query: Add Query class and begin implementing decode

Author: ohsayan

src/skytable_py/__init__.py

@@ -13,4 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .connection import Config, Connection
+from .connection import Connection
+from .query import Query, UInt, SInt
+from .config import Config

src/skytable_py/config.py

@@ -0,0 +1,62 @@
+# Copyright 2024, Sayan Nandan <[email protected]>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import asyncio
+from .connection import Connection
+from .exception import ClientException
+
+
+class Config:
+    def __init__(self, username: str, password: str, host: str = "127.0.0.1", port: int = 2003) -> None:
+        self._username = username
+        self._password = password
+        self._host = host
+        self._port = port
+
+    def get_username(self) -> str:
+        return self._username
+
+    def get_password(self) -> str:
+        return self._password
+
+    def get_host(self) -> str:
+        return self._host
+
+    def get_port(self) -> int:
+        return self._port
+
+    def __hs(self) -> bytes:
+        return f"H\0\0\0\0\0{len(self.get_username())}\n{len(self.get_password())}\n{self.get_username()}{self.get_password()}".encode()
+
+    async def connect(self) -> Connection:
+        """
+        Establish a connection to the database instance using the set configuration.
+
+        ## Exceptions
+        Exceptions are raised in the following scenarios:
+        - If the server responds with a handshake error
+        - If the server sends an unknown handshake (usually caused by version incompatibility)
+        """
+        reader, writer = await asyncio.open_connection(self.get_host(), self.get_port())
+        con = Connection(reader, writer)
+        await con._write_all(self.__hs())
+        resp = await con._read_exact(4)
+        a, b, c, d = resp[0], resp[1], resp[2], resp[3]
+        if resp == b"H\0\0\0":
+            return con
+        elif a == ord(b'H') and b == 0 and c == 1:
+            raise ClientException(f"handshake error {d}")
+        else:
+            raise ClientException("unknown handshake")

src/skytable_py/connection.py

@@ -13,15 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import asyncio
 from asyncio import StreamReader, StreamWriter
-
-
-class ClientException(Exception):
-    """
-    An exception thrown by this client library
-    """
-    pass
+from .query import Query
+from .exception import ProtocolException
 
 
 class Connection:
@@ -32,6 +26,8 @@ class Connection:
     def __init__(self, reader: StreamReader, writer: StreamWriter) -> None:
         self._reader = reader
         self._writer = writer
+        self._cursor = 0
+        self.buffer = bytes()
 
     async def _write_all(self, bytes: bytes):
         self._write(bytes)
@@ -40,6 +36,9 @@ async def _write_all(self, bytes: bytes):
     def _write(self, bytes: bytes) -> None:
         self._writer.write(bytes)
 
+    def __buffer(self) -> bytes:
+        return self.buffer[:self._cursor]
+
     async def _flush(self):
         await self._writer.drain()
 
@@ -53,46 +52,59 @@ async def close(self):
         self._writer.close()
         await self._writer.wait_closed()
 
-
-class Config:
-    def __init__(self, username: str, password: str, host: str = "127.0.0.1", port: int = 2003) -> None:
-        self._username = username
-        self._password = password
-        self._host = host
-        self._port = port
-
-    def get_username(self) -> str:
-        return self._username
-
-    def get_password(self) -> str:
-        return self._password
-
-    def get_host(self) -> str:
-        return self._host
-
-    def get_port(self) -> int:
-        return self._port
-
-    def __hs(self) -> bytes:
-        return f"H\0\0\0\0\0{len(self.get_username())}\n{len(self.get_password())}\n{self.get_username()}{self.get_password()}".encode()
-
-    async def connect(self) -> Connection:
-        """
-        Establish a connection to the database instance using the set configuration.
-
-        ## Exceptions
-        Exceptions are raised in the following scenarios:
-        - If the server responds with a handshake error
-        - If the server sends an unknown handshake (usually caused by version incompatibility)
-        """
-        reader, writer = await asyncio.open_connection(self.get_host(), self.get_port())
-        con = Connection(reader, writer)
-        await con._write_all(self.__hs())
-        resp = await con._read_exact(4)
-        a, b, c, d = resp[0], resp[1], resp[2], resp[3]
-        if resp == b"H\0\0\0":
-            return con
-        elif a == ord(b'H') and b == 0 and c == 1:
-            raise ClientException(f"handshake error {d}")
-        else:
-            raise ClientException("unknown handshake")
+    def __parse_string(self) -> None | str:
+        strlen = self.__parse_int()
+        if strlen:
+            if len(self.__buffer()) >= strlen:
+                strlen = self.__buffer()[:strlen].decode()
+                self._cursor += strlen
+                return strlen
+
+    def __parse_binary(self) -> None | bytes:
+        binlen = self.__parse_int()
+        if binlen:
+            if len(self.__buffer()) >= binlen:
+                binlen = self.__buffer()[:binlen].decode()
+                self._cursor += binlen
+                return binlen
+
+    def __parse_int(self) -> None | int:
+        i = 0
+        strlen = 0
+        stop = False
+        buffer = self.__buffer()
+
+        while i < len(buffer) and not stop:
+            digit = None
+            if 48 <= buffer[i] <= 57:
+                digit = buffer[i] - 48
+
+            if digit is not None:
+                strlen = (10 * strlen) + digit
+                i += 1
+            else:
+                raise ProtocolException("invalid response from server")
+
+            if i < len(buffer) and buffer[i] == ord(b'\n'):
+                stop = True
+                i += 1
+
+        if stop:
+            self._cursor += i
+            self._cursor += 1  # for LF
+            return strlen
+
+    async def run_simple_query(self, query: Query):
+        query_window_str = str(len(query._q_window))
+        total_packet_size = len(query_window_str) + 1 + len(query._buffer)
+        # write metaframe
+        metaframe = f"S{str(total_packet_size)}\n{query_window_str}\n"
+        await self._write_all(metaframe.encode())
+        # write dataframe
+        await self._write_all(query._buffer)
+        # now enter read loop
+        while True:
+            read = await self._reader.read(1024)
+            if len(read) == 0:
+                raise ConnectionResetError
+            self.buffer = self.buffer + read

