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BaseYStore

Bases: ABC

Source code in pycrdt_websocket/ystore.py 
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class BaseYStore(ABC):
    metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None = None
    version = 2
    _started: Event | None = None
    _starting: bool = False
    _task_group: TaskGroup | None = None

    @abstractmethod
    def __init__(
        self, path: str, metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None = None
    ): ...

    @abstractmethod
    async def write(self, data: bytes) -> None: ...

    @abstractmethod
    async def read(self) -> AsyncIterator[tuple[bytes, bytes, float]]:
        if False:
            yield

    @property
    def started(self) -> Event:
        if self._started is None:
            self._started = Event()
        return self._started

    async def __aenter__(self) -> BaseYStore:
        if self._task_group is not None:
            raise RuntimeError("YStore already running")

        async with AsyncExitStack() as exit_stack:
            tg = create_task_group()
            self._task_group = await exit_stack.enter_async_context(tg)
            self._exit_stack = exit_stack.pop_all()
            tg.start_soon(self.start)

        return self

    async def __aexit__(self, exc_type, exc_value, exc_tb):
        if self._task_group is None:
            raise RuntimeError("YStore not running")

        self._task_group.cancel_scope.cancel()
        self._task_group = None
        return await self._exit_stack.__aexit__(exc_type, exc_value, exc_tb)

    async def start(self, *, task_status: TaskStatus[None] = TASK_STATUS_IGNORED):
        """Start the store.

        Arguments:
            task_status: The status to set when the task has started.
        """
        if self._starting:
            return
        else:
            self._starting = True

        if self._task_group is not None:
            raise RuntimeError("YStore already running")

        self.started.set()
        self._starting = False
        task_status.started()

    def stop(self) -> None:
        """Stop the store."""
        if self._task_group is None:
            raise RuntimeError("YStore not running")

        self._task_group.cancel_scope.cancel()
        self._task_group = None

    async def get_metadata(self) -> bytes:
        """
        Returns:
            The metadata.
        """
        if self.metadata_callback is None:
            return b""

        metadata = self.metadata_callback()
        if isawaitable(metadata):
            metadata = await metadata
        metadata = cast(bytes, metadata)
        return metadata

    async def encode_state_as_update(self, ydoc: Doc) -> None:
        """Store a YDoc state.

        Arguments:
            ydoc: The YDoc from which to store the state.
        """
        update = ydoc.get_update()
        await self.write(update)

    async def apply_updates(self, ydoc: Doc) -> None:
        """Apply all stored updates to the YDoc.

        Arguments:
            ydoc: The YDoc on which to apply the updates.
        """
        async for update, *rest in self.read():
            ydoc.apply_update(update)

apply_updates(ydoc) async

Apply all stored updates to the YDoc.

Parameters:

Name Type Description Default
ydoc Doc

The YDoc on which to apply the updates.

 required
Source code in pycrdt_websocket/ystore.py 
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async def apply_updates(self, ydoc: Doc) -> None:
    """Apply all stored updates to the YDoc.

    Arguments:
        ydoc: The YDoc on which to apply the updates.
    """
    async for update, *rest in self.read():
        ydoc.apply_update(update)

encode_state_as_update(ydoc) async

Store a YDoc state.

Parameters:

Name Type Description Default
ydoc Doc

The YDoc from which to store the state.

 required
Source code in pycrdt_websocket/ystore.py 
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async def encode_state_as_update(self, ydoc: Doc) -> None:
    """Store a YDoc state.

    Arguments:
        ydoc: The YDoc from which to store the state.
    """
    update = ydoc.get_update()
    await self.write(update)

get_metadata() async

Returns:

Type Description
bytes

The metadata.
Source code in pycrdt_websocket/ystore.py 
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async def get_metadata(self) -> bytes:
    """
    Returns:
        The metadata.
    """
    if self.metadata_callback is None:
        return b""

    metadata = self.metadata_callback()
    if isawaitable(metadata):
        metadata = await metadata
    metadata = cast(bytes, metadata)
    return metadata

start(*, task_status=TASK_STATUS_IGNORED) async

Start the store.

