Python: Add ASGI lifespan state support.

Lifespan state is a special dict in asgi lifespan scope, which allow
applications to persist data from the lifespan cycle to request/response
handling. The scope["state"] namespace provides a place to store these
sorts of things. The server will ensure that a shallow copy of the
namespace is passed into each subsequent request/response call into the
application.

Some frameworks are already taking advantage of this feature, for
example, starlette, and without this feature they wouldn't work
properly.

Signed-off-by: synodriver <diguohuangjiajinweijun@gmail.com>
Reviewed-by: Andrew Clayton <a.clayton@nginx.com>
[ Minor code tweaks to avoid lines > 80 chars, static a function and
  re-work the PyMemberDef structure initialisation for Python <3.7
  and -Wwrite-strings compatibility - Andrew ]
Tested-by: <https://github.com/synodriver>
Tested-by: <https://github.com/hawiliali>
Closes: <https://github.com/nginx/unit/issues/864>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

1 files changed, 28 insertions, 2 deletions

diff --git a/src/python/nxt_python_asgi.c b/src/python/nxt_python_asgi.c
index 9f6cde3b..5882491b 100644
--- a/src/python/nxt_python_asgi.c
+++ b/src/python/nxt_python_asgi.c
@@ -450,6 +450,7 @@ static void
 nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
 {
     PyObject                *scope, *res, *task, *receive, *send, *done, *asgi;
+    PyObject                *state, *newstate, *lifespan;
     PyObject                *stage2;
     nxt_python_target_t     *target;
     nxt_py_asgi_ctx_data_t  *ctx_data;
@@ -493,15 +494,41 @@ nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
     }
 
     req->data = asgi;
+    ctx_data = req->ctx->data;
     target = &nxt_py_targets->target[req->request->app_target];
+    lifespan = ctx_data->target_lifespans[req->request->app_target];
+    state = PyObject_GetAttr(lifespan, nxt_py_state_str);
+    if (nxt_slow_path(state == NULL)) {
+        nxt_unit_req_alert(req, "Python failed to get 'state' attribute");
+        nxt_unit_request_done(req, NXT_UNIT_ERROR);
+
+        goto release_done;
+    }
+
+    newstate = PyDict_Copy(state);
+    if (nxt_slow_path(newstate == NULL)) {
+        nxt_unit_req_alert(req, "Python failed to call state.copy()");
+        nxt_unit_request_done(req, NXT_UNIT_ERROR);
+        Py_DECREF(state);
+        goto release_done;
+    }
+    Py_DECREF(state);
 
     scope = nxt_py_asgi_create_http_scope(req, target);
     if (nxt_slow_path(scope == NULL)) {
         nxt_unit_request_done(req, NXT_UNIT_ERROR);
-
+        Py_DECREF(newstate);
         goto release_done;
     }
 
+    if (nxt_slow_path(PyDict_SetItem(scope, nxt_py_state_str, newstate)
+                      == -1))
+    {
+        Py_DECREF(newstate);
+        goto release_scope;
+    }
+    Py_DECREF(newstate);
+
     if (!target->asgi_legacy) {
         nxt_unit_req_debug(req, "Python call ASGI 3.0 application");
 
@@ -555,7 +582,6 @@ nxt_py_asgi_request_handler(nxt_unit_request_info_t *req)
         goto release_scope;
     }
 
-    ctx_data = req->ctx->data;
 
     task = PyObject_CallFunctionObjArgs(ctx_data->loop_create_task, res, NULL);
     if (nxt_slow_path(task == NULL)) {