Exemplo n.º 1
0
    def on_post(self, req, resp):
        resp.status = falcon.HTTP_200

        substrate = SubstrateInterface(SUBSTRATE_RPC_URL)
        head_hash = substrate.get_chain_head()
        substrate.init_runtime(head_hash)
        runtime = Runtime.query(self.session).get(substrate.runtime_version)

        if runtime:
            return

        harvester = PolkascanHarvesterService(
            db_session=self.session,
            type_registry=TYPE_REGISTRY,
            type_registry_file=TYPE_REGISTRY_FILE)

        spec_version = substrate.runtime_version
        harvester.process_metadata(spec_version, head_hash)
        self.session.commit()
        resp.media = {'status': 'success', 'data': {}}
Exemplo n.º 2
0
class PolkascanHarvesterService(BaseService):

    def __init__(self, db_session, type_registry='default', type_registry_file=None):
        self.db_session = db_session

        if type_registry_file:
            custom_type_registry = load_type_registry_file(type_registry_file)
        else:
            custom_type_registry = None

        self.substrate = SubstrateInterface(
            url=settings.SUBSTRATE_RPC_URL,
            type_registry=custom_type_registry,
            type_registry_preset=type_registry
        )
        self.metadata_store = {}

    def process_genesis(self, block):

        # Set block time of parent block
        child_block = Block.query(self.db_session).filter_by(parent_hash=block.hash).first()
        block.set_datetime(child_block.datetime)

        # Retrieve genesis accounts
        if settings.get_versioned_setting('SUBSTRATE_STORAGE_INDICES', block.spec_version_id) == 'Accounts':

            # Get accounts from storage keys
            storage_key_prefix = self.substrate.generate_storage_hash(
                storage_module='System',
                storage_function='Account',
                metadata_version=settings.SUBSTRATE_METADATA_VERSION
            )

            rpc_result = self.substrate.rpc_request(
                'state_getKeys',
                [storage_key_prefix, block.hash]
            ).get('result')
            # Extract accounts from storage key
            genesis_accounts = [storage_key[-64:] for storage_key in rpc_result if len(storage_key) == 162]

            for account_id in genesis_accounts:
                account_audit = AccountAudit(
                    account_id=account_id,
                    block_id=block.id,
                    extrinsic_idx=None,
                    event_idx=None,
                    type_id=settings.ACCOUNT_AUDIT_TYPE_NEW
                )

                account_audit.save(self.db_session)

        elif settings.get_versioned_setting('SUBSTRATE_STORAGE_INDICES', block.spec_version_id) == 'EnumSet':

            genesis_account_page_count = self.substrate.get_runtime_state(
                module="Indices",
                storage_function="NextEnumSet",
                block_hash=block.hash
            ).get('result', 0)

            # Get Accounts on EnumSet
            block.count_accounts_new = 0
            block.count_accounts = 0

            for enum_set_nr in range(0, genesis_account_page_count + 1):

                genesis_accounts = self.substrate.get_runtime_state(
                    module="Indices",
                    storage_function="EnumSet",
                    params=[enum_set_nr],
                    block_hash=block.hash
                ).get('result')

                if genesis_accounts:
                    block.count_accounts_new += len(genesis_accounts)
                    block.count_accounts += len(genesis_accounts)

                    for idx, account_id in enumerate(genesis_accounts):
                        account_audit = AccountAudit(
                            account_id=account_id.replace('0x', ''),
                            block_id=block.id,
                            extrinsic_idx=None,
                            event_idx=None,
                            type_id=settings.ACCOUNT_AUDIT_TYPE_NEW
                        )

                        account_audit.save(self.db_session)

                        account_index_id = enum_set_nr * 64 + idx

                        account_index_audit = AccountIndexAudit(
                            account_index_id=account_index_id,
                            account_id=account_id.replace('0x', ''),
                            block_id=block.id,
                            extrinsic_idx=None,
                            event_idx=None,
                            type_id=settings.ACCOUNT_INDEX_AUDIT_TYPE_NEW
                        )

                        account_index_audit.save(self.db_session)

        block.save(self.db_session)

        # Add hardcoded account like treasury stored in settings
        for account_id in settings.SUBSTRATE_TREASURY_ACCOUNTS:
            account_audit = AccountAudit(
                account_id=account_id,
                block_id=block.id,
                extrinsic_idx=None,
                event_idx=None,
                data={'is_treasury': True},
                type_id=settings.ACCOUNT_AUDIT_TYPE_NEW
            )

            account_audit.save(self.db_session)

