Use ObjectLifeCycle for InetLayer (#10522)

* Use ObjectLifeCycle for InetLayer

#### Problem

Working toward #7715 Virtualize System and Inet interfaces

#### Change overview

Revise ObjectLifeCycle and use it for InetLayer

#### Testing

CI; no changes to visibile functionality intended.

* change Reset() to expect Shutdown state

src/inet/InetLayer.cpp

@@ -101,8 +101,6 @@ void InetLayer::UpdateSnapshot(chip::System::Stats::Snapshot & aSnapshot)
  */
 InetLayer::InetLayer()
 {
-    State = kState_NotInitialized;
-
 #if CHIP_SYSTEM_CONFIG_USE_LWIP
     if (!sInetEventHandlerDelegate.IsInitialized())
         sInetEventHandlerDelegate.Init(HandleInetLayerEvent);
@@ -237,9 +235,7 @@ void InetLayer::DroppableEventDequeued(void)
 CHIP_ERROR InetLayer::Init(chip::System::Layer & aSystemLayer, void * aContext)
 {
     Inet::RegisterLayerErrorFormatter();
-
-    if (State != kState_NotInitialized)
-        return CHIP_ERROR_INCORRECT_STATE;
+    VerifyOrReturnError(mLayerState.SetInitializing(), CHIP_ERROR_INCORRECT_STATE);
 
     // Platform-specific initialization may elect to set this data
     // member. Ensure it is set to a sane default value before
@@ -256,7 +252,7 @@ CHIP_ERROR InetLayer::Init(chip::System::Layer & aSystemLayer, void * aContext)
     static_cast<System::LayerLwIP *>(mSystemLayer)->AddEventHandlerDelegate(sInetEventHandlerDelegate);
 #endif // CHIP_SYSTEM_CONFIG_USE_LWIP
 
-    State = kState_Initialized;
+    mLayerState.SetInitialized();
 
     return CHIP_NO_ERROR;
 }
@@ -271,35 +267,34 @@ CHIP_ERROR InetLayer::Init(chip::System::Layer & aSystemLayer, void * aContext)
  */
 CHIP_ERROR InetLayer::Shutdown()
 {
+    VerifyOrReturnError(mLayerState.SetShuttingDown(), CHIP_ERROR_INCORRECT_STATE);
+
     CHIP_ERROR err = CHIP_NO_ERROR;
 
-    if (State == kState_Initialized)
-    {
 #if INET_CONFIG_ENABLE_TCP_ENDPOINT
-        // Abort all TCP endpoints owned by this instance.
-        TCPEndPoint::sPool.ForEachActiveObject([&](TCPEndPoint * lEndPoint) {
-            if ((lEndPoint != nullptr) && lEndPoint->IsCreatedByInetLayer(*this))
-            {
-                lEndPoint->Abort();
-            }
-            return true;
-        });
+    // Abort all TCP endpoints owned by this instance.
+    TCPEndPoint::sPool.ForEachActiveObject([&](TCPEndPoint * lEndPoint) {
+        if ((lEndPoint != nullptr) && lEndPoint->IsCreatedByInetLayer(*this))
+        {
+            lEndPoint->Abort();
+        }
+        return true;
+    });
 #endif // INET_CONFIG_ENABLE_TCP_ENDPOINT
 
 #if INET_CONFIG_ENABLE_UDP_ENDPOINT
-        // Close all UDP endpoints owned by this instance.
-        UDPEndPoint::sPool.ForEachActiveObject([&](UDPEndPoint * lEndPoint) {
-            if ((lEndPoint != nullptr) && lEndPoint->IsCreatedByInetLayer(*this))
-            {
-                lEndPoint->Close();
-            }
-            return true;
-        });
+    // Close all UDP endpoints owned by this instance.
+    UDPEndPoint::sPool.ForEachActiveObject([&](UDPEndPoint * lEndPoint) {
+        if ((lEndPoint != nullptr) && lEndPoint->IsCreatedByInetLayer(*this))
+        {
+            lEndPoint->Close();
+        }
+        return true;
+    });
 #endif // INET_CONFIG_ENABLE_UDP_ENDPOINT
-    }
-
-    State = kState_NotInitialized;
 
