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slabs.c
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/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* arcus-memcached - Arcus memory cache server
* Copyright 2010-2014 NAVER Corp.
* Copyright 2014-2015 JaM2in Co., Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Slabs memory allocation, based on powers-of-N. Slabs are up to 1MB in size
* and are divided into chunks. The chunk sizes start off at the size of the
* "item" structure plus space for a small key and value. They increase by
* a multiplier factor from there, up to half the maximum slab size. The last
* slab size is always 1MB, since that's the maximum item size allowed by the
* memcached protocol.
*/
#include "config.h"
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <pthread.h>
#include <inttypes.h>
#include <stdarg.h>
#include "default_engine.h"
#define RESERVED_SLABS 4
#define RESERVED_SLAB_RATIO 5
#define MAX_SPACE_SHORTAGE_LEVEL 100
#define SSL_FOR_BACKGROUND_EVICT 10 /* space shortage level for background evict */
#define SSL_CHECK_BY_MEM_REQUEST 100 /* space shortage level check tick by slab*/
/* should be computed manually */
#define SMMGR_NUM_CLASSES 1025
//#define SMMGR_NUM_CLASSES 81
//#define SMMGR_NUM_CLASSES 9
//#define SMMGR_FREE_MINSIZE 32
//#define SMMGR_NUM_CLASSES 8
//#define SMMGR_FREE_MINSIZE 64
//#define SMMGR_NUM_CLASSES 5
//#define SMMGR_FREE_MINSIZE 512
/* sm slot head */
typedef struct _sm_slot {
uint32_t status; /* 0: free slot */
uint16_t offset;
uint16_t length;
struct _sm_slot *prev;
struct _sm_slot *next;
} sm_slot_t;
/* sm slot tail */
typedef struct _sm_tail {
uint16_t offset;
uint16_t length; /* 0: free slot */
} sm_tail_t;
/* sm block */
typedef struct _sm_blck {
struct _sm_blck *prev;
struct _sm_blck *next;
uint32_t frspc; /* (NOT USED) free slot space in each block */
uint32_t frcnt; /* (NOT USED) free slot count in each block */
} sm_blck_t;
/* sm slot list */
typedef struct _sm_slist {
sm_slot_t *head;
sm_slot_t *tail;
uint64_t space;
uint64_t count;
} sm_slist_t;
/* sm block list */
typedef struct _sm_blist {
sm_blck_t *head;
sm_blck_t *tail;
uint64_t count;
} sm_blist_t;
typedef struct _sm_anchor {
int space_shortage_level; /* 0, 1 ~ 100 */
int blck_clsid; /* slab class id of block */
int blck_tsize; /* block total size */
int blck_bsize; /* block body size */
int used_num_classes; /* # of used slot classes */
int free_num_classes; /* # of free slot classes */
int used_minid; /* min sm classid of used slots */
int used_maxid; /* max sm classid of used slots */
int free_minid; /* max sm classid of free slots */
int free_maxid; /* max sm classid of free slots (excluding the largest free slot) */
sm_blist_t used_blist; /* used block list */
sm_slist_t free_slist[SMMGR_NUM_CLASSES]; /* free slot list */
sm_slist_t used_slist[SMMGR_NUM_CLASSES]; /* used slot info */
uint64_t used_total_space; /* the amount of used space */
uint64_t free_small_space; /* the amount of free space that can't be used */
uint64_t free_avail_space; /* the amount of free space that can be used */
uint64_t free_chunk_space; /* the amount of free chunk space */
uint64_t free_limit_space; /* the amount of minimum free space that must be maintained */
uint32_t num_smmgr_request; /* the number that do_smmgr_alloc/do_smmgr_free are invoked */
} sm_anchor_t;
#define SMMGR_BLOCK_SIZE (64*1024)
#define SMMGR_SLOT_SIZE(size) (((((size)+sizeof(sm_tail_t)-1) / 8) + 1) * 8)
#define SMMGR_MIN_SLOT_SIZE 32
#define SMMGR_MAX_SLOT_SIZE SMMGR_SLOT_SIZE(MAX_SM_VALUE_SIZE)
static sm_anchor_t sm_anchor;
static EXTENSION_LOGGER_DESCRIPTOR *logger;
/*
* Forward Declarations
*/
static void *do_slabs_alloc(struct default_engine *engine, const size_t size, unsigned int id);
static void do_slabs_free(struct default_engine *engine, void *ptr, const size_t size, unsigned int id);
static int do_slabs_newslab(struct default_engine *engine, const unsigned int id);
static void *memory_allocate(struct default_engine *engine, size_t size);
#ifndef DONT_PREALLOC_SLABS
/* Preallocate as many slab pages as possible (called from slabs_init)
on start-up, so users don't get confused out-of-memory errors when
they do have free (in-slab) space, but no space to make new slabs.
