[tutorial] edited hands-on practices (#1899)

* Add handson to ColossalAI.

* Change names of handsons and edit sequence parallel example.

* Edit wrong folder name

* resolve conflict

* delete readme

examples/tutorial/opt/inference/cache.py

@@ -0,0 +1,64 @@
+from collections import OrderedDict
+from threading import Lock
+from contextlib import contextmanager
+from typing import List, Any, Hashable, Dict
+
+
+class MissCacheError(Exception):
+    pass
+
+
+class ListCache:
+    def __init__(self, cache_size: int, list_size: int, fixed_keys: List[Hashable] = []) -> None:
+        """Cache a list of values. The fixed keys won't be removed. For other keys, LRU is applied.
+        When the value list is not full, a cache miss occurs. Otherwise, a cache hit occurs. Redundant values will be removed.
+
+        Args:
+            cache_size (int): Max size for LRU cache.
+            list_size (int): Value list size.
+            fixed_keys (List[Hashable], optional): The keys which won't be removed. Defaults to [].
+        """
+        self.cache_size = cache_size
+        self.list_size = list_size
+        self.cache: OrderedDict[Hashable, List[Any]] = OrderedDict()
+        self.fixed_cache: Dict[Hashable, List[Any]] = {}
+        for key in fixed_keys:
+            self.fixed_cache[key] = []
+        self._lock = Lock()
+
+    def get(self, key: Hashable) -> List[Any]:
+        with self.lock():
+            if key in self.fixed_cache:
+                l = self.fixed_cache[key]
+                if len(l) >= self.list_size:
+                    return l
+            elif key in self.cache:
+                self.cache.move_to_end(key)
+                l = self.cache[key]
+                if len(l) >= self.list_size:
+                    return l
+        raise MissCacheError()
+
+    def add(self, key: Hashable, value: Any) -> None:
+        with self.lock():
+            if key in self.fixed_cache:
+                l = self.fixed_cache[key]
+                if len(l) < self.list_size and value not in l:
+                    l.append(value)
+            elif key in self.cache:
+                self.cache.move_to_end(key)
+                l = self.cache[key]
+                if len(l) < self.list_size and value not in l:
+                    l.append(value)
+            else:
+                if len(self.cache) >= self.cache_size:
+                    self.cache.popitem(last=False)
+                self.cache[key] = [value]
+
+    @contextmanager
+    def lock(self):
+        try:
+            self._lock.acquire()
+            yield
+        finally:
+            self._lock.release()