Create code base for vmware vio driver

This patch is to create code base for vio driver.

Issue-ids: MULTIVIM-37
Change-Id: I81a9a5b178ad4a177e4635d5e7caee831dc1dde2
Signed-off-by: xinhuili <lxinhui@vmware.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/vio/pub/utils/share_lock.py b/vio/pub/utils/share_lock.py
new file mode 100644
index 0000000..ffdcdc4
--- /dev/null
+++ b/vio/pub/utils/share_lock.py
@@ -0,0 +1,80 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# Copyright 2017 VMware Corporation.
+#
+# 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 time
+
+import redis
+
+from vio.pub.config.config import REDIS_HOST, REDIS_PORT, REDIS_PASSWD
+
+
+class SharedLock:
+    def __init__(self, lock_key, host=REDIS_HOST, port=REDIS_PORT, password=REDIS_PASSWD, db=9, lock_timeout=5 * 60):
+        self.lock_key = lock_key
+        self.lock_timeout = lock_timeout
+        self.redis = redis.Redis(host=host, port=port, db=db, password=password)
+        self.acquire_time = -1
+
+    def acquire(self):
+        begin = now = int(time.time())
+        while (now - begin) < self.lock_timeout:
+
+            result = self.redis.setnx(self.lock_key, now + self.lock_timeout + 1)
+            if result == 1 or result is True:
+                self.acquire_time = now
+                return True
+
+            current_lock_timestamp = self.redis.get(self.lock_key)
+            if not current_lock_timestamp:
+                time.sleep(1)
+                continue
+
+            current_lock_timestamp = int(current_lock_timestamp)
+
+            if now > current_lock_timestamp:
+                next_lock_timestamp = self.redis.getset(self.lock_key, now + self.lock_timeout + 1)
+                if not next_lock_timestamp:
+                    time.sleep(1)
+                    continue
+                next_lock_timestamp = int(next_lock_timestamp)
+
+                if next_lock_timestamp == current_lock_timestamp:
+                    self.acquire_time = now
+                    return True
+            else:
+                time.sleep(1)
+                continue
+        return False
+
+    def release(self):
+        now = int(time.time())
+        if now > self.acquire_time + self.lock_timeout:
+            # key expired, do nothing and let other clients handle it
+            return
+        self.acquire_time = None
+        self.redis.delete(self.lock_key)
+
+
+def do_biz_with_share_lock(lock_name, callback):
+    lock = SharedLock(lock_name)
+    try:
+        if not lock.acquire():
+            raise Exception(lock_name + " timeout")
+        callback()
+    except Exception as e:
+        raise e
+    finally:
+        lock.release()