!')


@app.route('/search4', methods=['POST'])
def do_search() -> str:
    @copy_current_request_context
    def log_request(req: 'flask_request', res: str) -> None:
        time.sleep(15)
        with UseDatabase(dbconfig) as cursor:
            _sql = '''
select phrase, letters, ip, browser_string, results
from log
'''
            cursor.execute(_sql)
            contents = cursor.fetchall()

        titles = ('phrase', 'letters', '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,)

    phrase = request.form['phrase']
    letters = request.form['letters']
    results = str(vsearch.search4letters(phrase, letters))
    try:
        t = Thread(target=log_request, args=(request, results))
        t.start()
    except Exception as err:
        print(type(err), err)
    title = '検索結果'
    return render_template(
        'results.html',
        the_title=title,
        the_phrase=phrase,
        the_letters=letters,
        the_results=results)


@app.route('/viewlog')
def view_the_log() -> str:
    try:
        with UseDatabase(dbconfig) as cursor:
            _sql = '''
select phrase, letters, ip, browser_string, results
from log
'''
            cursor.execute(_sql)
            contents = cursor.fetchall()

        titles = ('phrase', 'letters', '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}')
    except Exception as err:
        print(type(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, cmd(コマンドプロンプト), 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 - - [02/Jan/2019 22:33:51] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [02/Jan/2019 22:33:51] "GET /static/hf.css HTTP/1.1" 404 -
127.0.0.1 - - [02/Jan/2019 22:33:51] "GET /favicon.ico HTTP/1.1" 404 -
127.0.0.1 - - [02/Jan/2019 22:34:04] "POST /search4 HTTP/1.1" 200 -
127.0.0.1 - - [02/Jan/2019 22:34:04] "GET /static/hf.css HTTP/1.1" 404 -
127.0.0.1 - - [02/Jan/2019 22:34:04] "GET /favicon.ico HTTP/1.1" 404 -
  C-c C-c$

前回のエラーは発生しない事を確認できた。