experimentn: support async client

src/clickhouse_orm/aio/database.py

@@ -0,0 +1,377 @@
+import datetime
+import logging
+from math import ceil
+from typing import Type, Optional, Generator
+
+import httpx
+import pytz
+
+from clickhouse_orm.models import MODEL, ModelBase
+from clickhouse_orm.utils import parse_tsv, import_submodules
+from clickhouse_orm.database import Database, ServerError, DatabaseException, logger, Page
+
+
+class AioDatabase(Database):
+
+    def __init__(
+        self, db_name, db_url='http://localhost:18123/', username=None,
+        password=None, readonly=False, auto_create=True, timeout=60,
+        verify_ssl_cert=True, log_statements=False
+    ):
+        self.db_name = db_name
+        self.db_url = db_url
+        self.readonly = False
+        self._readonly = readonly
+        self.auto_create = auto_create
+        self.timeout = timeout
+        self.request_session = httpx.AsyncClient(verify=verify_ssl_cert, timeout=timeout)
+        if username:
+            self.request_session.auth = (username, password or '')
+        self.log_statements = log_statements
+        self.settings = {}
+        self._db_check = False
+        self.db_exists = False
+
+    async def db_check(self):
+        if self._db_check:
+            return
+        self.db_exists = await self._is_existing_database()
+        if self._readonly:
+            if not self.db_exists:
+                raise DatabaseException(
+                    'Database does not exist, and cannot be created under readonly connection'
+                )
+            self.connection_readonly = await self._is_connection_readonly()
+            self.readonly = True
+        elif self.auto_create and not self.db_exists:
+            await self.create_database()
+        self.server_version = await self._get_server_version()
+        if self.server_version > (1, 1, 53981):
+            self.server_timezone = await self._get_server_timezone()
+        else:
+            self.server_timezone = pytz.utc
+        self.has_codec_support = self.server_version >= (19, 1, 16)
+        self.has_low_cardinality_support = self.server_version >= (19, 0)
+        self._db_check = True
+
+    async def close(self):
+        await self.request_session.aclose()
+
+    async def _send(self, data, settings=None, stream=False):
+        r = await super()._send(data, settings, stream)
+        if r.status_code != 200:
+            raise ServerError(r.text)
+        return r
+
+    async def count(
+        self,
+        model_class,
+        conditions=None
+    ) -> int:
+        """
+        Counts the number of records in the model's table.
+
+        - `model_class`: the model to count.
+        - `conditions`: optional SQL conditions (contents of the WHERE clause).
+        """
+        from clickhouse_orm.query import Q
+
+        if not self._db_check:
+            raise DatabaseException(
+                'The AioDatabase object must execute the `db_check` method before it can be used'
+            )
+
+        query = 'SELECT count() FROM $table'
+        if conditions:
+            if isinstance(conditions, Q):
+                conditions = conditions.to_sql(model_class)
+            query += ' WHERE ' + str(conditions)
+        query = self._substitute(query, model_class)
+        r = await self._send(query)
+        return int(r.text) if r.text else 0
+
+    async def create_database(self):
+        """
+        Creates the database on the ClickHouse server if it does not already exist.
+        """
+        if not self._db_check:
+            raise DatabaseException(
+                'The AioDatabase object must execute the `db_check` method before it can be used'
+            )
+
+        await self._send('CREATE DATABASE IF NOT EXISTS `%s`' % self.db_name)
+        self.db_exists = True
+
+    async def drop_database(self):
+        """
+        Deletes the database on the ClickHouse server.
+        """
+        if not self._db_check:
+            raise DatabaseException(
+                'The AioDatabase object must execute the `db_check` method before it can be used'
+            )
+
+        await self._send('DROP DATABASE `%s`' % self.db_name)
+        self.db_exists = False
+
+    async def create_table(self, model_class: Type[MODEL]) -> None:
+        """
+        Creates a table for the given model class, if it does not exist already.
+        """
+        if not self._db_check:
+            raise DatabaseException(
+                'The AioDatabase object must execute the `db_check` method before it can be used'
+            )
+
+        if model_class.is_system_model():
+            raise DatabaseException("You can't create system table")
+        if getattr(model_class, 'engine') is None:
+            raise DatabaseException("%s class must define an engine" % model_class.__name__)
+        await self._send(model_class.create_table_sql(self))
+
+    async def drop_table(self, model_class: Type[MODEL]) -> None:
+        """
+        Drops the database table of the given model class, if it exists.
+        """
+        if not self._db_check:
+            raise DatabaseException(
+                'The AioDatabase object must execute the `db_check` method before it can be used'
+            )
+
