Implemented cron jobs

doc

@@ -1 +1 @@
-Subproject commit 0cf3d59c8b37f84e915f5e30e7447f0611cc1238
+Subproject commit cb222b6a7131c24b958740bd5974fca26b450654

matemat/webserver/__init__.py

@@ -8,5 +8,5 @@ server will attempt to serve the request with a static resource in a previously
 
 from .requestargs import RequestArgument, RequestArguments
 from .responses import PageletResponse, RedirectResponse, TemplateResponse
-from .httpd import MatematWebserver, HttpHandler, pagelet, pagelet_init
+from .httpd import MatematWebserver, HttpHandler, pagelet, pagelet_init, pagelet_cron
 from .config import parse_config_file

matemat/webserver/httpd.py

@@ -11,6 +11,7 @@ from http.server import HTTPServer, BaseHTTPRequestHandler
 from http.cookies import SimpleCookie
 from uuid import uuid4
 from datetime import datetime, timedelta
+from threading import Event, Timer, Thread
 
 import jinja2
 
@@ -41,6 +42,9 @@ _PAGELET_PATHS: Dict[str, Callable[[str,  # HTTP method (GET, POST, ...)
 # The pagelet initialization functions, to be executed upon startup
 _PAGELET_INIT_FUNCTIONS: Set[Callable[[Dict[str, str], logging.Logger], None]] = set()
 
+_PAGELET_CRON_STATIC_EVENT: Event = Event()
+_PAGELET_CRON_RUNNER: Callable[[Callable[[Dict[str, str], jinja2.Environment, logging.Logger], None]], None] = None
+
 # Inactivity timeout for client sessions
 _SESSION_TIMEOUT: int = 3600
 _MAX_POST: int = 1_000_000
@@ -118,6 +122,90 @@ def pagelet_init(fun: Callable[[Dict[str, str], logging.Logger], None]):
     _PAGELET_INIT_FUNCTIONS.add(fun)
 
 
+class _GlobalEventTimer(Thread):
+    """
+    A timer similar to threading.Timer, except that waits on an externally supplied threading.Event instance,
+    therefore allowing all timers waiting on the same event to be cancelled at once.
+    """
+
+    def __init__(self, interval: float, event: Event, fun, *args, **kwargs):
+        """
+        Create a new _GlobalEventTimer.
+        :param interval: The delay after which to run the function.
+        :param event: The external threading.Event to wait on.
+        :param fun: The function to call.
+        :param args: The positional arguments to pass to the function.
+        :param kwargs: The keyword arguments to pass to the function.
+        """
+        Thread.__init__(self)
+        self.interval = interval
+        self.fun = fun
+        self.args = args if args is not None else []
+        self.kwargs = kwargs if kwargs is not None else {}
+        self.event = event
+
+    def run(self):
+        self.event.wait(self.interval)
+        if not self.event.is_set():
+            self.fun(*self.args, **self.kwargs)
+        # Do NOT call event.set(), as done in threading.Timer, as that would cancel all other timers
+
+
+def pagelet_cron(weeks: int = 0,
+                 days: int = 0,
+                 hours: int = 0,
+                 seconds: int = 0,
+                 minutes: int = 0,
+                 milliseconds: int = 0,
+                 microseconds: int = 0):
+    """
+    Annotate a function to act as a pagelet cron function.  The function will be called in a regular interval, defined
+    by the arguments passed to the decorator, which are passed to a timedelta object.
+
+    The function must have the following signature:
+
+        (config: Dict[str, str], jinja_env: jinja2.Environment, logger: logging.Logger) -> None
+
+        config:       The mutable dictionary of variables read from the [Pagelets] section of the configuration file.
+        jinja_env:    The Jinja2 environment used by the web server.
+        logger:       The server's logger instance.
+        returns:      Nothing.
+
+    :param weeks: Number of weeks in the interval.
+    :param days: Number of days in the interval.
+    :param hours: Number of hours in the interval.
+    :param seconds: Number of seconds in the interval.
+    :param minutes: Number of minutes in the interval.
+    :param milliseconds: Number of milliseconds in the interval.
+    :param microseconds: Number of microseconds in the interval.
+    """
+
+    def cron_wrapper(fun: Callable[[Dict[str, str], jinja2.Environment, logging.Logger], None]):
+        # Create the timedelta object
+        delta: timedelta = timedelta(weeks=weeks,
+                                     days=days,
+                                     hours=hours,
+                                     seconds=seconds,
+                                     minutes=minutes,
+                                     milliseconds=milliseconds,
+                                     microseconds=microseconds)
+
+        # This function is called once in the specified interval
+        def cron():
+            # Set a new timer
+            t: Timer = _GlobalEventTimer(delta.total_seconds(), _PAGELET_CRON_STATIC_EVENT, cron)
+            t.start()
+            # Have the cron job be picked up by the cron runner provided by the web server
+            if _PAGELET_CRON_RUNNER is not None:
+                _PAGELET_CRON_RUNNER(fun)
+
+        # Set a timer to run the cron job after the specified interval
+        timer: Timer = _GlobalEventTimer(delta.total_seconds(), _PAGELET_CRON_STATIC_EVENT, cron)
+        timer.start()
+
+    return cron_wrapper
+
+
 class MatematHTTPServer(HTTPServer):
     """
     A http.server.HTTPServer subclass that acts as a container for data that must be persistent between requests.
@@ -212,10 +300,14 @@ class MatematWebserver(object):
         running.  If any exception is raised in the initialization phase, the program is terminated with a non-zero
         exit code.
         """
+        global _PAGELET_CRON_RUNNER
+        try:
             try:
                 # Run all pagelet initialization functions
                 for fun in _PAGELET_INIT_FUNCTIONS:
                     fun(self._httpd.pagelet_variables, self._httpd.logger)
+                # Set pagelet cron runner to self
+                _PAGELET_CRON_RUNNER = self._cron_runner
             except BaseException as e:
                 # If an error occurs, log it and terminate
                 self._httpd.logger.exception(e)
@@ -223,6 +315,14 @@ class MatematWebserver(object):
                 raise e
             # If pagelet initialization went fine, start the HTTP server
             self._httpd.serve_forever()
+        finally:
+            # Cancel all cron timers at once when the webserver is shutting down
+            _PAGELET_CRON_STATIC_EVENT.set()
+
+    def _cron_runner(self, fun: Callable[[Dict[str, str], jinja2.Environment, logging.Logger], None]):
+        fun(self._httpd.pagelet_variables,
+            self._httpd.jinja_env,
+            self._httpd.logger)
 
