#include "portable.h"
#include "xbt/xbt_os_thread.h"
#include "xbt/mmalloc.h"
+#include "xbt/ex.h"
#include <semaphore.h>
#ifdef HAVE_LIMITS_H
const char *xbt_thread_self_name(void);
-/* Data structure giving per-block information. */
-typedef union {
- /* Heap information for a busy block. */
- struct {
- /* Zero for a large block, or positive giving the
- logarithm to the base two of the fragment size. */
- int type;
- union {
- struct {
- size_t nfree; /* Free fragments in a fragmented block. */
- size_t first; /* First free fragment of the block. */
- } frag;
- struct {
- size_t size; /* Size (in blocks) of a large cluster. */
- size_t busy_size;
- } block;
- } info;
- } busy;
- /* Heap information for a free block (that may be the first of
- a free cluster). */
- struct {
- size_t size; /* Size (in blocks) of a free cluster. */
- size_t next; /* Index of next free cluster. */
- size_t prev; /* Index of previous free cluster. */
- } free;
+/* Data structure giving per-block information.
+ *
+ * There is one such structure in the mdp->heapinfo array,
+ * that is addressed by block number.
+ *
+ * There is several types of blocks in memory:
+ * - full busy blocks: used when we are asked to malloc a block which size is > BLOCKSIZE/2
+ * In this situation, the full block is given to the malloc.
+ *
+ * - fragmented busy blocks: when asked for smaller amount of memory.
+ * Fragment sizes are only power of 2. When looking for such a free fragment,
+ * we get one from mdp->fraghead (that contains a linked list of blocks fragmented at that
+ * size and containing a free fragment), or we get a fresh block that we fragment.
+ *
+ * - free blocks are grouped by clusters, that are chained together.
+ * When looking for free blocks, we traverse the mdp->heapinfo looking
+ * for a cluster of free blocks that would be large enough.
+ *
+ * The size of the cluster is only to be trusted in the first block of the cluster, not in the middle blocks.
+ *
+ * The type field is consistently updated for every blocks, even within clusters of blocks.
+ * You can crawl the array and rely on that value.
+ *
+ * TODO:
+ * - add an indication of the requested size in each fragment, similarly to busy_block.busy_size
+ * - make room to store the backtrace of where the blocks and fragment were malloced, too.
+ */
+typedef struct {
+ int type; /* 0: busy large block
+ >0: busy fragmented (fragments of size 2^type bytes)
+ <0: free block */
+ union {
+ /* Heap information for a busy block. */
+ struct {
+ size_t nfree; /* Free fragments in a fragmented block. */
+ size_t first; /* First free fragment of the block. */
+ } busy_frag;
+ struct {
+ size_t size; /* Size (in blocks) of a large cluster. */
+ size_t busy_size; /* Actually used space, in bytes */
+ } busy_block;
+ /* Heap information for a free block (that may be the first of a free cluster). */
+ struct {
+ size_t size; /* Size (in blocks) of a free cluster. */
+ size_t next; /* Index of next free cluster. */
+ size_t prev; /* Index of previous free cluster. */
+ } free_block;
+ };
} malloc_info;
/* Doubly linked lists of free fragments. */
struct list {
- struct list *next;
- struct list *prev;
+ struct list *next;
+ struct list *prev;
};
/* Internal structure that defines the format of the malloc-descriptor.
struct mdesc {
- /* Semaphore locking the access to the heap */
- sem_t sem;
+ /* Semaphore locking the access to the heap */
+ sem_t sem;
- /* Number of processes that attached the heap */
- unsigned int refcount;
+ /* Number of processes that attached the heap */
+ unsigned int refcount;
- /* Chained lists of mdescs */
- struct mdesc *next_mdesc;
-
- /* The "magic number" for an mmalloc file. */
- char magic[MMALLOC_MAGIC_SIZE];
+ /* Chained lists of mdescs */
+ struct mdesc *next_mdesc;
- /* The size in bytes of this structure, used as a sanity check when reusing
- a previously created mapped file. */
- unsigned int headersize;
-
- /* The version number of the mmalloc package that created this file. */
- unsigned char version;
-
- /* Some flag bits to keep track of various internal things. */
- unsigned int flags;
-
- /* Number of info entries. */
- size_t heapsize;
+ /* The "magic number" for an mmalloc file. */
+ char magic[MMALLOC_MAGIC_SIZE];
- /* Pointer to first block of the heap (base of the first block). */
- void *heapbase;
+ /* The size in bytes of this structure, used as a sanity check when reusing
+ a previously created mapped file. */
+ unsigned int headersize;
- /* Current search index for the heap table. */
- /* Search index in the info table. */
- size_t heapindex;
+ /* The version number of the mmalloc package that created this file. */
+ unsigned char version;
- /* Limit of valid info table indices. */
- size_t heaplimit;
+ /* Some flag bits to keep track of various internal things. */
+ unsigned int flags;
- /* Block information table.
- Allocated with malign/__mmalloc_free (not mmalloc/mfree). */
- /* Table indexed by block number giving per-block information. */
+ /* Number of info entries. */
+ size_t heapsize;
- malloc_info *heapinfo;
+ /* Pointer to first block of the heap (base of the first block). */
+ void *heapbase;
- /* Free list headers for each fragment size. */
- /* Free lists for each fragment size. */
+ /* Current search index for the heap table. */
+ /* Search index in the info table. */
+ size_t heapindex;
- struct list fraghead[BLOCKLOG];
+ /* Limit of valid info table indices. */
+ size_t heaplimit;
- /* List of blocks allocated by memalign. */
+ /* Block information table.
+ Allocated with malign/mfree (not mmalloc/mfree). */
+ /* Table indexed by block number giving per-block information. */
+ malloc_info *heapinfo;
- struct alignlist *aligned_blocks;
+ /* List of all blocks containing free fragments of this size. The array indice is the log2 of requested size */
+ struct list fraghead[BLOCKLOG];
- /* The base address of the memory region for this malloc heap. This
+ /* The base address of the memory region for this malloc heap. This
is the location where the bookkeeping data for mmap and for malloc
begins. */
- void *base;
+ void *base;
- /* The current location in the memory region for this malloc heap which
+ /* The current location in the memory region for this malloc heap which
represents the end of memory in use. */
- void *breakval;
+ void *breakval;
- /* The end of the current memory region for this malloc heap. This is
+ /* The end of the current memory region for this malloc heap. This is
the first location past the end of mapped memory. */
- void *top;
+ void *top;
- /* Open file descriptor for the file to which this malloc heap is mapped.
+ /* Open file descriptor for the file to which this malloc heap is mapped.
This will always be a valid file descriptor, since /dev/zero is used
by default if no open file is supplied by the client. Also note that
it may change each time the region is mapped and unmapped. */
- int fd;
+ int fd;
};
#define MMALLOC_ANONYMOUS (1 << 1) /* Use anonymous mapping */
#define MMALLOC_INITIALIZED (1 << 2) /* Initialized mmalloc */
-/* Internal version of `mfree' used in `morecore'. */
-
-extern void __mmalloc_free(struct mdesc *mdp, void *ptr);
-
/* A default malloc descriptor for the single sbrk() managed region. */
extern struct mdesc *__mmalloc_default_mdp;
/* Thread-safety (if the sem is already created) FIXME: KILLIT*/
#define LOCK(mdp) \
- sem_wait(&mdp->sem)
+ sem_wait(&mdp->sem)
#define UNLOCK(mdp) \
- sem_post(&mdp->sem)
+ sem_post(&mdp->sem)
#endif /* __MMPRIVATE_H */
