+ detect_atomic_leftover(io_db["path_save"], io_db["tmp_suffix"])
+ detect_atomic_leftover(io_db["path_record"], io_db["tmp_suffix"])
+
+
+def cleanup_server_io():
+ """Close and (if io_db["kicked_by_rival"] false) remove files in io_db."""
+ def helper(file_key, path_key):
+ if file_key in io_db:
+ io_db[file_key].close()
+ if not io_db["kicked_by_rival"] \
+ and os.access(io_db[path_key], os.F_OK):
+ os.remove(io_db[path_key])
+ helper("file_out", "path_out")
+ helper("file_in", "path_in")
+ helper("file_worldstate", "path_worldstate")
+ if "file_record" in io_db:
+ io_db["file_record"].close()
+
+
+def obey(command, prefix, replay=False, do_record=False):
+ """Call function from commands_db mapped to command's first token.
+
+ The command string is tokenized by shlex.split(comments=True). If replay is
+ set, a non-meta command from the commands_db merely triggers obey() on the
+ next command from the records file. If not, and do do_record is set,
+ non-meta commands are recorded via record(), and save_world() is called.
+ The prefix string is inserted into the server's input message between its
+ beginning 'input ' & ':'. All activity is preceded by a server_test() call.
+ """
+ server_test()
+ print("input " + prefix + ": " + command)
+ try:
+ tokens = shlex.split(command, comments=True)
+ except ValueError as err:
+ print("Can't tokenize command string: " + str(err) + ".")
+ return
+ if len(tokens) > 0 and tokens[0] in commands_db \
+ and len(tokens) >= commands_db[tokens[0]][0] + 1:
+ if commands_db[tokens[0]][1]:
+ commands_db[tokens[0]][2]()
+ elif replay:
+ print("Due to replay mode, reading command as 'go on in record'.")
+ line = io_db["file_record"].readline()
+ if len(line) > 0:
+ obey(line.rstrip(), io_db["file_record"].prefix
+ + str(io_db["file_record"].line_n))
+ io_db["file_record"].line_n = io_db["file_record"].line_n + 1
+ else:
+ print("Reached end of record file.")
+ else:
+ commands_db[tokens[0]][2](*tokens[1:])
+ if do_record:
+ record(command)
+ save_world()
+ else:
+ print("Invalid command/argument, or bad number of tokens.")
+
+
+def atomic_write(path, text, do_append=False):
+ """Atomic write of text to file at path, appended if do_append is set."""
+ path_tmp = path + io_db["tmp_suffix"]
+ mode = "w"
+ if do_append:
+ mode = "a"
+ if os.access(path, os.F_OK):
+ shutil.copyfile(path, path_tmp)
+ file = open(path_tmp, mode)
+ file.write(text)
+ file.flush()
+ os.fsync(file.fileno())
+ file.close()
+ if os.access(path, os.F_OK):
+ os.remove(path)
+ os.rename(path_tmp, path)
+
+
+def record(command):
+ """Append command string plus newline to record file. (Atomic.)"""
+ # This misses some optimizations from the original record(), namely only
+ # finishing the atomic write with expensive flush() and fsync() every 15
+ # seconds unless explicitely forced. Implement as needed.
+ atomic_write(io_db["path_record"], command + "\n", do_append=True)
+
+
+def save_world():
+ # Dummy for saving all commands to reconstruct current world state.
+ # Misses same optimizations as record() from the original record().
+ atomic_write(io_db["path_save"], "TURN " + str(world_db["TURN"]) + "\n")
+
+
+def obey_lines_in_file(path, name, do_record=False):
+ """Call obey() on each line of path's file, use name in input prefix."""
+ file = open(path, "r")
+ line_n = 1
+ for line in file.readlines():
+ obey(line.rstrip(), name + "file line " + str(line_n),
+ do_record=do_record)
+ line_n = line_n + 1
+ file.close()
+
+
+def parse_command_line_arguments():
+ """Return settings values read from command line arguments."""
+ parser = argparse.ArgumentParser()
+ parser.add_argument('-s', nargs='?', type=int, dest='replay', const=1,
+ action='store')
+ opts, unknown = parser.parse_known_args()
+ return opts
+
+
+def server_test():
+ """Ensure valid server out file belonging to current process.
+
+ This is done by comparing io_db["teststring"] to what's found at the start
+ of the current file at io_db["path_out"]. On failure, set
+ io_db["kicked_by_rival"] and raise SystemExit.
+ """
+ if not os.access(io_db["path_out"], os.F_OK):
+ raise SystemExit("Server output file has disappeared.")
