Implement API for getting memory allocation statistics

malloc_heap.go

@@ -10,3 +10,19 @@ func getChunk() []byte {
 func putChunk(chunk []byte) {
 	// No-op.
 }
+
+// GetOffHeapMemoryStats returns the memory allocation statistics from off-heap
+// memory. This function returns two numbers:
+//
+//   - The first number represents the total memory allocated from the off-heap,
+//     including both used and free memory.
+//
+//   - The second number represents the memory size which is allocated from
+//     the off-heap but currently not in use (free memory).
+//
+// Note that these statistics provide insights into the off-heap memory usage,
+// which is memory managed directly by the application and not subject to golang
+// garbage collection.
+func GetOffHeapMemoryStats() (uint64, uint64) {
+	return 0, 0
+}

malloc_mmap.go

@@ -16,6 +16,10 @@ const chunksPerAlloc = 1024
 var (
 	freeChunks     []*[chunkSize]byte
 	freeChunksLock sync.Mutex
+
+	// Statistics of memory allocated via off-heap, guarded by lock.
+	allocatedSize uint64 // The total memory size allocated from the offheap
+	freeChunkSize uint64 // The total memory size allocated but not used
 )
 
 func getChunk() []byte {
@@ -31,12 +35,15 @@ func getChunk() []byte {
 			p := (*[chunkSize]byte)(unsafe.Pointer(&data[0]))
 			freeChunks = append(freeChunks, p)
 			data = data[chunkSize:]
+			allocatedSize += chunkSize
+			freeChunkSize += chunkSize
 		}
 	}
 	n := len(freeChunks) - 1
 	p := freeChunks[n]
 	freeChunks[n] = nil
 	freeChunks = freeChunks[:n]
+	freeChunkSize -= chunkSize
 	freeChunksLock.Unlock()
 	return p[:]
 }
@@ -50,5 +57,25 @@ func putChunk(chunk []byte) {
 
 	freeChunksLock.Lock()
 	freeChunks = append(freeChunks, p)
+	freeChunkSize += chunkSize
 	freeChunksLock.Unlock()
 }
+
+// GetOffHeapMemoryStats returns the memory allocation statistics from off-heap
+// memory. This function returns two numbers:
+//
+//   - The first number represents the total memory allocated from the off-heap,
+//     including both used and free memory.
+//
+//   - The second number represents the memory size which is allocated from
+//     the off-heap but currently not in use (free memory).
+//
+// Note that these statistics provide insights into the off-heap memory usage,
+// which is memory managed directly by the application and not subject to golang
+// garbage collection.
+func GetOffHeapMemoryStats() (uint64, uint64) {
+	freeChunksLock.Lock()
+	defer freeChunksLock.Unlock()
+
+	return allocatedSize, freeChunkSize
+}