Use iteration pattern to get the fixed user label list (#16861)

* Use iteration pattern to get the fixed user label list

* Remove the unnecessary check condition

src/app/clusters/fixed-label-server/fixed-label-server.cpp

@@ -28,6 +28,7 @@
 #include <app/util/attribute-storage.h>
 #include <lib/support/CodeUtils.h>
 #include <lib/support/logging/CHIPLogging.h>
+#include <platform/DeviceInfoProvider.h>
 #include <platform/PlatformManager.h>
 
 using namespace chip;
@@ -53,18 +54,23 @@ class FixedLabelAttrAccess : public AttributeAccessInterface
 CHIP_ERROR FixedLabelAttrAccess::ReadLabelList(EndpointId endpoint, AttributeValueEncoder & aEncoder)
 {
     CHIP_ERROR err = CHIP_NO_ERROR;
-    DeviceLayer::AttributeList<app::Clusters::FixedLabel::Structs::LabelStruct::Type, DeviceLayer::kMaxFixedLabels> labelList;
 
-    if (DeviceLayer::PlatformMgr().GetFixedLabelList(endpoint, labelList) == CHIP_NO_ERROR)
+    DeviceLayer::DeviceInfoProvider::FixedLabelIterator * it = DeviceLayer::GetDeviceInfoProvider()->IterateFixedLabel(endpoint);
+
+    if (it)
     {
-        err = aEncoder.EncodeList([&labelList](const auto & encoder) -> CHIP_ERROR {
-            for (auto label : labelList)
+        err = aEncoder.EncodeList([&it](const auto & encoder) -> CHIP_ERROR {
+            FixedLabel::Structs::LabelStruct::Type fixedlabel;
+
+            while (it->Next(fixedlabel))
             {
-                ReturnErrorOnFailure(encoder.Encode(label));
+                ReturnErrorOnFailure(encoder.Encode(fixedlabel));
             }
 
             return CHIP_NO_ERROR;
         });
+
+        it->Release();
     }
     else
     {

src/app/clusters/user-label-server/user-label-server.cpp

@@ -28,6 +28,7 @@
 #include <app/util/attribute-storage.h>
 #include <lib/support/CodeUtils.h>
 #include <lib/support/logging/CHIPLogging.h>
+#include <platform/DeviceInfoProvider.h>
 #include <platform/PlatformManager.h>
 
 using namespace chip;

src/include/platform/DeviceInfoProvider.h

@@ -0,0 +1,109 @@
+/*
+ *
+ *    Copyright (c) 2022 Project CHIP Authors
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+#pragma once
+
+#include <algorithm>
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <app-common/zap-generated/cluster-objects.h>
+#include <app/util/basic-types.h>
+#include <lib/core/CHIPError.h>
+#include <platform/AttributeList.h>
+
+namespace chip {
+namespace DeviceLayer {
+
+static constexpr size_t kMaxLabelNameLength  = 16;
+static constexpr size_t kMaxLabelValueLength = 16;
+
+class DeviceInfoProvider
+{
+public:
+    /**
+     * Template used to iterate the stored group data
+     */
+    template <typename T>
+    class Iterator
+    {
+    public:
+        virtual ~Iterator() = default;
+        /**
+         *  @retval The number of entries in total that will be iterated.
+         */
+        virtual size_t Count() = 0;
+        /**
+         *  @param[out] item  Value associated with the next element in the iteration.
+         *  @retval true if the next entry is successfully retrieved.
+         *  @retval false if no more entries can be found.
+         */
+        virtual bool Next(T & item) = 0;
+        /**
+         * Release the memory allocated by this iterator.
+         * Must be called before the pointer goes out of scope.
+         */
+        virtual void Release() = 0;
+
+    protected:
+        Iterator() = default;
+    };
+
+    using FixedLabelType = app::Clusters::FixedLabel::Structs::LabelStruct::Type;
+
+    using FixedLabelIterator = Iterator<FixedLabelType>;
+
+    DeviceInfoProvider() = default;
+
+    virtual ~DeviceInfoProvider() = default;
+
+    // Not copyable
+    DeviceInfoProvider(const DeviceInfoProvider &) = delete;
+    DeviceInfoProvider & operator=(const DeviceInfoProvider &) = delete;
+
+    // Iterators
+    /**
+     *  Creates an iterator that may be used to obtain the list of user labels associated with the given endpoint.
+     *  In order to release the allocated memory, the Release() method must be called after the iteration is finished.
+     *  Modifying the user label during the iteration is currently not supported, and may yield unexpected behaviour.
+     *  @retval An instance of EndpointIterator on success
+     *  @retval nullptr if no iterator instances are available.
+     */
+    virtual FixedLabelIterator * IterateFixedLabel(EndpointId endpoint) = 0;
+};
+
+/**
+ * Instance getter for the global DeviceInfoProvider.
+ *
+ * Callers have to externally synchronize usage of this function.
+ *
+ * @return The global Device Info Provider. Assume never null.
+ */
+DeviceInfoProvider * GetDeviceInfoProvider();
+
+/**
+ * Instance setter for the global DeviceInfoProvider.
+ *
+ * Callers have to externally synchronize usage of this function.
+ *
+ * If the `provider` is nullptr, no change is done.
+ *
+ * @param[in] provider the Device Info Provider
+ */
+void SetDeviceInfoProvider(DeviceInfoProvider * provider);
+
+} // namespace DeviceLayer
+} // namespace chip

src/include/platform/PlatformManager.h

@@ -37,7 +37,6 @@ class DiscoveryImplPlatform;
 
 namespace DeviceLayer {
 
-static constexpr size_t kMaxFixedLabels   = 10;
 static constexpr size_t kMaxUserLabels    = 10;
 static constexpr size_t kMaxLanguageTags  = 254; // Maximum number of entry type 'ARRAY' supports
 static constexpr size_t kMaxCalendarTypes = 12;
@@ -195,8 +194,6 @@ class PlatformManager
     bool IsChipStackLockedByCurrentThread() const;
 #endif
 
