Malloc in C#

This is a port of DlMalloc by Doug Lea into C#.

The original source code is here, dlmalloc.c, and the result of the port is here: DlMallocBase.cs. This base class is used to create two allocators, a memory alloctor and an array segment allocator.

Memory allocator: DlMallocMemory.cs

The memory allocator works just like malloc in C and can be used only in unsafe code. An example of how to use this allocator:

        // Create just one instance of the allocator
        static DlMallocMemory sMallocMemory = new DlMallocMemory();

        unsafe static void MemoryExample()
        {
            byte* memory = (byte*)sMallocMemory.Malloc(256);
            // Use the memory, then eventually free it
            sMallocMemory.Free(memory);
        }

Array Segment Allocator: DlMallocSegment.cs

The array segment allocator works with ArraySegment<byte> and can be used in safe code (although, the class itself is unsafe):

        // Create just one instance of the allocator
        static DlMallocSegment sMallocSegment = new DlMallocSegment();

        static void SegmentExample()
        {
            ArraySegment<byte> memory = sMallocSegment.Malloc(256);
            // Use the memory, then eventually free it
            sMallocSegment.Free(memory);
        }

Thread safety considerations

Not thread safe. If you use DLMalloc C# in a multi-threaded environment, be sure to lock all uses of Malloc and Free. Or better yet, wrap it all in a DlMallocThreadSafe class.

CPU considerations

DlMalloc C# will run on either 32 bit or 64 bit systems by detecting the pointer size at runtime.

Port Info

I stripped out a lot of unused functionality. CALL_MORECORE (a pass through to sbrk) is gone and replaced by just CALL_MMAP and CALL_MUNMAP which has become CallMoreCore and CallReleaseCore.

size_t has been left in place, but is now always 64 bits on all systems. There are many places where the C# code could be changed to use uint or ulong, but since the original code uses size_t everywhere it was easier to leave it as-is and use 64 bits everywhere.

There is still a lot that could be improved and made to look more C# like, but this is all for now.

obones / DlMalloc