Normalize exceptions

bigchaindb/backend/connection.py

@@ -32,6 +32,7 @@ def connect(backend=None, host=None, port=None, name=None, replicaset=None):
         based on the given (or defaulted) :attr:`backend`.
 
     Raises:
+        :exc:`~ConnectionError`: If the connection to the database fails.
         :exc:`~ConfigurationError`: If the given (or defaulted) :attr:`backend`
             is not supported or could not be loaded.
     """
@@ -77,6 +78,13 @@ class Connection:
 
         Args:
             query: the query to run
+        Raises:
+            :exc:`~DuplicateKeyError`: If the query fails because of a
+                duplicate key constraint.
+            :exc:`~OperationFailure`: If the query fails for any other
+                reason.
+            :exc:`~ConnectionError`: If the connection to the database
+                fails.
         """
 
         raise NotImplementedError()

bigchaindb/backend/exceptions.py

@@ -1,9 +1,17 @@
 from bigchaindb.exceptions import BigchainDBError
 
 
-class ConnectionError(BigchainDBError):
+class BackendError(BigchainDBError):
-    """Exception raised when the connection to the DataBase fails."""
+    """Top level exception for any backend exception."""
 
 
-class DatabaseOpFailedError(BigchainDBError):
+class ConnectionError(BackendError):
-    """Exception for database operation errors."""
+    """Exception raised when the connection to the backend fails."""
+
+
+class OperationError(BackendError):
+    """Exception raised when a backend operation fails."""
+
+
+class DuplicateKeyError(OperationError):
+    """Exception raised when an insert fails because the key is not unique"""

bigchaindb/backend/mongodb/changefeed.py

@@ -1,15 +1,15 @@
+import os
 import logging
 import time
 
 import pymongo
-from pymongo import errors
 
 from bigchaindb import backend
 from bigchaindb.backend.changefeed import ChangeFeed
 from bigchaindb.backend.utils import module_dispatch_registrar
 from bigchaindb.backend.mongodb.connection import MongoDBConnection
-from bigchaindb.backend.exceptions import (DatabaseOpFailedError,
+from bigchaindb.backend.exceptions import BackendError
-                                           ConnectionError)
+
 
 logger = logging.getLogger(__name__)
 register_changefeed = module_dispatch_registrar(backend.changefeed)
@@ -30,11 +30,8 @@ class MongoDBChangeFeed(ChangeFeed):
             try:
                 self.run_changefeed()
                 break
-            except (errors.ConnectionFailure, errors.OperationFailure,
+            except BackendError:
-                    errors.AutoReconnect,
+                logger.exception('Error connecting to the database, retrying')
-                    errors.ServerSelectionTimeoutError,
-                    DatabaseOpFailedError, ConnectionError) as exc:
-                logger.exception(exc)
                 time.sleep(1)
 
     def run_changefeed(self):
@@ -43,9 +40,10 @@ class MongoDBChangeFeed(ChangeFeed):
         namespace = '{}.{}'.format(dbname, table)
         # last timestamp in the oplog. We only care for operations happening
         # in the future.
-        last_ts = self.connection.conn.local.oplog.rs.find()\
+        last_ts = self.connection.run(
-                      .sort('$natural', pymongo.DESCENDING).limit(1)\
+            self.connection.query().local.oplog.rs.find()
-                      .next()['ts']
+            .sort('$natural', pymongo.DESCENDING).limit(1)
+            .next()['ts'])
         # tailable cursor. A tailable cursor will remain open even after the
         # last result was returned. ``TAILABLE_AWAIT`` will block for some
         # timeout after the last result was returned. If no result is received
@@ -56,6 +54,7 @@ class MongoDBChangeFeed(ChangeFeed):
         )
 
         while cursor.alive:
+            print(os.getpid(), 'alive')
             try:
                 record = cursor.next()
             except StopIteration:

bigchaindb/backend/mongodb/connection.py

@@ -2,13 +2,14 @@ import time
 import logging
 from itertools import repeat
 
-from pymongo import MongoClient
+import pymongo
-from pymongo import errors
 
 import bigchaindb
 from bigchaindb.utils import Lazy
-from bigchaindb.common import exceptions
+from bigchaindb.common.exceptions import ConfigurationError
-from bigchaindb.backend import exceptions as backend_exceptions
+from bigchaindb.backend.exceptions import (DuplicateKeyError,
+                                           OperationError,
+                                           ConnectionError)
 from bigchaindb.backend.connection import Connection
 
 logger = logging.getLogger(__name__)
@@ -59,18 +60,33 @@ class MongoDBConnection(Connection):
     def db(self):
         return self.conn[self.dbname]
 
