add some mongodb setup

bigchaindb/backend/mongodb/connection.py

@@ -0,0 +1,46 @@
+import time
+import logging
+
+from pymongo import MongoClient
+from pymongo.errors import ConnectionError
+
+import bigchaindb
+from bigchaindb.backend.connection import Connection
+
+logger = logging.getLogger(__name__)
+
+class MongoDBConnection(Connection):
+
+    def __init__(self, host=None, port=None, db=None, max_tries=3):
+        """Create a new Connection instance.
+
+        Args:
+            host (str, optional): the host to connect to.
+            port (int, optional): the port to connect to.
+            db (str, optional): the database to use.
+            max_tries (int, optional): how many tries before giving up.
+        """
+
+        self.host = host or bigchaindb.config['database']['host']
+        self.port = port or bigchaindb.config['database']['port']
+        self.db = db or bigchaindb.config['database']['name']
+        self.max_tries = max_tries
+        self.conn = None
+
+    @property
+    def db(self):
+        if self.conn is None:
+            self._connect()
+
+        else:
+            return self.conn[self.db]
+
+    def _connect(self):
+        for i in range(self.max_tries):
+            try:
+                self.conn = MongoClient(self.host, self.port)
+            except ConnectionError as exc:
+                if i + 1 == self.max_tries:
+                    raise
+                else:
+                    time.sleep(2**i)

bigchaindb/backend/mongodb/query.py

@@ -0,0 +1,42 @@
+from bigchaindb.backend import query
+from bigchaindb.backend.mongodb.connection import MongoDBConnection
+
+
+@query.write_transaction.register(MongoDBConnection)
+def write_transaction(conn, signed_transaction):
+    return conn.db['backlog'].insert_one(signed_transaction)
+
+
+@query.write_vote.register(MongoDBConnection)
+def write_vote(conn, vote):
+    return conn.db['votes'].insert_one(vote)
+
+
+@query.write_block.register(MongoDBConnection)
+def write_block(conn, block):
+    return conn.db['bigchain'].insert_one(block.to_dict())
+
+
+@query.genesis_block_exists.register(MongoDBConnection)
+def genesis_block_exists(conn):
+    return conn.db['bigchain'].count() > 0
+
+
+@query.search_block_election_on_index.register(MongoDBConnection)
+def search_block_election_on_index(conn, value, index):
+    return conn.db['bigchain']\
+        .find({index: value}, projection={'votes', 'id', 'block.voters'})
+
+
+@query.get_votes_on_block.register(MongoDBConnection)
+def get_votes_on_block(conn, block_id):
+    return conn.db['votes'].find({'vote.voting_for_block': block_id})
+
+
+@query.transaction_exists.register(MongoDBConnection)
+def transaction_exists(conn, transaction_id):
+    if conn.db['bigchain']\
+       .find_one({'block.transactions.id': transaction_id}):
+        return True
+    else:
+        return False