/**
* 为slabclass[id]分配一个新的slab，成功返回1，否则返回0
*
* 1. 确定slab的长度len
* 2. 分配len大小的内存(预分配的内存中划分或者调malloc()分配)
* 3. 把所分配的内存初始化成item链表，链接到slabclass[id]的slot中
* 4. slabclass[i]属性的更新：slabs数增1
* 5. 已分配内存数的更新
*/
static int do_slabs_newslab(const unsigned int id) {
slabclass_t *p = &slabclass[id]; //指向第i个slabclass
int len = settings.slab_reassign ? settings.item_size_max //是否开启可自定slab大小，否则使用默认的大小1M
: p->size * p->perslab;
char *ptr;
//grow_slab_list初始化slabclass的slab_list，而slab_list中的指针指向每个slab
//memory_allocate从内存池申请1M的空间
if ((mem_limit && mem_malloced + len > mem_limit && p->slabs > 0) ||
(grow_slab_list(id) == 0) ||
((ptr = memory_allocate((size_t)len)) == 0)) {
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
return 0;
}
memset(ptr, 0, (size_t)len);
//将申请到的1M空间按照slabclass的size进行切分
split_slab_page_into_freelist(ptr, id);
p->slab_list[p->slabs++] = ptr;//循环分配
mem_malloced += len;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE(id);
return 1;
}
static int do_slabs_newslab(const unsigned int id) {
slabclass_t *p = &slabclass[id];
#ifdef ALLOW_SLABS_REASSIGN
int len = POWER_BLOCK;
#else
int len = p->size * p->perslab;
#endif
char *ptr;
if ((mem_limit && mem_malloced + len > mem_limit && p->slabs > 0) ||
(grow_slab_list(id) == 0) ||
((ptr = memory_allocate((size_t)len)) == 0)) {
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
return 0;
}
memset(ptr, 0, (size_t)len);
p->end_page_ptr = ptr;
p->end_page_free = p->perslab;
p->slab_list[p->slabs++] = ptr;
mem_malloced += len;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE(id);
return 1;
}
//slabclass_t中slab的数目是慢慢增多的。该函数的作用就是为slabclass_t申请多一个slab
//参数id指明是slabclass数组中的那个slabclass_t
static int do_slabs_newslab(const unsigned int id) {
slabclass_t *p = &slabclass[id];
//settings.slab_reassign的默认值为false，这里就采用false
int len = settings.slab_reassign ? settings.item_size_max
: p->size * p->perslab;//其积 <= settings.item_size_max
char *ptr;
//mem_malloced的值通过环境变量设置，默认为0
if ((mem_limit && mem_malloced + len > mem_limit && p->slabs > 0) ||
(grow_slab_list(id) == 0) ||//增长slab_list(失败返回0)。一般都会成功,除非无法分配内存
((ptr = memory_allocate((size_t)len)) == 0)) {//分配len字节内存(也就是一个页)
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
return 0;
}
memset(ptr, 0, (size_t)len);//清零内存块是必须的
//将这块内存切成一个个的item，当然item的大小有id所控制
split_slab_page_into_freelist(ptr, id);
//将分配得到的内存页交由slab_list掌管
p->slab_list[p->slabs++] = ptr;
mem_malloced += len;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE(id);
return 1;
}
static int do_slabs_newslab(const unsigned int id) {
slabclass_t *p = &slabclass[id];
slabclass_t *g = &slabclass[SLAB_GLOBAL_PAGE_POOL];
int len = settings.slab_reassign ? settings.item_size_max
: p->size * p->perslab;
char *ptr;
if ((mem_limit && mem_malloced + len > mem_limit && p->slabs > 0
&& g->slabs == 0)) {
mem_limit_reached = true;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
return 0;
}
if ((grow_slab_list(id) == 0) ||
(((ptr = get_page_from_global_pool()) == NULL) &&
((ptr = memory_allocate((size_t)len)) == 0))) {
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
return 0;
}
memset(ptr, 0, (size_t)len);
split_slab_page_into_freelist(ptr, id);
p->slab_list[p->slabs++] = ptr;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE(id);
return 1;
}
static int do_slabs_newslab(const unsigned int id) {
slabclass_t *p = &slabclass[id];
int len = settings.slab_reassign ? settings.item_size_max
: p->size * p->perslab;
char *ptr;
if ((mem_limit && mem_malloced + len > mem_limit && p->slabs > 0) ||
(grow_slab_list(id) == 0) ||
((ptr = memory_allocate((size_t)len)) == 0)) {