        # Check for sudo accounts
        try:
            # Update sudo key
            sudo_key = self.substrate.get_runtime_state(
                module='Sudo',
                storage_function='Key',
                block_hash=block.hash
            ).get('result')

            account_audit = AccountAudit(
                account_id=sudo_key.replace('0x', ''),
                block_id=block.id,
                extrinsic_idx=None,
                event_idx=None,
                data={'is_sudo': True},
                type_id=settings.ACCOUNT_AUDIT_TYPE_NEW
            )

            account_audit.save(self.db_session)
        except ValueError:
            pass

        # Create initial session
        initial_session_event = NewSessionEventProcessor(
            block=block, event=Event(), substrate=self.substrate
        )

        if settings.get_versioned_setting('NEW_SESSION_EVENT_HANDLER', block.spec_version_id):
            initial_session_event.add_session(db_session=self.db_session, session_id=0)
        else:
            initial_session_event.add_session_old(db_session=self.db_session, session_id=0)

    def process_metadata(self, spec_version, block_hash):

        # Check if metadata already in store
        if spec_version not in self.metadata_store:
            print('Metadata: CACHE MISS', spec_version)

            runtime_version_data = self.substrate.get_block_runtime_version(block_hash)

            runtime = Runtime.query(self.db_session).get(spec_version)

            if runtime:
                self.metadata_store[spec_version] = self.substrate.get_block_metadata(block_hash=block_hash)

            else:
                self.db_session.begin(subtransactions=True)
                try:

                    # Store metadata in database
                    runtime = Runtime(
                        id=spec_version,
                        impl_name=runtime_version_data["implName"],
                        impl_version=runtime_version_data["implVersion"],
                        spec_name=runtime_version_data["specName"],
                        spec_version=spec_version,
                        json_metadata=str(self.substrate.metadata_decoder.data),
                        json_metadata_decoded=self.substrate.metadata_decoder.value,
                        apis=runtime_version_data["apis"],
                        authoring_version=runtime_version_data["authoringVersion"],
                        count_call_functions=0,
                        count_events=0,
                        count_modules=len(self.substrate.metadata_decoder.metadata.modules),
                        count_storage_functions=0,
                        count_constants=0,
                        count_errors=0
                    )

                    runtime.save(self.db_session)

                    print('store version to db', self.substrate.metadata_decoder.version)

                    for module in self.substrate.metadata_decoder.metadata.modules:

                        # Check if module exists
                        if RuntimeModule.query(self.db_session).filter_by(
                            spec_version=spec_version,
                            module_id=module.get_identifier()
                        ).count() == 0:
                            module_id = module.get_identifier()
                        else:
                            module_id = '{}_1'.format(module.get_identifier())

                        # Storage backwards compt check
                        if module.storage and isinstance(module.storage, list):
                            storage_functions = module.storage
                        elif module.storage and isinstance(getattr(module.storage, 'value'), dict):
                            storage_functions = module.storage.items
                        else:
                            storage_functions = []

                        runtime_module = RuntimeModule(
                            spec_version=spec_version,
                            module_id=module_id,
                            prefix=module.prefix,
                            name=module.name,
                            count_call_functions=len(module.calls or []),
                            count_storage_functions=len(storage_functions),
                            count_events=len(module.events or []),
                            count_constants=len(module.constants or []),
                            count_errors=len(module.errors or []),
                        )
                        runtime_module.save(self.db_session)

                        # Update totals in runtime
                        runtime.count_call_functions += runtime_module.count_call_functions
                        runtime.count_events += runtime_module.count_events
                        runtime.count_storage_functions += runtime_module.count_storage_functions
                        runtime.count_constants += runtime_module.count_constants
                        runtime.count_errors += runtime_module.count_errors

                        if len(module.calls or []) > 0:
                            for idx, call in enumerate(module.calls):
                                runtime_call = RuntimeCall(
                                    spec_version=spec_version,
                                    module_id=module_id,
                                    call_id=call.get_identifier(),
                                    index=idx,
                                    name=call.name,
                                    lookup=call.lookup,
                                    documentation='\n'.join(call.docs),
                                    count_params=len(call.args)
                                )
                                runtime_call.save(self.db_session)

                                for arg in call.args:
                                    runtime_call_param = RuntimeCallParam(
                                        runtime_call_id=runtime_call.id,
                                        name=arg.name,
                                        type=arg.type
                                    )
                                    runtime_call_param.save(self.db_session)

