add LSET and LINDEX

Author: JosuaKrause

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [release candidate]
+
+### Added
+
+- `LSET` and `LINDEX` ([#19])
+
 ## [0.7.0] - 2024-04-21
 
 ### Added
@@ -79,3 +85,4 @@
 [#15]: https://github.com/JosuaKrause/redipy/pull/15
 [#17]: https://github.com/JosuaKrause/redipy/pull/17
 [#18]: https://github.com/JosuaKrause/redipy/pull/18
+[#19]: https://github.com/JosuaKrause/redipy/pull/19

src/redipy/api.py

@@ -441,6 +441,43 @@ def lrange(self, key: str, start: int, stop: int) -> None:
         """
         raise NotImplementedError()
 
+    def lset(self, key: str, index: int, value: str) -> None:
+        """
+        Sets the value of a list element at the given index. The index can be
+        negative to index from the back. The function will raise if the index
+        is out of bounds.
+
+        See also the redis documentation: https://redis.io/commands/lset/
+
+        The pipeline value is None.
+
+        Args:
+            key (str): The key.
+
+            index (int): The index. Can be negative to index from the back.
+
+            value (str): The value.
+        """
+        raise NotImplementedError()
+
+    def lindex(self, key: str, index: int) -> None:
+        """
+        Retrieves the value of a list element at the given index. The index can
+        be negative to index from the back. None is returned for an out of
+        bounds index.
+
+        See also the redis documentation: https://redis.io/commands/lindex/
+
+        The pipeline value is the value at the index or None if the index was
+        out of bounds.
+
+        Args:
+            key (str): The key.
+
+            index (int): The index. Can be negative to index from the back.
+        """
+        raise NotImplementedError()
+
     def llen(self, key: str) -> None:
         """
         Computes the length of the list associated with the key.
@@ -1212,6 +1249,42 @@ def lrange(self, key: str, start: int, stop: int) -> list[str]:
         """
         raise NotImplementedError()
 
+    def lset(self, key: str, index: int, value: str) -> None:
+        """
+        Sets the value of a list element at the given index. The index can be
+        negative to index from the back. The function will raise if the index
+        is out of bounds.
+
+        See also the redis documentation: https://redis.io/commands/lset/
+
+        Args:
+            key (str): The key.
+
+            index (int): The index. Can be negative to index from the back.
+
+            value (str): The value.
+        """
+        raise NotImplementedError()
+
+    def lindex(self, key: str, index: int) -> str | None:
+        """
+        Retrieves the value of a list element at the given index. The index can
+        be negative to index from the back. None is returned for an out of
+        bounds index.
+
+        See also the redis documentation: https://redis.io/commands/lindex/
+
+        Args:
+            key (str): The key.
+
+            index (int): The index. Can be negative to index from the back.
+
+        Returns:
+            str | None: The value at the index or None if the index was out of
+                bounds.
+        """
+        raise NotImplementedError()
+
     def llen(self, key: str) -> int:
         """
         Computes the length of the list associated with the key.

src/redipy/helpers/cache.py

@@ -24,7 +24,8 @@
 V = TypeVar('V')
 
 
-class RCache(Generic[K, V]):
+class RCache(Generic[K, V]):  # pylint: disable=too-few-public-methods
+    """A redis based cache with in-flight computation detection."""
     def __init__(
             self,
             rt: RedisClientAPI,
@@ -34,6 +35,26 @@ def __init__(
             compute: Callable[[K], V],
             value_store: Callable[[V], str],
             value_read: Callable[[str], V]) -> None:
+        """
+        Creates a redis based cache.
+
+        Args:
+            rt (RedisClientAPI): The redis client.
+
+            prefix (str): The key prefix.
+
+            hasher (Callable[[K], str]): Function to create a hash for a given
+                key.
+
+            compute (Callable[[K], V]): Compute the actual value for a given
+                key.
+
+            value_store (Callable[[V], str]): Convert the value into a string
+                for storing. The string must never be empty.
+
+            value_read (Callable[[str], V]): Convert a string into a value for
+                retrieving.
+        """
         self._rt = rt
         self._prefix = prefix
         self._hasher = hasher
@@ -48,6 +69,26 @@ def _redis_key(self, hash_str: str) -> str:
         return f"{prefix}{hash_str}"
 
     def get_value(self, key: K, *, timeout: float = 300.0) -> V:
+        """
+        Retrieves the value of the given key. If the value is not already
+        cached it is computed. If a value is being computed elsewhere at the
+        moment the function call blocks until the computation is complete.
+        During this, if timeout is reached, the computation will start again.
+
+        Args:
+            key (K): The key.
+
+            timeout (float, optional): Timeout before starting to compute the
+                value ourself if another computation was already in-flight
+                in seconds. Defaults to 300.0.
+
+        Raises:
+            ValueError: If the value string is the empty string after
+                converting the result.
+
+        Returns:
+            V: The result value.
+        """
         rt = self._rt
         hash_str = self._hasher(key)
         rkey = self._redis_key(hash_str)

src/redipy/helpers/mavg.py

@@ -12,32 +12,32 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """A moving average implementation."""
-from redipy.api import RedisClientAPI
-from redipy.backend.backend import ExecFunction
-from redipy.symbolic.seq import FnContext
+# from redipy.api import RedisClientAPI
+# from redipy.backend.backend import ExecFunction
+# from redipy.symbolic.seq import FnContext
 
 
-class RMovingAverage:
-    def __init__(self, rt: RedisClientAPI) -> None:
-        self._rt = rt
-        self._update = self._update_script()
+# class RMovingAverage:
+#     def __init__(self, rt: RedisClientAPI) -> None:
+#         self._rt = rt
+#         self._update = self._update_script()
 