+    mLayerState.SetShutdown();
+    mLayerState.Reset(); // Return to uninitialized state to permit re-initialization.
     return err;
 }
 
@@ -455,7 +450,7 @@ CHIP_ERROR InetLayer::NewTCPEndPoint(TCPEndPoint ** retEndPoint)
 
     *retEndPoint = nullptr;
 
-    VerifyOrReturnError(State == kState_Initialized, CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mLayerState.IsInitialized(), CHIP_ERROR_INCORRECT_STATE);
 
     *retEndPoint = TCPEndPoint::sPool.TryCreate();
     if (*retEndPoint == nullptr)
@@ -495,7 +490,7 @@ CHIP_ERROR InetLayer::NewUDPEndPoint(UDPEndPoint ** retEndPoint)
 
     *retEndPoint = nullptr;
 
-    VerifyOrReturnError(State == kState_Initialized, CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mLayerState.IsInitialized(), CHIP_ERROR_INCORRECT_STATE);
 
     *retEndPoint = UDPEndPoint::sPool.TryCreate();
     if (*retEndPoint == nullptr)

src/inet/InetLayer.h

@@ -69,6 +69,7 @@
 #include <system/SystemStats.h>
 
 #include <lib/support/DLLUtil.h>
+#include <lib/support/ObjectLifeCycle.h>
 
 #if INET_CONFIG_MAX_DROPPABLE_EVENTS
 
@@ -124,16 +125,6 @@ class DLL_EXPORT InetLayer
 #endif // INET_CONFIG_ENABLE_UDP_ENDPOINT
 
 public:
-    /**
-     *  The current state of the InetLayer object.
-     *
-     */
-    volatile enum {
-        kState_NotInitialized     = 0, /**< Not initialized state. */
-        kState_Initialized        = 1, /**< Initialized state. */
-        kState_ShutdownInProgress = 2, /**< State where Shutdown has been triggered. */
-    } State;                           /**< [READ-ONLY] Current state. */
-
     InetLayer();
 
     CHIP_ERROR Init(chip::System::Layer & aSystemLayer, void * aContext);
@@ -224,6 +215,7 @@ class DLL_EXPORT InetLayer
 #endif // INET_CONFIG_ENABLE_TCP_ENDPOINT && INET_TCP_IDLE_CHECK_INTERVAL > 0
 
 private:
+    ObjectLifeCycle mLayerState;
     void * mContext;
     void * mPlatformData;
     chip::System::Layer * mSystemLayer;

src/lib/support/ObjectLifeCycle.h

@@ -26,75 +26,55 @@ namespace chip {
  * Track the life cycle of an object.
  *
  * <pre>
- *                  ┌───────────────┐  Init  ┌─────────────┐  Shutdown  ┌──────────┐  Destroy  ┌───────────┐
- * Construction ───>│ Uninitialized ├───────>│ Initialized ├───────────>│ Shutdown ├──────────>│ Destroyed │
- *                  └──────────┬────┘        └─────────────┘            └─────┬────┘           └───────────┘
- *                      ^      │                               Reset          │
- *                      └──────┴<─────────────────────────────────────────────┘
+ *
+ *      Construction
+ *          ↓
+ *      Uninitialized ‹─┐
+ *          ↓           │
+ *      Initializing    │
+ *          ↓           │
+ *      Initialized     │
+ *          ↓           │
+ *      ShuttingDown    │
+ *          ↓           │
+ *      Shutdown ───────┘
+ *          ↓
+ *      Destroyed
+ *
  * </pre>
  */
-struct ObjectLifeCycle
+class ObjectLifeCycle
 {
-    /**
-     * @returns true if and only if the object is in the Initialized state.
-     */
-    bool IsInitialized() const { return mState == State::Initialized; }
-
-    /**
-     * Transition from Uninitialized to Initialized.
-     *
-     * Typical use is `VerifyOrReturnError(state.Init(), CHIP_ERROR_INCORRECT_STATE)`; this function returns `bool` rather than
-     * a `CHIP_ERROR` so that error source tracking will record the call point rather than this function itself.
-     *
-     * @return true     if the state was Uninitialized and is now Initialized.
-     * @return false    otherwise.
-     */
-    bool Init()
+public:
+    enum class State : uint8_t
     {
-        if (mState == State::Uninitialized)
-        {
-            mState = State::Initialized;
-            return true;
-        }
-        return false;
-    }
+        Uninitialized = 0, ///< Pre-initialized state.
+        Initializing  = 1, ///< State during intialization.
+        Initialized   = 2, ///< Initialized (active) state.
+        ShuttingDown  = 3, ///< State during shutdown.
+        Shutdown      = 4, ///< Post-shutdown state.
+        Destroyed     = 5, ///< Post-destructor state.
+    };
+
+    ObjectLifeCycle() : mState(State::Uninitialized) {}
+    ~ObjectLifeCycle() { mState = State::Destroyed; }
 