Parameters:

Name Type Description Default
task_status TaskStatus[None]

The status to set when the task has started.

 TASK_STATUS_IGNORED
Source code in pycrdt_websocket/ystore.py 
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async def start(self, *, task_status: TaskStatus[None] = TASK_STATUS_IGNORED):
    """Start the store.

    Arguments:
        task_status: The status to set when the task has started.
    """
    if self._starting:
        return
    else:
        self._starting = True

    if self._task_group is not None:
        raise RuntimeError("YStore already running")

    self.started.set()
    self._starting = False
    task_status.started()

stop()

Stop the store.

Source code in pycrdt_websocket/ystore.py 
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def stop(self) -> None:
    """Stop the store."""
    if self._task_group is None:
        raise RuntimeError("YStore not running")

    self._task_group.cancel_scope.cancel()
    self._task_group = None

FileYStore

Bases: BaseYStore

A YStore which uses one file per document.

Source code in pycrdt_websocket/ystore.py 
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class FileYStore(BaseYStore):
    """A YStore which uses one file per document."""

    path: str
    metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None
    lock: Lock

    def __init__(
        self,
        path: str,
        metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None = None,
        log: Logger | None = None,
    ) -> None:
        """Initialize the object.

        Arguments:
            path: The file path used to store the updates.
            metadata_callback: An optional callback to call to get the metadata.
            log: An optional logger.
        """
        self.path = path
        self.metadata_callback = metadata_callback
        self.log = log or getLogger(__name__)
        self.lock = Lock()

    async def check_version(self) -> int:
        """Check the version of the store format.

        Returns:
            The offset where the data is located in the file.
        """
        if not await anyio.Path(self.path).exists():
            version_mismatch = True
        else:
            version_mismatch = False
            move_file = False
            async with await anyio.open_file(self.path, "rb") as f:
                header = await f.read(8)
                if header == b"VERSION:":
                    version = int(await f.readline())
                    if version == self.version:
                        offset = await f.tell()
                    else:
                        version_mismatch = True
                else:
                    version_mismatch = True
                if version_mismatch:
                    move_file = True
            if move_file:
                new_path = await get_new_path(self.path)
                self.log.warning("YStore version mismatch, moving %s to %s", self.path, new_path)
                await anyio.Path(self.path).rename(new_path)
        if version_mismatch:
            async with await anyio.open_file(self.path, "wb") as f:
                version_bytes = f"VERSION:{self.version}\n".encode()
                await f.write(version_bytes)
                offset = len(version_bytes)
        return offset

    async def read(self) -> AsyncIterator[tuple[bytes, bytes, float]]:
        """Async iterator for reading the store content.

        Returns:
            A tuple of (update, metadata, timestamp) for each update.
        """
        async with self.lock:
            if not await anyio.Path(self.path).exists():
                raise YDocNotFound
            offset = await self.check_version()
            async with await anyio.open_file(self.path, "rb") as f:
                await f.seek(offset)
                data = await f.read()
                if not data:
                    raise YDocNotFound
        i = 0
        for d in Decoder(data).read_messages():
            if i == 0:
                update = d
            elif i == 1:
                metadata = d
            else:
                timestamp = struct.unpack("<d", d)[0]
                yield update, metadata, timestamp
            i = (i + 1) % 3

    async def write(self, data: bytes) -> None:
        """Store an update.

        Arguments:
            data: The update to store.
        """
        parent = Path(self.path).parent
        async with self.lock:
            await anyio.Path(parent).mkdir(parents=True, exist_ok=True)
            await self.check_version()
            async with await anyio.open_file(self.path, "ab") as f:
                data_len = write_var_uint(len(data))
                await f.write(data_len + data)
                metadata = await self.get_metadata()
                metadata_len = write_var_uint(len(metadata))
                await f.write(metadata_len + metadata)
                timestamp = struct.pack("<d", time.time())
                timestamp_len = write_var_uint(len(timestamp))
                await f.write(timestamp_len + timestamp)

__init__(path, metadata_callback=None, log=None)

Initialize the object.

