buffered_call.py

def call_on_full_list_buffer(fn, buffer_size):
    buffer = _call_on_full_list_buffer(fn, buffer_size)
    next(buffer)
    return buffer


def _call_on_full_list_buffer(fn, buffer_size):
    buffer = []
    values = []
    while True:
        if not values:
            values = yield

        if len(buffer) + len(values) < buffer_size:
            buffer.extend(values)
            values.clear()
        else:
            chunk_end = buffer_size - len(buffer)
            for i in range(chunk_end):
                buffer.append(values[i])
            fn(buffer)
            # lose reference to the previous buffer list as `fn` usually has side effects
            buffer = []
            values = values[chunk_end:]