commit dfababfc65fb9f07050070910be0cc015df4fd2c
author Nan Zhou <nanzhoumails@gmail.com> Tue May 17 23:12:06 2022 +0000
committer Nan Zhou <nanzhoumails@gmail.com> Wed May 25 23:51:36 2022 +0000
tree 1e5afc9e9b1c933de7be31ab61ced4ee2fa440e6
parent ef00d7d42cc8f7d90957ab7ca1f678cd531c2cb4

health: take json_ptr instead of reference when filling status

The existing codes populates the health status on the |AsyncResponse| or
a given JSON reference. This doesn't work if we want to populates status
on an array of objects, since the array can be resized which changes the
address of each object.

This commit changed the contructor to take a JSON pointer instead.
|HealthPopulate| will populates status on
|AsyncResponse->res.jsonValue|[json_ptr]. If the point can't be resolved
in the |jsonValue|, |HealthPopulate| populates nothing.

Fixed all places where the old reference based constructor is used.

This commit is extremely useful when implementing efficient level-1
expand handler on ResourceCollections. It also prevents issues on
reference lifecycles.

Tested:
1. It builds
2. Tested DIMM/System/Storage health on real hardware, works as expected
3. Tested on Redfish Service Validator, no new failures on health
properties.

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: I305515522af50b48be92a3f4689d8166f3bc0cc0

redfish-core/lib/health.hpp

diff --git a/redfish-core/lib/health.hpp b/redfish-core/lib/health.hpp
index 31adf7b..254f8e9 100644
--- a/redfish-core/lib/health.hpp
+++ b/redfish-core/lib/health.hpp
@@ -22,6 +22,7 @@
 #include <boost/container/flat_set.hpp>
 #include <dbus_singleton.hpp>
 #include <dbus_utility.hpp>
+#include <nlohmann/json.hpp>
 
 #include <variant>
 
@@ -30,14 +31,18 @@
 
 struct HealthPopulate : std::enable_shared_from_this<HealthPopulate>
 {
+    // By default populate status to "/Status" of |asyncResp->res.jsonValue|.
     HealthPopulate(const std::shared_ptr<bmcweb::AsyncResp>& asyncRespIn) :
-        asyncResp(asyncRespIn), jsonStatus(asyncResp->res.jsonValue["Status"])
+        asyncResp(asyncRespIn), statusPtr("/Status")
     {}
 
+    // Takes a JSON pointer rather than a reference. This is pretty useful when
+    // the address of the status JSON might change, for example, elements in an
+    // array.
     HealthPopulate(const std::shared_ptr<bmcweb::AsyncResp>& asyncRespIn,
-                   nlohmann::json& status) :
+                   const nlohmann::json::json_pointer& ptr) :
         asyncResp(asyncRespIn),
-        jsonStatus(status)
+        statusPtr(ptr)
     {}
 
     HealthPopulate(const HealthPopulate&) = delete;
@@ -47,6 +52,7 @@
 
     ~HealthPopulate()
     {
+        nlohmann::json& jsonStatus = asyncResp->res.jsonValue[statusPtr];
         nlohmann::json& health = jsonStatus["Health"];
         nlohmann::json& rollup = jsonStatus["HealthRollup"];
 
@@ -232,7 +238,9 @@
     }
 
     std::shared_ptr<bmcweb::AsyncResp> asyncResp;
-    nlohmann::json& jsonStatus;
+
+    // Will populate the health status into |asyncResp_json[statusPtr]|
+    nlohmann::json::json_pointer statusPtr;
 
     // we store pointers to other HealthPopulate items so we can update their
     // members and reduce dbus calls. As we hold a shared_ptr to them, they get

redfish-core/lib/storage.hpp

diff --git a/redfish-core/lib/storage.hpp b/redfish-core/lib/storage.hpp
index c86adab..ab59c33 100644
--- a/redfish-core/lib/storage.hpp
+++ b/redfish-core/lib/storage.hpp
@@ -248,10 +248,13 @@
                     // be resized, as json::array uses vector underneath and we
                     // need references to its members that won't change
                     size_t count = 0;
+                    // Pointer based on |asyncResp->res.jsonValue|
+                    nlohmann::json::json_pointer rootPtr =
+                        "/StorageControllers"_json_pointer;
                     for (const auto& [path, interfaceDict] : subtree)
                     {
                         auto subHealth = std::make_shared<HealthPopulate>(
-                            asyncResp, root[count]["Status"]);
+                            asyncResp, rootPtr / count / "Status");
                         subHealth->inventory.emplace_back(path);
                         health->inventory.emplace_back(path);
                         health->children.emplace_back(subHealth);

redfish-core/lib/systems.hpp

diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index 58bab2d..b11bb90 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -269,10 +269,10 @@
                 }
 
                 auto memoryHealth = std::make_shared<HealthPopulate>(
-                    aResp, aResp->res.jsonValue["MemorySummary"]["Status"]);
+                    aResp, "/MemorySummary/Status"_json_pointer);
 
                 auto cpuHealth = std::make_shared<HealthPopulate>(
-                    aResp, aResp->res.jsonValue["ProcessorSummary"]["Status"]);
+                    aResp, "/ProcessorSummary/Status"_json_pointer);
 
                 systemHealth->children.emplace_back(memoryHealth);
                 systemHealth->children.emplace_back(cpuHealth);