                        if len(module.events or []) > 0:
                            for event_index, event in enumerate(module.events):
                                runtime_event = RuntimeEvent(
                                    spec_version=spec_version,
                                    module_id=module_id,
                                    event_id=event.name,
                                    index=event_index,
                                    name=event.name,
                                    lookup=event.lookup,
                                    documentation='\n'.join(event.docs),
                                    count_attributes=len(event.args)
                                )
                                runtime_event.save(self.db_session)

                                for arg_index, arg in enumerate(event.args):
                                    runtime_event_attr = RuntimeEventAttribute(
                                        runtime_event_id=runtime_event.id,
                                        index=arg_index,
                                        type=arg
                                    )
                                    runtime_event_attr.save(self.db_session)

                        if len(storage_functions) > 0:
                            for idx, storage in enumerate(storage_functions):

                                # Determine type
                                type_hasher = None
                                type_key1 = None
                                type_key2 = None
                                type_value = None
                                type_is_linked = None
                                type_key2hasher = None

                                if storage.type.get('PlainType'):
                                    type_value = storage.type.get('PlainType')

                                elif storage.type.get('MapType'):
                                    type_hasher = storage.type['MapType'].get('hasher')
                                    type_key1 = storage.type['MapType'].get('key')
                                    type_value = storage.type['MapType'].get('value')
                                    type_is_linked = storage.type['MapType'].get('isLinked', False)

                                elif storage.type.get('DoubleMapType'):
                                    type_hasher = storage.type['DoubleMapType'].get('hasher')
                                    type_key1 = storage.type['DoubleMapType'].get('key1')
                                    type_key2 = storage.type['DoubleMapType'].get('key2')
                                    type_value = storage.type['DoubleMapType'].get('value')
                                    type_key2hasher = storage.type['DoubleMapType'].get('key2Hasher')

                                runtime_storage = RuntimeStorage(
                                    spec_version=spec_version,
                                    module_id=module_id,
                                    index=idx,
                                    name=storage.name,
                                    lookup=None,
                                    default=storage.fallback,
                                    modifier=storage.modifier,
                                    type_hasher=type_hasher,
                                    storage_key=xxh128(module.prefix.encode()) + xxh128(storage.name.encode()),
                                    type_key1=type_key1,
                                    type_key2=type_key2,
                                    type_value=type_value,
                                    type_is_linked=type_is_linked,
                                    type_key2hasher=type_key2hasher,
                                    documentation='\n'.join(storage.docs)
                                )
                                runtime_storage.save(self.db_session)

                        if len(module.constants or []) > 0:
                            for idx, constant in enumerate(module.constants):

                                # Decode value
                                try:
                                    value_obj = ScaleDecoder.get_decoder_class(
                                        constant.type,
                                        ScaleBytes(constant.constant_value)
                                    )
                                    value_obj.decode()
                                    value = value_obj.serialize()
                                except ValueError:
                                    value = constant.constant_value
                                except RemainingScaleBytesNotEmptyException:
                                    value = constant.constant_value
                                except NotImplementedError:
                                    value = constant.constant_value

                                if type(value) is list or type(value) is dict:
                                    value = json.dumps(value)

                                runtime_constant = RuntimeConstant(
                                    spec_version=spec_version,
                                    module_id=module_id,
                                    index=idx,
                                    name=constant.name,
                                    type=constant.type,
                                    value=value,
                                    documentation='\n'.join(constant.docs)
                                )
                                runtime_constant.save(self.db_session)

                        if len(module.errors or []) > 0:
                            for idx, error in enumerate(module.errors):
                                runtime_error = RuntimeErrorMessage(
                                    spec_version=spec_version,
                                    module_id=module_id,
                                    index=idx,
                                    name=error.name,
                                    documentation='\n'.join(error.docs)
                                )
                                runtime_error.save(self.db_session)

                        runtime.save(self.db_session)

                    # Process types
                    for runtime_type_data in list(self.substrate.get_type_registry(block_hash=block_hash).values()):

                        runtime_type = RuntimeType(
                            spec_version=runtime_type_data["spec_version"],
                            type_string=runtime_type_data["type_string"],
                            decoder_class=runtime_type_data["decoder_class"],
                            is_primitive_core=runtime_type_data["is_primitive_core"],
                            is_primitive_runtime=runtime_type_data["is_primitive_runtime"]
                        )
                        runtime_type.save(self.db_session)

                    self.db_session.commit()

                    # Put in local store
                    self.metadata_store[spec_version] = self.substrate.metadata_decoder
                except SQLAlchemyError as e:
                    self.db_session.rollback()

    def add_block(self, block_hash):

