[Zephyr] Expose heap usage statistics (#10058)

Implement methods used by Software Diagnostics Cluster
for Zephyr-based platforms.

src/platform/Zephyr/PlatformManagerImpl.cpp

@@ -27,12 +27,12 @@
 
 #include <platform/internal/CHIPDeviceLayerInternal.h>
 
+#include <lib/support/logging/CHIPLogging.h>
 #include <platform/PlatformManager.h>
 #include <platform/internal/GenericPlatformManagerImpl_Zephyr.cpp>
 
 #include <drivers/entropy.h>
-
-#include <lib/support/logging/CHIPLogging.h>
+#include <malloc.h>
 
 namespace chip {
 namespace DeviceLayer {
@@ -87,5 +87,41 @@ CHIP_ERROR PlatformManagerImpl::_InitChipStack(void)
     return err;
 }
 
+CHIP_ERROR PlatformManagerImpl::_GetCurrentHeapFree(uint64_t & currentHeapFree)
+{
+#ifdef CONFIG_NEWLIB_LIBC
+    // This will return the amount of memory which has been allocated from the system, but is not
+    // used right now. Ideally, this value should be increased by the amount of memory which can
+    // be allocated from the system, but Zephyr does not expose that number.
+    currentHeapFree = mallinfo().fordblks;
+    return CHIP_NO_ERROR;
+#else
+    return CHIP_ERROR_UNSUPPORTED_CHIP_FEATURE;
+#endif
+}
+
+CHIP_ERROR PlatformManagerImpl::_GetCurrentHeapUsed(uint64_t & currentHeapUsed)
+{
+#ifdef CONFIG_NEWLIB_LIBC
+    currentHeapUsed = mallinfo().uordblks;
+    return CHIP_NO_ERROR;
+#else
+    return CHIP_ERROR_UNSUPPORTED_CHIP_FEATURE;
+#endif
+}
+
+CHIP_ERROR PlatformManagerImpl::_GetCurrentHeapHighWatermark(uint64_t & currentHeapHighWatermark)
+{
+#ifdef CONFIG_NEWLIB_LIBC
+    // ARM newlib does not provide a way to obtain the peak heap usage, so for now just return
+    // the amount of memory allocated from the system which should be an upper bound of the peak
+    // usage provided that the heap is not very fragmented.
+    currentHeapHighWatermark = mallinfo().arena;
+    return CHIP_NO_ERROR;
+#else
+    return CHIP_ERROR_UNSUPPORTED_CHIP_FEATURE;
+#endif
+}
+
 } // namespace DeviceLayer
 } // namespace chip

src/platform/Zephyr/PlatformManagerImpl.h

@@ -52,6 +52,9 @@ class PlatformManagerImpl final : public PlatformManager, public Internal::Gener
     // ===== Methods that implement the PlatformManager abstract interface.
 
     CHIP_ERROR _InitChipStack(void);
+    CHIP_ERROR _GetCurrentHeapFree(uint64_t & currentHeapFree);
+    CHIP_ERROR _GetCurrentHeapUsed(uint64_t & currentHeapUsed);
+    CHIP_ERROR _GetCurrentHeapHighWatermark(uint64_t & currentHeapHighWatermark);
 
     // ===== Members for internal use by the following friends.