Introduce a way to loop over endpoints that have a given server clust…

…er. (#12542)

We have several places that are doing this, all of them in
not-so-great ways (e.g. mapping indices to endpoint ids and then back
to indices, which is O(N^2) in number of endpoints).  Better to have a
utility that does it right.

src/app/clusters/general_diagnostics_server/general_diagnostics_server.cpp

@@ -170,49 +170,31 @@ CHIP_ERROR GeneralDiagosticsAttrAccess::Read(const ConcreteReadAttributePath & a
 
 class GeneralDiagnosticsDelegate : public DeviceLayer::ConnectivityManagerDelegate, public DeviceLayer::GeneralDiagnosticsDelegate
 {
+    static void ReportAttributeOnAllEndpoints(AttributeId attribute)
+    {
+        ForAllEndpointsWithServerCluster(
+            GeneralDiagnostics::Id,
+            [](EndpointId endpoint, intptr_t context) -> Loop {
+                MatterReportingAttributeChangeCallback(endpoint, GeneralDiagnostics::Id, static_cast<AttributeId>(context));
+                return Loop::Continue;
+            },
+            attribute);
+    }
 
     // Gets called when any network interface on the Node is updated.
     void OnNetworkInfoChanged() override
     {
         ChipLogProgress(Zcl, "GeneralDiagnosticsDelegate: OnNetworkInfoChanged");
 
-        for (uint16_t index = 0; index < emberAfEndpointCount(); index++)
-        {
-            if (emberAfEndpointIndexIsEnabled(index))
-            {
-                EndpointId endpointId = emberAfEndpointFromIndex(index);
-
-                if (emberAfContainsServer(endpointId, GeneralDiagnostics::Id))
-                {
-                    // If General Diagnostics cluster is implemented on this endpoint
-                    MatterReportingAttributeChangeCallback(endpointId, GeneralDiagnostics::Id,
-                                                           GeneralDiagnostics::Attributes::NetworkInterfaces::Id);
-                }
-            }
-        }
+        ReportAttributeOnAllEndpoints(GeneralDiagnostics::Attributes::NetworkInterfaces::Id);
     }
 
     // Gets called when the device has been rebooted.
     void OnDeviceRebooted() override
     {
         ChipLogProgress(Zcl, "GeneralDiagnosticsDelegate: OnDeviceRebooted");
 
-        for (uint16_t index = 0; index < emberAfEndpointCount(); index++)
-        {
-            if (emberAfEndpointIndexIsEnabled(index))
-            {
-                EndpointId endpointId = emberAfEndpointFromIndex(index);
-
-                if (emberAfContainsServer(endpointId, GeneralDiagnostics::Id))
-                {
-                    // If General Diagnostics cluster is implemented on this endpoint
-                    MatterReportingAttributeChangeCallback(endpointId, GeneralDiagnostics::Id,
-                                                           GeneralDiagnostics::Attributes::RebootCount::Id);
-                    MatterReportingAttributeChangeCallback(endpointId, GeneralDiagnostics::Id,
-                                                           GeneralDiagnostics::Attributes::BootReasons::Id);
-                }
-            }
-        }
+        ReportAttributeOnAllEndpoints(GeneralDiagnostics::Attributes::BootReasons::Id);
     }
 
     // Get called when the Node detects a hardware fault has been raised.
@@ -221,62 +203,23 @@ class GeneralDiagnosticsDelegate : public DeviceLayer::ConnectivityManagerDelega
     {
         ChipLogProgress(Zcl, "GeneralDiagnosticsDelegate: OnHardwareFaultsDetected");
 