        # Check if block is already process
        if Block.query(self.db_session).filter_by(hash=block_hash).count() > 0:
            raise BlockAlreadyAdded(block_hash)

        if settings.SUBSTRATE_MOCK_EXTRINSICS:
            self.substrate.mock_extrinsics = settings.SUBSTRATE_MOCK_EXTRINSICS

        json_block = self.substrate.get_chain_block(block_hash)

        parent_hash = json_block['block']['header'].pop('parentHash')
        block_id = json_block['block']['header'].pop('number')
        extrinsics_root = json_block['block']['header'].pop('extrinsicsRoot')
        state_root = json_block['block']['header'].pop('stateRoot')
        digest_logs = json_block['block']['header'].get('digest', {}).pop('logs', None)

        # Convert block number to numeric
        if not block_id.isnumeric():
            block_id = int(block_id, 16)

        # ==== Get block runtime from Substrate ==================

        self.substrate.init_runtime(block_hash=block_hash)

        self.process_metadata(self.substrate.runtime_version, block_hash)

        # ==== Get parent block runtime ===================

        if block_id > 0:
            json_parent_runtime_version = self.substrate.get_block_runtime_version(parent_hash)

            parent_spec_version = json_parent_runtime_version.get('specVersion', 0)

            self.process_metadata(parent_spec_version, parent_hash)
        else:
            parent_spec_version = self.substrate.runtime_version

        # ==== Set initial block properties =====================

        block = Block(
            id=block_id,
            parent_id=block_id - 1,
            hash=block_hash,
            parent_hash=parent_hash,
            state_root=state_root,
            extrinsics_root=extrinsics_root,
            count_extrinsics=0,
            count_events=0,
            count_accounts_new=0,
            count_accounts_reaped=0,
            count_accounts=0,
            count_events_extrinsic=0,
            count_events_finalization=0,
            count_events_module=0,
            count_events_system=0,
            count_extrinsics_error=0,
            count_extrinsics_signed=0,
            count_extrinsics_signedby_address=0,
            count_extrinsics_signedby_index=0,
            count_extrinsics_success=0,
            count_extrinsics_unsigned=0,
            count_sessions_new=0,
            count_contracts_new=0,
            count_log=0,
            range10000=math.floor(block_id / 10000),
            range100000=math.floor(block_id / 100000),
            range1000000=math.floor(block_id / 1000000),
            spec_version_id=self.substrate.runtime_version,
            logs=digest_logs
        )

        # Set temp helper variables
        block._accounts_new = []
        block._accounts_reaped = []

        # ==== Get block events from Substrate ==================
        extrinsic_success_idx = {}
        events = []

        try:
            events_decoder = self.substrate.get_block_events(block_hash, self.metadata_store[parent_spec_version])

            event_idx = 0

            for event in events_decoder.elements:

                event.value['module_id'] = event.value['module_id'].lower()

                model = Event(
                    block_id=block_id,
                    event_idx=event_idx,
                    phase=event.value['phase'],
                    extrinsic_idx=event.value['extrinsic_idx'],
                    type=event.value['type'],
                    spec_version_id=parent_spec_version,
                    module_id=event.value['module_id'],
                    event_id=event.value['event_id'],
                    system=int(event.value['module_id'] == 'system'),
                    module=int(event.value['module_id'] != 'system'),
                    attributes=event.value['params'],
                    codec_error=False
                )

                # Process event

                if event.value['phase'] == 0:
                    block.count_events_extrinsic += 1
                elif event.value['phase'] == 1:
                    block.count_events_finalization += 1

                if event.value['module_id'] == 'system':

                    block.count_events_system += 1

                    # Store result of extrinsic
                    if event.value['event_id'] == 'ExtrinsicSuccess':
                        extrinsic_success_idx[event.value['extrinsic_idx']] = True
                        block.count_extrinsics_success += 1

                    if event.value['event_id'] == 'ExtrinsicFailed':
                        extrinsic_success_idx[event.value['extrinsic_idx']] = False
                        block.count_extrinsics_error += 1
                else:

                    block.count_events_module += 1

                model.save(self.db_session)

                events.append(model)

                event_idx += 1

            block.count_events = len(events_decoder.elements)

        except SubstrateRequestException:
            block.count_events = 0

        # === Extract extrinsics from block ====

        extrinsics_data = json_block['block'].pop('extrinsics')

        block.count_extrinsics = len(extrinsics_data)

        extrinsic_idx = 0

        extrinsics = []

        for extrinsic in extrinsics_data:

            extrinsics_decoder = ExtrinsicsDecoder(
                data=ScaleBytes(extrinsic),
                metadata=self.metadata_store[parent_spec_version]
            )

            extrinsic_data = extrinsics_decoder.decode()