+ file = open(io_db["path_out"], "r")
+ test = file.readline().rstrip("\n")
+ file.close()
+ if test != io_db["teststring"]:
+ io_db["kicked_by_rival"] = True
+ msg = "Server test string in server output file does not match. This" \
+ " indicates that the current server process has been " \
+ "superseded by another one."
+ raise SystemExit(msg)
+
+
+def read_command():
+ """Return next newline-delimited command from server in file.
+
+ Keep building return string until a newline is encountered. Pause between
+ unsuccessful reads, and after too much waiting, run server_test().
+ """
+ wait_on_fail = 1
+ max_wait = 5
+ now = time.time()
+ command = ""
+ while True:
+ add = io_db["file_in"].readline()
+ if len(add) > 0:
+ command = command + add
+ if len(command) > 0 and "\n" == command[-1]:
+ command = command[:-1]
+ break
+ else:
+ time.sleep(wait_on_fail)
+ if now + max_wait < time.time():
+ server_test()
+ now = time.time()
+ return command
+
+
+def replay_game():
+ """Replay game from record file.
+
+ Use opts.replay as breakpoint turn to which to replay automatically before
+ switching to manual input by non-meta commands in server input file
+ triggering further reads of record file. Ensure opts.replay is at least 1.
+ """
+ if opts.replay < 1:
+ opts.replay = 1
+ print("Replay mode. Auto-replaying up to turn " + str(opts.replay) +
+ " (if so late a turn is to be found).")
+ if not os.access(io_db["path_record"], os.F_OK):
+ raise SystemExit("No record file found to replay.")
+ io_db["file_record"] = open(io_db["path_record"], "r")
+ io_db["file_record"].prefix = "record file line "
+ io_db["file_record"].line_n = 1
+ while world_db["turn"] < opts.replay:
+ line = io_db["file_record"].readline()
+ if "" == line:
+ break
+ obey(line.rstrip(), io_db["file_record"].prefix
+ + str(io_db["file_record"].line_n))
+ io_db["file_record"].line_n = io_db["file_record"].line_n + 1
+ while True:
+ obey(read_command(), "in file", replay=True)
+
+
+def play_game():
+ """Play game by server input file commands. Before, load save file found.
+
+ If no save file is found, a new world is generated from the commands in the
+ world config plus a 'MAKE WORLD [current Unix timestamp]'. Record this
+ command and all that follow via the server input file.
+ """
+ if os.access(io_db["path_save"], os.F_OK):
+ obey_lines_in_file(io_db["path_save"], "save")
+ else:
+ if not os.access(io_db["path_worldconf"], os.F_OK):
+ msg = "No world config file from which to start a new world."
+ raise SystemExit(msg)
+ obey_lines_in_file(io_db["path_worldconf"], "world config ",
+ do_record=True)
+ obey("MAKE_WORLD " + str(int(time.time())), "in file", do_record=True)
+ while True:
+ obey(read_command(), "in file", do_record=True)
+
+
+def command_makeworld(seed):
+ """Mere dummy so far."""
+ print("I would build a whole world now if only I knew how.")
+
+
+def command_ping():
+ """Send PONG line to server output file."""
+ io_db["file_out"].write("PONG\n")
+ io_db["file_out"].flush()
+
+
+def command_quit():
+ """Abort server process."""
+ raise SystemExit("received QUIT command")
+
+
+def command_turn(turn_string):
+ """Set turn to what's described in turn_string."""
+ world_db["TURN"] = int(turn_string)
+
+
+"""Commands database.
+
+Map command start tokens to ([0]) minimum number of expected command arguments,
+([1]) the command's meta-ness (i.e. is it to be written to the record file, is
+it to be ignored in replay mode if read from server input file), and ([2]) a
+function to be called on it.
+"""
+commands_db = {
+ "QUIT": (0, True, command_quit),
+ "PING": (0, True, command_ping),
+ "MAKE_WORLD": (1, False, command_makeworld),
+ "TURN": (1, False, command_turn)
+}
+
+
+"""World state database,"""
+world_db = {
+ "TURN": 0
+}
+
+
+"""File IO database."""
+io_db = {
+ "path_save": "save",
+ "path_record": "record",
+ "path_worldconf": "confserver/world",
+ "path_server": "server/",
+ "path_in": "server/in",
+ "path_out": "server/out",
+ "path_worldstate": "server/worldstate",
+ "tmp_suffix": "_tmp",
+ "kicked_by_rival": False
+}