+        if model_class.is_system_model():
+            raise DatabaseException("You can't drop system table")
+        await self._send(model_class.drop_table_sql(self))
+
+    async def does_table_exist(self, model_class: Type[MODEL]) -> bool:
+        """
+        Checks whether a table for the given model class already exists.
+        Note that this only checks for existence of a table with the expected name.
+        """
+        if not self._db_check:
+            raise DatabaseException(
+                'The AioDatabase object must execute the `db_check` method before it can be used'
+            )
+
+        sql = "SELECT count() FROM system.tables WHERE database = '%s' AND name = '%s'"
+        r = await self._send(sql % (self.db_name, model_class.table_name()))
+        return r.text.strip() == '1'
+
+    async def get_model_for_table(
+        self,
+        table_name: str,
+        system_table: bool = False
+    ):
+        """
+        Generates a model class from an existing table in the database.
+        This can be used for querying tables which don't have a corresponding model class,
+        for example system tables.
+
+        - `table_name`: the table to create a model for
+        - `system_table`: whether the table is a system table, or belongs to the current database
+        """
+        db_name = 'system' if system_table else self.db_name
+        sql = "DESCRIBE `%s`.`%s` FORMAT TSV" % (db_name, table_name)
+        lines = await self._send(sql)
+        fields = [parse_tsv(line)[:2] async for line in lines.aiter_lines()]
+        model = ModelBase.create_ad_hoc_model(fields, table_name)
+        if system_table:
+            model._system = model._readonly = True
+        return model
+
+    async def insert(self, model_instances, batch_size=1000):
+        """
+        Insert records into the database.
+
+        - `model_instances`: any iterable containing instances of a single model class.
+        - `batch_size`: number of records to send per chunk (use a lower number if your records are very large).
+        """
+        from io import BytesIO
+
+        i = iter(model_instances)
+        try:
+            first_instance = next(i)
+        except StopIteration:
+            return  # model_instances is empty
+        model_class = first_instance.__class__
+
+        if first_instance.is_read_only() or first_instance.is_system_model():
+            raise DatabaseException("You can't insert into read only and system tables")
+
+        fields_list = ','.join(
+            ['`%s`' % name for name in first_instance.fields(writable=True)])
+        fmt = 'TSKV' if model_class.has_funcs_as_defaults() else 'TabSeparated'
+        query = 'INSERT INTO $table (%s) FORMAT %s\n' % (fields_list, fmt)
+
+        def gen():
+            buf = BytesIO()
+            buf.write(self._substitute(query, model_class).encode('utf-8'))
+            first_instance.set_database(self)
+            buf.write(first_instance.to_db_string())
+            # Collect lines in batches of batch_size
+            lines = 2
+            for instance in i:
+                instance.set_database(self)
+                buf.write(instance.to_db_string())
+                lines += 1
+                if lines >= batch_size:
+                    # Return the current batch of lines
+                    yield buf.getvalue()
+                    # Start a new batch
+                    buf = BytesIO()
+                    lines = 0
+            # Return any remaining lines in partial batch
+            if lines:
+                yield buf.getvalue()
+        await self._send(gen())
+
+    async def select(
+        self,
+        query: str,
+        model_class: Optional[Type[MODEL]] = None,
+        settings: Optional[dict] = None
+    ) -> Generator[MODEL, None, None]:
+        """
+        Performs a query and returns a generator of model instances.
+
+        - `query`: the SQL query to execute.
+        - `model_class`: the model class matching the query's table,
+          or `None` for getting back instances of an ad-hoc model.
+        - `settings`: query settings to send as HTTP GET parameters
+        """
+        query += ' FORMAT TabSeparatedWithNamesAndTypes'
+        query = self._substitute(query, model_class)
+        r = await self._send(query, settings, True)
+        try:
+            field_names, field_types = None, None
+            async for line in r.aiter_lines():
+                # skip blank line left by WITH TOTALS modifier
+                if not field_names:
+                    field_names = parse_tsv(line)
+                elif not field_types:
+                    field_types = parse_tsv(line)
+                    model_class = model_class or ModelBase.create_ad_hoc_model(
+                        zip(field_names, field_types))
+                elif line:
+                    yield model_class.from_tsv(line, field_names, self.server_timezone, self)
+        finally:
+            await r.aclose()
+
+    async def raw(self, query: str, settings: Optional[dict] = None, stream: bool = False) -> str:
+        """
+        Performs a query and returns its output as text.
+
+        - `query`: the SQL query to execute.
+        - `settings`: query settings to send as HTTP GET parameters
