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Diffstat (limited to 'src/defrag.c')
| -rw-r--r-- | src/defrag.c | 1079 |
1 files changed, 1079 insertions, 0 deletions
diff --git a/src/defrag.c b/src/defrag.c new file mode 100644 index 0000000..ff63cf8 --- /dev/null +++ b/src/defrag.c @@ -0,0 +1,1079 @@ +/* + * Active memory defragmentation + * Try to find key / value allocations that need to be re-allocated in order + * to reduce external fragmentation. + * We do that by scanning the keyspace and for each pointer we have, we can try to + * ask the allocator if moving it to a new address will help reduce fragmentation. + * + * Copyright (c) 2020, Redis Labs, Inc + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * * Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * * Neither the name of Redis nor the names of its contributors may be used + * to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include "server.h" +#include "cluster.h" +#include <time.h> +#include <assert.h> +#include <stddef.h> + +#ifdef HAVE_DEFRAG + +/* this method was added to jemalloc in order to help us understand which + * pointers are worthwhile moving and which aren't */ +int je_get_defrag_hint(void* ptr); + +/* Defrag helper for generic allocations. + * + * returns NULL in case the allocation wasn't moved. + * when it returns a non-null value, the old pointer was already released + * and should NOT be accessed. */ +void* activeDefragAlloc(void *ptr) { + size_t size; + void *newptr; + if(!je_get_defrag_hint(ptr)) { + server.stat_active_defrag_misses++; + return NULL; + } + /* move this allocation to a new allocation. + * make sure not to use the thread cache. so that we don't get back the same + * pointers we try to free */ + size = zmalloc_size(ptr); + newptr = zmalloc_no_tcache(size); + memcpy(newptr, ptr, size); + zfree_no_tcache(ptr); + server.stat_active_defrag_hits++; + return newptr; +} + +/*Defrag helper for sds strings + * + * returns NULL in case the allocation wasn't moved. + * when it returns a non-null value, the old pointer was already released + * and should NOT be accessed. */ +sds activeDefragSds(sds sdsptr) { + void* ptr = sdsAllocPtr(sdsptr); + void* newptr = activeDefragAlloc(ptr); + if (newptr) { + size_t offset = sdsptr - (char*)ptr; + sdsptr = (char*)newptr + offset; + return sdsptr; + } + return NULL; +} + +/* Defrag helper for robj and/or string objects + * + * returns NULL in case the allocation wasn't moved. + * when it returns a non-null value, the old pointer was already released + * and should NOT be accessed. */ +robj *activeDefragStringOb(robj* ob) { + robj *ret = NULL; + if (ob->refcount!=1) + return NULL; + + /* try to defrag robj (only if not an EMBSTR type (handled below). */ + if (ob->type!=OBJ_STRING || ob->encoding!=OBJ_ENCODING_EMBSTR) { + if ((ret = activeDefragAlloc(ob))) { + ob = ret; + } + } + + /* try to defrag string object */ + if (ob->type == OBJ_STRING) { + if(ob->encoding==OBJ_ENCODING_RAW) { + sds newsds = activeDefragSds((sds)ob->ptr); + if (newsds) { + ob->ptr = newsds; + } + } else if (ob->encoding==OBJ_ENCODING_EMBSTR) { + /* The sds is embedded in the object allocation, calculate the + * offset and update the pointer in the new allocation. */ + long ofs = (intptr_t)ob->ptr - (intptr_t)ob; + if ((ret = activeDefragAlloc(ob))) { + ret->ptr = (void*)((intptr_t)ret + ofs); + } + } else if (ob->encoding!