if maxslabs is 18 (POWER_LARGEST - POWER_SMALLEST + 1), then all
slab types can be made. if max memory is less than 18 MB, only the
smaller ones will be made. */
static void slabs_preallocate (const unsigned int maxslabs);
#endif
/*
* Figures out which slab class (chunk size) is required to store an item of
* a given size.
*
* Given object size, return id to use when allocating/freeing memory for object
* 0 means error: can't store such a large object
*/
unsigned int slabs_clsid(struct default_engine *engine, const size_t size)
{
int res = POWER_SMALLEST;
if (size == 0)
return 0;
while (size > engine->slabs.slabclass[res].size)
if (res++ == engine->slabs.power_largest) /* won't fit in the biggest slab */
return 0;
return res;
}
static void do_slabs_check_space_shortage_level(struct default_engine *engine)
{
uint64_t curr_avail_space = sm_anchor.free_chunk_space
+ sm_anchor.free_avail_space;
if (curr_avail_space < sm_anchor.free_limit_space) {
/* How do we compute the space_shortage_level ?
* Use the following formula.
* => (free_limit_space / (curr_avail_space / N)) - (N-1)
*/
int ssl; /* space shortage level */
int num=10; /* N */
if ((curr_avail_space / num) > 0) {
ssl = (sm_anchor.free_limit_space / (curr_avail_space / num)) - (num-1);
if (ssl > MAX_SPACE_SHORTAGE_LEVEL) ssl = MAX_SPACE_SHORTAGE_LEVEL;
} else {
ssl = MAX_SPACE_SHORTAGE_LEVEL;
}
sm_anchor.space_shortage_level = ssl;
} else {
sm_anchor.space_shortage_level = 0;
}
}
static void do_smmgr_init(struct default_engine *engine)
{
/* small memory allocator */
sm_anchor.space_shortage_level = 0;
sm_anchor.blck_clsid = 0;
sm_anchor.blck_tsize = SMMGR_BLOCK_SIZE;
sm_anchor.blck_bsize = sm_anchor.blck_tsize - sizeof(sm_blck_t);
sm_anchor.used_num_classes = 0;
sm_anchor.free_num_classes = 0;
sm_anchor.used_minid = SMMGR_NUM_CLASSES;
sm_anchor.used_maxid = -1;
sm_anchor.free_minid = SMMGR_NUM_CLASSES;
sm_anchor.free_maxid = -1;
sm_anchor.used_blist.head = NULL;
sm_anchor.used_blist.tail = NULL;
sm_anchor.used_blist.count = 0;
for (int i = 0; i < SMMGR_NUM_CLASSES; i++) {
sm_anchor.free_slist[i].head = NULL;
sm_anchor.free_slist[i].tail = NULL;
sm_anchor.free_slist[i].space = 0;
sm_anchor.free_slist[i].count = 0;
sm_anchor.used_slist[i].head = NULL;
sm_anchor.used_slist[i].tail = NULL;
sm_anchor.used_slist[i].space = 0;
sm_anchor.used_slist[i].count = 0;
}
sm_anchor.used_total_space = 0;
sm_anchor.free_small_space = 0;
sm_anchor.free_avail_space = 0;
sm_anchor.free_chunk_space = 0;
sm_anchor.free_limit_space = 0;
sm_anchor.num_smmgr_request = 0;
/* slab allocator */
/* slab class 0 is used for collection items ans small-sized kv items */
engine->slabs.slabclass[0].size = sm_anchor.blck_tsize;
engine->slabs.slabclass[0].perslab = engine->config.item_size_max / engine->slabs.slabclass[0].size;
engine->slabs.slabclass[0].rsvd_slabs = 0; // undefined
}
static inline int do_smmgr_memid(size_t size)
{
if (size < 8192) return (int)(size/8);
else return SMMGR_NUM_CLASSES-1;
#if 0
int memid = -1;
int limit = SMMGR_FREE_MINSIZE;
while (size >= limit && memid < (SMMGR_NUM_CLASSES-1)) {
limit *= 2;
memid += 1;
}
assert(memid < SMMGR_NUM_CLASSES);
return memid;
#endif
#if 0
int memid;
if (size < 2048) {
if (size < 1024) memid = ( 0 + ((size ) / 32));
else memid = (32 + ((size-1024) / 64));
} else if (size < 8192) {
if (size < 4096) memid = (48 + ((size-2048) / 128));
else memid = (64 + ((size-4096) / 256));
} else {
memid = SMMGR_NUM_CLASSES-1;
}
assert(memid < SMMGR_NUM_CLASSES);
return memid;
#endif
#if 0
int memid;
