From 3bef7d02527eb6eea0fe408499978cc9fc52117b Mon Sep 17 00:00:00 2001
From: Ingo Weinhold <ingo_weinhold@gmx.de>
Date: Sat, 29 Mar 2008 23:55:34 +0000
Subject: [PATCH] Added functions malloc_referenced[_{acquire,release}]() that
 implement reference counted memory allocations. Can be used for sharing
 immutable structures.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24666 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 headers/private/kernel/heap.h |  4 ++++
 src/system/kernel/heap.cpp    | 37 +++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/headers/private/kernel/heap.h b/headers/private/kernel/heap.h
index 0f60cf4d14..329fc650e1 100644
--- a/headers/private/kernel/heap.h
+++ b/headers/private/kernel/heap.h
@@ -26,6 +26,10 @@ void *memalign(size_t alignment, size_t size);
 
 void deferred_free(void* block);
 
+void* malloc_referenced(size_t size);
+void* malloc_referenced_acquire(void* data);
+void malloc_referenced_release(void* data);
+
 status_t heap_init(addr_t heapBase, size_t heapSize);
 status_t heap_init_post_sem();
 status_t heap_init_post_thread();
diff --git a/src/system/kernel/heap.cpp b/src/system/kernel/heap.cpp
index f90e24aefe..4201d7ad6b 100644
--- a/src/system/kernel/heap.cpp
+++ b/src/system/kernel/heap.cpp
@@ -1273,3 +1273,40 @@ deferred_free(void* block)
 	InterruptsSpinLocker _(sDeferredFreeListLock);
 	sDeferredFreeList.Add(entry);
 }
+
+
+void*
+malloc_referenced(size_t size)
+{
+	int32* referencedData = (int32*)malloc(size + 4);
+	if (referencedData == NULL)
+		return NULL;
+
+	*referencedData = 1;
+
+	return referencedData + 1;
+}
+
+
+void*
+malloc_referenced_acquire(void* data)
+{
+	if (data != NULL) {
+		int32* referencedData = (int32*)data - 1;
+		atomic_add(referencedData, 1);
+	}
+
+	return data;
+}
+
+
+void
+malloc_referenced_release(void* data)
+{
+	if (data == NULL)
+		return;
+
+	int32* referencedData = (int32*)data - 1;
+	if (atomic_add(referencedData, -1) < 1)
+		free(referencedData);
+}