Support n in OpenAI API completions (#3446)

Co-authored-by: Shan Yu <shanyu1@g.ucla.edu>
Co-authored-by: Yineng Zhang <me@zhyncs.com>
Co-authored-by: chuyue sun <chuyue@lmsys.us-northcentral1-a.compute.internal>

examples/frontend_language/quick_start/openai_example_n.py

@@ -0,0 +1,73 @@
+"""
+Usage:
+export OPENAI_API_KEY=sk-******
+python3 openai_example_chat.py
+"""
+
+import json
+
+import sglang as sgl
+
+
+@sgl.function
+def multi_turn_question(s, question_1, question_2):
+    s += sgl.system("You are a helpful assistant.")
+    s += sgl.user(question_1)
+    s += sgl.assistant(sgl.gen("answer_1", max_tokens=1024, n=2))
+    s += sgl.user(question_2)
+    s += sgl.assistant(
+        sgl.gen(
+            "answer_2",
+            max_tokens=1024,
+        )
+    )
+
+
+def single():
+    state = multi_turn_question.run(
+        question_1="What is the capital of the United States?",
+        question_2="List two local attractions.",
+    )
+
+    for m in state.messages():
+        print(m["role"], ":", m["content"])
+
+    print("\n-- answer_1 --\n", state["answer_1"])
+    print("\n-- answer_2 --\n", state["answer_2"])
+    assert isinstance(state["answer_1"], list)
+    assert len(state["answer_1"]) == 2
+    assert isinstance(state["answer_2"], str)
+
+
+def batch():
+    states = multi_turn_question.run_batch(
+        [
+            {
+                "question_1": "What is the capital of the United States?",
+                "question_2": "List two local attractions.",
+            },
+            {
+                "question_1": "What is the capital of France?",
+                "question_2": "What is the population of this city?",
+            },
+        ]
+    )
+
+    for s in states:
+        print(s.messages())
+        print("\n-- answer_1 --\n", s["answer_1"])
+        print("\n-- answer_2 --\n", s["answer_2"])
+        assert isinstance(s["answer_1"], list)
+        assert len(s["answer_1"]) == 2
+        assert isinstance(s["answer_2"], str)
+
+
+if __name__ == "__main__":
+    sgl.set_default_backend(sgl.OpenAI("o1"))
+
+    # Run a single request
+    print("\n========== single ==========\n")
+    single()
+    # Run a batch of requests
+    print("\n========== batch ==========\n")
+    batch()