+    def query(self):
+        return Lazy()
+
+    def collection(self, name):
+        """Return a lazy object that can be used to compose a query.
+
+        Args:
+            name (str): the name of the collection to query.
+        """
+        return self.query()[self.dbname][name]
+
     def run(self, query):
-        attempt = 0
-        for i in self.max_tries_counter:
-            attempt += 1
         try:
-                return query.run(self.conn[self.dbname])
+            return query.run(self.conn)
-            except errors.AutoReconnect:
+        except pymongo.errors.DuplicateKeyError as exc:
-                if attempt == self.max_tries:
+            raise DuplicateKeyError from exc
-                    raise
+        except pymongo.errors.OperationFailure as exc:
-                self._connect()
+            raise OperationError from exc
 
     def _connect(self):
+        """Try to connect to the database.
+
+        Raises:
+            :exc:`~ConnectionError`: If the connection to the database
+                fails.
+        """
+
         attempt = 0
         for i in self.max_tries_counter:
             attempt += 1
@@ -83,30 +99,24 @@ class MongoDBConnection(Connection):
 
                 # FYI: this might raise a `ServerSelectionTimeoutError`,
                 # that is a subclass of `ConnectionFailure`.
-                self.connection = MongoClient(self.host,
+                self.connection = pymongo.MongoClient(self.host,
                                                       self.port,
                                                       replicaset=self.replicaset,
                                                       serverselectiontimeoutms=self.connection_timeout)
-            except (errors.ConnectionFailure, errors.AutoReconnect) as exc:
+
+            # `initialize_replica_set` might raise `ConnectionFailure` or `OperationFailure`.
+            except (pymongo.errors.ConnectionFailure,
+                    pymongo.errors.OperationFailure) as exc:
                 logger.warning('Attempt %s/%s. Connection to %s:%s failed after %sms.',
                                attempt, self.max_tries if self.max_tries != 0 else '∞',
                                self.host, self.port, self.connection_timeout)
                 if attempt == self.max_tries:
                     logger.critical('Cannot connect to the Database. Giving up.')
-                    raise backend_exceptions.ConnectionError() from exc
+                    raise ConnectionError() from exc
             else:
                 break
 
 
-def collection(name):
-    """Return a lazy object that can be used to compose a query.
-
-    Args:
-        name (str): the name of the collection to query.
-    """
-    return Lazy()[name]
-
-
 def initialize_replica_set(host, port, connection_timeout):
     """Initialize a replica set. If already initialized skip."""
 
@@ -114,7 +124,7 @@ def initialize_replica_set(host, port, connection_timeout):
     # The reason we do this instead of `backend.connect` is that
     # `backend.connect` will connect you to a replica set but this fails if
     # you try to connect to a replica set that is not yet initialized
-    conn = MongoClient(host=host,
+    conn = pymongo.MongoClient(host=host,
                        port=port,
                        serverselectiontimeoutms=connection_timeout)
     _check_replica_set(conn)
@@ -125,7 +135,7 @@ def initialize_replica_set(host, port, connection_timeout):
 
     try:
         conn.admin.command('replSetInitiate', config)
-    except errors.OperationFailure as exc_info:
+    except pymongo.errors.OperationFailure as exc_info:
         if exc_info.details['codeName'] == 'AlreadyInitialized':
             return
         raise
@@ -153,12 +163,12 @@ def _check_replica_set(conn):
         repl_opts = options['parsed']['replication']
         repl_set_name = repl_opts.get('replSetName', None) or repl_opts['replSet']
     except KeyError:
-        raise exceptions.ConfigurationError('mongod was not started with'
+        raise ConfigurationError('mongod was not started with'
                                             ' the replSet option.')
 