=OBJ_ENCODING_INT) { + serverPanic("Unknown string encoding"); + } + } + return ret; +} + +/* Defrag helper for lua scripts + * + * returns NULL in case the allocation wasn't moved. + * when it returns a non-null value, the old pointer was already released + * and should NOT be accessed. */ +luaScript *activeDefragLuaScript(luaScript *script) { + luaScript *ret = NULL; + + /* try to defrag script struct */ + if ((ret = activeDefragAlloc(script))) { + script = ret; + } + + /* try to defrag actual script object */ + robj *ob = activeDefragStringOb(script->body); + if (ob) script->body = ob; + + return ret; +} + +/* Defrag helper for dict main allocations (dict struct, and hash tables). + * receives a pointer to the dict* and implicitly updates it when the dict + * struct itself was moved. Returns a stat of how many pointers were moved. */ +void dictDefragTables(dict* d) { + dictEntry **newtable; + /* handle the first hash table */ + newtable = activeDefragAlloc(d->ht_table[0]); + if (newtable) + d->ht_table[0] = newtable; + /* handle the second hash table */ + if (d->ht_table[1]) { + newtable = activeDefragAlloc(d->ht_table[1]); + if (newtable) + d->ht_table[1] = newtable; + } +} + +/* Internal function used by zslDefrag */ +void zslUpdateNode(zskiplist *zsl, zskiplistNode *oldnode, zskiplistNode *newnode, zskiplistNode **update) { + int i; + for (i = 0; i < zsl->level; i++) { + if (update[i]->level[i].forward == oldnode) + update[i]->level[i].forward = newnode; + } + serverAssert(zsl->header!=oldnode); + if (newnode->level[0].forward) { + serverAssert(newnode->level[0].forward->backward==oldnode); + newnode->level[0].forward->backward = newnode; + } else { + serverAssert(zsl->tail==oldnode); + zsl->tail = newnode; + } +} + +/* Defrag helper for sorted set. + * Update the robj pointer, defrag the skiplist struct and return the new score + * reference. We may not access oldele pointer (not even the pointer stored in + * the skiplist), as it was already freed. Newele may be null, in which case we + * only need to defrag the skiplist, but not update the obj pointer. + * When return value is non-NULL, it is the score reference that must be updated + * in the dict record. */ +double *zslDefrag(zskiplist *zsl, double score, sds oldele, sds newele) { + zskiplistNode *update[ZSKIPLIST_MAXLEVEL], *x, *newx; + int i; + sds ele = newele? newele: oldele; + + /* find the skiplist node referring to the object that was moved, + * and all pointers that need to be updated if we'll end up moving the skiplist node. */ + x = zsl->header; + for (i = zsl->level-1; i >= 0; i--) { + while (x->level[i].forward && + x->level[i].forward->ele != oldele && /* make sure not to access the + ->obj pointer if it matches + oldele */ + (x->level[i].forward->score < score || + (x->level[i].forward->score == score && + sdscmp(x->level[i].forward->ele,ele) < 0))) + x = x->level[i].forward; + update[i] = x; + } + + /* update the robj pointer inside the skip list record. */ + x = x->level[0].forward; + serverAssert(x && score == x->score && x->ele==oldele); + if (newele) + x->ele = newele; + + /* try to defrag the skiplist record itself */ + newx = activeDefragAlloc(x); + if (newx) { + zslUpdateNode(zsl, x, newx, update); + return &newx->score; + } + return NULL; +} + +/* Defrag helper for sorted set. + * Defrag a single dict entry key name, and corresponding skiplist struct */ +void activeDefragZsetEntry(zset *zs, dictEntry *de) { + sds newsds; + double* newscore; + sds sdsele = dictGetKey(de); + if ((newsds = activeDefragSds(sdsele))) + dictSetKey(zs->dict, de, newsds); + newscore = zslDefrag(zs->zsl, *(double*)dictGetVal(de), sdsele, newsds); + if (newscore) { + dictSetVal(zs->dict, de, newscore); + } +} + +#define DEFRAG_SDS_DICT_NO_VAL 0 +#define DEFRAG_SDS_DICT_VAL_IS_SDS 1 +#define DEFRAG_SDS_DICT_VAL_IS_STROB 2 +#define DEFRAG_SDS_DICT_VAL_VOID_PTR 3 +#define DEFRAG_SDS_DICT_VAL_LUA_SCRIPT 4 + +void activeDefragSdsDictCallback(void *privdata, const dictEntry *de) { + UNUSED(privdata); + UNUSED(de); +} + +/* Defrag a dict with sds key and optional value (either ptr, sds