/* Default header file for malloc-2.8.x, written by Doug Lea and released to the public domain, as explained at http://creativecommons.org/publicdomain/zero/1.0/ */ #ifndef MALLOC_280_H #define MALLOC_280_H #ifdef __cplusplus extern "C" { #endif #include /* for size_t */ #ifndef HAVE_USR_INCLUDE_MALLOC_H #ifndef _MALLOC_H #ifndef MALLINFO_FIELD_TYPE #define MALLINFO_FIELD_TYPE size_t #endif /* MALLINFO_FIELD_TYPE */ #ifndef STRUCT_MALLINFO_DECLARED #define STRUCT_MALLINFO_DECLARED 1 struct mallinfo { MALLINFO_FIELD_TYPE arena; /* non-mmapped space allocated from system */ MALLINFO_FIELD_TYPE ordblks; /* number of free chunks */ MALLINFO_FIELD_TYPE smblks; /* always 0 */ MALLINFO_FIELD_TYPE hblks; /* always 0 */ MALLINFO_FIELD_TYPE hblkhd; /* space in mmapped regions */ MALLINFO_FIELD_TYPE usmblks; /* maximum total allocated space */ MALLINFO_FIELD_TYPE fsmblks; /* always 0 */ MALLINFO_FIELD_TYPE uordblks; /* total allocated space */ MALLINFO_FIELD_TYPE fordblks; /* total free space */ MALLINFO_FIELD_TYPE keepcost; /* releasable (via malloc_trim) space */ }; #endif /* STRUCT_MALLINFO_DECLARED */ #endif /* _MALLOC_H */ #endif /* HAVE_USR_INCLUDE_MALLOC_H */ /* malloc(size_t n) Returns a pointer to a newly allocated chunk of at least n bytes, or null if no space is available, in which case errno is set to ENOMEM on ANSI C systems. If n is zero, malloc returns a minimum-sized chunk. (The minimum size is 16 bytes on most 32bit systems, and 32 bytes on 64bit systems.) Note that size_t is an unsigned type, so calls with arguments that would be negative if signed are interpreted as requests for huge amounts of space, which will often fail. The maximum supported value of n differs across systems, but is in all cases less than the maximum representable value of a size_t. */ void* dlmalloc(size_t); /* free(void* p) Releases the chunk of memory pointed to by p, that had been previously allocated using malloc or a related routine such as realloc. It has no effect if p is null. If p was not malloced or already freed, free(p) will by default cuase the current program to abort. */ void dlfree(void*); /* calloc(size_t n_elements, size_t element_size); Returns a pointer to n_elements * element_size bytes, with all locations set to zero. */ void* dlcalloc(size_t, size_t); /* realloc(void* p, size_t n) Returns a pointer to a chunk of size n that contains the same data as does chunk p up to the minimum of (n, p's size) bytes, or null if no space is available. The returned pointer may or may not be the same as p. The algorithm prefers extending p in most cases when possible, otherwise it employs the equivalent of a malloc-copy-free sequence. If p is null, realloc is equivalent to malloc. If space is not available, realloc returns null, errno is set (if on ANSI) and p is NOT freed. if n is for fewer bytes than already held by p, the newly unused space is lopped off and freed if possible. realloc with a size argument of zero (re)allocates a minimum-sized chunk. The old unix realloc convention of allowing the last-free'd chunk to be used as an argument to realloc is not supported. */ void* dlrealloc(void*, size_t); /* realloc_in_place(void* p, size_t n) Resizes the space allocated for p to size n, only if this can be done without moving p (i.e., only if there is adjacent space available if n is greater than p's current allocated size, or n is less than or equal to p's size). This may be used instead of plain realloc if an alternative allocation strategy is needed upon failure to expand space; for example, reallocation of a buffer that must be memory-aligned or cleared. You can use realloc_in_place to trigger these alternatives only when needed. Returns p if successful; otherwise null. */ void* dlrealloc_in_place(void*, size_t); /* memalign(size_t alignment, size_t n); Returns a pointer to a newly allocated chunk of n bytes, aligned in accord with the alignment argument. The alignment argument should be a power of two. If the argument is not a power of two, the nearest greater power is used. 8-byte alignment is guaranteed by normal malloc calls, so don't bother calling memalign with an argument of 8 or less. Overreliance on memalign is a sure way to fragment space. */ void* dlmemalign(size_t, size_t); /* int posix_memalign(void** pp, size_t alignment, size_t n); Allocates a chunk of n bytes, aligned in accord with the alignment argument. Differs from memalign only in that it (1) assigns the allocated memory to *pp rather than returning it, (2) fails and returns EINVAL if the alignment is not a power of two (3) fails and returns ENOMEM if memory cannot be allocated. */ int dlposix_memalign(void**, size_t, size_t); /* valloc(size_t n); Equivalent to memalign(pagesize, n), where pagesize is the page size of the system. If the pagesize is unknown, 4096 is used. */ void* dlvalloc(size_t); /* mallopt(int parameter_number, int parameter_value) Sets tunable parameters The format is to provide a (parameter-number, parameter-value) pair. mallopt then sets the corresponding parameter to the argument value if it can (i.e., so long as the value is meaningful), and returns 1 if successful else 0. SVID/XPG/ANSI defines four standard param numbers for mallopt, normally defined in malloc.h. None of these are use in this malloc, so setting them has no effect. But this malloc also supports other options in mallopt: Symbol param # default allowed param values M_TRIM_THRESHOLD -1 2*1024*1024 any (-1U disables trimming) M_GRANULARITY -2 page size any power of 2 >= page size M_MMAP_THRESHOLD -3 256*1024 any (or 0 if no MMAP support) */ int dlmallopt(int, int); #define M_TRIM_THRESHOLD (-1) #define M_GRANULARITY (-2) #define M_MMAP_THRESHOLD (-3) /* malloc_footprint(); Returns the number of bytes obtained from the system. The total number of bytes allocated by malloc, realloc etc., is less than this value. Unlike mallinfo, this function returns only a precomputed result, so can be called frequently to monitor memory consumption. Even if locks are otherwise defined, this function does not use them, so results might not be up to date. */ size_t dlmalloc_footprint(void); /* malloc_max_footprint(); Returns the maximum number of bytes obtained from the system. This value will be greater than current footprint if deallocated space has been reclaimed by the system. The peak number of bytes allocated by malloc, realloc etc., is less than this value. Unlike mallinfo, this function returns only a precomputed result, so can be called frequently to monitor memory consumption. Even if locks are otherwise defined, this function does not use them, so results might not be up to date. */ size_t dlmalloc_max_footprint(void); /* malloc_footprint_limit(); Returns the number of bytes that the heap is allowed to obtain from the system, returning the last value returned by malloc_set_footprint_limit, or the maximum size_t value if never set. The returned value reflects a permission. There is no guarantee that this number of bytes can actually be obtained from the system. */ size_t dlmalloc_footprint_limit(void); /* malloc_set_footprint_limit(); Sets the maximum number of bytes to obtain from the system, causing failure returns from malloc and related functions upon attempts to exceed this value. The argument value may be subject to page rounding to an enforceable limit; this actual value is returned. Using an argument of the maximum possible size_t effectively disables checks. If the argument is less than or equal to the current malloc_footprint, then all future allocations that require additional system memory will fail. However, invocation cannot retroactively deallocate existing used memory. */ size_t dlmalloc_set_footprint_limit(size_t bytes); /* malloc_inspect_all(void(*handler)(void *start, void *end, size_t used_bytes, void* callback_arg), void* arg); Traverses the heap and calls the given handler for each managed region, skipping all bytes that are (or may be) used for bookkeeping purposes. Traversal does not include include chunks that have been directly memory mapped. Each reported region begins at the start address, and continues up to but not including the end address. The first used_bytes of the region contain allocated data. If used_bytes is zero, the region is unallocated. The handler is invoked with the given callback argument. If locks are defined, they are held during the entire traversal. It is a bad idea to invoke other malloc functions from within the handler. For example, to count the number of in-use chunks with size greater than 1000, you could write: static int count = 0; void count_chunks(void* start, void* end, size_t used, void* arg) { if (used >= 1000) ++count; } then: malloc_inspect_all(count_chunks, NULL); malloc_inspect_all is compiled only if MALLOC_INSPECT_ALL is defined. */ void dlmalloc_inspect_all(void(*handler)(void*, void *, size_t, void*), void* arg); /* independent_calloc(size_t n_elements, size_t element_size, void* chunks[]); independent_calloc is similar to calloc, but instead of returning a single cleared space, it returns an array of pointers to n_elements independent elements that can hold contents of size elem_size, each of which starts out cleared, and can be independently freed, realloc'ed etc. The elements are guaranteed to be adjacently allocated (this is not guaranteed to occur with multiple callocs or mallocs), which may also improve cache locality in some applications. The "chunks" argument is optional (i.e., may be null, which is probably the most typical usage). If it is null, the returned array is itself dynamically allocated and should also be freed when it is no longer needed. Otherwise, the chunks array must be of at least n_elements in length. It is filled in with the pointers to the chunks. In either case, independent_calloc returns this pointer array, or null if the allocation failed. If n_elements is zero and "chunks" is null, it returns a chunk representing an array with zero elements (which should be freed if not wanted). Each element must be freed when it is no longer needed. This can be done all at once using bulk_free. independent_calloc simplifies and speeds up implementations of many kinds of pools. It may also be useful when constructing large data structures that initially have a fixed number of fixed-sized nodes, but the number is not known at compile time, and some of the nodes may later need to be freed. For example: struct Node { int item; struct Node* next; }; struct Node* build_list() { struct Node** pool; int n = read_number_of_nodes_needed(); if (n <= 0) return 0; pool = (struct Node**)(independent_calloc(n, sizeof(struct Node), 0); if (pool == 0) die(); // organize into a linked list... struct Node* first = pool[0]; for (i = 0; i < n-1; ++i) pool[i]->next = pool[i+1]; free(pool); // Can now free the array (or not, if it is needed later) return first; } */ void** dlindependent_calloc(size_t, size_t, void**); /* independent_comalloc(size_t n_elements, size_t sizes[], void* chunks[]); independent_comalloc allocates, all at once, a set of n_elements chunks with sizes indicated in the "sizes" array. It returns an array of pointers to these elements, each of which can be independently freed, realloc'ed etc. The elements are guaranteed to be adjacently allocated (this is not guaranteed to occur with multiple callocs or mallocs), which may also improve cache locality in some applications. The "chunks" argument is optional (i.e., may be null). If it is null the returned array is itself dynamically allocated and should also be freed when it is no longer needed. Otherwise, the chunks array must be of at least n_elements in length. It is filled in with the pointers to the chunks. In either case, independent_comalloc returns this pointer array, or null if the allocation failed. If n_elements is zero and chunks is null, it returns a chunk representing an array with zero elements (which should be freed if not wanted). Each element must be freed when it is no longer needed. This can be done all at once using bulk_free. independent_comallac differs from independent_calloc in that each element may have a different size, and also that it does not automatically clear elements. independent_comalloc can be used to speed up allocation in cases where several structs or objects must always be allocated at the same time. For example: struct Head { ... } struct Foot { ... } void send_message(char* msg) { int msglen = strlen(msg); size_t sizes[3] = { sizeof(struct Head), msglen, sizeof(struct Foot) }; void* chunks[3]; if (independent_comalloc(3, sizes, chunks) == 0) die(); struct Head* head = (struct Head*)(chunks[0]); char* body = (char*)(chunks[1]); struct Foot* foot = (struct Foot*)(chunks[2]); // ... } In general though, independent_comalloc is worth using only for larger values of n_elements. For small values, you probably won't detect enough difference from series of malloc calls to bother. Overuse of independent_comalloc can increase overall memory usage, since it cannot reuse existing noncontiguous small chunks that might be available for some of the elements. */ void** dlindependent_comalloc(size_t, size_t*, void**); /* bulk_free(void* array[], size_t n_elements) Frees and clears (sets to null) each non-null pointer in the given array. This is likely to be faster than freeing them one-by-one. If footers are used, pointers that have been allocated in different mspaces are not freed or cleared, and the count of all such pointers is returned. For large arrays of pointers with poor locality, it may be worthwhile to sort this array before calling bulk_free. */ size_t dlbulk_free(void**, size_t n_elements); /* pvalloc(size_t n); Equivalent to valloc(minimum-page-that-holds(n)), that is, round up n to nearest pagesize. */ void* dlpvalloc(size_t); /* malloc_trim(size_t pad); If possible, gives memory back to the system (via negative arguments to sbrk) if there is unused memory at the `high' end of the malloc pool or in unused MMAP segments. You can call this after freeing large blocks of memory to potentially reduce the system-level memory requirements of a program. However, it cannot guarantee to reduce memory. Under some allocation patterns, some large free blocks of memory will be locked between two used chunks, so they cannot be given back to the system. The `pad' argument to malloc_trim represents the amount of free trailing space to leave untrimmed. If this argument is zero, only the minimum amount of memory to maintain internal data structures will be left. Non-zero arguments can be supplied to maintain enough trailing space to service future expected allocations without having to re-obtain memory from the system. Malloc_trim returns 1 if it actually released any memory, else 0. */ int dlmalloc_trim(size_t); /* malloc_stats(); Prints on stderr the amount of space obtained from the system (both via sbrk and mmap), the maximum amount (which may be more than current if malloc_trim and/or munmap got called), and the current number of bytes allocated via malloc (or realloc, etc) but not yet freed. Note that this is the number of bytes allocated, not the number requested. It will be larger than the number requested because of alignment and bookkeeping overhead. Because it includes alignment wastage as being in use, this figure may be greater than zero even when no user-level chunks are allocated. The reported current and maximum system memory can be inaccurate if a program makes other calls to system memory allocation functions (normally sbrk) outside of malloc. malloc_stats prints only the most commonly interesting statistics. More information can be obtained by calling mallinfo. malloc_stats is not compiled if NO_MALLOC_STATS is defined. */ void dlmalloc_stats(void); /* malloc_usable_size(void* p); Returns the number of bytes you can actually use in an allocated chunk, which may be more than you requested (although often not) due to alignment and minimum size constraints. You can use this many bytes without worrying about overwriting other allocated objects. This is not a particularly great programming practice. malloc_usable_size can be more useful in debugging and assertions, for example: p = malloc(n); assert(malloc_usable_size(p) >= 256); */ size_t dlmalloc_usable_size(const void*); #ifdef __cplusplus } /* extern "C" */ #endif #endif /* MALLOC_280_H */