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"""Thread that sends random weighted requests on a TestService stub."""

import random
import threading
import time
import traceback


def _weighted_test_case_generator(weighted_cases):
    weight_sum = sum(weighted_cases.itervalues())

    while True:
        val = random.uniform(0, weight_sum)
        partial_sum = 0
        for case in weighted_cases:
            partial_sum += weighted_cases[case]
            if val <= partial_sum:
                yield case
                break


class TestRunner(threading.Thread):

    def __init__(self, stub, test_cases, hist, exception_queue, stop_event):
        super(TestRunner, self).__init__()
        self._exception_queue = exception_queue
        self._stop_event = stop_event
        self._stub = stub
        self._test_cases = _weighted_test_case_generator(test_cases)
        self._histogram = hist

    def run(self):
        while not self._stop_event.is_set():
            try:
                test_case = next(self._test_cases)
                start_time = time.time()
                test_case.test_interoperability(self._stub, None)
                end_time = time.time()
                self._histogram.add((end_time - start_time) * 1e9)
            except Exception as e:
                traceback.print_exc()
                self._exception_queue.put(
                    Exception("An exception occured during test {}"
                              .format(test_case), e))