     /**
-     * Transition from Initialized to Shutdown.
-     *
-     * Typical use is `VerifyOrReturnError(state.Shutdown(), CHIP_ERROR_INCORRECT_STATE)`; this function returns `bool` rather than
-     * a `CHIP_ERROR` so that error source tracking will record the call point rather than this function itself.
-     *
-     * @return true     if the state was Initialized and is now Shutdown.
-     * @return false    otherwise.
+     * @returns true if and only if the object is in the Initialized state.
      */
-    bool Shutdown()
-    {
-        if (mState == State::Initialized)
-        {
-            mState = State::Shutdown;
-            return true;
-        }
-        return false;
-    }
+    bool IsInitialized() const { return mState == State::Initialized; }
 
-    /**
-     * Transition from Shutdown back to Uninitialized, or remain Uninitialized.
-     *
-     * Typical use is `VerifyOrReturnError(state.Reset(), CHIP_ERROR_INCORRECT_STATE)`; this function returns `bool` rather than
-     * a `CHIP_ERROR` so that error source tracking will record the call point rather than this function itself.
+    /*
+     * State transitions.
      *
-     * @return true     if the state was Uninitialized or Shutdown and is now Uninitialized.
-     * @return false    otherwise.
+     * Typical use is `VerifyOrReturnError(state.SetInitializing(), CHIP_ERROR_INCORRECT_STATE)`; these functions return `bool`
+     * rather than a `CHIP_ERROR` so that error source tracking will record the call point rather than this function itself.
      */
-    bool Reset()
-    {
-        if (mState == State::Shutdown)
-        {
-            mState = State::Uninitialized;
-        }
-        return mState == State::Uninitialized;
-    }
+    bool SetInitializing() { return Transition<State::Uninitialized, State::Initializing>(); }
+    bool SetInitialized() { return Transition<State::Initializing, State::Initialized>(); }
+    bool SetShuttingDown() { return Transition<State::Initialized, State::ShuttingDown>(); }
+    bool SetShutdown() { return Transition<State::ShuttingDown, State::Shutdown>(); }
+    bool Reset() { return Transition<State::Shutdown, State::Uninitialized>(); }
 
     /**
      * Transition from Uninitialized or Shutdown to Destroyed.
@@ -115,21 +95,21 @@ struct ObjectLifeCycle
         return false;
     }
 
-    /**
-     * Return the current state as an integer. This is intended for troubleshooting or logging, since there is no code access to
-     * the meaning of the integer value.
-     */
-    explicit operator int() const { return static_cast<int>(mState); }
+    State GetState() const { return mState; }
 
 private:
-    enum class State : uint8_t
+    template <State FROM, State TO>
+    bool Transition()
     {
-        Uninitialized = 0, /**< Pre-initialized state; */
-        Initialized   = 1, /**< Initialized state. */
-        Shutdown      = 2, /**< Post-Shutdown state. */
-        Destroyed     = 3, /**< Post-destructor state. */
-    };
-    State mState = State::Uninitialized;
+        if (mState == FROM)
+        {
+            mState = TO;
+            return true;
+        }
+        return false;
+    }
+
+    State mState;
 };
 