     bdb_repl_set_name = bigchaindb.config['database']['replicaset']
     if repl_set_name != bdb_repl_set_name:
-        raise exceptions.ConfigurationError('The replicaset configuration of '
+        raise ConfigurationError('The replicaset configuration of '
                                             'bigchaindb (`{}`) needs to match '
                                             'the replica set name from MongoDB'
                                             ' (`{}`)'

bigchaindb/backend/mongodb/query.py

@@ -10,8 +10,9 @@ from pymongo import errors
 from bigchaindb import backend
 from bigchaindb.common.exceptions import CyclicBlockchainError
 from bigchaindb.common.transaction import Transaction
+from bigchaindb.backend.exceptions import DuplicateKeyError
 from bigchaindb.backend.utils import module_dispatch_registrar
-from bigchaindb.backend.mongodb.connection import MongoDBConnection, collection
+from bigchaindb.backend.mongodb.connection import MongoDBConnection
 
 
 register_query = module_dispatch_registrar(backend.query)
@@ -21,9 +22,9 @@ register_query = module_dispatch_registrar(backend.query)
 def write_transaction(conn, signed_transaction):
     try:
         return conn.run(
-            collection('backlog')
+            conn.collection('backlog')
             .insert_one(signed_transaction))
-    except errors.DuplicateKeyError:
+    except DuplicateKeyError:
         return
 
 
@@ -32,7 +33,7 @@ def update_transaction(conn, transaction_id, doc):
     # with mongodb we need to add update operators to the doc
     doc = {'$set': doc}
     return conn.run(
-        collection('backlog')
+        conn.collection('backlog')
         .find_one_and_update(
             {'id': transaction_id},
             doc,
@@ -42,14 +43,14 @@ def update_transaction(conn, transaction_id, doc):
 @register_query(MongoDBConnection)
 def delete_transaction(conn, *transaction_id):
     return conn.run(
-        collection('backlog')
+        conn.collection('backlog')
         .delete_many({'id': {'$in': transaction_id}}))
 
 
 @register_query(MongoDBConnection)
 def get_stale_transactions(conn, reassign_delay):
     return conn.run(
-        collection('backlog')
+        conn.collection('backlog')
         .find({'assignment_timestamp': {'$lt': time() - reassign_delay}},
               projection={'_id': False}))
 
@@ -58,7 +59,7 @@ def get_stale_transactions(conn, reassign_delay):
 def get_transaction_from_block(conn, transaction_id, block_id):
     try:
         return conn.run(
-            collection('bigchain')
+            conn.collection('bigchain')
             .aggregate([
                 {'$match': {'id': block_id}},
                 {'$project': {
@@ -84,7 +85,7 @@ def get_transaction_from_block(conn, transaction_id, block_id):
 @register_query(MongoDBConnection)
 def get_transaction_from_backlog(conn, transaction_id):
     return conn.run(
-        collection('backlog')
+        conn.collection('backlog')
         .find_one({'id': transaction_id},
                   projection={'_id': False,
                               'assignee': False,
@@ -94,7 +95,7 @@ def get_transaction_from_backlog(conn, transaction_id):
 @register_query(MongoDBConnection)
 def get_blocks_status_from_transaction(conn, transaction_id):
     return conn.run(
-        collection('bigchain')
+        conn.collection('bigchain')
         .find({'block.transactions.id': transaction_id},
               projection=['id', 'block.voters']))
 
@@ -139,7 +140,7 @@ def get_txids_filtered(conn, asset_id, operation=None):
 @register_query(MongoDBConnection)
 def get_asset_by_id(conn, asset_id):
     cursor = conn.run(
-        collection('bigchain')
+        conn.collection('bigchain')
         .aggregate([
             {'$match': {
                 'block.transactions.id': asset_id,
@@ -160,7 +161,7 @@ def get_asset_by_id(conn, asset_id):
 @register_query(MongoDBConnection)
 def get_spent(conn, transaction_id, output):
     cursor = conn.run(
-        collection('bigchain').aggregate([
+        conn.collection('bigchain').aggregate([
             {'$unwind': '$block.transactions'},
             {'$match': {
                 'block.transactions.inputs.fulfills.txid': transaction_id,
@@ -175,7 +176,7 @@ def get_spent(conn, transaction_id, output):
 @register_query(MongoDBConnection)
 def get_owned_ids(conn, owner):
     cursor = conn.run(
-        collection('bigchain')
+        conn.collection('bigchain')
         .aggregate([
             {'$unwind': '$block.transactions'},
             {'$match': {
@@ -192,7 +193,7 @@ def get_owned_ids(conn, owner):
 @register_query(MongoDBConnection)
 def get_votes_by_block_id(conn, block_id):
     return conn.run(
-        collection('votes')
+        conn.collection('votes')
         .find({'vote.voting_for_block': block_id},
               projection={'_id': False}))
 