-    CHIP_ERROR GetFixedLabelList(EndpointId endpoint,
-                                 AttributeList<app::Clusters::FixedLabel::Structs::LabelStruct::Type, kMaxFixedLabels> & labelList);
     CHIP_ERROR SetUserLabelList(EndpointId endpoint,
                                 AttributeList<app::Clusters::UserLabel::Structs::LabelStruct::Type, kMaxUserLabels> & labelList);
     CHIP_ERROR GetUserLabelList(EndpointId endpoint,
@@ -456,13 +453,6 @@ inline CHIP_ERROR PlatformManager::StartChipTimer(System::Clock::Timeout duratio
 {
     return static_cast<ImplClass *>(this)->_StartChipTimer(duration);
 }
-
-inline CHIP_ERROR PlatformManager::GetFixedLabelList(
-    EndpointId endpoint, AttributeList<app::Clusters::FixedLabel::Structs::LabelStruct::Type, kMaxFixedLabels> & labelList)
-{
-    return static_cast<ImplClass *>(this)->_GetFixedLabelList(endpoint, labelList);
-}
-
 inline CHIP_ERROR
 PlatformManager::SetUserLabelList(EndpointId endpoint,
                                   AttributeList<app::Clusters::UserLabel::Structs::LabelStruct::Type, kMaxUserLabels> & labelList)

src/include/platform/internal/GenericPlatformManagerImpl.h

@@ -60,9 +60,6 @@ class GenericPlatformManagerImpl
     void _ScheduleWork(AsyncWorkFunct workFunct, intptr_t arg);
     void _DispatchEvent(const ChipDeviceEvent * event);
 
-    CHIP_ERROR
-    _GetFixedLabelList(EndpointId endpoint,
-                       AttributeList<app::Clusters::FixedLabel::Structs::LabelStruct::Type, kMaxFixedLabels> & labelList);
     CHIP_ERROR _SetUserLabelList(EndpointId endpoint,
                                  AttributeList<app::Clusters::UserLabel::Structs::LabelStruct::Type, kMaxUserLabels> & labelList);
     CHIP_ERROR _GetUserLabelList(EndpointId endpoint,
@@ -86,13 +83,6 @@ class GenericPlatformManagerImpl
 // Instruct the compiler to instantiate the template only when explicitly told to do so.
 extern template class GenericPlatformManagerImpl<PlatformManagerImpl>;
 
-template <class ImplClass>
-inline CHIP_ERROR GenericPlatformManagerImpl<ImplClass>::_GetFixedLabelList(
-    EndpointId endpoint, AttributeList<app::Clusters::FixedLabel::Structs::LabelStruct::Type, kMaxFixedLabels> & labelList)
-{
-    return CHIP_ERROR_UNSUPPORTED_CHIP_FEATURE;
-}
-
 template <class ImplClass>
 inline CHIP_ERROR GenericPlatformManagerImpl<ImplClass>::_SetUserLabelList(
     EndpointId endpoint, AttributeList<app::Clusters::UserLabel::Structs::LabelStruct::Type, kMaxUserLabels> & labelList)

src/platform/BUILD.gn

@@ -321,6 +321,7 @@ if (chip_device_platform != "none") {
       "../include/platform/internal/testing/ConfigUnitTest.h",
       "CommissionableDataProvider.cpp",
       "DeviceControlServer.cpp",
+      "DeviceInfoProvider.cpp",
       "DiagnosticDataProvider.cpp",
       "Entropy.cpp",
       "FailSafeContext.cpp",

src/platform/DeviceInfoProvider.cpp

@@ -0,0 +1,68 @@
+/*
+ *
+ *    Copyright (c) 2022 Project CHIP Authors
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+/**
+ *    @file
+ *          Provides implementations for the DeviceInfoProvider APIs.
+ *          This implementation is common across all platforms.
+ */
+
+#include <lib/support/CodeUtils.h>
+#include <platform/DeviceInfoProvider.h>
+
+namespace chip {
+namespace DeviceLayer {
+
+class DeviceInfoProvider;
+
+namespace {
+
+DeviceInfoProvider * gDeviceInfoProvider = nullptr;
+
+} // namespace
+
+/**
+ * Instance getter for the global DeviceInfoProvider.
+ *
+ * Callers have to externally synchronize usage of this function.
+ *
+ * @return The global Device Info provider. Assume never null.
+ */
+DeviceInfoProvider * GetDeviceInfoProvider()
+{
+    return gDeviceInfoProvider;
+}
+
+/**
+ * Instance setter for the global DeviceInfoProvider.
+ *
+ * Callers have to externally synchronize usage of this function.
+ *
+ * If the `provider` is nullptr, no change is done.
+ *
+ * @param[in] provider the global Device Info Provider.
+ */
+void SetDeviceInfoProvider(DeviceInfoProvider * provider)
+{
+    if (provider)
+    {
+        gDeviceInfoProvider = provider;
+    }
+}
+
+} // namespace DeviceLayer
+} // namespace chip

src/platform/Linux/BUILD.gn

@@ -53,6 +53,8 @@ static_library("Linux") {
     "ConnectivityManagerImpl.h",
     "ConnectivityUtils.cpp",
     "ConnectivityUtils.h",
+    "DeviceInfoProviderImpl.cpp",
+    "DeviceInfoProviderImpl.h",
     "DeviceNetworkProvisioningDelegateImpl.cpp",
     "DeviceNetworkProvisioningDelegateImpl.h",
     "DiagnosticDataProviderImpl.cpp",