 } // namespace chip

src/system/SystemLayer.h

@@ -32,7 +32,6 @@
 
 #include <lib/support/CodeUtils.h>
 #include <lib/support/DLLUtil.h>
-#include <lib/support/ObjectLifeCycle.h>
 #include <system/SystemError.h>
 #include <system/SystemEvent.h>
 #include <system/SystemObject.h>

src/system/SystemLayerImplLibevent.cpp

@@ -55,7 +55,7 @@ System::SocketEvents SocketEventsFromLibeventFlags(short eventFlags)
 
 CHIP_ERROR LayerImplLibevent::Init(System::Layer & systemLayer)
 {
-    VerifyOrReturnError(!mLayerState.IsInitialized(), CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mLayerState.SetInitializing(), CHIP_ERROR_INCORRECT_STATE);
 
     RegisterPOSIXErrorFormatter();
 
@@ -83,7 +83,7 @@ CHIP_ERROR LayerImplLibevent::Init(System::Layer & systemLayer)
 
     Mutex::Init(mTimerListMutex);
 
-    VerifyOrReturnError(mLayerState.Init(), CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mLayerState.SetInitialized(), CHIP_ERROR_INCORRECT_STATE);
     return CHIP_NO_ERROR;
 }
 
@@ -111,7 +111,7 @@ void LayerImplLibevent::MdnsTimeoutCallbackHandler()
 
 CHIP_ERROR LayerImplLibevent::Shutdown()
 {
-    VerifyOrReturnError(mLayerState.Shutdown(), CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mLayerState.SetShuttingDown(), CHIP_ERROR_INCORRECT_STATE);
 
     event_base_loopbreak(mEventBase);
 
@@ -133,6 +133,7 @@ CHIP_ERROR LayerImplLibevent::Shutdown()
     mEventBase   = nullptr;
     mSystemLayer = nullptr;
 
+    mLayerState.SetShutdown();
     mLayerState.Reset(); // Return to uninitialized state to permit re-initialization.
     return CHIP_NO_ERROR;
 }

src/system/SystemLayerImplLibevent.h

@@ -44,7 +44,7 @@ class LayerImplLibevent : public LayerSocketsLoop
 {
 public:
     LayerImplLibevent() : mEventBase(nullptr), mMdnsTimeoutEvent(nullptr) {}
-    ~LayerImplLibevent() { mLayerState.Destroy(); }
+    ~LayerImplLibevent() = default;
 
     // Layer overrides.
     CHIP_ERROR Init() override;

src/system/SystemLayerImplLwIP.cpp

@@ -34,19 +34,20 @@ LayerImplLwIP::LayerImplLwIP() : mHandlingTimerComplete(false), mEventDelegateLi
 
 CHIP_ERROR LayerImplLwIP::Init()
 {
-    VerifyOrReturnError(!mLayerState.IsInitialized(), CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mLayerState.SetInitializing(), CHIP_ERROR_INCORRECT_STATE);
 
     RegisterLwIPErrorFormatter();
 
     ReturnErrorOnFailure(mTimerList.Init());
 
-    VerifyOrReturnError(mLayerState.Init(), CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mLayerState.SetInitialized(), CHIP_ERROR_INCORRECT_STATE);
     return CHIP_NO_ERROR;
 }
 
 CHIP_ERROR LayerImplLwIP::Shutdown()
 {
-    VerifyOrReturnError(mLayerState.Shutdown(), CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mLayerState.SetShuttingDown(), CHIP_ERROR_INCORRECT_STATE);
+    mLayerState.SetShutdown();
     mLayerState.Reset(); // Return to uninitialized state to permit re-initialization.
     return CHIP_NO_ERROR;
 }

src/system/SystemLayerImplLwIP.h

@@ -32,7 +32,7 @@ class LayerImplLwIP : public LayerLwIP
 {
 public:
     LayerImplLwIP();
-    ~LayerImplLwIP() { mLayerState.Destroy(); }
+    ~LayerImplLwIP() = default;
 
     // Layer overrides.
     CHIP_ERROR Init() override;