or robj string) */ +void activeDefragSdsDict(dict* d, int val_type) { + unsigned long cursor = 0; + dictDefragFunctions defragfns = { + .defragAlloc = activeDefragAlloc, + .defragKey = (dictDefragAllocFunction *)activeDefragSds, + .defragVal = (val_type == DEFRAG_SDS_DICT_VAL_IS_SDS ? (dictDefragAllocFunction *)activeDefragSds : + val_type == DEFRAG_SDS_DICT_VAL_IS_STROB ? (dictDefragAllocFunction *)activeDefragStringOb : + val_type == DEFRAG_SDS_DICT_VAL_VOID_PTR ? (dictDefragAllocFunction *)activeDefragAlloc : + val_type == DEFRAG_SDS_DICT_VAL_LUA_SCRIPT ? (dictDefragAllocFunction *)activeDefragLuaScript : + NULL) + }; + do { + cursor = dictScanDefrag(d, cursor, activeDefragSdsDictCallback, + &defragfns, NULL); + } while (cursor != 0); +} + +/* Defrag a list of ptr, sds or robj string values */ +void activeDefragList(list *l, int val_type) { + listNode *ln, *newln; + for (ln = l->head; ln; ln = ln->next) { + if ((newln = activeDefragAlloc(ln))) { + if (newln->prev) + newln->prev->next = newln; + else + l->head = newln; + if (newln->next) + newln->next->prev = newln; + else + l->tail = newln; + ln = newln; + } + if (val_type == DEFRAG_SDS_DICT_VAL_IS_SDS) { + sds newsds, sdsele = ln->value; + if ((newsds = activeDefragSds(sdsele))) + ln->value = newsds; + } else if (val_type == DEFRAG_SDS_DICT_VAL_IS_STROB) { + robj *newele, *ele = ln->value; + if ((newele = activeDefragStringOb(ele))) + ln->value = newele; + } else if (val_type == DEFRAG_SDS_DICT_VAL_VOID_PTR) { + void *newptr, *ptr = ln->value; + if ((newptr = activeDefragAlloc(ptr))) + ln->value = newptr; + } + } +} + +void activeDefragQuickListNode(quicklist *ql, quicklistNode **node_ref) { + quicklistNode *newnode, *node = *node_ref; + unsigned char *newzl; + if ((newnode = activeDefragAlloc(node))) { + if (newnode->prev) + newnode->prev->next = newnode; + else + ql->head = newnode; + if (newnode->next) + newnode->next->prev = newnode; + else + ql->tail = newnode; + *node_ref = node = newnode; + } + if ((newzl = activeDefragAlloc(node->entry))) + node->entry = newzl; +} + +void activeDefragQuickListNodes(quicklist *ql) { + quicklistNode *node = ql->head; + while (node) { + activeDefragQuickListNode(ql, &node); + node = node->next; + } +} + +/* when the value has lots of elements, we want to handle it later and not as + * part of the main dictionary scan. this is needed in order to prevent latency + * spikes when handling large items */ +void defragLater(redisDb *db, dictEntry *kde) { + sds key = sdsdup(dictGetKey(kde)); + listAddNodeTail(db->defrag_later, key); +} + +/* returns 0 if no more work needs to be been done, and 1 if time is up and more work is needed. */ +long scanLaterList(robj *ob, unsigned long *cursor, long long endtime) { + quicklist *ql = ob->ptr; + quicklistNode *node; + long iterations = 0; + int bookmark_failed = 0; + if (ob->type != OBJ_LIST || ob->encoding != OBJ_ENCODING_QUICKLIST) + return 0; + + if (*cursor == 0) { + /* if cursor is 0, we start new iteration */ + node = ql->head; + } else { + node = quicklistBookmarkFind(ql, "_AD"); + if (!node) { + /* if the bookmark was deleted, it means we reached the end. */ + *cursor = 0; + return 0; + } + node = node->next; + } + + (*cursor)++; + while (node) { + activeDefragQuickListNode(ql, &node); + server.stat_active_defrag_scanned++; + if (++iterations > 128 && !bookmark_failed) { + if (ustime() > endtime) { + if (!quicklistBookmarkCreate(&ql, "_AD", node)) { + bookmark_failed = 1; + } else { + ob->ptr = ql; /* bookmark creation may have re-allocated the quicklist */ + return 1; + } + } + iterations = 0; + } + node = node->next; + } + quicklistBookmarkDelete(ql, "_AD"); + *cursor = 0; + return bookmark_failed? 