+        - `stream`: if true, the HTTP response from ClickHouse will be streamed.
+        """
+        query = self._substitute(query, None)
+        return (await self._send(query, settings=settings, stream=stream)).text
+
+    async def paginate(
+        self,
+        model_class: Type[MODEL],
+        order_by: str,
+        page_num: int = 1,
+        page_size: int = 100,
+        conditions=None,
+        settings: Optional[dict] = None
+    ):
+        """
+        Selects records and returns a single page of model instances.
+
+        - `model_class`: the model class matching the query's table,
+          or `None` for getting back instances of an ad-hoc model.
+        - `order_by`: columns to use for sorting the query (contents of the ORDER BY clause).
+        - `page_num`: the page number (1-based), or -1 to get the last page.
+        - `page_size`: number of records to return per page.
+        - `conditions`: optional SQL conditions (contents of the WHERE clause).
+        - `settings`: query settings to send as HTTP GET parameters
+
+        The result is a namedtuple containing `objects` (list), `number_of_objects`,
+        `pages_total`, `number` (of the current page), and `page_size`.
+        """
+        from clickhouse_orm.query import Q
+
+        count = await self.count(model_class, conditions)
+        pages_total = int(ceil(count / float(page_size)))
+        if page_num == -1:
+            page_num = max(pages_total, 1)
+        elif page_num < 1:
+            raise ValueError('Invalid page number: %d' % page_num)
+        offset = (page_num - 1) * page_size
+        query = 'SELECT * FROM $table'
+        if conditions:
+            if isinstance(conditions, Q):
+                conditions = conditions.to_sql(model_class)
+            query += ' WHERE ' + str(conditions)
+        query += ' ORDER BY %s' % order_by
+        query += ' LIMIT %d, %d' % (offset, page_size)
+        query = self._substitute(query, model_class)
+        return Page(
+            objects=[r async for r in self.select(query, model_class, settings)] if count else [],
+            number_of_objects=count,
+            pages_total=pages_total,
+            number=page_num,
+            page_size=page_size
+        )
+
+    async def migrate(self, migrations_package_name, up_to=9999):
+        """
+        Executes schema migrations.
+
+        - `migrations_package_name` - fully qualified name of the Python package
+          containing the migrations.
+        - `up_to` - number of the last migration to apply.
+        """
+        from ..migrations import MigrationHistory
+
+        logger = logging.getLogger('migrations')
+        applied_migrations = await self._get_applied_migrations(migrations_package_name)
+        modules = import_submodules(migrations_package_name)
+        unapplied_migrations = set(modules.keys()) - applied_migrations
+        for name in sorted(unapplied_migrations):
+            logger.info('Applying migration %s...', name)
+            for operation in modules[name].operations:
+                operation.apply(self)
+            await self.insert([MigrationHistory(
+                package_name=migrations_package_name,
+                module_name=name,
+                applied=datetime.date.today()
+            )])
+            if int(name[:4]) >= up_to:
+                break
+
+    async def _is_existing_database(self):
+        r = await self._send(
+            "SELECT count() FROM system.databases WHERE name = '%s'" % self.db_name
+        )
+        return r.text.strip() == '1'
+
+    async def _is_connection_readonly(self):
+        r = await self._send("SELECT value FROM system.settings WHERE name = 'readonly'")
+        return r.text.strip() != '0'
+
+    async def _get_server_timezone(self):
+        try:
+            r = await self._send('SELECT timezone()')
+            return pytz.timezone(r.text.strip())
+        except ServerError as e:
+            logger.exception('Cannot determine server timezone (%s), assuming UTC', e)
+            return pytz.utc
+
+    async def _get_server_version(self, as_tuple=True):
+        try:
+            r = await self._send('SELECT version();')
+            ver = r.text
+        except ServerError as e:
+            logger.exception('Cannot determine server version (%s), assuming 1.1.0', e)
+            ver = '1.1.0'
+        return tuple(int(n) for n in ver.split('.') if n.isdigit()) if as_tuple else ver
+
+    async def _get_applied_migrations(self, migrations_package_name):
+        from ..migrations import MigrationHistory
+
+        await self.create_table(MigrationHistory)
+        query = "SELECT module_name from $table WHERE package_name = '%s'" % migrations_package_name
+        query = self._substitute(query, MigrationHistory)
+        return set(obj.module_name async for obj in self.select(query))

src/clickhouse_orm/query.py

@@ -349,6 +349,10 @@ class QuerySet(object):
         """
         return self._database.select(self.as_sql(), self._model_cls)
 
+    async def __aiter__(self):
+        async for r in self._database.select(self.as_sql(), self._model_cls):
+            yield r
+
     def __bool__(self):
         """
         Returns true if this queryset matches any rows.