src.fairreckitlib.core.threading.thread_processor

  1"""This module contains a processor that handles active threads.
  2
  3Classes:
  4
  5    ThreadProcessor: class that starts new and stops running threads.
  6
  7This program has been developed by students from the bachelor Computer Science at
  8Utrecht University within the Software Project course.
  9© Copyright Utrecht University (Department of Information and Computing Sciences)
 10"""
 11
 12import time
 13from typing import List
 14
 15from .thread_base import ThreadBase
 16
 17
 18class ThreadProcessor:
 19    """Processor for multiple threads (derived from ThreadBase class).
 20
 21    Keeps track of all threads that are started by this processor.
 22    The processor acquires ownership of these aforementioned threads and
 23    will dispose of them after they are finished.
 24    Additionally, these threads can be stopped as well.
 25
 26    Public methods:
 27
 28    get_active_threads
 29    get_num_active
 30    is_active_thread
 31    start
 32    stop
 33    """
 34
 35    def __init__(self):
 36        """Construct the ThreadProcessor."""
 37        self.threads = {}
 38
 39    def get_active_threads(self) -> List[str]:
 40        """Get the names of any active threads.
 41
 42        Returns:
 43            a list of thread names that are currently running.
 44        """
 45        active_threads = []
 46
 47        for thread_name, _ in self.threads.items():
 48            active_threads.append(thread_name)
 49
 50        return active_threads
 51
 52    def get_num_active(self) -> int:
 53        """Get the number of active threads for this processor.
 54
 55        Returns:
 56            the number of threads.
 57        """
 58        return len(self.threads)
 59
 60    def is_active_thread(self, thread_name: str) -> bool:
 61        """Get if the thread with the specified name is active.
 62
 63        Args:
 64            thread_name: the name of the thread to query.
 65
 66        Returns:
 67            whether the thread is handled by the processor.
 68        """
 69        return thread_name in self.threads
 70
 71    def start(self, thread: ThreadBase) -> None:
 72        """Start the specified thread.
 73
 74        The processor takes ownership of the thread and will clean it up
 75        after it is done running.
 76        This function returns a KeyError when a thread with the same name
 77        is already being handled by the processor.
 78
 79        Args:
 80            thread: the thread to start.
 81        """
 82        thread_name = thread.get_name()
 83        if self.is_active_thread(thread_name):
 84            raise KeyError('Thread already active with name:', thread_name)
 85
 86        self.threads[thread_name] = thread
 87
 88        thread.start(self.remove)
 89        # delay so the thread can start up
 90        time.sleep(0.05)
 91
 92    def stop(self, thread_name: str) -> None:
 93        """Stop the thread with the specified name.
 94
 95        The processor requests the thread to stop running.
 96        This function returns a KeyError when a thread with the specified name
 97        is not being handled by the processor.
 98
 99        Args:
100            thread_name: the name of the thread to stop.
101        """
102        if not self.is_active_thread(thread_name):
103            raise KeyError('Thread not active with name:', thread_name)
104
105        # request the thread to stop, it will remove itself after it is done running
106        self.threads[thread_name].stop()
107
108    def remove(self, thread):
109        """Remove the thread from the processor."""
110        del self.threads[thread.get_name()]