First step into a new block allocation strategy for the block_cache

(right now, it's still malloc/free, just encapsulated in an allocator class).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12662 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/cache/BlockAllocator.cpp

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2005, Axel Dörfler, [email protected]. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include "BlockAllocator.h"
+
+#include <KernelExport.h>
+#include <util/AutoLock.h>
+
+
+BlockAllocator::AllocatorList BlockAllocator::sList;
+mutex BlockAllocator::sMutex;
+
+
+BlockAllocator::BlockAllocator(size_t size)
+	:
+	fSize(size)
+{
+}
+
+
+BlockAllocator::~BlockAllocator()
+{
+}
+
+
+void *
+BlockAllocator::Get()
+{
+	return malloc(fSize);
+}
+
+
+void
+BlockAllocator::Put(void *block)
+{
+	free(block);
+}
+
+
+void
+BlockAllocator::Acquire()
+{
+	fRefCount++;
+}
+
+
+int32
+BlockAllocator::Release()
+{
+	return --fRefCount;
+}
+
+
+//	#pragma mark - static
+
+
+// static
+BlockAllocator *
+BlockAllocator::GetAllocator(size_t size)
+{
+	MutexLocker locker(&sMutex);
+
+	// search for allocator in list
+
+	AllocatorList::Iterator iterator = sList.GetIterator();
+	while (iterator.HasNext()) {
+		BlockAllocator *allocator = iterator.Next();
+
+		if (allocator->Size() == size) {
+			allocator->Acquire();
+			return allocator;
+		}
+	}
+
+	// it's not yet there, create new one
+
+	BlockAllocator *allocator = new BlockAllocator(size);
+	if (allocator == NULL)
+		return NULL;
+
+	sList.Add(allocator);
+	return allocator;
+}
+
+
+// static
+void
+BlockAllocator::PutAllocator(BlockAllocator *allocator)
+{
+	MutexLocker locker(&sMutex);
+
+	if (!allocator->Release()) {
+		sList.Remove(allocator);
+		delete allocator;
+	}
+}
+
+
+//	#pragma mark -
+
+
+extern "C" status_t
+init_block_allocator(void)
+{
+	status_t status = mutex_init(&BlockAllocator::sMutex, "block allocator");
+	if (status < B_OK)
+		return status;
+
+	new(&BlockAllocator::sList) DoublyLinkedList<BlockAllocator>;
+		// static initializers do not work in the kernel,
+		// so we have to do it here, manually
+	return B_OK;
+}
+