阶段2（上）：后端专题 Go/Gin/PostgreSQL/MySQL/Redis/MQ/gRPC 的课程、企业场景、面试题和可运行示例

topics/backend/grpc-microservices/examples/grpc-user/demo.py

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+# requires: grpc, grpc_tools
+"""gRPC 演示：从 user.proto 生成代码 → 启动服务端 → 客户端调用（一元、服务端流、超时、错误码）。
+
+运行：pip install grpcio grpcio-tools && python demo.py
+生成的代码放在临时目录，不污染仓库。
+"""
+import importlib
+import sys
+import tempfile
+import time
+from concurrent import futures
+from pathlib import Path
+
+import grpc
+from grpc_tools import protoc
+
+HERE = Path(__file__).resolve().parent
+
+
+def generate(out: Path):
+    rc = protoc.main(["protoc", f"-I{HERE}", f"--python_out={out}", f"--grpc_python_out={out}", str(HERE / "user.proto")])
+    assert rc == 0, "protoc 生成失败"
+    sys.path.insert(0, str(out))
+    return importlib.import_module("user_pb2"), importlib.import_module("user_pb2_grpc")
+
+
+def main() -> None:
+    with tempfile.TemporaryDirectory() as tmp:
+        pb, pb_grpc = generate(Path(tmp))
+        users = {i: pb.User(id=i, name=f"用户{i}", email=f"u{i}@example.com") for i in range(1, 6)}
+
+        class UserService(pb_grpc.UserServiceServicer):
+            def GetUser(self, request, context):
+                if request.id == 99:
+                    time.sleep(0.5)  # 模拟慢请求
+                user = users.get(request.id)
+                if user is None:
+                    context.abort(grpc.StatusCode.NOT_FOUND, f"用户 {request.id} 不存在")
+                return user
+
+            def ListUsers(self, request, context):
+                for i, u in enumerate(users.values()):
+                    if i >= request.page_size:
+                        break
+                    yield u
+
+        server = grpc.server(futures.ThreadPoolExecutor(max_workers=4))
+        pb_grpc.add_UserServiceServicer_to_server(UserService(), server)
+        port = server.add_insecure_port("127.0.0.1:0")  # 0 = 随机可用端口
+        server.start()
+        try:
+            with grpc.insecure_channel(f"127.0.0.1:{port}") as ch:
+                stub = pb_grpc.UserServiceStub(ch)
+                u = stub.GetUser(pb.GetUserRequest(id=1), timeout=1.0)  # 每次调用都带超时
+                print("一元调用：", u.id, u.name)
+                assert u.name == "用户1"
+
+                names = [x.name for x in stub.ListUsers(pb.ListUsersRequest(page_size=3), timeout=1.0)]
+                print("服务端流：", names)
+                assert len(names) == 3
+
+                try:
+                    stub.GetUser(pb.GetUserRequest(id=42), timeout=1.0)
+                    raise AssertionError("应该返回 NOT_FOUND")
+                except grpc.RpcError as e:
+                    print("错误码：", e.code().name, e.details())
+                    assert e.code() == grpc.StatusCode.NOT_FOUND
+
+                try:
+                    stub.GetUser(pb.GetUserRequest(id=99), timeout=0.1)
+                    raise AssertionError("应该超时")
+                except grpc.RpcError as e:
+                    print("超时：", e.code().name)
+                    assert e.code() == grpc.StatusCode.DEADLINE_EXCEEDED
+        finally:
+            server.stop(grace=None)
+    print("gRPC 演示通过")
+
+
+if __name__ == "__main__":
+    main()