if (size < 2048) {
if (size < 1024) memid = ( 0 + ((size ) / 16));
else memid = ( 64 + ((size-1024) / 32));
} else if (size < 8192) {
if (size < 4096) memid = ( 96 + ((size-2048) / 64));
else memid = (128 + ((size-4096) / 128));
} else {
memid = SMMGR_NUM_CLASSES-1;
}
assert(memid < SMMGR_NUM_CLASSES);
return memid;
#endif
#if 0
int memid;
if (size <= 2048) {
if (size <= 512) memid = (0 + ((size -1) / 16));
else if (size <= 1024) memid = (32 + ((size- 512-1) / 32));
else memid = (48 + ((size-1024-1) / 64));
} else {
if (size <= 4096) memid = (64 + ((size-2048-1) / 128));
else if (size <= 8192) memid = (80 + ((size-4096-1) / 256));
else memid = 96;
}
assert(memid < SMMGR_NUM_CLASSES);
return memid;
#endif
}
static void do_smmgr_used_slot_list_add(int targ)
{
if (targ < sm_anchor.used_minid) {
sm_anchor.used_minid = targ;
}
if (targ > sm_anchor.used_maxid) {
/* adjust free_space small & avail */
int smid = (sm_anchor.used_maxid < 0 ? 0 : sm_anchor.used_maxid);
for ( ; smid < targ; smid++) {
if (sm_anchor.free_slist[smid].space > 0) {
sm_anchor.free_small_space += sm_anchor.free_slist[smid].space;
sm_anchor.free_avail_space -= sm_anchor.free_slist[smid].space;
}
}
sm_anchor.used_maxid = targ;
}
sm_anchor.used_num_classes += 1;
}
static void do_smmgr_used_slot_list_del(int targ)
{
int smid;
if (targ == sm_anchor.used_minid) {
if (sm_anchor.used_total_space > 0) {
for (smid = sm_anchor.used_minid+1; smid <= sm_anchor.used_maxid; smid++) {
if (sm_anchor.used_slist[smid].count > 0) break;
}
sm_anchor.used_minid = smid;
} else {
sm_anchor.used_minid = SMMGR_NUM_CLASSES;
}
}
if (targ == sm_anchor.used_maxid) {
if (sm_anchor.used_total_space > 0) {
for (smid = sm_anchor.used_maxid-1; smid >= sm_anchor.used_minid; smid--) {
if (sm_anchor.used_slist[smid].count > 0) break;
}
sm_anchor.used_maxid = smid;
} else {
sm_anchor.used_maxid = -1;
}
/* adjust free_space small & avail */
smid = (sm_anchor.used_maxid < 0 ? 0 : sm_anchor.used_maxid);
for ( ; smid < targ; smid++) {
if (sm_anchor.free_slist[smid].space > 0) {
sm_anchor.free_small_space -= sm_anchor.free_slist[smid].space;
sm_anchor.free_avail_space += sm_anchor.free_slist[smid].space;
}
}
}
sm_anchor.used_num_classes -= 1;
}
static void do_smmgr_free_slot_list_add(int targ)
{
if (targ < (SMMGR_NUM_CLASSES-1)) {
if (sm_anchor.free_minid > targ) {
sm_anchor.free_minid = targ;
}
if (sm_anchor.free_maxid < targ) {
sm_anchor.free_maxid = targ;
}
sm_anchor.free_num_classes += 1;
}
/*****
if (sm_anchor.free_maxid < targ) {
sm_anchor.free_maxid = targ;
}
*****/
}
static void do_smmgr_free_slot_list_del(int targ)
{
if (targ < (SMMGR_NUM_CLASSES-1)) {
int smid;
if (targ == sm_anchor.free_minid) {
if (sm_anchor.free_minid < sm_anchor.free_maxid) {
for (smid = sm_anchor.free_minid+1; smid <= sm_anchor.free_maxid; smid++) {
if (sm_anchor.free_slist[smid].head != NULL) break;
}
sm_anchor.free_minid = smid;
} else {
sm_anchor.free_minid = SMMGR_NUM_CLASSES;
}
}
if (targ == sm_anchor.free_maxid) {
if (sm_anchor.free_maxid > sm_anchor.free_minid) {
for (smid = sm_anchor.free_maxid-1; smid >= sm_anchor.free_minid; smid--) {
if (sm_anchor.free_slist[smid].head != NULL) break;
}
sm_anchor.free_maxid = smid;
} else {
sm_anchor.free_maxid = -1;
}
}
sm_anchor.free_num_classes -= 1;
}
}
static void do_smmgr_used_slot_init(sm_slot_t *slot, uint16_t offset, uint16_t length)
{
sm_tail_t *tail = (sm_tail_t*)((char*)slot + length - sizeof(sm_tail_t));
tail->offset = offset;
tail->length = length; /* used slot */
/* Set it as used slot.
