Added example answers for chapters 13 and 14 to fix #1

CH_14_multithreading_and_multiprocessing/exercise_02/solution_00.py

@@ -0,0 +1,74 @@
+# Read all files in a directory and sum the size of the files by
+# reading each file using `concurrent.futures`. If you want an
+# extra challenge, walk through the directories recursively by
+# letting the thread/process queue new items while running.
+
+import concurrent.futures
+import logging
+import pathlib
+import time
+
+# Our current directory
+PATH = pathlib.Path(__file__).parent
+
+
+def get_size(path: pathlib.Path) -> int:
+    size = path.stat().st_size
+    logging.info('%s is %d bytes', path, size)
+    return size
+
+
+def get_total_size(path) -> int:
+    with concurrent.futures.ThreadPoolExecutor() as executor:
+        return sum(executor.map(get_size, path.iterdir()))
+
+
+def get_size_or_queue(
+        executor: concurrent.futures.Executor,
+        futures: list[concurrent.futures.Future],
+        path: pathlib.Path,
+) -> int:
+    # If the path is a directory, queue up the children
+    if path.is_dir():
+        for child in path.iterdir():
+            futures.append(executor.submit(
+                get_size_or_queue, executor, futures, child))
+
+        # A directory has size 0 but we recurse into it
+        return 0
+    else:
+        return get_size(path)
+
+
+def get_total_size_recursive(path) -> int:
+    with concurrent.futures.ThreadPoolExecutor() as executor:
+        futures = []
+
+        # Note that we are using a regular list as a queue. This is
+        # thread-safe because `list.append()` is atomic.
+        futures.append(executor.submit(
+            get_size_or_queue, executor, futures, path))
+
+        total_size = 0
+        for future in futures:
+            total_size += future.result()
+
+        return total_size
+
+
+def main(path: pathlib.Path):
+    total_size = get_total_size(path)
+    print(f'Total size for {path} is: {total_size}')
+
+    # Sleep so editors such as Pycharm don't mix the output
+    time.sleep(0.5)
+
+    total_size = get_total_size_recursive(path)
+    print(f'Recursive total size for {path} is: {total_size}')
+
+
+if __name__ == '__main__':
+    logging.basicConfig(level=logging.INFO)
+
+    # Use the parent directory to get a reasonable list of files
+    main(PATH.parent)