integrated portalocker with htmltmpl

planet/htmltmpl.py

@@ -44,6 +44,7 @@ import cgi          # for HTML escaping of variables
 import urllib       # for URL escaping of variables
 import cPickle      # for template compilation
 import gettext
+import portalocker  # for locking
 
 INCLUDE_DIR = "inc"
 
@@ -57,25 +58,6 @@ PARAM_ESCAPE = 2
 PARAM_GLOBAL = 3
 PARAM_GETTEXT_STRING = 1
 
-# Find a way to lock files. Currently implemented only for UNIX and windows.
-LOCKTYPE_FCNTL = 1
-LOCKTYPE_MSVCRT = 2
-LOCKTYPE = None
-try:
-    import fcntl
-except:
-    try:
-        import msvcrt
-    except:
-        LOCKTYPE = None
-    else:
-        LOCKTYPE = LOCKTYPE_MSVCRT
-else:
-    LOCKTYPE = LOCKTYPE_FCNTL
-LOCK_EX = 1
-LOCK_SH = 2
-LOCK_UN = 3
-
 ##############################################
 #          CLASS: TemplateManager            #
 ##############################################
@@ -129,13 +111,6 @@ class TemplateManager:
 
             The <em>TemplateError</em>exception is raised when the precompiled
             template cannot be saved. Precompilation is enabled by default.
-
-            Precompilation is available only on UNIX and Windows platforms,
-            because proper file locking which is necessary to ensure
-            multitask safe behaviour is platform specific and is not
-            implemented for other platforms. Attempts to enable precompilation
-            on the other platforms result in raise of the
-            <em>TemplateError</em> exception.
             
             @param comments Enable or disable template comments.
             This optional parameter can be used to enable or disable
@@ -159,13 +134,6 @@ class TemplateManager:
         self._gettext = gettext
         self._debug = debug
 
-        # Find what module to use to lock files.
-        # File locking is necessary for the 'precompile' feature to be
-        # multitask/thread safe. Currently it works only on UNIX
-        # and Windows. Anyone willing to implement it on Mac ?
-        if precompile and not LOCKTYPE:
-                raise TemplateError, "Template precompilation is not "\
-                                     "available on this platform."
         self.DEB("INIT DONE")
 
     def prepare(self, file):
@@ -260,33 +228,6 @@ class TemplateManager:
         """
         if self._debug: print >> sys.stderr, str
 
-    def lock_file(self, file, lock):
-        """ Provide platform independent file locking.
-            @hidden
-        """
-        fd = file.fileno()
-        if LOCKTYPE == LOCKTYPE_FCNTL:
-            if lock == LOCK_SH:
-                fcntl.flock(fd, fcntl.LOCK_SH)
-            elif lock == LOCK_EX:
-                fcntl.flock(fd, fcntl.LOCK_EX)
-            elif lock == LOCK_UN:
-                fcntl.flock(fd, fcntl.LOCK_UN)
-            else:
-                raise TemplateError, "BUG: bad lock in lock_file"
-        elif LOCKTYPE == LOCKTYPE_MSVCRT:
-            if lock == LOCK_SH:
-                # msvcrt does not support shared locks :-(
-                msvcrt.locking(fd, msvcrt.LK_LOCK, 1)
-            elif lock == LOCK_EX:
-                msvcrt.locking(fd, msvcrt.LK_LOCK, 1)
-            elif lock == LOCK_UN:
-                msvcrt.locking(fd, msvcrt.LK_UNLCK, 1)
-            else:
-                raise TemplateError, "BUG: bad lock in lock_file"
-        else:
-            raise TemplateError, "BUG: bad locktype in lock_file"
-
     def compile(self, file):
         """ Compile the template.
             @hidden
@@ -322,7 +263,7 @@ class TemplateManager:
             file = None
             try:
                 file = open(filename, "rb")
-                self.lock_file(file, LOCK_SH)
+                portalocker.lock(file, portalocker.LOCK_SH)
                 precompiled = cPickle.load(file)
             except IOError, (errno, errstr):
                 raise TemplateError, "IO error in load precompiled "\
@@ -338,7 +279,7 @@ class TemplateManager:
                 return precompiled
         finally:
             if file:
-                self.lock_file(file, LOCK_UN)
+                portalocker.unlock(file)
                 file.close()
             if remove_bad and os.path.isfile(filename):
                 # X: We may lose the original exception here, raising OSError.
@@ -369,7 +310,7 @@ class TemplateManager:
             file = None
             try:
                 file = open(filename, "wb")   # may truncate existing file
-                self.lock_file(file, LOCK_EX)
+                portalocker.lock(file, portalocker.LOCK_EX)
                 BINARY = 1
                 READABLE = 0
                 if self._debug:
@@ -393,7 +334,7 @@ class TemplateManager:
                 self.DEB("SAVING PRECOMPILED")
         finally:
             if file:
-                self.lock_file(file, LOCK_UN)
+                portalocker.unlock(file)
                 file.close()
             if remove_bad and os.path.isfile(filename):
                 # X: We may lose the original exception here, raising OSError.

