Add squashed update after deleting document history (#53)

tests/conftest.py

@@ -1,11 +1,28 @@
 import subprocess
 
 import pytest
+import y_py as Y
 from websockets import serve  # type: ignore
 
 from ypy_websocket import WebsocketServer
 
 
+class TestYDoc:
+    def __init__(self):
+        self.ydoc = Y.YDoc()
+        self.array = self.ydoc.get_array("array")
+        self.state = None
+        self.value = 0
+
+    def update(self):
+        with self.ydoc.begin_transaction() as txn:
+            self.array.append(txn, self.value)
+        self.value += 1
+        update = Y.encode_state_as_update(self.ydoc, self.state)
+        self.state = Y.encode_state_vector(self.ydoc)
+        return update
+
+
 @pytest.fixture
 async def yws_server(request):
     try:
@@ -23,3 +40,8 @@ def yjs_client(request):
     p = subprocess.Popen(["node", f"tests/yjs_client_{client_id}.js"])
     yield p
     p.kill()
+
+
+@pytest.fixture
+def test_ydoc():
+    return TestYDoc()

tests/test_ystore.py

@@ -59,29 +59,28 @@ async def test_ystore(YStore):
 
 
 @pytest.mark.asyncio
-async def test_document_ttl_sqlite_ystore():
+async def test_document_ttl_sqlite_ystore(test_ydoc):
     store_name = "my_store"
     ystore = MySQLiteYStore(store_name, metadata_callback=MetadataCallback(), delete_db=True)
-
-    await ystore.write(b"a")
-    async with aiosqlite.connect(ystore.db_path) as db:
-        assert (await (await db.execute("SELECT count(*) FROM yupdates")).fetchone())[0] == 1
-
     now = time.time()
 
-    # assert that adding a record before document TTL doesn't delete document history
-    with patch("time.time") as mock_time:
-        mock_time.return_value = now
-        await ystore.write(b"b")
-        async with aiosqlite.connect(ystore.db_path) as db:
-            assert (await (await db.execute("SELECT count(*) FROM yupdates")).fetchone())[0] == 2
+    for i in range(3):
+        # assert that adding a record before document TTL doesn't delete document history
+        with patch("time.time") as mock_time:
+            mock_time.return_value = now
+            await ystore.write(test_ydoc.update())
+            async with aiosqlite.connect(ystore.db_path) as db:
+                assert (await (await db.execute("SELECT count(*) FROM yupdates")).fetchone())[
+                    0
+                ] == i + 1
 
     # assert that adding a record after document TTL deletes previous document history
     with patch("time.time") as mock_time:
-        mock_time.return_value = now + ystore.document_ttl + 1000
-        await ystore.write(b"c")
+        mock_time.return_value = now + ystore.document_ttl + 1
+        await ystore.write(test_ydoc.update())
         async with aiosqlite.connect(ystore.db_path) as db:
-            assert (await (await db.execute("SELECT count(*) FROM yupdates")).fetchone())[0] == 1
+            # two updates in DB: one squashed update and the new update
+            assert (await (await db.execute("SELECT count(*) FROM yupdates")).fetchone())[0] == 2
 
 
 @pytest.mark.asyncio

ypy_websocket/ystore.py

@@ -224,7 +224,6 @@ async def read(self) -> AsyncIterator[Tuple[bytes, bytes]]:  # type: ignore
             raise YDocNotFound
 
     async def write(self, data: bytes) -> None:
-        metadata = await self.get_metadata()
         await self.db_initialized
         async with aiosqlite.connect(self.db_path) as db:
             # first, determine time elapsed since last update
@@ -235,11 +234,26 @@ async def write(self, data: bytes) -> None:
             row = await cursor.fetchone()
             diff = (time.time() - row[0]) if row else 0
 
-            # if diff > document_ttl, delete document history
             if diff > self.document_ttl:
+                # squash updates
+                ydoc = Y.YDoc()
+                async with db.execute(
+                    "SELECT yupdate FROM yupdates WHERE path = ?", (self.path,)
+                ) as cursor:
+                    async for update, in cursor:
+                        Y.apply_update(ydoc, update)
+                # delete history
                 await db.execute("DELETE FROM yupdates WHERE path = ?", (self.path,))
+                # insert squashed updates
+                squashed_update = Y.encode_state_as_update(ydoc)
+                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()),