* In eager invalidation, incomplete slot can be inspected.
* At that time, the slot must be regared as an used slot.
*/
slot->status = (uint32_t)-1; /* used slot */
}
static void do_smmgr_free_slot_init(sm_slot_t *slot, uint16_t offset, uint16_t length)
{
sm_tail_t *tail = (sm_tail_t*)((char*)slot + length - sizeof(sm_tail_t));
tail->offset = offset;
tail->length = 0; /* free slot */
slot->status = 0; /* free slot */
slot->offset = offset;
slot->length = length;
}
static void do_smmgr_free_slot_link(sm_slot_t *slot)
{
sm_slist_t *list;
int smid;
if (slot->length < SMMGR_MIN_SLOT_SIZE) {
sm_anchor.free_small_space += slot->length;
return;
}
smid = do_smmgr_memid(slot->length);
list = &sm_anchor.free_slist[smid];
if (list->head == NULL) {
assert(list->tail == NULL && list->count == 0 && list->space == 0);
slot->prev = NULL;
slot->next = NULL;
list->head = slot;
list->tail = slot;
list->space = slot->length;
list->count = 1;
do_smmgr_free_slot_list_add(smid);
} else {
assert(list->tail != NULL && list->count > 0 && list->space > 0);
slot->prev = list->tail;
slot->next = NULL;
slot->prev->next = slot;
list->tail = slot;
list->space += slot->length;
list->count += 1;
}
if (smid < sm_anchor.used_maxid) {
sm_anchor.free_small_space += slot->length;
} else {
sm_anchor.free_avail_space += slot->length;
}
}
static void do_smmgr_free_slot_unlink(sm_slot_t *slot)
{
sm_slist_t *list;
int smid;
if (slot->length < SMMGR_MIN_SLOT_SIZE) {
sm_anchor.free_small_space -= slot->length;
return;
}
smid = do_smmgr_memid(slot->length);
if (smid < sm_anchor.used_maxid) {
sm_anchor.free_small_space -= slot->length;
} else {
sm_anchor.free_avail_space -= slot->length;
}
list = &sm_anchor.free_slist[smid];
if (list->count == 1) {
assert(list->space == slot->length && list->head == slot && list->tail == slot);
list->head = NULL;
list->tail = NULL;
list->space = 0;
list->count = 0;
do_smmgr_free_slot_list_del(smid);
} else {
assert(list->count > 1 && list->space > slot->length &&
list->head != NULL && list->tail != NULL);
if (slot->prev != NULL) slot->prev->next = slot->next;
if (slot->next != NULL) slot->next->prev = slot->prev;
if (list->head == slot) list->head = slot->next;
if (list->tail == slot) list->tail = slot->prev;
list->space -= slot->length;
list->count -= 1;
}
}
static void do_smmgr_free_slot_replace(sm_slot_t *old_slot, sm_slot_t *new_slot, int smid)
{
sm_slist_t *list = &sm_anchor.free_slist[smid];
assert(list->head == old_slot);
uint16_t diff_leng = old_slot->length - new_slot->length;
new_slot->prev = NULL;
if (old_slot->next == NULL) {
new_slot->next = NULL;
list->tail = new_slot;
} else {
new_slot->next = old_slot->next;
new_slot->next->prev = new_slot;
}
list->head = new_slot;
list->space -= diff_leng;
if (smid < sm_anchor.used_maxid) {
sm_anchor.free_small_space -= diff_leng;
} else {
sm_anchor.free_avail_space -= diff_leng;
}
}
#if 0 // can be used later
static void do_smmgr_used_blck_check(void)
{
sm_blck_t *blck;
sm_slot_t *slot;
sm_tail_t *tail;
uint64_t blck_count = 0;
uint64_t used_count = 0;
uint64_t free_count = 0;
uint32_t comp_length;
blck = sm_anchor.used_blist.head;
while (blck != NULL) {
blck_count += 1;
tail = (sm_tail_t*)((char*)blck + sm_anchor.blck_tsize - sizeof(sm_tail_t));
