Server/py: Minor comment improvement.

[plomrogue] / plomrogue-server.py

diff --git a/plomrogue-server.py b/plomrogue-server.py
index 568b21cf4db9b00c9caf4beeb55c798a90f37aae..c80bbf15eee49b0306ff07ed81dec2ff520c424f 100755 (executable)
--- a/plomrogue-server.py
+++ b/plomrogue-server.py
@@ -2,6 +2,7 @@ import argparse
 import errno
 import os
 import shlex
+import shutil
 import time
 
 
@@ -71,17 +72,27 @@ def obey(cmd, io_db, prefix):
         raise SystemExit("received QUIT command")
     elif "MAKE_WORLD" == tokens[0] and 2 == len(tokens):
         print("I would generate a new world now, if only I knew how.")
-        record(cmd, io_db["path_record"])
+        record(cmd, io_db)
     else:
         print("Invalid command/argument, or bad number of tokens.")
 
 
-def record(cmd, path_recordfile):
-    """Append cmd string plus newline to file at path_recordfile."""
-    # Doesn't yet replace old record() fully.
-    file = open(path_recordfile, "a")
+def record(cmd, io_db):
+    """Append cmd string plus newline to file at path_recordfile. (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.
+    path_tmp = io_db["path_record"] + io_db["tmp_suffix"]
+    if os.access(io_db["path_record"], os.F_OK):
+        shutil.copyfile(io_db["path_record"], path_tmp)
+    file = open(path_tmp, "a")
     file.write(cmd + "\n")
+    file.flush()
+    os.fsync(file.fileno())
     file.close()
+    if os.access(io_db["path_record"], os.F_OK):
+        os.remove(io_db["path_record"])
+    os.rename(path_tmp, io_db["path_record"])
 
 
 def obey_lines_in_file(path, name):