            # Lookup result of extrinsic
            extrinsic_success = extrinsic_success_idx.get(extrinsic_idx, False)

            model = Extrinsic(
                block_id=block_id,
                extrinsic_idx=extrinsic_idx,
                extrinsic_hash=extrinsics_decoder.extrinsic_hash,
                extrinsic_length=extrinsic_data.get('extrinsic_length'),
                extrinsic_version=extrinsic_data.get('version_info'),
                signed=extrinsics_decoder.contains_transaction,
                unsigned=not extrinsics_decoder.contains_transaction,
                signedby_address=bool(extrinsics_decoder.contains_transaction and extrinsic_data.get('account_id')),
                signedby_index=bool(extrinsics_decoder.contains_transaction and extrinsic_data.get('account_index')),
                address_length=extrinsic_data.get('account_length'),
                address=extrinsic_data.get('account_id'),
                account_index=extrinsic_data.get('account_index'),
                account_idx=extrinsic_data.get('account_idx'),
                signature=extrinsic_data.get('signature'),
                nonce=extrinsic_data.get('nonce'),
                era=extrinsic_data.get('era'),
                call=extrinsic_data.get('call_code'),
                module_id=extrinsic_data.get('call_module'),
                call_id=extrinsic_data.get('call_function'),
                params=extrinsic_data.get('params'),
                spec_version_id=parent_spec_version,
                success=int(extrinsic_success),
                error=int(not extrinsic_success),
                codec_error=False
            )
            model.save(self.db_session)

            extrinsics.append(model)

            extrinsic_idx += 1

            # Process extrinsic
            if extrinsics_decoder.contains_transaction:
                block.count_extrinsics_signed += 1

                if model.signedby_address:
                    block.count_extrinsics_signedby_address += 1
                if model.signedby_index:
                    block.count_extrinsics_signedby_index += 1

                # Add search index for signed extrinsics
                search_index = SearchIndex(
                    index_type_id=settings.SEARCH_INDEX_SIGNED_EXTRINSIC,
                    block_id=block.id,
                    extrinsic_idx=model.extrinsic_idx,
                    account_id=model.address
                )
                search_index.save(self.db_session)

            else:
                block.count_extrinsics_unsigned += 1

            # Process extrinsic processors
            for processor_class in ProcessorRegistry().get_extrinsic_processors(model.module_id, model.call_id):
                extrinsic_processor = processor_class(block, model, substrate=self.substrate)
                extrinsic_processor.accumulation_hook(self.db_session)
                extrinsic_processor.process_search_index(self.db_session)

        # Process event processors
        for event in events:
            extrinsic = None
            if event.extrinsic_idx is not None:
                try:
                    extrinsic = extrinsics[event.extrinsic_idx]
                except IndexError:
                    extrinsic = None

            for processor_class in ProcessorRegistry().get_event_processors(event.module_id, event.event_id):
                event_processor = processor_class(block, event, extrinsic,
                                                  metadata=self.metadata_store.get(block.spec_version_id),
                                                  substrate=self.substrate)
                event_processor.accumulation_hook(self.db_session)
                event_processor.process_search_index(self.db_session)

        # Process block processors
        for processor_class in ProcessorRegistry().get_block_processors():
            block_processor = processor_class(block, substrate=self.substrate, harvester=self)
            block_processor.accumulation_hook(self.db_session)

        # Debug info
        if settings.DEBUG:
            block.debug_info = json_block

        # ==== Save data block ==================================

        block.save(self.db_session)

        return block

    def remove_block(self, block_hash):
        # Retrieve block
        block = Block.query(self.db_session).filter_by(hash=block_hash).first()

        # Revert event processors
        for event in Event.query(self.db_session).filter_by(block_id=block.id):
            for processor_class in ProcessorRegistry().get_event_processors(event.module_id, event.event_id):
                event_processor = processor_class(block, event, None)
                event_processor.accumulation_revert(self.db_session)

        # Revert extrinsic processors
        for extrinsic in Extrinsic.query(self.db_session).filter_by(block_id=block.id):
            for processor_class in ProcessorRegistry().get_extrinsic_processors(extrinsic.module_id, extrinsic.call_id):
                extrinsic_processor = processor_class(block, extrinsic)
                extrinsic_processor.accumulation_revert(self.db_session)

