Testing the docscript

Author: Mohan Kishore

.gitignore

@@ -100,3 +100,7 @@ ENV/
 
 # mypy
 .mypy_cache/
+
+# IDE(s)
+.idea/
+*.iml

.travis.yml

@@ -1,28 +1,17 @@
-# Config file for automatic testing at travis-ci.org
-
 language: python
 python:
-  - 3.6
-  - 3.5
-  - 3.4
-  - 2.7
-
-# Command to install dependencies, e.g. pip install -r requirements.txt --use-mirrors
+- 3.6
+- 3.5
+- 3.4
+- 2.7
 install: pip install -U tox-travis
-
-# Command to run tests, e.g. python setup.py test
 script: tox
-
-# Assuming you have installed the travis-ci CLI tool, after you
-# create the Github repo and add it to Travis, run the
-# following command to finish PyPI deployment setup:
-# $ travis encrypt --add deploy.password
 deploy:
   provider: pypi
   distributions: sdist bdist_wheel
   user: mohankishore
   password:
-    secure: PLEASE_REPLACE_ME
+    secure: 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
   on:
     tags: true
     repo: mohankishore/python_dynamodb_lock

python_dynamodb_lock/__init__.py

@@ -5,3 +5,4 @@
 __author__ = """Mohan Kishore"""
 __email__ = 'mohankishore@yahoo.com'
 __version__ = '0.1.0'
+__copyright__ = 'Copyright (C) 2018 Mohan Kishore'

