/* Default header file for malloc-2.8.x, written by Doug Lea and released to the public domain, as explained at http://creativecommons.org/licenses/publicdomain. last update: Wed May 27 14:25:17 2009 Doug Lea (dl at gee) This header is for ANSI C/C++ only. You can set any of the following #defines before including: * If USE_DL_PREFIX is defined, it is assumed that malloc.c was also compiled with this option, so all routines have names starting with "dl". * If HAVE_USR_INCLUDE_MALLOC_H is defined, it is assumed that this file will be #included AFTER . This is needed only if your system defines a struct mallinfo that is incompatible with the standard one declared here. Otherwise, you can include this file INSTEAD of your system system . At least on ANSI, all declarations should be compatible with system versions * If MSPACES is defined, declarations for mspace versions are included. */ #ifndef MALLOC_280_H #define MALLOC_280_H #define USE_DL_PREFIX #ifdef __cplusplus extern "C" { #endif #include /* for size_t */ #ifndef ONLY_MSPACES #define ONLY_MSPACES 0 /* define to a value */ #endif /* ONLY_MSPACES */ #ifndef NO_MALLINFO #define NO_MALLINFO 0 #endif /* NO_MALLINFO */ #if !ONLY_MSPACES #ifndef USE_DL_PREFIX #define dlcalloc calloc #define dlfree free #define dlmalloc malloc #define dlmemalign memalign #define dlrealloc realloc #define dlvalloc valloc #define dlpvalloc pvalloc #define dlmallinfo mallinfo #define dlmallopt mallopt #define dlmalloc_trim malloc_trim #define dlmalloc_stats malloc_stats #define dlmalloc_usable_size malloc_usable_size #define dlmalloc_footprint malloc_footprint #define dlindependent_calloc independent_calloc #define dlindependent_comalloc independent_comalloc #endif /* USE_DL_PREFIX */ #if !NO_MALLINFO #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 */ #endif /* !NO_MALLINFO */ /* 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); /* 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); /* 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(); #if !NO_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. */ struct mallinfo dlmallinfo(void); #endif /* NO_MALLINFO */ /* 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 individually freed when it is no longer needed. If you'd like to instead be able to free all at once, you should instead use regular calloc and assign pointers into this space to represent elements. (In this case though, you cannot independently free elements.) 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 individually freed when it is no longer needed. If you'd like to instead be able to free all at once, you should instead use a single regular malloc, and assign pointers at particular offsets in the aggregate space. (In this case though, you cannot independently free elements.) 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**); /* 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. */ void dlmalloc_stats(); #endif /* !ONLY_MSPACES */ /* 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(void*); #if MSPACES /* mspace is an opaque type representing an independent region of space that supports mspace_malloc, etc. */ typedef void* mspace; /* create_mspace creates and returns a new independent space with the given initial capacity, or, if 0, the default granularity size. It returns null if there is no system memory available to create the space. If argument locked is non-zero, the space uses a separate lock to control access. The capacity of the space will grow dynamically as needed to service mspace_malloc requests. You can control the sizes of incremental increases of this space by compiling with a different DEFAULT_GRANULARITY or dynamically setting with mallopt(M_GRANULARITY, value). */ mspace create_mspace(size_t capacity, int locked); /* destroy_mspace destroys the given space, and attempts to return all of its memory back to the system, returning the total number of bytes freed. After destruction, the results of access to all memory used by the space become undefined. */ size_t destroy_mspace(mspace msp); /* create_mspace_with_base uses the memory supplied as the initial base of a new mspace. Part (less than 128*sizeof(size_t) bytes) of this space is used for bookkeeping, so the capacity must be at least this large. (Otherwise 0 is returned.) When this initial space is exhausted, additional memory will be obtained from the system. Destroying this space will deallocate all additionally allocated space (if possible) but not the initial base. */ mspace create_mspace_with_base(void* base, size_t capacity, int locked); /* mspace_track_large_chunks controls whether requests for large chunks are allocated in their own untracked mmapped regions, separate from others in this mspace. By default large chunks are not tracked, which reduces fragmentation. However, such chunks are not necessarily released to the system upon destroy_mspace. Enabling tracking by setting to true may increase fragmentation, but avoids leakage when relying on destroy_mspace to release all memory allocated using this space. The function returns the previous setting. */ int mspace_track_large_chunks(mspace msp, int enable); /* mspace_malloc behaves as malloc, but operates within the given space. */ void* mspace_malloc(mspace msp, size_t bytes); /* mspace_free behaves as free, but operates within the given space. If compiled with FOOTERS==1, mspace_free is not actually needed. free may be called instead of mspace_free because freed chunks from any space are handled by their originating spaces. */ void mspace_free(mspace msp, void* mem); /* mspace_realloc behaves as realloc, but operates within the given space. If compiled with FOOTERS==1, mspace_realloc is not actually needed. realloc may be called instead of mspace_realloc because realloced chunks from any space are handled by their originating spaces. */ void* mspace_realloc(mspace msp, void* mem, size_t newsize); /* mspace_calloc behaves as calloc, but operates within the given space. */ void* mspace_calloc(mspace msp, size_t n_elements, size_t elem_size); /* mspace_memalign behaves as memalign, but operates within the given space. */ void* mspace_memalign(mspace msp, size_t alignment, size_t bytes); /* mspace_independent_calloc behaves as independent_calloc, but operates within the given space. */ void** mspace_independent_calloc(mspace msp, size_t n_elements, size_t elem_size, void* chunks[]); /* mspace_independent_comalloc behaves as independent_comalloc, but operates within the given space. */ void** mspace_independent_comalloc(mspace msp, size_t n_elements, size_t sizes[], void* chunks[]); /* mspace_footprint() returns the number of bytes obtained from the system for this space. */ size_t mspace_footprint(mspace msp); #if !NO_MALLINFO /* mspace_mallinfo behaves as mallinfo, but reports properties of the given space. */ struct mallinfo mspace_mallinfo(mspace msp); #endif /* NO_MALLINFO */ /* malloc_usable_size(void* p) behaves the same as malloc_usable_size; */ size_t mspace_usable_size(void* mem); /* mspace_malloc_stats behaves as malloc_stats, but reports properties of the given space. */ void mspace_malloc_stats(mspace msp); /* mspace_trim behaves as malloc_trim, but operates within the given space. */ int mspace_trim(mspace msp, size_t pad); /* An alias for mallopt. */ int mspace_mallopt(int, int); #endif /* MSPACES */ #ifdef __cplusplus }; /* end of extern "C" */ #endif #endif /* MALLOC_280_H */