server : allow to get default generation settings for completion (ggml-org#5307)

Author: z80maniac

examples/server/README.md

@@ -264,7 +264,21 @@ Notice that each `probs` is an array of length `n_probs`.
 
     It also accepts all the options of `/completion` except `stream` and `prompt`.
 
-- **GET** `/props`: Return the required assistant name and anti-prompt to generate the prompt in case you have specified a system prompt for all slots.
+- **GET** `/props`: Return current server settings.
+
+### Result JSON
+
+```json
+{
+  "assistant_name": "",
+  "user_name": "",
+  "default_generation_settings": { ... }
+}
+```
+
+- `assistant_name` - the required assistant name to generate the prompt in case you have specified a system prompt for all slots.
+- `user_name` - the required anti-prompt to generate the prompt in case you have specified a system prompt for all slots.
+- `default_generation_settings` - the default generation settings for the `/completion` endpoint, has the same fields as the `generation_settings` response object from the `/completion` endpoint.
 
 - **POST** `/v1/chat/completions`: OpenAI-compatible Chat Completions API. Given a ChatML-formatted json description in `messages`, it returns the predicted completion. Both synchronous and streaming mode are supported, so scripted and interactive applications work fine. While no strong claims of compatibility with OpenAI API spec is being made, in our experience it suffices to support many apps. Only ChatML-tuned models, such as Dolphin, OpenOrca, OpenHermes, OpenChat-3.5, etc can be used with this endpoint. Compared to `api_like_OAI.py` this API implementation does not require a wrapper to be served.
 

examples/server/server.cpp

@@ -334,6 +334,7 @@ struct llama_server_context
 
     // slots / clients
     std::vector<llama_client_slot> slots;
+    json default_generation_settings_for_props;
 
     llama_server_queue queue_tasks;
     llama_server_response queue_results;
@@ -430,6 +431,9 @@ struct llama_server_context
             slots.push_back(slot);
         }
 
+        default_generation_settings_for_props = get_formated_generation(slots.front());
+        default_generation_settings_for_props["seed"] = -1;
+
         batch = llama_batch_init(n_ctx, 0, params.n_parallel);
 
         // empty system prompt
@@ -2614,7 +2618,8 @@ int main(int argc, char **argv)
                 res.set_header("Access-Control-Allow-Origin", req.get_header_value("Origin"));
                 json data = {
                     { "user_name",      llama.name_user.c_str() },
-                    { "assistant_name", llama.name_assistant.c_str() }
+                    { "assistant_name", llama.name_assistant.c_str() },
+                    { "default_generation_settings", llama.default_generation_settings_for_props }
                 };
                 res.set_content(data.dump(), "application/json; charset=utf-8");
             });