        # Revert block processors
        for processor_class in ProcessorRegistry().get_block_processors():
            block_processor = processor_class(block)
            block_processor.accumulation_revert(self.db_session)

        # Delete events
        for item in Event.query(self.db_session).filter_by(block_id=block.id):
            self.db_session.delete(item)
        # Delete extrinsics
        for item in Extrinsic.query(self.db_session).filter_by(block_id=block.id):
            self.db_session.delete(item)

        # Delete block
        self.db_session.delete(block)

    def sequence_block(self, block, parent_block_data=None, parent_sequenced_block_data=None):

        sequenced_block = BlockTotal(
            id=block.id
        )

        # Process block processors
        for processor_class in ProcessorRegistry().get_block_processors():
            block_processor = processor_class(block, sequenced_block, substrate=self.substrate)
            block_processor.sequencing_hook(
                self.db_session,
                parent_block_data,
                parent_sequenced_block_data
            )

        extrinsics = Extrinsic.query(self.db_session).filter_by(block_id=block.id).order_by('extrinsic_idx')

        for extrinsic in extrinsics:
            # Process extrinsic processors
            for processor_class in ProcessorRegistry().get_extrinsic_processors(extrinsic.module_id, extrinsic.call_id):
                extrinsic_processor = processor_class(block, extrinsic, substrate=self.substrate)
                extrinsic_processor.sequencing_hook(
                    self.db_session,
                    parent_block_data,
                    parent_sequenced_block_data
                )

        events = Event.query(self.db_session).filter_by(block_id=block.id).order_by('event_idx')

        # Process event processors
        for event in events:
            extrinsic = None
            if event.extrinsic_idx is not None:
                try:
                    extrinsic = extrinsics[event.extrinsic_idx]
                except IndexError:
                    extrinsic = None

            for processor_class in ProcessorRegistry().get_event_processors(event.module_id, event.event_id):
                event_processor = processor_class(block, event, extrinsic, substrate=self.substrate)
                event_processor.sequencing_hook(
                    self.db_session,
                    parent_block_data,
                    parent_sequenced_block_data
                )

        sequenced_block.save(self.db_session)

        return sequenced_block

    def integrity_checks(self):

        # 1. Check finalized head
        substrate = SubstrateInterface(settings.SUBSTRATE_RPC_URL)

        if settings.FINALIZATION_BY_BLOCK_CONFIRMATIONS > 0:
            finalized_block_hash = substrate.get_chain_head()
            finalized_block_number = max(
                substrate.get_block_number(finalized_block_hash) - settings.FINALIZATION_BY_BLOCK_CONFIRMATIONS, 0
            )
        else:
            finalized_block_hash = substrate.get_chain_finalised_head()
            finalized_block_number = substrate.get_block_number(finalized_block_hash)

        # 2. Check integrity head
        integrity_head = Status.get_status(self.db_session, 'INTEGRITY_HEAD')

        if not integrity_head.value:
            # Only continue if block #1 exists
            if Block.query(self.db_session).filter_by(id=1).count() == 0:
                raise BlockIntegrityError('Chain not at genesis')

            integrity_head.value = 0
        else:
            integrity_head.value = int(integrity_head.value)

        start_block_id = max(integrity_head.value - 1, 0)
        end_block_id = finalized_block_number
        chunk_size = 1000
        parent_block = None

        if start_block_id < end_block_id:
            # Continue integrity check

            # print('== Start integrity checks from {} to {} =='.format(start_block_id, end_block_id))

            for block_nr in range(start_block_id, end_block_id, chunk_size):
                # TODO replace limit with filter_by block range
                block_range = Block.query(self.db_session).order_by('id')[block_nr:block_nr + chunk_size]
                for block in block_range:
                    if parent_block:
                        if block.id != parent_block.id + 1:

                            # Save integrity head if block hash of parent matches with hash in node
                            if parent_block.hash == substrate.get_block_hash(integrity_head.value):
                                integrity_head.save(self.db_session)
                                self.db_session.commit()

                            raise BlockIntegrityError('Block #{} is missing.. stopping check '.format(parent_block.id + 1))
                        elif block.parent_hash != parent_block.hash:

                            self.process_reorg_block(parent_block)
                            self.process_reorg_block(block)

                            self.remove_block(block.hash)
                            self.remove_block(parent_block.hash)
                            self.db_session.commit()

