# The functions in this module are meant to run on a separate worker process.
# Exception: in single process mode _execute_test is called directly.
import time
import traceback

import lit.Test
import lit.util

_lit_config = None
_parallelism_semaphores = None

def initializer(lit_config, parallelism_semaphores):
    """Copy expensive repeated data into worker processes"""
    global _lit_config
    global _parallelism_semaphores
    _lit_config = lit_config
    _parallelism_semaphores = parallelism_semaphores

def run_one_test(test_index, test):
    """Run one test in a multiprocessing.Pool

    Side effects in this function and functions it calls are not visible in the
    main lit process.

    Arguments and results of this function are pickled, so they should be cheap
    to copy. For efficiency, we copy all data needed to execute all tests into
    each worker and store it in the worker_* global variables. This reduces the
    cost of each task.

    Returns an index and a Result, which the parent process uses to update
    the display.
    """
    try:
        _execute_test_in_parallelism_group(test, _lit_config,
                                           _parallelism_semaphores)
        return (test_index, test)
    except KeyboardInterrupt:
        # If a worker process gets an interrupt, abort it immediately.
        lit.util.abort_now()
    except:
        traceback.print_exc()

def _execute_test_in_parallelism_group(test, lit_config, parallelism_semaphores):
    """Execute one test inside the appropriate parallelism group"""
    pg = test.config.parallelism_group
    if callable(pg):
        pg = pg(test)

    if pg:
        semaphore = parallelism_semaphores[pg]
        try:
            semaphore.acquire()
            _execute_test(test, lit_config)
        finally:
            semaphore.release()
    else:
        _execute_test(test, lit_config)


def _execute_test(test, lit_config):
    """Execute one test"""
    start = time.time()
    result = _execute_test_handle_errors(test, lit_config)
    end = time.time()

    result.elapsed = end - start
    test.setResult(result)


def _execute_test_handle_errors(test, lit_config):
    try:
        return _adapt_result(test.config.test_format.execute(test, lit_config))
    except KeyboardInterrupt:
        raise
    except:
        if lit_config.debug:
            raise
        output = 'Exception during script execution:\n'
        output += traceback.format_exc()
        output += '\n'
        return lit.Test.Result(lit.Test.UNRESOLVED, output)


# Support deprecated result from execute() which returned the result
# code and additional output as a tuple.
def _adapt_result(result):
    if isinstance(result, lit.Test.Result):
        return result
    assert isinstance(result, tuple)
    code, output = result
    return lit.Test.Result(code, output)