Merged changes from cce branch (r3727:HEAD/4008); the branch is now in sync with trunk

1 files changed, 79 insertions, 0 deletions

diff --git a/paste/transaction.py b/paste/transaction.py
new file mode 100644
index 0000000..17b434d
--- /dev/null
+++ b/paste/transaction.py
@@ -0,0 +1,79 @@
+# (c) 2005 Clark C. Evans
+# This module is part of the Python Paste Project and is released under
+# the MIT License: http://www.opensource.org/licenses/mit-license.php
+"""
+Middleware related to transactions and database connections.
+
+At this time it is very basic; but will eventually sprout all that
+two-phase commit goodness that I don't need. 
+"""
+from paste.httpexceptions import HTTPError, HTTPException
+
+class ConnectionFactory(object):
+    """
+    Provides a callable interface for connecting to ADBAPI databases in
+    a WSGI style (using the environment).  More advanced connection
+    factories might use the REMOTE_USER and/or other environment
+    variables to make the connection returned depend upon the request.
+    """
+    def __init__(self, module, *args, **kwargs):
+        #assert getattr(module,'threadsaftey',0) > 0
+        self.module = module
+        self.args = args
+        self.kwargs = kwargs
+
+        # deal with database string quoting issues
+        self.quote = lambda s: "'%s'" % s.replace("'","''")
+        if hasattr(self.module,'PgQuoteString'):
+            self.quote = self.module.PgQuoteString
+
+    def __call__(self, environ):
+        conn = self.module.connect(*self.args,**self.kwargs)
+        conn.__dict__['module'] = self.module
+        conn.__dict__['quote'] = self.quote
+        return conn
+
+def BasicTransactionHandler(application, factory):
+    """
+    Provides a simple mechanism for starting a transaction based on the
+    factory; and for either committing or rolling back the transaction
+    depending on the result.  It checks for the response's current
+    status code either through the latest call to start_response; or
+    through a HTTPException's code.  If it is a 100, 200, or 300; the
+    transaction is committed; otherwise it is rolled back.
+    """
+
+    def basic_transaction(environ, start_response):
+        conn = factory(environ)
+        environ['paste.connection'] = conn
+        should_commit = [500]
+        def finalizer():
+            if should_commit.pop() < 400:
+                conn.commit()
+            else:
+                conn.rollback()
+            conn.close()
+        def basictrans_start_response(status, headers, exc_info = None):
+            should_commit.append(int(status.split(" ")[0]))
+            return start_response(status, headers, exc_info)
+        try:
+            for chunk in application(environ, basictrans_start_response):
+                yield chunk
+        except Exception, e:
+            if isinstance(e,HTTPException):
+                should_commit.append(e.code)
+            finalizer()
+            raise
+        finalizer()
+    return basic_transaction
+
+__all__ = ['ConnectionFactory','BasicTransactionHandler']
+
+if '__main__' == __name__ and False:
+    from pyPgSQL import PgSQL
+    factory = ConnectionFactory(PgSQL,database="testing")
+    conn = factory(None)
+    curr = conn.cursor()
+    curr.execute("SELECT now(), %s" % conn.quote("B'n\\'gles"))
+    (time,bing) = curr.fetchone()
+    print bing, time