ft_memalloc

42born2code school project consisting in creating a thread-safe dynamic memory allocator library.

Compile the library

Use make command to compile the library. To overload the system memory-allocator you have to set these environment variables.

if [ "$(uname)" == "Linux" ]; then
    export LD_LIBRARY_PATH=$(dirname $(readlink -f path_to_depo/libft_malloc.so))/
    export LD_PRELOAD=$(readlink -f path_to_depo/libft_malloc.so)
else
    export DYLD_LIBRARY_PATH=path_to_depo/
    export DYLD_INSERT_LIBRARIES="path_to_depo/libft_malloc.so"
    export DYLD_FORCE_FLAT_NAMESPACE=1 
fi

Library description

• This memory allocator use the First-Fit method.
• Size separate treatment. TINY < SMALL < LARGE.
• Pre-allocation is done for TINY and SMALL allocation.
• Minimal overhead.

The library includes the following functions:

void    free(void *ptr);
void    *malloc(size_t size);
void    *calloc(size_t count, size_t size);
void    *realloc(void *ptr, size_t size);
void    *reallocf(void *ptr, size_t size);
void    show_alloc_mem(void);

show_alloc_mem show the allocated memory status.

Tests

You can use the test/test.py to test the library.

$> ./test.py
#####Test malloc
Page reclaims for test0 (NO MALLOC, initial PR):     252
Page reclaims for test1 (WITH MALLOC, PR Full Load): 520
Page reclaims for test2:                             252
For test1 (minus test0 for compensation) the PR is:  268 --> Score (out of 5):
5/5
entre 255 et 272 pages, le malloc fonctionne et l'overhead est raisonnable
#####Test free
Page reclaims for test0 (NO MALLOC, initial PR):     252
Page reclaims for test2:                             252
delta PR between test2 and test0:                    0
Max 3 page reclaim more than test0. The free is working as expected !
#####Test realloc
OK
#####Test realloc++
OK
#####Test Thread-Safe
OK
#####Test errors
OK
#####Test print_alloc_mem
SMALL
10C6B4000 - 10C6B4400 : 1024 octets
LARGE
10D7D8028 - 1157D8028 : 134217728 octets
10C7D7028 - 10D7D7028 : 16777216 octets
10C6D6028 - 10C7D6028 : 1048576 octets
10C6CD028 - 10C6D5028 : 32768 octets
#####Test `ls` command
OK
#####Test `ls -l` command
OK
#####Test `ls -lR ..` command
OK
#####Test `ls -Rla ~` command
OK
#####Test `grep malloc *` command
OK