while (((char*)tail - (char*)blck) > sizeof(sm_blck_t)) {
slot = (sm_slot_t*)((char*)blck + tail->offset);
if (tail->length > 8) { /* used slot */
used_count += 1;
assert(slot->status != 0);
} else { /* free slot */
free_count += 1;
comp_length = (char*)tail - (char*)slot + sizeof(sm_tail_t);
assert(slot->status == 0);
assert(slot->offset == tail->offset);
assert(slot->length == comp_length);
}
tail = (sm_tail_t*)((char*)slot - sizeof(sm_tail_t));
}
blck = blck->next;
}
assert(blck_count == sm_anchor.used_blist.count);
}
#endif
static void do_smmgr_used_blck_link(sm_blck_t *blck)
{
blck->frspc = 0;
blck->frcnt = 0;
blck->prev = sm_anchor.used_blist.tail;
blck->next = NULL;
if (sm_anchor.used_blist.head == NULL) {
sm_anchor.used_blist.head = blck;
sm_anchor.used_blist.tail = blck;
} else {
blck->prev->next = blck;
sm_anchor.used_blist.tail = blck;
}
sm_anchor.used_blist.count += 1;
}
static void do_smmgr_used_blck_unlink(sm_blck_t *blck)
{
if (blck->prev != NULL) blck->prev->next = blck->next;
if (blck->next != NULL) blck->next->prev = blck->prev;
if (sm_anchor.used_blist.head == blck) sm_anchor.used_blist.head = blck->next;
if (sm_anchor.used_blist.tail == blck) sm_anchor.used_blist.tail = blck->prev;
sm_anchor.used_blist.count -= 1;
}
static sm_blck_t *do_smmgr_blck_alloc(struct default_engine *engine)
{
sm_blck_t *blck = (sm_blck_t *)do_slabs_alloc(engine, sm_anchor.blck_tsize, sm_anchor.blck_clsid);
if (blck != NULL) {
if (sm_anchor.free_limit_space > 0) {
sm_anchor.free_chunk_space -= sm_anchor.blck_tsize;
}
do_smmgr_used_blck_link(blck);
} else {
logger->log(EXTENSION_LOG_INFO, NULL, "no more small memory chunk\n");
}
return blck;
}
static void do_smmgr_blck_free(struct default_engine *engine, sm_blck_t *blck)
{
do_smmgr_used_blck_unlink(blck);
do_slabs_free(engine, blck, sm_anchor.blck_tsize, sm_anchor.blck_clsid);
if (sm_anchor.free_limit_space > 0) {
sm_anchor.free_chunk_space += sm_anchor.blck_tsize;
}
}
static void *do_smmgr_alloc(struct default_engine *engine, const size_t size)
{
sm_slot_t *cur_slot = NULL;
int smid, targ;
int slen;
if (sm_anchor.free_limit_space > 0) {
if ((++sm_anchor.num_smmgr_request) > SSL_CHECK_BY_MEM_REQUEST) {
sm_anchor.num_smmgr_request = 0;
do_slabs_check_space_shortage_level(engine);
if (sm_anchor.space_shortage_level >= SSL_FOR_BACKGROUND_EVICT)
coll_del_thread_wakeup(engine);
}
}
slen = SMMGR_SLOT_SIZE(size);
if (slen < SMMGR_MIN_SLOT_SIZE)
slen = SMMGR_MIN_SLOT_SIZE;
targ = do_smmgr_memid(slen);
/* allocate slot from free slot list */
#if 0 // check
if (targ <= sm_anchor.free_maxid) {
for (smid = targ; smid <= sm_anchor.free_maxid; smid++) {
if (sm_anchor.free_slist[smid].head != NULL) break;
}
} else {
smid = SMMGR_NUM_CLASSES-1;
}
cur_slot = sm_anchor.free_slist[smid].head;
#endif
#if 0 // check
if (targ <= sm_anchor.free_maxid) {
if (sm_anchor.free_slist[targ].head != NULL) smid = targ;
else smid = sm_anchor.free_maxid;
} else {
smid = SMMGR_NUM_CLASSES-1;
}
cur_slot = sm_anchor.free_slist[smid].head;
#endif
#if 0
for (smid = targ; smid < sm_anchor.free_maxid; smid += targ) {
if (sm_anchor.free_slist[smid].head != NULL) {
cur_slot = sm_anchor.free_slist[smid].head; break;
}
}
