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#!/usr/bin/env PYTHONHASHSEED=1234 python3
# Copyright 2014-2019 Brett Slatkin, Pearson Education Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#     http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Reproduce book environment
import random
random.seed(1234)
import logging
from pprint import pprint
from sys import stdout as STDOUT
# Write all output to a temporary directory
import atexit
import tempfile
TEST_DIR = tempfile.TemporaryDirectory()
atexit.register(TEST_DIR.cleanup)
# Make sure Windows processes exit cleanly
OLD_CWD = os.getcwd()
atexit.register(lambda: os.chdir(OLD_CWD))
os.chdir(TEST_DIR.name)
def close_open_files():
    everything = gc.get_objects()
    for obj in everything:
        if isinstance(obj, io.IOBase):
            obj.close()
atexit.register(close_open_files)
# Example 1
ALIVE = '*'
EMPTY = '-'
class Grid:
    def __init__(self, height, width):
        self.height = height
        self.width = width
        self.rows = []
        for _ in range(self.height):
            self.rows.append([EMPTY] * self.width)
    def get(self, y, x):
        return self.rows[y % self.height][x % self.width]
    def set(self, y, x, state):
        self.rows[y % self.height][x % self.width] = state
    def __str__(self):
        output = ''
        for row in self.rows:
            for cell in row:
                output += cell
            output += '\n'
        return output
from threading import Lock
class LockingGrid(Grid):
    def __init__(self, height, width):
        super().__init__(height, width)
        self.lock = Lock()
    def __str__(self):
        with self.lock:
            return super().__str__()
    def get(self, y, x):
        with self.lock:
            return super().get(y, x)
    def set(self, y, x, state):
        with self.lock:
            return super().set(y, x, state)
def count_neighbors(y, x, get):
    n_ = get(y - 1, x + 0)  # North
    ne = get(y - 1, x + 1)  # Northeast
    e_ = get(y + 0, x + 1)  # East
    se = get(y + 1, x + 1)  # Southeast
    s_ = get(y + 1, x + 0)  # South
    sw = get(y + 1, x - 1)  # Southwest
    w_ = get(y + 0, x - 1)  # West
    nw = get(y - 1, x - 1)  # Northwest
    neighbor_states = [n_, ne, e_, se, s_, sw, w_, nw]
    count = 0
    for state in neighbor_states:
        if state == ALIVE:
            count += 1
    return count
def game_logic(state, neighbors):
    # Do some blocking input/output in here:
    data = my_socket.recv(100)
def game_logic(state, neighbors):
    if state == ALIVE:
        if neighbors < 2:
            return EMPTY     # Die: Too few
        elif neighbors > 3:
            return EMPTY     # Die: Too many
        if neighbors == 3:
            return ALIVE     # Regenerate
    return state
def step_cell(y, x, get, set):
    state = get(y, x)
    neighbors = count_neighbors(y, x, get)
    next_state = game_logic(state, neighbors)
    set(y, x, next_state)
# Example 2
from concurrent.futures import ThreadPoolExecutor
def simulate_pool(pool, grid):
    next_grid = LockingGrid(grid.height, grid.width)
    futures = []
    for y in range(grid.height):
        for x in range(grid.width):
            args = (y, x, grid.get, next_grid.set)
            future = pool.submit(step_cell, *args)  # Fan out
            futures.append(future)
    for future in futures:
        future.result()                             # Fan in
    return next_grid
# Example 3
class ColumnPrinter:
    def __init__(self):
        self.columns = []
    def append(self, data):
        self.columns.append(data)
    def __str__(self):
        row_count = 1
        for data in self.columns:
            row_count = max(
                row_count, len(data.splitlines()) + 1)
        rows = [''] * row_count
        for j in range(row_count):
            for i, data in enumerate(self.columns):
                line = data.splitlines()[max(0, j - 1)]
                if j == 0:
                    padding = ' ' * (len(line) // 2)
                    rows[j] += padding + str(i) + padding
                else:
                    rows[j] += line
                if (i + 1) < len(self.columns):
                    rows[j] += ' | '
        return '\n'.join(rows)
grid = LockingGrid(5, 9)
grid.set(0, 3, ALIVE)
grid.set(1, 4, ALIVE)
grid.set(2, 2, ALIVE)
grid.set(2, 3, ALIVE)
grid.set(2, 4, ALIVE)
columns = ColumnPrinter()
with ThreadPoolExecutor(max_workers=10) as pool:
    for i in range(5):
        columns.append(str(grid))
        grid = simulate_pool(pool, grid)
print(columns)
# Example 4
    def game_logic(state, neighbors):
        raise OSError('Problem with I/O')
    with ThreadPoolExecutor(max_workers=10) as pool:
        task = pool.submit(game_logic, ALIVE, 3)
        task.result()
    logging.exception('Expected')
    assert False
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