1: 0; +} + +typedef struct { + zset *zs; +} scanLaterZsetData; + +void scanLaterZsetCallback(void *privdata, const dictEntry *_de) { + dictEntry *de = (dictEntry*)_de; + scanLaterZsetData *data = privdata; + activeDefragZsetEntry(data->zs, de); + server.stat_active_defrag_scanned++; +} + +void scanLaterZset(robj *ob, unsigned long *cursor) { + if (ob->type != OBJ_ZSET || ob->encoding != OBJ_ENCODING_SKIPLIST) + return; + zset *zs = (zset*)ob->ptr; + dict *d = zs->dict; + scanLaterZsetData data = {zs}; + dictDefragFunctions defragfns = {.defragAlloc = activeDefragAlloc}; + *cursor = dictScanDefrag(d, *cursor, scanLaterZsetCallback, &defragfns, &data); +} + +/* Used as scan callback when all the work is done in the dictDefragFunctions. */ +void scanCallbackCountScanned(void *privdata, const dictEntry *de) { + UNUSED(privdata); + UNUSED(de); + server.stat_active_defrag_scanned++; +} + +void scanLaterSet(robj *ob, unsigned long *cursor) { + if (ob->type != OBJ_SET || ob->encoding != OBJ_ENCODING_HT) + return; + dict *d = ob->ptr; + dictDefragFunctions defragfns = { + .defragAlloc = activeDefragAlloc, + .defragKey = (dictDefragAllocFunction *)activeDefragSds + }; + *cursor = dictScanDefrag(d, *cursor, scanCallbackCountScanned, &defragfns, NULL); +} + +void scanLaterHash(robj *ob, unsigned long *cursor) { + if (ob->type != OBJ_HASH || ob->encoding != OBJ_ENCODING_HT) + return; + dict *d = ob->ptr; + dictDefragFunctions defragfns = { + .defragAlloc = activeDefragAlloc, + .defragKey = (dictDefragAllocFunction *)activeDefragSds, + .defragVal = (dictDefragAllocFunction *)activeDefragSds + }; + *cursor = dictScanDefrag(d, *cursor, scanCallbackCountScanned, &defragfns, NULL); +} + +void defragQuicklist(redisDb *db, dictEntry *kde) { + robj *ob = dictGetVal(kde); + quicklist *ql = ob->ptr, *newql; + serverAssert(ob->type == OBJ_LIST && ob->encoding == OBJ_ENCODING_QUICKLIST); + if ((newql = activeDefragAlloc(ql))) + ob->ptr = ql = newql; + if (ql->len > server.active_defrag_max_scan_fields) + defragLater(db, kde); + else + activeDefragQuickListNodes(ql); +} + +void defragZsetSkiplist(redisDb *db, dictEntry *kde) { + robj *ob = dictGetVal(kde); + zset *zs = (zset*)ob->ptr; + zset *newzs; + zskiplist *newzsl; + dict *newdict; + dictEntry *de; + struct zskiplistNode *newheader; + serverAssert(ob->type == OBJ_ZSET && ob->encoding == OBJ_ENCODING_SKIPLIST); + if ((newzs = activeDefragAlloc(zs))) + ob->ptr = zs = newzs; + if ((newzsl = activeDefragAlloc(zs->zsl))) + zs->zsl = newzsl; + if ((newheader = activeDefragAlloc(zs->zsl->header))) + zs->zsl->header = newheader; + if (dictSize(zs->dict) > server.active_defrag_max_scan_fields) + defragLater(db, kde); + else { + dictIterator *di = dictGetIterator(zs->dict); + while((de = dictNext(di)) != NULL) { + activeDefragZsetEntry(zs, de); + } + dictReleaseIterator(di); + } + /* handle the dict struct */ + if ((newdict = activeDefragAlloc(zs->dict))) + zs->dict = newdict; + /* defrag the dict tables */ + dictDefragTables(zs->dict); +} + +void defragHash(redisDb *db, dictEntry *kde) { + robj *ob = dictGetVal(kde); + dict *d, *newd; + serverAssert(ob->type == OBJ_HASH && ob->encoding == OBJ_ENCODING_HT); + d = ob->ptr; + if (dictSize(d) > server.active_defrag_max_scan_fields) + defragLater(db, kde); + else + activeDefragSdsDict(d, DEFRAG_SDS_DICT_VAL_IS_SDS); + /* handle the dict struct */ + if ((newd = activeDefragAlloc(ob->ptr))) + ob->ptr = newd; + /* defrag the dict tables */ + dictDefragTables(ob->ptr); +} + +void defragSet(redisDb *db, dictEntry *kde) { + robj *ob = dictGetVal(kde); + dict *d, *newd; + serverAssert(ob->type == OBJ_SET && ob->encoding == OBJ_ENCODING_HT); + d = ob->ptr; + if (dictSize(d) > server.active_defrag_max_scan_fields) + defragLater(db, kde); + else + activeDefragSdsDict(d, DEFRAG_SDS_DICT_NO_VAL); + /* handle