-        for (uint16_t index = 0; index < emberAfEndpointCount(); index++)
-        {
-            if (emberAfEndpointIndexIsEnabled(index))
-            {
-                EndpointId endpointId = emberAfEndpointFromIndex(index);
-
-                if (emberAfContainsServer(endpointId, GeneralDiagnostics::Id))
-                {
-                    // If General Diagnostics cluster is implemented on this endpoint
-                    MatterReportingAttributeChangeCallback(endpointId, GeneralDiagnostics::Id,
-                                                           GeneralDiagnostics::Attributes::ActiveHardwareFaults::Id);
-                }
-            }
-        }
+        ReportAttributeOnAllEndpoints(GeneralDiagnostics::Attributes::ActiveHardwareFaults::Id);
     }
 
     // Get called when the Node detects a radio fault has been raised.
     void OnRadioFaultsDetected(GeneralFaults<kMaxRadioFaults> & previous, GeneralFaults<kMaxRadioFaults> & current) override
     {
         ChipLogProgress(Zcl, "GeneralDiagnosticsDelegate: OnHardwareFaultsDetected");
 
-        for (uint16_t index = 0; index < emberAfEndpointCount(); index++)
-        {
-            if (emberAfEndpointIndexIsEnabled(index))
-            {
-                EndpointId endpointId = emberAfEndpointFromIndex(index);
-
-                if (emberAfContainsServer(endpointId, GeneralDiagnostics::Id))
-                {
-                    // If General Diagnostics cluster is implemented on this endpoint
-                    MatterReportingAttributeChangeCallback(endpointId, GeneralDiagnostics::Id,
-                                                           GeneralDiagnostics::Attributes::ActiveRadioFaults::Id);
-                }
-            }
-        }
+        ReportAttributeOnAllEndpoints(GeneralDiagnostics::Attributes::ActiveRadioFaults::Id);
     }
 
     // Get called when the Node detects a network fault has been raised.
     void OnNetworkFaultsDetected(GeneralFaults<kMaxNetworkFaults> & previous, GeneralFaults<kMaxNetworkFaults> & current) override
     {
         ChipLogProgress(Zcl, "GeneralDiagnosticsDelegate: OnHardwareFaultsDetected");
 
-        for (uint16_t index = 0; index < emberAfEndpointCount(); index++)
-        {
-            if (emberAfEndpointIndexIsEnabled(index))
-            {
-                EndpointId endpointId = emberAfEndpointFromIndex(index);
-
-                if (emberAfContainsServer(endpointId, GeneralDiagnostics::Id))
-                {
-                    // If General Diagnostics cluster is implemented on this endpoint
-                    MatterReportingAttributeChangeCallback(endpointId, GeneralDiagnostics::Id,
-                                                           GeneralDiagnostics::Attributes::ActiveNetworkFaults::Id);
-                }
-            }
-        }
+        ReportAttributeOnAllEndpoints(GeneralDiagnostics::Attributes::ActiveNetworkFaults::Id);
     }
 };
 

src/app/clusters/software_diagnostics_server/software_diagnostics_server.cpp

@@ -131,19 +131,10 @@ class SoftwareDiagnosticsDelegate : public DeviceLayer::SoftwareDiagnosticsDeleg
     {
         ChipLogProgress(Zcl, "SoftwareDiagnosticsDelegate: OnSoftwareFaultDetected");
 
-        for (uint16_t index = 0; index < emberAfEndpointCount(); index++)
-        {
-            if (emberAfEndpointIndexIsEnabled(index))
-            {
-                EndpointId endpointId = emberAfEndpointFromIndex(index);
-
-                if (emberAfContainsServer(endpointId, SoftwareDiagnostics::Id))
-                {
-                    // If Software Diagnostics cluster is implemented on this endpoint
-                    // TODO: Log SoftwareFault event
-                }
-            }
-        }
+        ForAllEndpointsWithServerCluster(GeneralDiagnostics::Id, [](EndpointId endpoint, intptr_t) -> Loop {
+            // TODO: Log SoftwareFault event and walk them all.
+            return Loop::Break;
+        });
     }
 };
 

src/app/util/af.h

@@ -72,6 +72,7 @@
 #include <app/util/debug-printing.h>
 #include <app/util/ember-print.h>
 
