What is the redis memory allocation?
This article introduces the relevant knowledge of "how redis memory allocation is". In the operation of actual cases, many people will encounter such a dilemma. Then let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!
Redis memory management encapsulates a series of malloc functions. Additional memory size information of the request is recorded.
# include
# include
Static size_t used_memory = 0
/ *
Allocate memory of sizeof (size_t) + size size. The first sizeof (size_t) bytes record the size of this allocation.
Record the total memory allocated and return the first address of the memory used to store the data, that is, across the sizeof (size_t) size of bytes
, /
Void * zmalloc (size_t size) {
Void * ptr = malloc (size+sizeof (size_t))
If (! ptr) return NULL
* ((size_t*) ptr) = size
Used_memory + = size+sizeof (size_t)
Return (char*) ptr+sizeof (size_t)
}
/ / reallocate memory. Ptr is the memory first address of the old data, and size is the memory size that needs to be shredded this time.
Void * zrealloc (void * ptr, size_t size) {
Void * realptr
Size_t oldsize
Void * newptr
/ / if ptr is empty, there is no old data. You can apply for a new piece of memory without data migration.
If (ptr = = NULL) return zmalloc (size)
/ / the amount of memory occupied by old data
Realptr = (char*) ptr-sizeof (size_t)
/ / get the memory size of the data part
Oldsize = * (size_t*) realptr)
/ / reallocate memory of size+sizeof (size_t) size using the memory address of the old data as the base address
Newptr = realloc (realptr,size+sizeof (size_t))
If (! newptr) return NULL
/ / memory size of recording data section
* ((size_t*) newptr) = size
/ / recalculate the total size of allocated memory. Sizeof (size_t) is still in use and does not need to be calculated.
Used_memory-= oldsize
Used_memory + = size
/ / return the first address of the memory where the data is stored
Return (char*) newptr+sizeof (size_t)
}
Void zfree (void * ptr) {
Void * realptr
Size_t oldsize
If (ptr = = NULL) return
/ / work out the real first address of memory
Realptr = (char*) ptr-sizeof (size_t)
Oldsize = * (size_t*) realptr)
/ / subtract the amount of memory freed
Used_memory-= oldsize+sizeof (size_t)
Free (realptr)
}
/ / copy string
Char * zstrdup (const char * s) {
Size_t l = strlen (s) + 1
Char * p = zmalloc (l)
Memcpy (pjorspen1)
Return p
}
Size_t zmalloc_used_memory (void) {
Return used_memory
}
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