initial commit

src/zcm.py

@@ -0,0 +1,97 @@
+#!/usr/bin/python3.5
+# encoding: utf8
+
+# Copyright (c) 2016 Andreas
+# See LICENSE for details.
+
+""" ZODB context manager """
+
+# from BTrees.IOBTree import IOBTree
+# from BTrees.OOBTree import OOBTree
+# from persistent import Persistent
+# from persistent.list import PersistentList as PList
+# from persistent.mapping import PersistentMapping as PDict
+
+from ZEO.ClientStorage import ClientStorage
+from ZODB import DB
+from ZODB.FileStorage import FileStorage
+
+
+class ZDatabase():
+    """ Provides a ZODB database context manager """
+
+    def __init__(self, uri, **kwargs):
+        self.storage = create_storage(uri)
+        self.db = DB(self.storage, **kwargs)
+
+    def __enter__(self):
+        return self.db
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.db.close()
+        return False
+
+
+class ZConnection():
+    """ Provides a ZODB connection with auto-abort (default).
+    Provides a tuple of connection and root object:
+        with ZConnection(db) as (cx, root):
+            root.one = "ok"
+    ZConnection implements a connection context manager.
+    Transaction context managers in contrast do auto-commit:
+        a) with db.transaction() as connection, or
+        b) with cx.transaction_manager as transaction, or
+        c) with transaction.manager as transaction  (for the thread-local transaction manager)
+    See also http://www.zodb.org/en/latest/guide/transactions-and-threading.html
+    """
+    def __init__(self, db, auto_commit=False, transaction_manager=None):
+        self.db = db
+        self.auto_commit = auto_commit
+        self.transaction_manager = transaction_manager
+        self.cx = None
+
+    def __enter__(self):
+        if self.transaction_manager:
+            self.cx = self.db.open(self.transaction_manager)
+        else:
+            self.cx = self.db.open()
+        return self.cx, self.cx.root()
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        if self.auto_commit:
+            self.cx.transaction_manager.commit()
+        self.cx.close()
+        return False
+
+
+def create_storage(uri):
+    """ supported URIs
+    file://e:/workspaces/zeo/bots.fs
+    zeo://localhost:8001
+    e:/workspaces/zeo/bots.fs
+    @see https://en.wikipedia.org/wiki/Uniform_Resource_Identifier
+    """
+    if uri.startswith("file://"):
+        storage = FileStorage(uri[7:])
+    elif uri.startswith("zeo://"):
+        addr, port = uri[6:].split(":")
+        # addr_ = addr.encode("ASCII")
+        storage = ClientStorage((addr, int(port)))
+    else:
+        storage = FileStorage(uri)
+    return storage
+
+
+def database(uri):
+    """ convenience function for single thread, return one connection from the pool """
+    storage = create_storage(uri)
+    db = DB(storage)
+    return db
+
+
+def connection(db):
+    """ Convenience function for multi thread, returns
+    connection, transaction manager and root
+    """
+    cx = db.open()
+    return cx, cx.root()