src/skytable_py/exception.py

@@ -0,0 +1,28 @@
+# Copyright 2024, Sayan Nandan <[email protected]>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+class ClientException(Exception):
+    """
+    An exception thrown by this client library
+    """
+    pass
+
+
+class ProtocolException(ClientException):
+    """
+    An exception thrown by the protocol
+    """
+    pass

src/skytable_py/query.py

@@ -0,0 +1,76 @@
+# Copyright 2024, Sayan Nandan <[email protected]>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from abc import ABC
+# internal
+from .exception import ClientException
+
+
+class Query:
+    def __init__(self, query: str, *argv) -> None:
+        self._buffer = query.encode()
+        self._param_cnt = 0
+        self._q_window = len(self._buffer)
+        for param in argv:
+            self.add_param(param)
+
+    def add_param(self, param: any) -> None:
+        payload, param_cnt = encode_parameter(param)
+        self._param_cnt += param_cnt
+        self._buffer = self._buffer + payload
+
+    def get_param_count(self) -> int:
+        return self._param_cnt
+
+
+class SkyhashParameter(ABC):
+    def encode_self(self) -> tuple[bytes, int]: pass
+
+
+class UInt(SkyhashParameter):
+    def __init__(self, v: int) -> None:
+        if v < 0:
+            raise ClientException("unsigned int can't be negative")
+        self.v = v
+
+    def encode_self(self) -> tuple[bytes, int]:
+        return (f"\x02{self.v}\n".encode(), 1)
+
+
+class SInt(SkyhashParameter):
+    def __init__(self, v: int) -> None:
+        self.v = v
+
+    def encode_self(self) -> tuple[bytes, int]:
+        return (f"\x03{self.v}\n".encode(), 1)
+
+
+def encode_parameter(parameter: any) -> tuple[bytes, int]:
+    encoded = None
+    if isinstance(parameter, SkyhashParameter):
+        return parameter.encode_self()
+    elif parameter is None:
+        encoded = "\0".encode()
+    elif isinstance(parameter, bool):
+        encoded = f"\1{1 if parameter else 0}".encode()
+    elif isinstance(parameter, float):
+        encoded = f"\x04{parameter}\n".encode()
+    elif isinstance(parameter, bytes):
+        encoded = f"\x05{len(parameter)}\n".encode() + parameter
+    elif isinstance(parameter, str):
+        encoded = f"\x06{len(parameter)}\n{parameter}".encode()
+    else:
+        raise ClientException("unsupported type")
+    return (encoded, 1)

tests/test_encoding.py

@@ -0,0 +1,54 @@
+# Copyright 2024, Sayan Nandan <[email protected]>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+from src.skytable_py.query import encode_parameter, UInt, SInt
+from src.skytable_py.exception import ClientException
+
+
+class TestConfig(unittest.TestCase):
+    def test_encode_null(self):
+        self.assertEqual(encode_parameter(None), (b"\0", 1))
+
+    def test_encode_bool(self):
+        self.assertEqual(encode_parameter(False), (b"\x010", 1))
+        self.assertEqual(encode_parameter(True), (b"\x011", 1))
+
+    def test_encode_uint(self):
+        self.assertEqual(encode_parameter(UInt(1234)), (b"\x021234\n", 1))
+
+    def test_encode_sint(self):
+        self.assertEqual(encode_parameter(SInt(-1234)), (b"\x03-1234\n", 1))
+
+    def test_encode_float(self):
+        self.assertEqual(encode_parameter(3.141592654),
+                         (b"\x043.141592654\n", 1))
+
+    def test_encode_bin(self):
+        self.assertEqual(encode_parameter(b"binary"), (b"\x056\nbinary", 1))
+
+    def test_encode_str(self):
+        self.assertEqual(encode_parameter("string"), (b"\x066\nstring", 1))
+
+    def test_int_causes_exception(self):
+        try:
+            encode_parameter(1234)
+        except ClientException as e:
+            if str(e) == "unsupported type":
+                pass
+            else:
+                self.fail(f"expected 'unsupported type' but got '{e}'")
+        else:
+            self.fail("expected exception but no exception was raised")