                            self.add_block(substrate.get_block_hash(block.id))
                            self.add_block(substrate.get_block_hash(parent_block.id))
                            self.db_session.commit()

                            integrity_head.value = parent_block.id - 1

                            # Save integrity head if block hash of parent matches with hash in node
                            #if parent_block.parent_hash == substrate.get_block_hash(integrity_head.value):
                            integrity_head.save(self.db_session)
                            self.db_session.commit()

                            raise BlockIntegrityError('Block #{} failed integrity checks, Re-adding #{}.. '.format(parent_block.id, block.id))
                        else:
                            integrity_head.value = block.id

                    parent_block = block

                    if block.id == end_block_id:
                        break

            if parent_block:
                if parent_block.hash == substrate.get_block_hash(int(integrity_head.value)):
                    integrity_head.save(self.db_session)
                    self.db_session.commit()

        return {'integrity_head': integrity_head.value}

    def start_sequencer(self):
        integrity_status = self.integrity_checks()
        self.db_session.commit()

        block_nr = None

        integrity_head = Status.get_status(self.db_session, 'INTEGRITY_HEAD')

        if not integrity_head.value:
            integrity_head.value = 0

        # 3. Check sequence head
        sequencer_head = self.db_session.query(func.max(BlockTotal.id)).one()[0]

        if sequencer_head is None:
            sequencer_head = -1

        # Start sequencing process

        sequencer_parent_block = BlockTotal.query(self.db_session).filter_by(id=sequencer_head).first()
        parent_block = Block.query(self.db_session).filter_by(id=sequencer_head).first()

        for block_nr in range(sequencer_head + 1, int(integrity_head.value) + 1):

            if block_nr == 0:
                # No block ever sequenced, check if chain is at genesis state
                assert (not sequencer_parent_block)

                block = Block.query(self.db_session).order_by('id').first()

                if not block:
                    self.db_session.commit()
                    return {'error': 'Chain not at genesis'}

                if block.id == 1:
                    # Add genesis block
                    block = self.add_block(block.parent_hash)

                if block.id != 0:
                    self.db_session.commit()
                    return {'error': 'Chain not at genesis'}

                self.process_genesis(block)

                sequencer_parent_block_data = None
                parent_block_data = None
            else:
                block_id = sequencer_parent_block.id + 1

                assert (block_id == block_nr)

                block = Block.query(self.db_session).get(block_nr)

                if not block:
                    self.db_session.commit()
                    return {'result': 'Finished at #{}'.format(sequencer_parent_block.id)}

                sequencer_parent_block_data = sequencer_parent_block.asdict()
                parent_block_data = parent_block.asdict()

            sequenced_block = self.sequence_block(block, parent_block_data, sequencer_parent_block_data)
            self.db_session.commit()

            parent_block = block
            sequencer_parent_block = sequenced_block

        if block_nr:
            return {'result': 'Finished at #{}'.format(block_nr)}
        else:
            return {'result': 'Nothing to sequence'}

    def process_reorg_block(self, block):

        # Check if reorg already exists
        if ReorgBlock.query(self.db_session).filter_by(hash=block.hash).count() == 0:

            model = ReorgBlock(**block.asdict())
            model.save(self.db_session)

            for extrinsic in Extrinsic.query(self.db_session).filter_by(block_id=block.id):
                model = ReorgExtrinsic(block_hash=block.hash, **extrinsic.asdict())
                model.save(self.db_session)

            for event in Event.query(self.db_session).filter_by(block_id=block.id):
                model = ReorgEvent(block_hash=block.hash, **event.asdict())
                model.save(self.db_session)

            for log in Log.query(self.db_session).filter_by(block_id=block.id):
                model = ReorgLog(block_hash=block.hash, **log.asdict())
                model.save(self.db_session)

    def rebuild_search_index(self):

        self.db_session.execute('truncate table {}'.format(SearchIndex.__tablename__))

        for block in Block.query(self.db_session).order_by('id').yield_per(1000):

            extrinsic_lookup = {}
            block._accounts_new = []
            block._accounts_reaped = []

            for extrinsic in Extrinsic.query(self.db_session).filter_by(block_id=block.id).order_by('extrinsic_idx'):
                extrinsic_lookup[extrinsic.extrinsic_idx] = extrinsic

                # Add search index for signed extrinsics
                if extrinsic.address:
                    search_index = SearchIndex(
                        index_type_id=settings.SEARCH_INDEX_SIGNED_EXTRINSIC,
                        block_id=block.id,
                        extrinsic_idx=extrinsic.extrinsic_idx,
                        account_id=extrinsic.address
                    )
                    search_index.save(self.db_session)