@@ -200,7 +201,7 @@ def get_votes_by_block_id(conn, block_id):
 @register_query(MongoDBConnection)
 def get_votes_by_block_id_and_voter(conn, block_id, node_pubkey):
     return conn.run(
-        collection('votes')
+        conn.collection('votes')
         .find({'vote.voting_for_block': block_id,
                'node_pubkey': node_pubkey},
               projection={'_id': False}))
@@ -209,14 +210,14 @@ def get_votes_by_block_id_and_voter(conn, block_id, node_pubkey):
 @register_query(MongoDBConnection)
 def write_block(conn, block):
     return conn.run(
-        collection('bigchain')
+        conn.collection('bigchain')
         .insert_one(block.to_dict()))
 
 
 @register_query(MongoDBConnection)
 def get_block(conn, block_id):
     return conn.run(
-        collection('bigchain')
+        conn.collection('bigchain')
         .find_one({'id': block_id},
                   projection={'_id': False}))
 
@@ -224,27 +225,27 @@ def get_block(conn, block_id):
 @register_query(MongoDBConnection)
 def has_transaction(conn, transaction_id):
     return bool(conn.run(
-        collection('bigchain')
+        conn.collection('bigchain')
         .find_one({'block.transactions.id': transaction_id})))
 
 
 @register_query(MongoDBConnection)
 def count_blocks(conn):
     return conn.run(
-        collection('bigchain')
+        conn.collection('bigchain')
         .count())
 
 
 @register_query(MongoDBConnection)
 def count_backlog(conn):
     return conn.run(
-        collection('backlog')
+        conn.collection('backlog')
         .count())
 
 
 @register_query(MongoDBConnection)
 def write_vote(conn, vote):
-    conn.run(collection('votes').insert_one(vote))
+    conn.run(conn.collection('votes').insert_one(vote))
     vote.pop('_id')
     return vote
 
@@ -252,7 +253,7 @@ def write_vote(conn, vote):
 @register_query(MongoDBConnection)
 def get_genesis_block(conn):
     return conn.run(
-        collection('bigchain')
+        conn.collection('bigchain')
         .find_one(
             {'block.transactions.0.operation': 'GENESIS'},
             {'_id': False}
@@ -262,7 +263,7 @@ def get_genesis_block(conn):
 @register_query(MongoDBConnection)
 def get_last_voted_block(conn, node_pubkey):
     last_voted = conn.run(
-            collection('votes')
+            conn.collection('votes')
             .find({'node_pubkey': node_pubkey},
                   sort=[('vote.timestamp', -1)]))
 

bigchaindb/backend/rethinkdb/admin.py

@@ -5,7 +5,7 @@ import rethinkdb as r
 
 from bigchaindb.backend import admin
 from bigchaindb.backend.schema import TABLES
-from bigchaindb.backend.exceptions import DatabaseOpFailedError
+from bigchaindb.backend.exceptions import OperationError
 from bigchaindb.backend.utils import module_dispatch_registrar
 from bigchaindb.backend.rethinkdb.connection import RethinkDBConnection
 
@@ -78,7 +78,7 @@ def reconfigure(connection, *, table, shards, replicas,
             <https://rethinkdb.com/api/python/reconfigure/>`_.
 
     Raises:
-        DatabaseOpFailedError: If the reconfiguration fails due to a
+        OperationError: If the reconfiguration fails due to a
             RethinkDB :exc:`ReqlOpFailedError` or
             :exc:`ReqlQueryLogicError`.
 