Parameters:

Name Type Description Default
path str

The file path used to store the updates.

 required
metadata_callback Callable[[], Awaitable[bytes] | bytes] | None

An optional callback to call to get the metadata.

 None
log Logger | None

An optional logger.

 None
Source code in pycrdt_websocket/ystore.py 
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def __init__(
    self,
    path: str,
    metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None = None,
    log: Logger | None = None,
) -> None:
    """Initialize the object.

    Arguments:
        path: The file path used to store the updates.
        metadata_callback: An optional callback to call to get the metadata.
        log: An optional logger.
    """
    self.path = path
    self.metadata_callback = metadata_callback
    self.log = log or getLogger(__name__)
    self.lock = Lock()

check_version() async

Check the version of the store format.

Returns:

Type Description
int

The offset where the data is located in the file.
Source code in pycrdt_websocket/ystore.py 
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async def check_version(self) -> int:
    """Check the version of the store format.

    Returns:
        The offset where the data is located in the file.
    """
    if not await anyio.Path(self.path).exists():
        version_mismatch = True
    else:
        version_mismatch = False
        move_file = False
        async with await anyio.open_file(self.path, "rb") as f:
            header = await f.read(8)
            if header == b"VERSION:":
                version = int(await f.readline())
                if version == self.version:
                    offset = await f.tell()
                else:
                    version_mismatch = True
            else:
                version_mismatch = True
            if version_mismatch:
                move_file = True
        if move_file:
            new_path = await get_new_path(self.path)
            self.log.warning("YStore version mismatch, moving %s to %s", self.path, new_path)
            await anyio.Path(self.path).rename(new_path)
    if version_mismatch:
        async with await anyio.open_file(self.path, "wb") as f:
            version_bytes = f"VERSION:{self.version}\n".encode()
            await f.write(version_bytes)
            offset = len(version_bytes)
    return offset

read() async

Async iterator for reading the store content.

Returns:

Type Description
AsyncIterator[tuple[bytes, bytes, float]]

A tuple of (update, metadata, timestamp) for each update.
Source code in pycrdt_websocket/ystore.py 
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async def read(self) -> AsyncIterator[tuple[bytes, bytes, float]]:
    """Async iterator for reading the store content.

    Returns:
        A tuple of (update, metadata, timestamp) for each update.
    """
    async with self.lock:
        if not await anyio.Path(self.path).exists():
            raise YDocNotFound
        offset = await self.check_version()
        async with await anyio.open_file(self.path, "rb") as f:
            await f.seek(offset)
            data = await f.read()
            if not data:
                raise YDocNotFound
    i = 0
    for d in Decoder(data).read_messages():
        if i == 0:
            update = d
        elif i == 1:
            metadata = d
        else:
            timestamp = struct.unpack("<d", d)[0]
            yield update, metadata, timestamp
        i = (i + 1) % 3

write(data) async

Store an update.

Parameters:

Name Type Description Default
data bytes

The update to store.

 required
Source code in pycrdt_websocket/ystore.py 
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async def write(self, data: bytes) -> None:
    """Store an update.

    Arguments:
        data: The update to store.
    """
    parent = Path(self.path).parent
    async with self.lock:
        await anyio.Path(parent).mkdir(parents=True, exist_ok=True)
        await self.check_version()
        async with await anyio.open_file(self.path, "ab") as f:
            data_len = write_var_uint(len(data))
            await f.write(data_len + data)
            metadata = await self.get_metadata()
            metadata_len = write_var_uint(len(metadata))
            await f.write(metadata_len + metadata)
            timestamp = struct.pack("<d", time.time())
            timestamp_len = write_var_uint(len(timestamp))
            await f.write(timestamp_len + timestamp)

TempFileYStore

Bases: FileYStore

A YStore which uses the system's temporary directory. Files are writen under a common directory. To prefix the directory name (e.g. /tmp/my_prefix_b4whmm7y/):

class PrefixTempFileYStore(TempFileYStore):
    prefix_dir = "my_prefix_"
Source code in pycrdt_websocket/ystore.py 
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class TempFileYStore(FileYStore):
    """A YStore which uses the system's temporary directory.
    Files are writen under a common directory.
    To prefix the directory name (e.g. /tmp/my_prefix_b4whmm7y/):

    ```py
    class PrefixTempFileYStore(TempFileYStore):
        prefix_dir = "my_prefix_"
    ```
    """

    prefix_dir: str | None = None
    base_dir: str | None = None

    def __init__(
        self,
        path: str,
        metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None = None,
        log: Logger | None = None,
    ):
        """Initialize the object.