if (cur_slot == NULL && targ < sm_anchor.free_maxid) {
smid = sm_anchor.free_maxid;
cur_slot = sm_anchor.free_slist[smid].head;
assert(cur_slot != NULL);
}
#endif
if (targ <= sm_anchor.free_maxid) {
if (sm_anchor.free_slist[targ].head != NULL) {
smid = targ;
} else if ((targ*2) <= sm_anchor.free_maxid) {
for (smid = targ*2; smid <= sm_anchor.free_maxid; smid++) {
if (sm_anchor.free_slist[smid].head != NULL) break;
}
} else {
smid = sm_anchor.free_maxid;
}
} else {
smid = SMMGR_NUM_CLASSES-1;
}
cur_slot = sm_anchor.free_slist[smid].head;
if (cur_slot == NULL) {
sm_blck_t *blck = do_smmgr_blck_alloc(engine);
if (blck == NULL) return NULL;
cur_slot = (sm_slot_t*)((char*)blck + sizeof(sm_blck_t) + slen);
do_smmgr_free_slot_init(cur_slot, sizeof(sm_blck_t) + slen, sm_anchor.blck_bsize - slen);
do_smmgr_free_slot_link(cur_slot);
cur_slot = (sm_slot_t*)((char*)blck + sizeof(sm_blck_t));
do_smmgr_used_slot_init(cur_slot, sizeof(sm_blck_t), slen);
} else {
if (cur_slot->length > slen) {
sm_slot_t *nxt_slot = (sm_slot_t*)((char*)cur_slot + slen);
if (smid != do_smmgr_memid(cur_slot->length - slen)) {
do_smmgr_free_slot_unlink(cur_slot);
do_smmgr_free_slot_init(nxt_slot, cur_slot->offset + slen, cur_slot->length - slen);
do_smmgr_free_slot_link(nxt_slot);
} else {
do_smmgr_free_slot_init(nxt_slot, cur_slot->offset + slen, cur_slot->length - slen);
do_smmgr_free_slot_replace(cur_slot, nxt_slot, smid);
}
} else {
do_smmgr_free_slot_unlink(cur_slot);
}
do_smmgr_used_slot_init(cur_slot, cur_slot->offset, slen);
}
/* used slot stats */
sm_anchor.used_total_space += slen;
sm_anchor.used_slist[targ].space += slen;
sm_anchor.used_slist[targ].count += 1;
if (sm_anchor.used_slist[targ].count == 1) {
do_smmgr_used_slot_list_add(targ);
}
//do_smmgr_used_blck_check();
return (void*)cur_slot;
}
static void do_smmgr_free(struct default_engine *engine, void *ptr, const size_t size)
{
sm_blck_t *cur_blck;
sm_slot_t *cur_slot;
sm_tail_t *cur_tail;
int targ;
int slen;
if (sm_anchor.free_limit_space > 0) {
if ((++sm_anchor.num_smmgr_request) > SSL_CHECK_BY_MEM_REQUEST) {
sm_anchor.num_smmgr_request = 0;
do_slabs_check_space_shortage_level(engine);
if (sm_anchor.space_shortage_level >= SSL_FOR_BACKGROUND_EVICT)
coll_del_thread_wakeup(engine);
}
}
slen = SMMGR_SLOT_SIZE(size);
if (slen < SMMGR_MIN_SLOT_SIZE)
slen = SMMGR_MIN_SLOT_SIZE;
targ = do_smmgr_memid(slen);
//do_smmgr_used_blck_check();
cur_tail = (sm_tail_t*)((char*)ptr + slen - sizeof(sm_tail_t));
assert(cur_tail->length == slen);
cur_blck = (sm_blck_t*)((char*)ptr - cur_tail->offset);
/* check if prev slot is in freed state. if then, merge with that */
if (cur_tail->offset > sizeof(sm_blck_t)) {
sm_slot_t *prv_slot;
sm_tail_t *prv_tail = (sm_tail_t*)((char*)ptr - sizeof(sm_tail_t));
if (prv_tail->length <= 8) { /* free slot */
prv_slot = (sm_slot_t*)((char*)cur_blck + prv_tail->offset);
assert(prv_slot->offset == prv_tail->offset);
do_smmgr_free_slot_unlink(prv_slot);
cur_tail->offset = prv_slot->offset;
cur_tail->length += prv_slot->length;
}
}
/* check if next slot is in freed state. if then, merge with that */
if ((cur_tail->offset + cur_tail->length) < sm_anchor.blck_tsize) {
sm_slot_t *nxt_slot = (sm_slot_t*)((char*)cur_tail + sizeof(sm_tail_t));
