Function dlmallinfo 

pub unsafe extern "C" fn dlmallinfo() -> MallInfo

mallinfo()

Returns (by copy) a struct containing various summary statistics:

• arena: current total non-mmapped bytes allocated from system
• ordblks: the number of free chunks
• smblks: always zero.
• hblks: current number of mmapped regions
• hblkhd: total bytes held in mmapped regions
• usmblks: the maximum total allocated space. This will be greater than current total if trimming has occurred.
• fsmblks: always zero
• uordblks: current total allocated space (normal or mmapped)
• fordblks: total free space
• keepcost: the maximum number of bytes that could ideally be released back to system via malloc_trim. (“ideally” means that it ignores page restrictions etc.)

Because these fields are ints, but internal bookkeeping may be kept as longs, the reported values may wrap around zero and thus be inaccurate.