python_dynamodb_lock/python_dynamodb_lock.py

@@ -1,3 +1,195 @@
 # -*- coding: utf-8 -*-
 
-"""Main module."""
+# TODO
+"""
+module comment
+"""
+import boto3
+import botocore
+import datetime
+import socket
+import time
+import threading
+import uuid
+
+
+class DynamoDBLockClient:
+    # TODO
+    """
+    class comment
+    """
+
+    DEFAULT_TABLE_NAME = 'lockTable'
+    DEFAULT_PARTITION_KEY_NAME = 'key'
+    DEFAULT_SORT_KEY_NAME = 'sort_key'
+    DEFAULT_LEASE_DURATION = datetime.timedelta(seconds=30)
+    DEFAULT_HEARTBEAT_PERIOD = datetime.timedelta(seconds=10)
+
+    def __init__(self,
+                 dynamodb_client,
+                 table_name = DEFAULT_TABLE_NAME,
+                 partition_key_name = DEFAULT_PARTITION_KEY_NAME,
+                 sort_key_name = DEFAULT_SORT_KEY_NAME,
+                 owner_name = None,
+                 lease_duration = DEFAULT_LEASE_DURATION,
+                 heartbeat_period = DEFAULT_HEARTBEAT_PERIOD
+                 ):
+        """
+        The constructor that support default values for all/most of the arguments.
+        
+        :param dynamodb_client: boto3.DynamoDB.Client - mandatory argument
+        :param table_name: str - defaults to 'lockTable' 
+        :param partition_key_name: str - defaults to 'key'
+        :param sort_key_name: str - defaults to 'sort_key'
+        :param owner_name: str - defaults to hostname + uuid
+        :param lease_duration: datetime.timedelta - The length of time that the lease for the lock 
+                will be granted for. i.e. if there is no heartbeat for this period of time, then 
+                the lock will be considered as expired. Defaults to 30 seconds.
+        :param heartbeat_period: datetime.timedelta - How often to update DynamoDB to note that the 
+                instance is still running. It is recommended to make this at least 3 times smaller 
+                than the leaseDuration. Defaults to 10 seconds.
+        """
+        self.uuid = uuid.uuid4()
+        self.dynamodb_client = dynamodb_client
+        self.table_name = table_name
+        self.partition_key_name = partition_key_name
+        self.sort_key_name = sort_key_name
+        self.owner_name = owner_name if owner_name else socket.getfqdn() + self.uuid
+        self.lease_duration = lease_duration
+        self.heartbeat_period = heartbeat_period
+        self.background_thread = self._start_background_thread()
+        self.locks = {}
+        self.shutting_down = False
+
+    def _start_background_thread(self):
+        """
+        Creates and starts a daemon thread - that calls DynamoDBLockClient.run() method.
+        """
+        background_thread = threading.Thread(
+            name='DynamoDBLockClient-' + uuid,
+            target=self
+        )
+        background_thread.daemon = True
+        background_thread.start()
+        return background_thread
+
+    def run(self):
+        """
+        Iterates over all the locks owned by this lock-client, and renews their leases.
+        """
+        while (True):
+            if self.shutting_down: return None
+
+            start_time = datetime.datetime.utcnow()
+            for lock in self.locks.itervalues():
+                self.send_heartbeat(lock)
+            end_time = datetime.datetime.utcnow()
+
+            if self.shutting_down: return None
+
+            elapsed_time = (end_time - start_time)
+            if elapsed_time < self.heartbeat_period:
+                time.sleep( (self.heartbeat_period - elapsed_time).total_seconds() )
+
+    def send_heartbeat(self, lock):
+        """
+        Renews the lease for the given lock
+        
+        :param lock: DynamoDBLock instance - that needs its lease to be renewed 
+        """
+        with lock.lock:
+            try:
+                # TODO actual impl
+                print
+                # update
+                # table
+                # keys
+                # SET #ld = :ld, #rvn = :newRvn
+                # attribute_exists(#pk) AND attribute_exists(#sk) AND #rvn = :rvn AND #on = :on
+                # attribute-names
+                # attribute-values
+            except botocore.exceptions.ClientError as e:
+                if e.response['Error']['Code'] == 'ConditionalCheckFailedException':
+                    # TODO: need to handle the case where the lock was "stolen" by someone else...
+                    print
+                else:
+                    print
+            except:
+                print
+
+
+    def close(self):
+        """
+        Shuts down the background thread and releases all locks. 
+        """
+        self.shutting_down = True
+        self.background_thread.join()
+        self.release_all_locks()
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        """
+        Calls the close() method
+        """
+        self.close()
+
+    def acquire_lock(self,
+                     partition_key,
+                     sort_key = None,
+                     retry_period = datetime.timedelta(seconds=2),
+                     retry_timeout = datetime.timedelta(seconds=5),
+                     additional_attributes = {}
+                     ):
+        """"""
+
+    def release_lock(self,
+                     lock,
+                     best_effort = False
+                     ):
+        """"""
+        with lock.lock:
+            try:
+                del self.locks[lock.uuid]
+                # TODO actual impl
+                # delete
+                # table
+                # keys
+                # attribute_exists(#pk) AND attribute_exists(#sk) AND #rvn = :rvn AND #on = :on
+                # attribute-names
+                # attribute-values
+            except botocore.exceptions.ClientError as e:
+                if e.response['Error']['Code'] == 'ConditionalCheckFailedException':
+                    # TODO: need to handle the case where the lock was "stolen" by someone else...
+                    print
+                else:
+                    # if not best_effort: raise error
+                    print
+            except:
+                print
+
+
+    # TODO: make this private?
+    def release_all_locks(self):
+        """"""
+        for lock in self.locks.itervalues():
+            self.release_lock(lock)
+
+    # get_lock
+    # get_all_locks
+
+
+
+class DynamoDBLock:
+    # TODO
+    """
+    class comment
+    """
+
+    def __init__(self,
+                 partition_key,
+                 sort_key = None,
+                 retry_period = datetime.timedelta(seconds=2),
+                 retry_timeout = datetime.timedelta(seconds=5),
+                 additional_attributes = {}
+                 ):
+        # TODO
+        """"""

requirements_dev.txt

@@ -8,3 +8,5 @@ coverage==4.5.1
 Sphinx==1.7.8
 twine==1.11.0
 sphinx_rtd_theme==0.4.1
+boto3==1.8.6
+botocore==1.11.6