sm_tail_t *nxt_tail;
if (nxt_slot->status == 0) { /* free slot */
nxt_tail = (sm_tail_t*)((char*)nxt_slot + nxt_slot->length - sizeof(sm_tail_t));
assert(nxt_tail->offset == nxt_slot->offset && nxt_tail->length <= 8);
do_smmgr_free_slot_unlink(nxt_slot);
nxt_tail->offset = cur_tail->offset;
nxt_tail->length = cur_tail->length + nxt_slot->length;
cur_tail = nxt_tail;
}
}
if (cur_tail->offset > sizeof(sm_blck_t) || cur_tail->length < sm_anchor.blck_bsize) {
cur_slot = (sm_slot_t*)((char*)cur_tail - cur_tail->length + sizeof(sm_tail_t));
do_smmgr_free_slot_init(cur_slot, cur_tail->offset, cur_tail->length);
do_smmgr_free_slot_link(cur_slot);
} else {
do_smmgr_blck_free(engine, cur_blck);
}
/* used slot stats */
assert(sm_anchor.used_slist[targ].count >= 1);
sm_anchor.used_total_space -= slen;
sm_anchor.used_slist[targ].space -= slen;
sm_anchor.used_slist[targ].count -= 1;
if (sm_anchor.used_slist[targ].count == 0) {
do_smmgr_used_slot_list_del(targ);
}
}
unsigned int slabs_space_size(struct default_engine *engine, const size_t size)
{
if (size <= MAX_SM_VALUE_SIZE) {
return SMMGR_SLOT_SIZE(size);
}
int clsid = slabs_clsid(engine, size);
if (clsid == 0)
return 0;
else
return engine->slabs.slabclass[clsid].size;
}
int slabs_space_shortage_level(void)
{
return sm_anchor.space_shortage_level;
}
/**
* Determines the chunk sizes and initializes the slab class descriptors
* accordingly.
*/
ENGINE_ERROR_CODE slabs_init(struct default_engine *engine,
const size_t limit, const double factor, const bool prealloc)
{
int i = POWER_SMALLEST - 1;
unsigned int size = sizeof(hash_item) + engine->config.chunk_size;
logger = engine->server.log->get_logger();
engine->slabs.mem_limit = limit;
engine->slabs.mem_reserved = (limit / 100) * RESERVED_SLAB_RATIO;
if (engine->slabs.mem_reserved < (RESERVED_SLABS*engine->config.item_size_max))
engine->slabs.mem_reserved = (RESERVED_SLABS*engine->config.item_size_max);
if (prealloc) {
/* Allocate everything in a big chunk with malloc */
engine->slabs.mem_base = malloc(engine->slabs.mem_limit);
if (engine->slabs.mem_base != NULL) {
engine->slabs.mem_current = engine->slabs.mem_base;
engine->slabs.mem_avail = engine->slabs.mem_limit;
} else {
return ENGINE_ENOMEM;
}
} else {
engine->slabs.mem_base = NULL;
engine->slabs.mem_current = NULL;
engine->slabs.mem_avail = 0;
}
memset(engine->slabs.slabclass, 0, sizeof(engine->slabs.slabclass));
while (++i < POWER_LARGEST && size <= engine->config.item_size_max / factor) {
/* Make sure items are always n-byte aligned */
if (size % CHUNK_ALIGN_BYTES)
size += CHUNK_ALIGN_BYTES - (size % CHUNK_ALIGN_BYTES);
engine->slabs.slabclass[i].size = size;
engine->slabs.slabclass[i].perslab = engine->config.item_size_max / engine->slabs.slabclass[i].size;
engine->slabs.slabclass[i].rsvd_slabs = RESERVED_SLABS;
size *= factor;
if (engine->config.verbose > 1) {
fprintf(stderr, "slab class %3d: chunk size %9u perslab %7u\n",
i, engine->slabs.slabclass[i].size, engine->slabs.slabclass[i].perslab);
}
}
engine->slabs.power_largest = i;
engine->slabs.slabclass[engine->slabs.power_largest].size = engine->config.item_size_max;
engine->slabs.slabclass[engine->slabs.power_largest].perslab = 1;
engine->slabs.slabclass[engine->slabs.power_largest].rsvd_slabs = RESERVED_SLABS;