+#include <lib/support/Iterators.h>
 #include <lib/support/SafeInt.h>
 
 /** @name Attribute Storage */
@@ -158,6 +159,24 @@ bool emberAfContainsServer(chip::EndpointId endpoint, chip::ClusterId clusterId)
  */
 bool emberAfContainsServerFromIndex(uint16_t index, chip::ClusterId clusterId);
 
+namespace chip {
+namespace app {
+
+using EndpointCallback = Loop (*)(EndpointId endpoint, intptr_t context);
+
+/**
+ * @brief calls user-supplied function for every endpoint that has the given
+ * server cluster, until either the function returns Loop::Break or we run out
+ * of endpoints.
+ *
+ * Returns Loop::Break if the callee did, or Loop::Finished if we ran out of
+ * endpoints.
+ */
+Loop ForAllEndpointsWithServerCluster(ClusterId clusterId, EndpointCallback callback, intptr_t context = 0);
+
+} // namespace app
+} // namespace chip
+
 /**
  * @brief Returns true if endpoint contains cluster client.
  *

src/app/util/attribute-storage.cpp

@@ -836,6 +836,36 @@ bool emberAfContainsServerFromIndex(uint16_t index, ClusterId clusterId)
     }
 }
 
+namespace chip {
+namespace app {
+
+Loop ForAllEndpointsWithServerCluster(ClusterId clusterId, EndpointCallback callback, intptr_t context)
+{
+    uint16_t count = emberAfEndpointCount();
+    for (uint16_t index = 0; index < count; ++index)
+    {
+        if (!emberAfEndpointIndexIsEnabled(index))
+        {
+            continue;
+        }
+
+        if (!emberAfContainsServerFromIndex(index, clusterId))
+        {
+            continue;
+        }
+
+        if (callback(emberAfEndpointFromIndex(index), context) == Loop::Break)
+        {
+            return Loop::Break;
+        }
+    }
+
+    return Loop::Finish;
+}
+
+} // namespace app
+} // namespace chip
+
 // Finds the cluster that matches endpoint, clusterId, direction, and manufacturerCode.
 EmberAfCluster * emberAfFindClusterWithMfgCode(EndpointId endpoint, ClusterId clusterId, EmberAfClusterMask mask,
                                                uint16_t manufacturerCode)

src/lib/support/BUILD.gn

@@ -78,6 +78,7 @@ static_library("support") {
     "FibonacciUtils.h",
     "FixedBufferAllocator.cpp",
     "FixedBufferAllocator.h",
+    "Iterators.h",
     "LifetimePersistedCounter.cpp",
     "LifetimePersistedCounter.h",
     "ObjectLifeCycle.h",

src/lib/support/Iterators.h

@@ -0,0 +1,43 @@
+/*
+ *    Copyright (c) 2021 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    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 <cstdint>
+
+namespace chip {
+
+/**
+ * Enum used to control iteration (e.g. via a callback function that is called
+ * for each of a set of elements).
+ *
+ * When used as the callback return type:
+ *   Continue: Continue the iteration.
+ *   Break: Stop the iteration.
+ *
+ * When used as the return type of the entire iteration procedure:
+ *   Break: Some callback returned Break.
+ *   Finish: All callbacks returned Continue.
+ */
+enum class Loop : uint8_t
+{
+    Continue,
+    Break,
+    Finish,
+};
+
+} // namespace chip

src/lib/support/Pool.h

@@ -24,6 +24,8 @@
 
 #include <system/SystemConfig.h>
 
+#include <lib/support/Iterators.h>
+
 #include <atomic>
 #include <limits>
 #include <new>
@@ -32,13 +34,6 @@
 
 namespace chip {
 
-enum class Loop : uint8_t
-{
-    Continue,
-    Break,
-    Finish,
-};
-
 namespace internal {
 
 class Statistics