target audience

MonMAlloc API Reference and Implementation Guide MonMAlloc (short for Monotonic Allocator) is a high-performance memory management library designed for scenarios where memory is allocated sequentially and rarely—if ever—freed until the end of a lifecycle. By leveraging a monotonic pointer increment strategy, it eliminates the overhead of complex free-list management and fragmentation-prone “best-fit” algorithms. API Reference

The MonMAlloc API follows standard C library conventions for ease of integration as a drop-in replacement for malloc(3). Core Functions Description monmalloc voidmonmalloc(size_t size)

Allocates size bytes of memory and returns a pointer to the start of the block. monfree void monfree(void* ptr)

No-op in the core monotonic implementation; memory is reclaimed only upon pool destruction. monrealloc void* monrealloc(void* ptr, size_t size)

Resizes the memory block. If the new size is larger, it often allocates a new block and copies data. moncalloc void* moncalloc(size_t nmemb, size_t size)

Allocates memory for an array of nmemb elements and initializes it to zero. Environment Variables & Macros

MONMALLOC_SIZE: Sets the maximum size of the pre-allocated memory pool at runtime.

DEBUG: When defined during compilation, enables tracing information for every allocation call.

THREADS: Enables thread-safety using a pthread mutex to ensure consistency across concurrent calls. Implementation Guide 1. Initialization

To use MonMAlloc, you must first define the memory pool. Unlike standard malloc, which interacts with the OS via brk or mmap for every call, MonMAlloc typically partitions a large, pre-allocated chunk.

// Example: Pre-allocating a 1GB pool #define POOL_SIZE (1024 * 1024 * 1024) static char memory_pool[POOL_SIZE]; static size_t offset = 0; Use code with caution. 2. Allocation Logic

The core logic involves advancing a pointer. This makes allocation a constant-time (O(1)) operation, often costing less than a CPU cycle—similar to stack allocation.

Alignment: Ensure every returned pointer starts at a multiple of 8 or 16 bytes to prevent hardware performance penalties.

Safety: Check if the requested size exceeds the remaining pool capacity to avoid buffer overflows. 3. Integration Strategies

Dynamic Overriding: On Unix-like systems, use LD_PRELOAD=libmonmalloc.so to force existing applications to use MonMAlloc without recompiling.

Static Linking: Compile monmalloc.c directly into your project for maximum performance and to avoid shared library overhead. 4. Best Use Cases MonMAlloc is ideal for: malloc(3) – Linux manual page – man7.org