        Arguments:
            path: The file path used to store the updates.
            metadata_callback: An optional callback to call to get the metadata.
            log: An optional logger.
        """
        full_path = str(Path(self.get_base_dir()) / path)
        super().__init__(full_path, metadata_callback=metadata_callback, log=log)

    def get_base_dir(self) -> str:
        """Get the base directory where the update file is written.

        Returns:
            The base directory path.
        """
        if self.base_dir is None:
            self.make_directory()
        assert self.base_dir is not None
        return self.base_dir

    def make_directory(self):
        """Create the base directory where the update file is written."""
        type(self).base_dir = tempfile.mkdtemp(prefix=self.prefix_dir)

__init__(path, metadata_callback=None, log=None)

Initialize the object.

Parameters:

Name Type Description Default
path str

The file path used to store the updates.

 required
metadata_callback Callable[[], Awaitable[bytes] | bytes] | None

An optional callback to call to get the metadata.

 None
log Logger | None

An optional logger.

 None
Source code in pycrdt_websocket/ystore.py 
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def __init__(
    self,
    path: str,
    metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None = None,
    log: Logger | None = None,
):
    """Initialize the object.

    Arguments:
        path: The file path used to store the updates.
        metadata_callback: An optional callback to call to get the metadata.
        log: An optional logger.
    """
    full_path = str(Path(self.get_base_dir()) / path)
    super().__init__(full_path, metadata_callback=metadata_callback, log=log)

get_base_dir()

Get the base directory where the update file is written.

Returns:

Type Description
str

The base directory path.
Source code in pycrdt_websocket/ystore.py 
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def get_base_dir(self) -> str:
    """Get the base directory where the update file is written.

    Returns:
        The base directory path.
    """
    if self.base_dir is None:
        self.make_directory()
    assert self.base_dir is not None
    return self.base_dir

make_directory()

Create the base directory where the update file is written.

Source code in pycrdt_websocket/ystore.py 
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def make_directory(self):
    """Create the base directory where the update file is written."""
    type(self).base_dir = tempfile.mkdtemp(prefix=self.prefix_dir)

SQLiteYStore

Bases: BaseYStore

A YStore which uses an SQLite database. Unlike file-based YStores, the Y updates of all documents are stored in the same database.

Subclass to point to your database file:

class MySQLiteYStore(SQLiteYStore):
    db_path = "path/to/my_ystore.db"
Source code in pycrdt_websocket/ystore.py 
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class SQLiteYStore(BaseYStore):
    """A YStore which uses an SQLite database.
    Unlike file-based YStores, the Y updates of all documents are stored in the same database.

    Subclass to point to your database file:

    ```py
    class MySQLiteYStore(SQLiteYStore):
        db_path = "path/to/my_ystore.db"
    ```
    """

    db_path: str = "ystore.db"
    # Determines the "time to live" for all documents, i.e. how recent the
    # latest update of a document must be before purging document history.
    # Defaults to never purging document history (None).
    document_ttl: int | None = None
    path: str
    lock: Lock
    db_initialized: Event

    def __init__(
        self,
        path: str,
        metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None = None,
        log: Logger | None = None,
    ) -> None:
        """Initialize the object.

        Arguments:
            path: The file path used to store the updates.
            metadata_callback: An optional callback to call to get the metadata.
            log: An optional logger.
        """
        self.path = path
        self.metadata_callback = metadata_callback
        self.log = log or getLogger(__name__)
        self.lock = Lock()
        self.db_initialized = Event()

    async def start(self, *, task_status: TaskStatus[None] = TASK_STATUS_IGNORED):
        """Start the SQLiteYStore.

