python: Break unixctl implementation into registry, client, and server.

[openvswitch] / python / ovs / unixctl / __init__.py

diff --git a/python/ovs/unixctl/__init__.py b/python/ovs/unixctl/__init__.py
new file mode 100644 (file)
index 0000000..715f2db
--- /dev/null
+++ b/python/ovs/unixctl/__init__.py
@@ -0,0 +1,83 @@
+# Copyright (c) 2011, 2012 Nicira, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import types
+
+import ovs.util
+
+commands = {}
+strtypes = types.StringTypes
+
+
+class _UnixctlCommand(object):
+    def __init__(self, usage, min_args, max_args, callback, aux):
+        self.usage = usage
+        self.min_args = min_args
+        self.max_args = max_args
+        self.callback = callback
+        self.aux = aux
+
+
+def _unixctl_help(conn, unused_argv, unused_aux):
+    reply = "The available commands are:\n"
+    command_names = sorted(commands.keys())
+    for name in command_names:
+        reply += "  "
+        usage = commands[name].usage
+        if usage:
+            reply += "%-23s %s" % (name, usage)
+        else:
+            reply += name
+        reply += "\n"
+    conn.reply(reply)
+
+
+def command_register(name, usage, min_args, max_args, callback, aux):
+    """ Registers a command with the given 'name' to be exposed by the
+    UnixctlServer. 'usage' describes the arguments to the command; it is used
+    only for presentation to the user in "help" output.
+
+    'callback' is called when the command is received.  It is passed a
+    UnixctlConnection object, the list of arguments as unicode strings, and
+    'aux'.  Normally 'callback' should reply by calling
+    UnixctlConnection.reply() or UnixctlConnection.reply_error() before it
+    returns, but if the command cannot be handled immediately, then it can
+    defer the reply until later.  A given connection can only process a single
+    request at a time, so a reply must be made eventually to avoid blocking
+    that connection."""
+
+    assert isinstance(name, strtypes)
+    assert isinstance(usage, strtypes)
+    assert isinstance(min_args, int)
+    assert isinstance(max_args, int)
+    assert isinstance(callback, types.FunctionType)
+
+    if name not in commands:
+        commands[name] = _UnixctlCommand(usage, min_args, max_args, callback,
+                                         aux)
+
+def socket_name_from_target(target):
+    assert isinstance(target, strtypes)
+
+    if target.startswith("/"):
+        return 0, target
+
+    pidfile_name = "%s/%s.pid" % (ovs.dirs.RUNDIR, target)
+    pid = ovs.daemon.read_pidfile(pidfile_name)
+    if pid < 0:
+        return -pid, "cannot read pidfile \"%s\"" % pidfile_name
+
+    return 0, "%s/%s.%d.ctl" % (ovs.dirs.RUNDIR, target, pid)
+
+command_register("help", "", 0, 0, _unixctl_help, None)