* Implement a signal mechanism for Windows utilising Windows 'Named Events'.

  See comments in WinSignalHandler.py for details.
* As Windows can not rename an open file, when the 'reopen' signal is
  received try and call a 'rotate' method rather than a reopen.  Rotation
  itself is implemented in zLOG.LogHandler

lib/python/Signals/Signals.py

@@ -18,14 +18,23 @@ $Id$
 __version__='$Revision: 1.3 $'[11:-2]
 
 import logging
-import sys
+import sys, os
 
 import Lifetime
 
-from SignalHandler import SignalHandler
-
 logger = logging.getLogger("Z2")
 
+if os.name == 'nt':
+    try:
+        from WinSignalHandler import SignalHandler
+    except ImportError:
+        msg = ('Can not install signal handlers.  Please install '
+               '(or upgrade) your pywin32 installation '
+               '(https://sf.net/projects/pywin32)')
+        logger.warning(msg)
+        SignalHandler = None
+else:
+    from SignalHandler import SignalHandler
 
 def shutdownFastHandler():
     """Shutdown cleanly on SIGTERM. This is registered first,
@@ -60,6 +69,24 @@ class LogfileReopenHandler:
             log.reopen()
         logger.info("Log files reopened successfully")
 
+# On Windows, a 'reopen' is useless - the file can not be renamed
+# while open, so we perform a trivial 'rotate'.
+class LogfileRotateHandler:
+    """Rotate log files on SIGUSR2. Only called on Windows. This is 
+       registered first, so it should be called after all other SIGUSR2 
+       handlers."""
+    def __init__(self, loggers):
+        self.loggers = [log for log in loggers if log is not None]
+
+    def __call__(self):
+        logger.debug("Log files rotation starting...")
+        for log in self.loggers:
+            for f in log.handler_factories:
+                handler = f()
+                if hasattr(handler, 'rotate') and callable(handler.rotate):
+                    handler.rotate()
+        logger.info("Log files rotation complete")
+
 def packHandler():
     """ Packs the main database.  Not safe to call under a signal
     handler, because it blocks the main thread """
@@ -74,14 +101,32 @@ def packHandler():
         
 
 def registerZopeSignals(loggers):
-    import signal
-    SignalHandler.registerHandler(signal.SIGTERM, shutdownFastHandler)
-    SignalHandler.registerHandler(signal.SIGINT, shutdownHandler)
-    SignalHandler.registerHandler(signal.SIGHUP, restartHandler)
-    SignalHandler.registerHandler(signal.SIGUSR2,
-                                  LogfileReopenHandler(loggers))
+    from signal import SIGTERM, SIGINT
+    try:
+        from signal import SIGHUP, SIGUSR1, SIGUSR2
+    except ImportError:
+        # Windows doesn't have these (but also doesn't care what the exact
+        # numbers are)
+        SIGHUP = 1
+        SIGUSR1 = 10
+        SIGUSR2 = 12
+
+    if not SignalHandler:
+        return
+    SignalHandler.registerHandler(SIGTERM, shutdownFastHandler)
+    SignalHandler.registerHandler(SIGINT, shutdownHandler)
+    if os.name != 'nt':
+        SignalHandler.registerHandler(SIGHUP, restartHandler)
+        SignalHandler.registerHandler(SIGUSR2, LogfileReopenHandler(loggers))
+    else:
+        # no restart handler on windows.
+        # Log files get 'rotated', not 'reopened'
+        SignalHandler.registerHandler(SIGUSR2, LogfileRotateHandler(loggers))
     # SIGUSR1 is nominally reserved for pack, but we dont have an
     # implementation that is stable yet because if the signal handler
     # fires it will be caught in the main thread and all network operations
     # will cease until it's finished.
-    #SignalHandler.registerHandler(signal.SIGUSR1, packHandler)
+    # (The above is *not* True for Windows - a different thread is used to
+    # catch the signals.  This probably could be switched on for Windows
+    # if anyone cares)
+    #SignalHandler.registerHandler(SIGUSR1, packHandler)