        Arguments:
            task_status: The status to set when the task has started.
        """
        if self._starting:
            return
        else:
            self._starting = True

        if self._task_group is not None:
            raise RuntimeError("YStore already running")

        async with create_task_group() as self._task_group:
            self._task_group.start_soon(self._init_db)
            self.started.set()
            self._starting = False
            task_status.started()

    async def _init_db(self):
        create_db = False
        move_db = False
        if not await anyio.Path(self.db_path).exists():
            create_db = True
        else:
            async with self.lock:
                async with aiosqlite.connect(self.db_path) as db:
                    cursor = await db.execute(
                        "SELECT count(name) FROM sqlite_master "
                        "WHERE type='table' and name='yupdates'"
                    )
                    table_exists = (await cursor.fetchone())[0]
                    if table_exists:
                        cursor = await db.execute("pragma user_version")
                        version = (await cursor.fetchone())[0]
                        if version != self.version:
                            move_db = True
                            create_db = True
                    else:
                        create_db = True
        if move_db:
            new_path = await get_new_path(self.db_path)
            self.log.warning("YStore version mismatch, moving %s to %s", self.db_path, new_path)
            await anyio.Path(self.db_path).rename(new_path)
        if create_db:
            async with self.lock:
                async with aiosqlite.connect(self.db_path) as db:
                    await db.execute(
                        "CREATE TABLE yupdates (path TEXT NOT NULL, yupdate BLOB, "
                        "metadata BLOB, timestamp REAL NOT NULL)"
                    )
                    await db.execute(
                        "CREATE INDEX idx_yupdates_path_timestamp ON yupdates (path, timestamp)"
                    )
                    await db.execute(f"PRAGMA user_version = {self.version}")
                    await db.commit()
        self.db_initialized.set()

    async def read(self) -> AsyncIterator[tuple[bytes, bytes, float]]:
        """Async iterator for reading the store content.

        Returns:
            A tuple of (update, metadata, timestamp) for each update.
        """
        await self.db_initialized.wait()
        try:
            async with self.lock:
                async with aiosqlite.connect(self.db_path) as db:
                    async with db.execute(
                        "SELECT yupdate, metadata, timestamp FROM yupdates WHERE path = ?",
                        (self.path,),
                    ) as cursor:
                        found = False
                        async for update, metadata, timestamp in cursor:
                            found = True
                            yield update, metadata, timestamp
                        if not found:
                            raise YDocNotFound
        except Exception:
            raise YDocNotFound

    async def write(self, data: bytes) -> None:
        """Store an update.

        Arguments:
            data: The update to store.
        """
        await self.db_initialized.wait()
        async with self.lock:
            async with aiosqlite.connect(self.db_path) as db:
                # first, determine time elapsed since last update
                cursor = await db.execute(
                    "SELECT timestamp FROM yupdates WHERE path = ? "
                    "ORDER BY timestamp DESC LIMIT 1",
                    (self.path,),
                )
                row = await cursor.fetchone()
                diff = (time.time() - row[0]) if row else 0

                if self.document_ttl is not None and diff > self.document_ttl:
                    # squash updates
                    ydoc = Doc()
                    async with db.execute(
                        "SELECT yupdate FROM yupdates WHERE path = ?", (self.path,)
                    ) as cursor:
                        async for (update,) in cursor:
                            ydoc.apply_update(update)
                    # delete history
                    await db.execute("DELETE FROM yupdates WHERE path = ?", (self.path,))
                    # insert squashed updates
                    squashed_update = ydoc.get_update()
                    metadata = await self.get_metadata()
                    await db.execute(
                        "INSERT INTO yupdates VALUES (?, ?, ?, ?)",
                        (self.path, squashed_update, metadata, time.time()),
                    )

                # finally, write this update to the DB
                metadata = await self.get_metadata()
                await db.execute(
                    "INSERT INTO yupdates VALUES (?, ?, ?, ?)",
                    (self.path, data, metadata, time.time()),
                )
                await db.commit()

__init__(path, metadata_callback=None, log=None)

Initialize the object.