@@ -96,7 +96,7 @@ def reconfigure(connection, *, table, shards, replicas,
     try:
         return connection.run(r.table(table).reconfigure(**params))
     except (r.ReqlOpFailedError, r.ReqlQueryLogicError) as e:
-        raise DatabaseOpFailedError from e
+        raise OperationError from e
 
 
 @register_admin(RethinkDBConnection)

bigchaindb/commands/bigchain.py

@@ -23,7 +23,7 @@ from bigchaindb.utils import ProcessGroup
 from bigchaindb import backend
 from bigchaindb.backend import schema
 from bigchaindb.backend.admin import set_replicas, set_shards
-from bigchaindb.backend.exceptions import (DatabaseOpFailedError,
+from bigchaindb.backend.exceptions import (OperationError,
                                            ConnectionError)
 from bigchaindb.commands import utils
 from bigchaindb import processes
@@ -252,7 +252,7 @@ def run_set_shards(args):
     conn = backend.connect()
     try:
         set_shards(conn, shards=args.num_shards)
-    except DatabaseOpFailedError as e:
+    except OperationError as e:
         logger.warn(e)
 
 
@@ -260,7 +260,7 @@ def run_set_replicas(args):
     conn = backend.connect()
     try:
         set_replicas(conn, replicas=args.num_replicas)
-    except DatabaseOpFailedError as e:
+    except OperationError as e:
         logger.warn(e)
 
 

tests/backend/mongodb/test_changefeed.py

@@ -1,7 +1,6 @@
 from unittest import mock
 
 import pytest
-from pymongo.errors import ConnectionFailure
 
 from multipipes import Pipe
 
@@ -152,14 +151,15 @@ def test_changefeed_prefeed(mock_cursor_next, mock_cursor_alive,
 
 @pytest.mark.bdb
 @mock.patch('pymongo.cursor.Cursor.alive', new_callable=mock.PropertyMock)
-@mock.patch('bigchaindb.backend.mongodb.changefeed.MongoDBChangeFeed.run_changefeed')  # noqa
+@mock.patch('bigchaindb.backend.mongodb.connection.MongoDBConnection.run')  # noqa
 def test_connection_failure(mock_run_changefeed, mock_cursor_alive):
     from bigchaindb.backend import get_changefeed, connect
+    from bigchaindb.backend.exceptions import ConnectionError
     from bigchaindb.backend.changefeed import ChangeFeed
 
     conn = connect()
     mock_cursor_alive.return_value = False
-    mock_run_changefeed.side_effect = [ConnectionFailure(), mock.DEFAULT]
+    mock_run_changefeed.side_effect = [ConnectionError(), mock.DEFAULT]
 
     changefeed = get_changefeed(conn, 'backlog', ChangeFeed.INSERT)
     changefeed.run_forever()

tests/backend/mongodb/test_connection.py

@@ -58,7 +58,7 @@ def test_connection_error(mock_sleep, mock_client, mock_init_repl_set):
     from bigchaindb.backend import connect
     from bigchaindb.backend.exceptions import ConnectionError
 
-    # force the driver to trow ConnectionFailure
+    # force the driver to throw ConnectionFailure
     # the mock on time.sleep is to prevent the actual sleep when running
     # the tests
     mock_client.side_effect = ConnectionFailure()

tests/backend/rethinkdb/test_admin.py

@@ -177,8 +177,8 @@ def test_reconfigure_replicas_without_nonvoting_replica_tags(rdb_conn,
                                                              db_name,
                                                              db_conn):
     from bigchaindb.backend.rethinkdb.admin import reconfigure
-    from bigchaindb.backend.exceptions import DatabaseOpFailedError
+    from bigchaindb.backend.exceptions import OperationError
-    with pytest.raises(DatabaseOpFailedError) as exc:
+    with pytest.raises(OperationError) as exc:
         reconfigure(db_conn, table='backlog', shards=1,
                     replicas={'default': 1}, primary_replica_tag='default')
     assert isinstance(exc.value.__cause__, r.ReqlQueryLogicError)
@@ -187,8 +187,8 @@ def test_reconfigure_replicas_without_nonvoting_replica_tags(rdb_conn,
 @pytest.mark.bdb
 def test_reconfigure_too_many_replicas(rdb_conn, db_name, db_conn):
     from bigchaindb.backend.rethinkdb.admin import reconfigure
-    from bigchaindb.backend.exceptions import DatabaseOpFailedError
+    from bigchaindb.backend.exceptions import OperationError
     replicas = _count_rethinkdb_servers() + 1
-    with pytest.raises(DatabaseOpFailedError) as exc:
+    with pytest.raises(OperationError) as exc:
         reconfigure(db_conn, table='backlog', shards=1, replicas=replicas)
     assert isinstance(exc.value.__cause__, r.ReqlOpFailedError)