# HG changeset patch
# User paulb
# Date 1132444839 0
# Node ID 26d9b08d05f5063a97551d1f96160680944d8bc9
# Parent  83fcc5d284e5b916236fcc1f519b3f17409e7583
[project @ 2005-11-20 00:00:39 by paulb]
Added primitive locking to the DirectoryRepository implementation.

diff -r 83fcc5d284e5 -r 26d9b08d05f5 WebStack/Repositories/Directory.py
--- a/WebStack/Repositories/Directory.py	Sat Nov 19 23:59:54 2005 +0000
+++ b/WebStack/Repositories/Directory.py	Sun Nov 20 00:00:39 2005 +0000
@@ -26,7 +26,7 @@
 
     "A directory repository providing session-like access to files."
 
-    def __init__(self, path, fsencoding=None):
+    def __init__(self, path, fsencoding=None, delay=1):
 
         """
         Initialise the repository using the given 'path' to indicate the
@@ -37,12 +37,17 @@
         character encoding used by the filesystem to represent filenames. By
         default, the default encoding is detected (or Unicode objects are used
         if appropriate).
+
+        The optional 'delay' argument specifies the time in seconds between each
+        poll of an opened repository file when that file is found to be locked
+        for editing.
         """
 
         if not os.path.exists(path):
             os.mkdir(path)
         self.path = path
         self.fsencoding = fsencoding
+        self.delay = delay
 
         # Guess the filesystem encoding.
 
@@ -71,7 +76,14 @@
             return name
 
     def keys(self):
-        return map(self._convert_fsname, os.listdir(self.path))
+        # NOTE: Special names converted using a simple rule.
+        l = []
+        for name in os.listdir(self.path):
+            if name.endswith(".edit"):
+                l.append(name[:-5])
+            else:
+                l.append(name)
+        return map(self._convert_fsname, l)
 
     def full_path(self, key):
         return os.path.join(self.path, self._convert_name(key))
@@ -93,23 +105,58 @@
             results.append(self[key])
         return results
 
-    def __getitem__(self, key):
-        f = open(os.path.join(self.path, self._convert_name(key)), "rb")
-        s = ""
-        try:
-            s = f.read()
-        finally:
-            f.close()
-        return s
+    def _wait_for_file(self, key):
+        filename = self.full_path(key)
+        if os.path.exists(filename) or os.path.exists(filename + ".edit"):
+            while 1:
+                try:
+                    os.rename(filename, filename + ".edit")
+                except OSError:
+                    time.sleep(self.delay)
+                else:
+                    break
+            return filename, 1
+        else:
+            return filename, 0
 
     def __delitem__(self, key):
-        os.remove(os.path.join(self.path, self._convert_name(key)))
+        filename = self.full_path(key)
+        if os.path.exists(filename) or os.path.exists(filename + ".edit"):
+            while 1:
+                try:
+                    os.remove(filename)
+                except OSError:
+                    time.sleep(self.delay)
+                else:
+                    break
+        else:
+            raise KeyError, key
+
+    def __getitem__(self, key):
+        filename, exists = self._wait_for_file(key)
+        if not exists:
+            raise KeyError, key
+        try:
+            f = open(filename + ".edit", "rb")
+            s = ""
+            try:
+                s = f.read()
+            finally:
+                f.close()
+        finally:
+            os.rename(filename + ".edit", filename)
+
+        return s
 
     def __setitem__(self, key, value):
-        f = open(os.path.join(self.path, self._convert_name(key)), "wb")
+        filename, exists = self._wait_for_file(key)
         try:
-            f.write(value)
+            f = open(filename + ".edit", "wb")
+            try:
+                f.write(value)
+            finally:
+                f.close()
         finally:
-            f.close()
+            os.rename(filename + ".edit", filename)
 
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