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
return 0;
}
memset(ptr, 0, (size_t)len);
p->end_page_ptr = ptr;
p->end_page_free = p->perslab;
p->slab_list[p->slabs++] = ptr;
#ifdef TEST_CLOCK
p->clock_max = p->slabs * p->perslab;
#endif
mem_malloced += len;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE(id);
return 1;
}
static int do_slabs_newslab(const unsigned int id) {
slabclass_t *p = &slabclass[id];
int len = settings.slab_reassign ? settings.item_size_max
: p->size * p->perslab;
char *ptr;
DBG_INFO(DBG_ASSOC_HOPSCOTCH, "%s:%d: mem_limit = %u, len = %u\n",
__func__, __LINE__, (unsigned int)mem_limit, (unsigned int)len);
DBG_INFO(DBG_ASSOC_HOPSCOTCH, "%s:%d: p->slabs = %u\n", __func__, __LINE__, p->slabs);
if ((mem_limit && mem_malloced + len > mem_limit && p->slabs > 0) ||
(grow_slab_list(id) == 0) ||
((ptr = memory_allocate((size_t)len)) == 0)) {
mem_limit_reached = true;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
DBG_INFO(DBG_ASSOC_HOPSCOTCH, "%s:%d: mem_limit = %u, mem_malloced = %u, len = %d\n", __func__, __LINE__,
(unsigned int)mem_limit, (unsigned int)mem_malloced, len);
DBG_INFO(DBG_ASSOC_HOPSCOTCH, "%s:%d: returning 0\n", __func__, __LINE__);
return 0;
}
memset(ptr, 0, (size_t)len);
// TODO: Should this be commented?
split_slab_page_into_freelist(ptr, id);
p->slab_list[p->slabs++] = ptr;
#ifdef HOPSCOTCH_CLOCK
p->clock_max = p->slabs * p->perslab;
#endif
mem_malloced += len;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE(id);
return 1;
}
static int do_slabs_newslab(struct default_engine *engine, const unsigned int id)
{
slabclass_t *p = &engine->slabs.slabclass[id];
int len = p->size * p->perslab;
char *ptr;
if ((engine->slabs.mem_limit && engine->slabs.mem_malloced + len > engine->slabs.mem_limit && p->slabs >= p->rsvd_slabs) ||
(grow_slab_list(engine, id) == 0) ||
((ptr = memory_allocate(engine, (size_t)len)) == 0)) {
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
return 0;
}
memset(ptr, 0, (size_t)len);
p->end_page_ptr = ptr;
p->end_page_free = p->perslab;
p->slab_list[p->slabs++] = ptr;
engine->slabs.mem_malloced += len;
if ((engine->slabs.mem_limit <= engine->slabs.mem_malloced) ||
((engine->slabs.mem_limit - engine->slabs.mem_malloced) < engine->slabs.mem_reserved))
{
if (engine->slabs.slabclass[sm_anchor.blck_clsid].rsvd_slabs == 0) { /* undefined */
/* define the reserved slab count of slab class 0 */
slabclass_t *z = &engine->slabs.slabclass[sm_anchor.blck_clsid];
unsigned int additional_slabs = (z->slabs/100) * RESERVED_SLAB_RATIO;
if (additional_slabs < RESERVED_SLABS)
additional_slabs = RESERVED_SLABS;
z->rsvd_slabs = z->slabs + additional_slabs;
sm_anchor.free_limit_space = (additional_slabs * z->perslab) * sm_anchor.blck_tsize;
sm_anchor.free_chunk_space = sm_anchor.free_limit_space
+ (z->sl_curr + z->end_page_free) * sm_anchor.blck_tsize;
}
}
MEMCACHED_SLABS_SLABCLASS_ALLOCATE(id);
return 1;
}
static int do_slabs_newslab(struct default_engine *engine, const unsigned int id) {
slabclass_t *p = &engine->slabs.slabclass[id];
int len = p->size * p->perslab;
char *ptr;
if ((engine->slabs.mem_limit && engine->slabs.mem_malloced + len > engine->slabs.mem_limit && p->slabs > 0) ||
(grow_slab_list(engine, id) == 0) ||
((ptr = memory_allocate(engine, (size_t)len)) == 0)) {
MEMCACHED_SLABS_SLABCLASS_ALLOCATE_FAILED(id);
return 0;
}
memset(ptr, 0, (size_t)len);
p->end_page_ptr = ptr;
p->end_page_free = p->perslab;
p->slab_list[p->slabs++] = ptr;
engine->slabs.mem_malloced += len;
MEMCACHED_SLABS_SLABCLASS_ALLOCATE(id);
return 1;
}