Parameters:

Name Type Description Default
path str

The file path used to store the updates.

 required
metadata_callback Callable[[], Awaitable[bytes] | bytes] | None

An optional callback to call to get the metadata.

 None
log Logger | None

An optional logger.

 None
Source code in pycrdt_websocket/ystore.py 
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def __init__(
    self,
    path: str,
    metadata_callback: Callable[[], Awaitable[bytes] | bytes] | None = None,
    log: Logger | None = None,
) -> None:
    """Initialize the object.

    Arguments:
        path: The file path used to store the updates.
        metadata_callback: An optional callback to call to get the metadata.
        log: An optional logger.
    """
    self.path = path
    self.metadata_callback = metadata_callback
    self.log = log or getLogger(__name__)
    self.lock = Lock()
    self.db_initialized = Event()

read() async

Async iterator for reading the store content.

Returns:

Type Description
AsyncIterator[tuple[bytes, bytes, float]]

A tuple of (update, metadata, timestamp) for each update.
Source code in pycrdt_websocket/ystore.py 
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async def read(self) -> AsyncIterator[tuple[bytes, bytes, float]]:
    """Async iterator for reading the store content.

    Returns:
        A tuple of (update, metadata, timestamp) for each update.
    """
    await self.db_initialized.wait()
    try:
        async with self.lock:
            async with aiosqlite.connect(self.db_path) as db:
                async with db.execute(
                    "SELECT yupdate, metadata, timestamp FROM yupdates WHERE path = ?",
                    (self.path,),
                ) as cursor:
                    found = False
                    async for update, metadata, timestamp in cursor:
                        found = True
                        yield update, metadata, timestamp
                    if not found:
                        raise YDocNotFound
    except Exception:
        raise YDocNotFound

start(*, task_status=TASK_STATUS_IGNORED) async

Start the SQLiteYStore.

Parameters:

Name Type Description Default
task_status TaskStatus[None]

The status to set when the task has started.

 TASK_STATUS_IGNORED
Source code in pycrdt_websocket/ystore.py 
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async def start(self, *, task_status: TaskStatus[None] = TASK_STATUS_IGNORED):
    """Start the SQLiteYStore.

    Arguments:
        task_status: The status to set when the task has started.
    """
    if self._starting:
        return
    else:
        self._starting = True

    if self._task_group is not None:
        raise RuntimeError("YStore already running")

    async with create_task_group() as self._task_group:
        self._task_group.start_soon(self._init_db)
        self.started.set()
        self._starting = False
        task_status.started()

write(data) async

Store an update.

Parameters:

Name Type Description Default
data bytes

The update to store.

 required
Source code in pycrdt_websocket/ystore.py 
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async def write(self, data: bytes) -> None:
    """Store an update.

    Arguments:
        data: The update to store.
    """
    await self.db_initialized.wait()
    async with self.lock:
        async with aiosqlite.connect(self.db_path) as db:
            # first, determine time elapsed since last update
            cursor = await db.execute(
                "SELECT timestamp FROM yupdates WHERE path = ? "
                "ORDER BY timestamp DESC LIMIT 1",
                (self.path,),
            )
            row = await cursor.fetchone()
            diff = (time.time() - row[0]) if row else 0

            if self.document_ttl is not None and diff > self.document_ttl:
                # squash updates
                ydoc = Doc()
                async with db.execute(
                    "SELECT yupdate FROM yupdates WHERE path = ?", (self.path,)
                ) as cursor:
                    async for (update,) in cursor:
                        ydoc.apply_update(update)
                # delete history
                await db.execute("DELETE FROM yupdates WHERE path = ?", (self.path,))
                # insert squashed updates
                squashed_update = ydoc.get_update()
                metadata = await self.get_metadata()
                await db.execute(
                    "INSERT INTO yupdates VALUES (?, ?, ?, ?)",
                    (self.path, squashed_update, metadata, time.time()),
                )

            # finally, write this update to the DB
            metadata = await self.get_metadata()
            await db.execute(
                "INSERT INTO yupdates VALUES (?, ?, ?, ?)",
                (self.path, data, metadata, time.time()),
            )
            await db.commit()