 
 class HttpHandler(BaseHTTPRequestHandler):

matemat/webserver/pagelets/receipt.py

@@ -0,0 +1,36 @@
+from typing import Any, Dict, List, Union
+
+from matemat.webserver import pagelet, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
+from matemat.db import MatematDatabase
+from matemat.db.primitives import Receipt
+from matemat.util.currency_format import format_chf
+
+
+@pagelet('/receipt')
+def show_receipt(method: str,
+                 path: str,
+                 args: RequestArguments,
+                 session_vars: Dict[str, Any],
+                 headers: Dict[str, str],
+                 config: Dict[str, str]) \
+                 -> Union[str, bytes, PageletResponse]:
+    if 'authenticated_user' not in session_vars:
+        return RedirectResponse('/')
+    # Connect to the database
+    with MatematDatabase(config['DatabaseFile']) as db:
+        # Fetch the authenticated user from the database
+        uid: int = session_vars['authenticated_user']
+        user = db.get_user(uid)
+        receipt: Receipt = db.create_receipt(user)
+    headers['Content-Type'] = 'text/plain; charset=utf-8'
+    fdate: str = receipt.from_date.strftime('%d.%m.%Y, %H:%M')
+    tdate: str = receipt.to_date.strftime('%d.%m.%Y, %H:%M')
+    username: str = receipt.user.name.rjust(40)
+    if len(receipt.transactions) == 0:
+        fbal: str = format_chf(receipt.user.balance).rjust(12)
+    else:
+        fbal = format_chf(receipt.transactions[0].old_balance).rjust(12)
+    tbal: str = format_chf(receipt.user.balance).rjust(12)
+    return TemplateResponse('receipt.txt',
+                            fdate=fdate, tdate=tdate, user=username, fbal=fbal, tbal=tbal,
+                            transactions=receipt.transactions, instance_name=config['InstanceName'])

matemat/webserver/test/test_pagelet_cron.py

@@ -0,0 +1,65 @@
+from typing import Dict
+
+import unittest
+
+import logging
+from threading import Lock, Thread, Timer
+from time import sleep
+import jinja2
+
+from matemat.webserver import MatematWebserver, pagelet_cron
+
+lock: Lock = Lock()
+
+cron1called: int = 0
+cron2called: int = 0
+
+
+@pagelet_cron(seconds=4)
+def cron1(config: Dict[str, str],
+          jinja_env: jinja2.Environment,
+          logger: logging.Logger) -> None:
+    global cron1called
+    with lock:
+        cron1called += 1
+
+
+@pagelet_cron(seconds=3)
+def cron2(config: Dict[str, str],
+          jinja_env: jinja2.Environment,
+          logger: logging.Logger) -> None:
+    global cron2called
+    with lock:
+        cron2called += 1
+
+
+class TestPageletCron(unittest.TestCase):
+
+    def setUp(self):
+        self.srv = MatematWebserver('::1', 0, '/nonexistent', '/nonexistent', {}, {},
+                                    logging.NOTSET, logging.NullHandler())
+        self.srv_port = int(self.srv._httpd.socket.getsockname()[1])
+        self.timer = Timer(10.0, self.srv._httpd.shutdown)
+        self.timer.start()
+
+    def tearDown(self):
+        self.timer.cancel()
+        if self.srv is not None:
+            self.srv._httpd.socket.close()
+
+    def test_cron(self):
+        """
+        Test that the cron functions are called properly.
+        """
+        thread = Thread(target=self.srv.start)
+        thread.start()
+        sleep(12)
+        self.srv._httpd.shutdown()
+        with lock:
+            self.assertEqual(2, cron1called)
+            self.assertEqual(3, cron2called)
+        # Make sure the cron threads were stopped
+        sleep(5)
+        with lock:
+            self.assertEqual(2, cron1called)
+            self.assertEqual(3, cron2called)