GPT Cache docs

docs/my-website/docs/caching/gpt_cache.md

@@ -6,7 +6,11 @@ GPTCache Docs: https://gptcache.readthedocs.io/en/latest/index.html#
 
 GPTCache Github: https://github.com/zilliztech/GPTCache
 
-## Usage
+In this document we cover:
+* Quick Start Usage
+* Advanced Usage - Set Custom Cache Keys
+
+## Quick Start Usage
 
 ### Install GPTCache
 ```
@@ -16,7 +20,7 @@ pip install gptcache
 ### Using GPT Cache with Litellm Completion()
 
 #### Using GPTCache
-In order to use GPTCache the following lines are used to instantiat it
+In order to use GPTCache the following lines are used to instantiate it
 ```python
 from gptcache import cache
 # set API keys in .env / os.environ
@@ -25,6 +29,8 @@ cache.set_openai_key()
 ```
 
 #### Full Code using GPTCache and LiteLLM
+By default GPT Cache uses the content in `messages` as the cache key
+
 ```python
 from gptcache import cache
 from litellm.gpt_cache import completion # import completion from litellm.cache
@@ -51,3 +57,69 @@ for _ in range(2):
     print("Time consuming: {:.2f}s".format(time.time() - start_time))
 ```
 
+## Advanced Usage - Set Custom Cache Keys
+
+By default gptcache uses the `messages` as the cache key
+
+GPTCache allows you to set custom cache keys by setting
+```python
+cache.init(pre_func=pre_cache_func)
+```
+
+In this code snippet below we define a `pre_func` that returns message content + model as key 
+
+### Defining a `pre_func` for GPTCache
+```python
+### using / setting up gpt cache
+from gptcache import cache
+from gptcache.processor.pre import last_content_without_prompt
+from typing import Dict, Any
+
+# use this function to set your cache keys -> gptcache
+# data are all the args passed to your completion call 
+def pre_cache_func(data: Dict[str, Any], **params: Dict[str, Any]) -> Any:
+        # use this to set cache key
+        print("in pre_cache_func")
+        last_content_without_prompt_val = last_content_without_prompt(data, **params)
+        print("last content without prompt", last_content_without_prompt_val)
+        print("model", data["model"])
+        cache_key = last_content_without_prompt_val + data["model"]
+        print("cache_key", cache_key)
+        return cache_key # using this as cache_key
+        
+```
+
+### Init Cache with `pre_func` to set custom keys
+
+```python
+# init GPT Cache with custom pre_func
+cache.init(pre_func=pre_cache_func)
+cache.set_openai_key()
+```
+
+## Using Cache 
+* Cache key is `message` + `model`
+
+We make 3 LLM API calls
+* 2 to OpenAI 
+* 1 to Cohere command nightly 
+
+```python
+messages = [{"role": "user", "content": "why should I use LiteLLM for completions()"}]
+response1 = completion(model="gpt-3.5-turbo", messages=messages)
+response2 = completion(model="gpt-3.5-turbo", messages=messages)
+response3 = completion(model="command-nightly", messages=messages) # calling cohere command nightly
+
+if response1["choices"] != response2["choices"]: # same models should cache 
+    print(f"Error occurred: Caching for same model+prompt failed")
+
+if response3["choices"] == response2["choices"]: # different models, don't cache 
+    # if models are different, it should not return cached response
+    print(f"Error occurred: Caching for different model+prompt failed")
+
+print("response1", response1)
+print("response2", response2)
+print("response3", response3)
+```
+
+