Add Python Consensus SDK

Signed-off-by: Nick Drozd <drozd@bitwise.io>

sdk/python/sawtooth_sdk/consensus/__init__.py

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+# Copyright 2018 Intel 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.
+# -----------------------------------------------------------------------------

sdk/python/sawtooth_sdk/consensus/driver.py

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+# Copyright 2018 Intel 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 abc
+
+
+class Driver(metaclass=abc.ABCMeta):
+    @abc.abstractmethod
+    def __init__(self, engine):
+        pass
+
+    @abc.abstractmethod
+    def start(self, endpoint):
+        pass
+
+    @abc.abstractmethod
+    def stop(self):
+        pass

sdk/python/sawtooth_sdk/consensus/engine.py

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+# Copyright 2018 Intel 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 abc
+
+
+class Engine(metaclass=abc.ABCMeta):
+    @abc.abstractmethod
+    def start(self, updates, service):
+        '''Called after the engine is initialized, when a connection to the
+        validator has been established. Notifications from the
+        validator are sent along UPDATES. SERVICE is used to send
+        requests to the validator.
+
+        Args:
+            updates (Queue)
+            service (Service)
+        '''
+
+    @abc.abstractmethod
+    def stop(self):
+        '''Called before the engine is dropped in order to give the engine a
+        chance to notify peers and clean up.'''
+
+    @abc.abstractproperty
+    def version(self):
+        '''Get the version of this engine.
+
+        Return:
+            str
+        '''
+
+    @abc.abstractproperty
+    def name(self):
+        '''Get the name of the engine, typically the algorithm being
+        implemented.
+
+        Return:
+            str
+        '''

sdk/python/sawtooth_sdk/consensus/exceptions.py

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+# Copyright 2018 Intel 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.
+# -----------------------------------------------------------------------------
+
+
+class InvalidState(Exception):
+    pass
+
+
+class ReceiveError(Exception):
+    pass
+
+
+class UnknownBlock(Exception):
+    pass
+
+
+class UnknownPeer(Exception):
+    pass

sdk/python/sawtooth_sdk/consensus/service.py

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+# Copyright 2018 Intel 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 abc
+
+
+class Block:
+    def __init__(self, block):
+        self.block_id = block.block_id
+        self.previous_id = block.previous_id
+        self.signer_id = block.signer_id
+        self.block_num = block.block_num
+        self.payload = block.payload
+
+
+class Service(metaclass=abc.ABCMeta):
+    '''Provides methods that allow the consensus engine to issue commands
+    and requests.'''
+
+    # -- P2P --
+
+    @abc.abstractmethod
+    def send_to(self, peer_id, message_type, payload):
+        '''Send a consensus message to a specific connected peer.
+
+        Args:
+            peer_id (bytes)
+            message_type (str)
+            payload (bytes)
+        '''
+
+    @abc.abstractmethod
+    def broadcast(self, message_type, payload):
+        '''Broadcast a message to all connected peers.
+
+        Args:
+            message_type (str)
+            payload (bytes)
+        '''
+
+    # -- Block Creation --
+
+    @abc.abstractmethod
+    def initialize_block(self, previous_id):
+        '''Initialize a new block with PREVIOUS_ID and begin adding batches to
+        it. If no PREVIOUS_ID is specified, the current head will be
+        used.
+
+        Args:
+            previous_id (bytes or None)
+        '''
+
+    @abc.abstractmethod
+    def finalize_block(self, data):
+        '''Stop adding batches to the current block and finalize it. Include
+        DATA in the block. If this call is successful, the consensus
+        engine will receive it afterwards.
+
+        Args:
+            data (bytes)
+
+        Return:
+            bytes
+        '''
+
+    @abc.abstractmethod
+    def cancel_block(self):
+        '''Stop adding batches to the current block and abandon it.'''
+
+    # -- Block Directives --
+
+    @abc.abstractmethod
+    def check_blocks(self, priority):
+        '''Update the prioritization of blocks to check to PRIORITY.
+
+        Args:
+            priority (list[bytes])
+        '''
+
+    @abc.abstractmethod
+    def commit_block(self, block_id):
+        '''Update the block that should be committed.
+
+        Args:
+            block_id (bytes)
+        '''
+
+    @abc.abstractmethod
+    def ignore_block(self, block_id):
+        '''Signal that this block is no longer being committed.
+
+        Args:
+            block_id (bytes)
+        '''
+
+    @abc.abstractmethod
+    def fail_block(self, block_id):
+        '''Mark this block as invalid from the perspective of consensus.
+
+        Args:
+            block_id (bytes)
+        '''
+
+    # -- Queries --
+
+    @abc.abstractmethod
+    def get_blocks(self, block_ids):
+        '''Retrive consensus-related information about blocks.
+
+        Args:
+            block_ids (list[bytes])
+
+        Return:
+            dict[bytes, block]
+        '''
+
+    @abc.abstractmethod
+    def get_settings(self, block_id, settings):
+        '''Read the value of settings as of the given block.
+
+        Args:
+            block_id (bytes)
+            settings (list[str])
+
+        Return:
+            dict[str, str]
+        '''
+
+    @abc.abstractmethod
+    def get_state(self, block_id, addresses):
+        '''Read values in state as of the given block.
+
+        Args:
+            block_id (bytes)
+            addresses (list[str])
+
+        Return:
+            dict[str, bytes]
+        '''