                # Process extrinsic processors
                for processor_class in ProcessorRegistry().get_extrinsic_processors(extrinsic.module_id, extrinsic.call_id):
                    extrinsic_processor = processor_class(block=block, extrinsic=extrinsic, substrate=self.substrate)
                    extrinsic_processor.process_search_index(self.db_session)

            for event in Event.query(self.db_session).filter_by(block_id=block.id).order_by('event_idx'):
                extrinsic = None
                if event.extrinsic_idx is not None:
                    try:
                        extrinsic = extrinsic_lookup[event.extrinsic_idx]
                    except (IndexError, KeyError):
                        extrinsic = None

                for processor_class in ProcessorRegistry().get_event_processors(event.module_id, event.event_id):
                    event_processor = processor_class(block, event, extrinsic,
                                                      metadata=self.metadata_store.get(block.spec_version_id),
                                                      substrate=self.substrate)
                    event_processor.process_search_index(self.db_session)

            self.db_session.commit()

    def create_full_balance_snaphot(self, block_id):

        block_hash = self.substrate.get_block_hash(block_id)

        # Determine if keys have Blake2_128Concat format so AccountId is stored in storage key
        storage_method = self.substrate.get_metadata_storage_function(
            module_name="System",
            storage_name="Account",
            block_hash=block_hash
        )

        if storage_method:
            if storage_method.get("type_hasher_key1") == "Blake2_128Concat":

                # get balances storage prefix
                storage_key_prefix = self.substrate.generate_storage_hash(
                    storage_module='System',
                    storage_function='Account',
                    metadata_version=settings.SUBSTRATE_METADATA_VERSION
                )

                rpc_result = self.substrate.rpc_request(
                    'state_getKeys',
                    [storage_key_prefix, block_hash]
                ).get('result')
                # Extract accounts from storage key
                accounts = [storage_key[-64:] for storage_key in rpc_result if len(storage_key) == 162]
            else:
                # Retrieve accounts from database for legacy blocks
                accounts = [account[0] for account in self.db_session.query(distinct(Account.id))]

            for account_id in accounts:

                self.create_balance_snapshot(block_id=block_id, account_id=account_id, block_hash=block_hash)

    def create_balance_snapshot(self, block_id, account_id, block_hash=None):

        if not block_hash:
            block_hash = self.substrate.get_block_hash(block_id)

        # Get balance for account
        try:
            account_info_data = self.substrate.get_runtime_state(
                module='System',
                storage_function='Account',
                params=['0x{}'.format(account_id)],
                block_hash=block_hash
            ).get('result')

            # Make sure no rows inserted before processing this record
            AccountInfoSnapshot.query(self.db_session).filter_by(block_id=block_id, account_id=account_id).delete()

            if account_info_data:
                account_info_obj = AccountInfoSnapshot(
                    block_id=block_id,
                    account_id=account_id,
                    account_info=account_info_data,
                    balance_free=account_info_data["data"]["free"],
                    balance_reserved=account_info_data["data"]["reserved"],
                    balance_total=account_info_data["data"]["free"] + account_info_data["data"]["reserved"],
                    nonce=account_info_data["nonce"]
                )
            else:
                account_info_obj = AccountInfoSnapshot(
                    block_id=block_id,
                    account_id=account_id,
                    account_info=None,
                    balance_free=None,
                    balance_reserved=None,
                    balance_total=None,
                    nonce=None
                )

            account_info_obj.save(self.db_session)
        except ValueError:
            pass

    def update_account_balances(self):
        # set balances according to most recent snapshot
        account_info = self.db_session.execute("""
                        select
                           a.account_id, 
                           a.balance_total,
                           a.balance_free,
                           a.balance_reserved,
                           a.nonce
                    from
                         data_account_info_snapshot as a
                    inner join (
                        select 
                            account_id, max(block_id) as max_block_id 
                        from data_account_info_snapshot 
                        group by account_id
                    ) as b
                    on a.account_id = b.account_id and a.block_id = b.max_block_id
                    """)

        for account_id, balance_total, balance_free, balance_reserved, nonce in account_info:
            Account.query(self.db_session).filter_by(id=account_id).update(
                {
                    Account.balance_total: balance_total,
                    Account.balance_free: balance_free,
                    Account.balance_reserved: balance_reserved,
                    Account.nonce: nonce,
                }, synchronize_session='fetch'
            )