if (engine->config.verbose > 1) {
fprintf(stderr, "slab class %3d: chunk size %9u perslab %7u\n",
i, engine->slabs.slabclass[i].size, engine->slabs.slabclass[i].perslab);
}
/* for the test suite: faking of how much we've already malloc'd */
{
char *t_initial_malloc = getenv("T_MEMD_INITIAL_MALLOC");
if (t_initial_malloc) {
engine->slabs.mem_malloced = (size_t)atol(t_initial_malloc);
}
}
#ifndef DONT_PREALLOC_SLABS
{
char *pre_alloc = getenv("T_MEMD_SLABS_ALLOC");
if (pre_alloc == NULL || atoi(pre_alloc) != 0) {
slabs_preallocate(power_largest);
}
}
#endif
do_smmgr_init(engine);
logger->log(EXTENSION_LOG_INFO, NULL, "SLABS module initialized.\n");
return ENGINE_SUCCESS;
}
void slabs_final(struct default_engine *engine)
{
/* Free memory allocated. */
/* Do nothing, currently. */
logger->log(EXTENSION_LOG_INFO, NULL, "SLABS module destroyed.\n");
}
#ifndef DONT_PREALLOC_SLABS
static void slabs_preallocate(const unsigned int maxslabs)
{
int i;
unsigned int prealloc = 0;
/* pre-allocate a 1MB slab in every size class so people don't get
confused by non-intuitive "SERVER_ERROR out of memory"
messages. this is the most common question on the mailing
list. if you really don't want this, you can rebuild without
these three lines. */
for (i = POWER_SMALLEST; i <= POWER_LARGEST; i++) {
if (++prealloc > maxslabs)
return;
do_slabs_newslab(i);
}
/* slab class 0 is used for collection items and small-size kv items */
do_slabs_newslab(0);
}
#endif
static int grow_slab_list (struct default_engine *engine, const unsigned int id)
{
slabclass_t *p = &engine->slabs.slabclass[id];
if (p->slabs == p->list_size) {
size_t new_size = (p->list_size != 0) ? p->list_size * 2 : 16;
void *new_list = realloc(p->slab_list, new_size * sizeof(void *));
if (new_list == 0) return 0;
p->list_size = new_size;
p->slab_list = new_list;
}
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;
}
/*@null@*/
static void *do_slabs_alloc(struct default_engine *engine, const size_t size, unsigned int id)
{
slabclass_t *p;
void *ret = NULL;
if (size <= MAX_SM_VALUE_SIZE) {
return do_smmgr_alloc(engine, size);
}
p = &engine->slabs.slabclass[id];
#ifdef USE_SYSTEM_MALLOC
if (engine->slabs.mem_limit && engine->slabs.mem_malloced + size > engine->slabs.mem_limit) {
MEMCACHED_SLABS_ALLOCATE_FAILED(size, id);
return 0;
}
engine->slabs.mem_malloced += size;
ret = malloc(size);
MEMCACHED_SLABS_ALLOCATE(size, id, 0, ret);
return ret;
#endif
/* fail unless we have space at the end of a recently allocated page,
we have something on our freelist, or we could allocate a new page */
if (! (p->end_page_ptr != 0 || p->sl_curr != 0 ||
do_slabs_newslab(engine, id) != 0)) {
/* We don't have more memory available */
ret = NULL;
} else if (p->sl_curr != 0) {
/* return off our freelist */
ret = p->slots[--p->sl_curr];
} else {
/* if we recently allocated a whole page, return from that */
assert(p->end_page_ptr != NULL);
ret = p->end_page_ptr;
if (--p->end_page_free != 0) {
p->end_page_ptr = ((caddr_t)p->end_page_ptr) + p->size;
} else {
p->end_page_ptr = 0;
}
}
if (ret) {
p->requested += size;
MEMCACHED_SLABS_ALLOCATE(size, id, p->size, ret);
} else {
MEMCACHED_SLABS_ALLOCATE_FAILED(size, id);