planet/portalocker.py

@@ -0,0 +1,93 @@
+# portalocker.py - Cross-platform (posix/nt) API for flock-style file locking.
+#                  Requires python 1.5.2 or better.
+# See http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65203/index_txt
+# Except where otherwise noted, recipes in the Python Cookbook are 
+# published under the Python license.
+
+"""Cross-platform (posix/nt) API for flock-style file locking.
+
+Synopsis:
+
+   import portalocker
+   file = open("somefile", "r+")
+   portalocker.lock(file, portalocker.LOCK_EX)
+   file.seek(12)
+   file.write("foo")
+   file.close()
+
+If you know what you're doing, you may choose to
+
+   portalocker.unlock(file)
+
+before closing the file, but why?
+
+Methods:
+
+   lock( file, flags )
+   unlock( file )
+
+Constants:
+
+   LOCK_EX
+   LOCK_SH
+   LOCK_NB
+
+I learned the win32 technique for locking files from sample code
+provided by John Nielsen <nielsenjf@my-deja.com> in the documentation
+that accompanies the win32 modules.
+
+Author: Jonathan Feinberg <jdf@pobox.com>
+Version: $Id: portalocker.py,v 1.3 2001/05/29 18:47:55 Administrator Exp $
+"""
+
+import os
+
+if os.name == 'nt':
+	import win32con
+	import win32file
+	import pywintypes
+	LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
+	LOCK_SH = 0 # the default
+	LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
+	# is there any reason not to reuse the following structure?
+	__overlapped = pywintypes.OVERLAPPED()
+elif os.name == 'posix':
+	import fcntl
+	LOCK_EX = fcntl.LOCK_EX
+	LOCK_SH = fcntl.LOCK_SH
+	LOCK_NB = fcntl.LOCK_NB
+else:
+	raise RuntimeError("PortaLocker only defined for nt and posix platforms")
+
+if os.name == 'nt':
+	def lock(file, flags):
+		hfile = win32file._get_osfhandle(file.fileno())
+		win32file.LockFileEx(hfile, flags, 0, -0x10000, __overlapped)
+
+	def unlock(file):
+		hfile = win32file._get_osfhandle(file.fileno())
+		win32file.UnlockFileEx(hfile, 0, -0x10000, __overlapped)
+
+elif os.name =='posix':
+	def lock(file, flags):
+		fcntl.flock(file.fileno(), flags)
+
+	def unlock(file):
+		fcntl.flock(file.fileno(), fcntl.LOCK_UN)
+
+if __name__ == '__main__':
+	from time import time, strftime, localtime
+	import sys
+	import portalocker
+
+	log = open('log.txt', "a+")
+	portalocker.lock(log, portalocker.LOCK_EX)
+
+	timestamp = strftime("%m/%d/%Y %H:%M:%S\n", localtime(time()))
+	log.write( timestamp )
+
+	print "Wrote lines. Hit enter to release lock."
+	dummy = sys.stdin.readline()
+
+	log.close()
+

planet/shell/tmpl.py

@@ -225,7 +225,7 @@ def template_info(source):
 
 def run(script, doc, output_file=None, options={}):
     """ process an HTMLTMPL file """
-    manager = htmltmpl.TemplateManager(precompile=(sys.platform.find('win')<0))
+    manager = htmltmpl.TemplateManager()
     template = manager.prepare(script)
     tp = htmltmpl.TemplateProcessor(html_escape=0)
     for key,value in template_info(doc).items():

tests/test_apply.py

@@ -32,7 +32,7 @@ class ApplyTest(unittest.TestCase):
         for file in ['index.html', 'default.css', 'images/foaf.png']:
             path = os.path.join(workdir, file)
             self.assertTrue(os.path.exists(path))
-            self.assertTrue(os.stat(path).st_size > 0)
+            self.assertTrue(os.stat(path).st_size > 0, file + ' has size 0')
 
         # verify that index.html is well formed, has content, and xml:lang
         html = open(os.path.join(workdir, 'index.html'))