-    def _update_script(self) -> ExecFunction:
-        ctx = FnContext()
+#     def _update_script(self) -> ExecFunction:
+#         ctx = FnContext()
 
 
-        rsize = RedisVar(ctx.add_key("size"))
-        base = ctx.add_local(ctx.add_key("frame"))
-        field = ctx.add_arg("field")
-        pos = ctx.add_local(ToNum(rsize.get_value(default=0)))
-        res = ctx.add_local(None)
-        cur = ctx.add_local(None)
-        rframe = RedisHash(cur)
+#         rsize = RedisVar(ctx.add_key("size"))
+#         base = ctx.add_local(ctx.add_key("frame"))
+#         field = ctx.add_arg("field")
+#         pos = ctx.add_local(ToNum(rsize.get_value(default=0)))
+#         res = ctx.add_local(None)
+#         cur = ctx.add_local(None)
+#         rframe = RedisHash(cur)
 
-        loop = ctx.while_(res.eq_(None).and_(pos.ge_(0)))
-        loop.add(cur.assign(Strs(base, ":", ToIntStr(pos))))
-        loop.add(res.assign(rframe.hget(field)))
-        loop.add(pos.assign(pos - 1))
+#         loop = ctx.while_(res.eq_(None).and_(pos.ge_(0)))
+#         loop.add(cur.assign(Strs(base, ":", ToIntStr(pos))))
+#         loop.add(res.assign(rframe.hget(field)))
+#         loop.add(pos.assign(pos - 1))
 
-        ctx.set_return_value(res)
-        return self._rt.register_script(ctx)
+#         ctx.set_return_value(res)
+#         return self._rt.register_script(ctx)

src/redipy/main.py

@@ -394,6 +394,12 @@ def rpop(
     def lrange(self, key: str, start: int, stop: int) -> list[str]:
         return self._rt.lrange(key, start, stop)
 
+    def lset(self, key: str, index: int, value: str) -> None:
+        self._rt.lset(key, index, value)
+
+    def lindex(self, key: str, index: int) -> str | None:
+        return self._rt.lindex(key, index)
+
     def llen(self, key: str) -> int:
         return self._rt.llen(key)
 

src/redipy/memory/rt.py

@@ -407,6 +407,14 @@ def lrange(self, key: str, start: int, stop: int) -> list[str]:
         with self.lock():
             return self._sm.lrange(key, start, stop)
 
+    def lset(self, key: str, index: int, value: str) -> None:
+        with self.lock():
+            self._sm.lset(key, index, value)
+
+    def lindex(self, key: str, index: int) -> str | None:
+        with self.lock():
+            return self._sm.lindex(key, index)
+
     def llen(self, key: str) -> int:
         with self.lock():
             return self._sm.llen(key)
@@ -675,6 +683,12 @@ def rpop(
     def lrange(self, key: str, start: int, stop: int) -> None:
         self.add_cmd(lambda: self._sm.lrange(key, start, stop))
 
+    def lset(self, key: str, index: int, value: str) -> None:
+        self.add_cmd(lambda: self._sm.lset(key, index, value))
+
+    def lindex(self, key: str, index: int) -> None:
+        self.add_cmd(lambda: self._sm.lindex(key, index))
+
     def llen(self, key: str) -> None:
         self.add_cmd(lambda: self._sm.llen(key))
 

src/redipy/memory/state.py

@@ -1435,6 +1435,21 @@ def lrange(self, key: str, start: int, stop: int) -> list[str]:
         queue.rotate(start)
         return res
 
+    def lset(self, key: str, index: int, value: str) -> None:
+        now_mono = self.get_mono()
+        queue = self._state.get_queue(key, now_mono)
+        queue[index] = value
+
+    def lindex(self, key: str, index: int) -> str | None:
+        now_mono = self.get_mono()
+        queue = self._state.readonly_queue(key, now_mono)
+        if not queue:
+            return None
+        try:
+            return queue[index]
+        except IndexError:
+            return None
+
     def llen(self, key: str) -> int:
         now_mono = self.get_mono()
         return self._state.queue_len(key, now_mono)

src/redipy/redis/conn.py

@@ -454,6 +454,14 @@ def lrange(self, key: str, start: int, stop: int) -> None:
         self._pipe.lrange(self.with_prefix(key), start, stop)
         self.add_fixup(to_list_str)
 
+    def lset(self, key: str, index: int, value: str) -> None:
+        self._pipe.lset(self.with_prefix(key), index, value)
+        self.add_fixup(lambda _: None)
+
+    def lindex(self, key: str, index: int) -> None:
+        self._pipe.lindex(self.with_prefix(key), index)
+        self.add_fixup(to_maybe_str)
+
     def llen(self, key: str) -> None:
         self._pipe.llen(self.with_prefix(key))
         self.add_fixup(int)
@@ -1088,6 +1096,14 @@ def lrange(self, key: str, start: int, stop: int) -> list[str]:
         with self.get_connection() as conn:
             return to_list_str(conn.lrange(self.with_prefix(key), start, stop))
 
+    def lset(self, key: str, index: int, value: str) -> None:
+        with self.get_connection() as conn:
+            conn.lset(self.with_prefix(key), index, value)
+
+    def lindex(self, key: str, index: int) -> str | None:
+        with self.get_connection() as conn:
+            return to_maybe_str(conn.lindex(self.with_prefix(key), index))
+
     def llen(self, key: str) -> int:
         with self.get_connection() as conn:
             return conn.llen(self.with_prefix(key))