the dict struct */ + if ((newd = activeDefragAlloc(ob->ptr))) + ob->ptr = newd; + /* defrag the dict tables */ + dictDefragTables(ob->ptr); +} + +/* Defrag callback for radix tree iterator, called for each node, + * used in order to defrag the nodes allocations. */ +int defragRaxNode(raxNode **noderef) { + raxNode *newnode = activeDefragAlloc(*noderef); + if (newnode) { + *noderef = newnode; + return 1; + } + return 0; +} + +/* returns 0 if no more work needs to be been done, and 1 if time is up and more work is needed. */ +int scanLaterStreamListpacks(robj *ob, unsigned long *cursor, long long endtime) { + static unsigned char last[sizeof(streamID)]; + raxIterator ri; + long iterations = 0; + if (ob->type != OBJ_STREAM || ob->encoding != OBJ_ENCODING_STREAM) { + *cursor = 0; + return 0; + } + + stream *s = ob->ptr; + raxStart(&ri,s->rax); + if (*cursor == 0) { + /* if cursor is 0, we start new iteration */ + defragRaxNode(&s->rax->head); + /* assign the iterator node callback before the seek, so that the + * initial nodes that are processed till the first item are covered */ + ri.node_cb = defragRaxNode; + raxSeek(&ri,"^",NULL,0); + } else { + /* if cursor is non-zero, we seek to the static 'last' */ + if (!raxSeek(&ri,">", last, sizeof(last))) { + *cursor = 0; + raxStop(&ri); + return 0; + } + /* assign the iterator node callback after the seek, so that the + * initial nodes that are processed till now aren't covered */ + ri.node_cb = defragRaxNode; + } + + (*cursor)++; + while (raxNext(&ri)) { + void *newdata = activeDefragAlloc(ri.data); + if (newdata) + raxSetData(ri.node, ri.data=newdata); + server.stat_active_defrag_scanned++; + if (++iterations > 128) { + if (ustime() > endtime) { + serverAssert(ri.key_len==sizeof(last)); + memcpy(last,ri.key,ri.key_len); + raxStop(&ri); + return 1; + } + iterations = 0; + } + } + raxStop(&ri); + *cursor = 0; + return 0; +} + +/* optional callback used defrag each rax element (not including the element pointer itself) */ +typedef void *(raxDefragFunction)(raxIterator *ri, void *privdata); + +/* defrag radix tree including: + * 1) rax struct + * 2) rax nodes + * 3) rax entry data (only if defrag_data is specified) + * 4) call a callback per element, and allow the callback to return a new pointer for the element */ +void defragRadixTree(rax **raxref, int defrag_data, raxDefragFunction *element_cb, void *element_cb_data) { + raxIterator ri; + rax* rax; + if ((rax = activeDefragAlloc(*raxref))) + *raxref = rax; + rax = *raxref; + raxStart(&ri,rax); + ri.node_cb = defragRaxNode; + defragRaxNode(&rax->head); + raxSeek(&ri,"^",NULL,0); + while (raxNext(&ri)) { + void *newdata = NULL; + if (element_cb) + newdata = element_cb(&ri, element_cb_data); + if (defrag_data && !newdata) + newdata = activeDefragAlloc(ri.data); + if (newdata) + raxSetData(ri.node, ri.data=newdata); + } + raxStop(&ri); +} + +typedef struct { + streamCG *cg; + streamConsumer *c; +} PendingEntryContext; + +void* defragStreamConsumerPendingEntry(raxIterator *ri, void *privdata) { + PendingEntryContext *ctx = privdata; + streamNACK *nack = ri->data, *newnack; + nack->consumer = ctx->c; /* update nack pointer to consumer */ + newnack = activeDefragAlloc(nack); + if (newnack) { + /* update consumer group pointer to the nack */ + void *prev; + raxInsert(ctx->cg->pel, ri->key, ri->key_len, newnack, &prev); + serverAssert(prev==nack); + } + return newnack; +} + +void* defragStreamConsumer(raxIterator *ri, void *privdata) { + streamConsumer *c = ri->data; + streamCG *cg = privdata; + void *newc = activeDefragAlloc(c); + if (newc) { + c = newc; + } + sds newsds = activeDefragSds(c->name); + if (newsds) + c->name = newsds; + if (c->pel) { + PendingEntryContext pel_ctx = {cg, c}; + defragRadixTree(&c->pel, 0, defragStreamConsumerPendingEntry, &pel_ctx); + } + return newc; /* returns NULL if c was not defragged */ +} + +void* defragStreamConsumerGroup(raxIterator *ri, void *privdata) { + streamCG *cg = ri->data; + UNUSED(privdata); + if (cg->consumers) + defragRadixTree(&cg->consumers, 0, defragStreamConsumer, cg); + if (cg->pel) + defragRadixTree(&cg->pel, 0, NULL, NULL); + return NULL; +} + +void defragStream(redisDb *db, dictEntry *kde) { + robj *ob = dictGetVal(kde); + serverAssert(ob->type == OBJ_STREAM && ob->encoding == OBJ_ENCODING_STREAM); + stream *s = ob->ptr, *news; + + /* handle the main struct */ + if ((news = activeDefragAlloc(s))) + ob->ptr = s = news; + + if (raxSize(s->rax) > server.active_defrag_max_scan_fields) { + rax *newrax = activeDefragAlloc(s->rax); + if (newrax) + s->rax = newrax; + defragLater(db, kde); + } else + defragRadixTree(&s->rax, 1, NULL, NULL); + + if (s->cgroups) + defragRadixTree(&s->cgroups, 1, defragStreamConsumerGroup, NULL); +} + +/* Defrag a module key. This is either done immediately or scheduled + * for later. Returns then number of pointers defragged. + */ +void defragModule(redisDb *db, dictEntry *kde) { + robj *obj = dictGetVal(kde); + serverAssert(obj->type == OBJ_MODULE); + + if (!moduleDefragValue(dictGetKey(kde), obj, db->id)) + defragLater(db, kde); +} + +/* for each key we scan in the main dict, this function will attempt to defrag + * all the various pointers it has. Returns a stat of how many pointers were + * moved. */ +void defragKey(redisDb *db, dictEntry *de) { + sds keysds = dictGetKey(de); + robj *newob, *ob; + unsigned char *newzl; + sds newsds; + + /* Try to defrag the key name. */ + newsds = activeDefragSds(keysds); + if (newsds) { + dictSetKey(db->dict, de, newsds); + if (dictSize(db->expires)) { + /* We can't search in db->expires for that key after we've released + * the pointer it holds, since it won't be able to do the string + * compare, but we can find the entry using key hash and pointer. */ + uint64_t hash = dictGetHash(db->dict, newsds); + dictEntry *expire_de = dictFindEntryByPtrAndHash(db->expires, keysds, hash); + if (expire_de) dictSetKey(db->expires, expire_de, newsds); + } + } + + /* Try to defrag robj and / or string value. */ + ob = dictGetVal(de); + if ((newob = activeDefragStringOb(ob))) { + dictSetVal(db->dict, de, newob); + ob = newob; + } + + if (ob->type == OBJ_STRING) { + /* Already handled in activeDefragStringOb. */ + } else if (ob->type == OBJ_LIST) { + if (ob->encoding == OBJ_ENCODING_QUICKLIST) { + defragQuicklist(db, de); + } else if (ob->encoding == OBJ_ENCODING_LISTPACK) { + if ((newzl = activeDefragAlloc(ob->ptr))) + ob->ptr = newzl; + } else { + serverPanic("Unknown list encoding"); + } + } else if (ob->type == OBJ_SET) { + if (ob->encoding == OBJ_ENCODING_HT) { + defragSet(db, de); + } else if (ob->encoding == OBJ_ENCODING_INTSET || + ob->encoding == OBJ_ENCODING_LISTPACK) + { + void *newptr, *ptr = ob->ptr; + if ((newptr = activeDefragAlloc(ptr))) + ob->ptr = newptr; + } else { + serverPanic("Unknown set encoding"); + } + } else if (ob->type == OBJ_ZSET) { + if (ob->encoding == OBJ_ENCODING_LISTPACK) { + if ((newzl = activeDefragAlloc(ob->ptr))) + ob->ptr = newzl; + } else if (ob->encoding == OBJ_ENCODING_SKIPLIST) { + defragZsetSkiplist(db, de); + } else { + serverPanic("Unknown sorted set encoding"); + } + } else if (ob->type == OBJ_HASH) { + if (ob->encoding == OBJ_ENCODING_LISTPACK) { + if ((newzl = activeDefragAlloc(ob->ptr))) + ob->ptr = newzl; + } else if (ob->encoding == OBJ_ENCODING_HT) { + defragHash(db, de); + } else { + serverPanic("Unknown hash encoding"); + } + } else if (ob->type == OBJ_STREAM) { + defragStream(db, de); + } else if (ob->type == OBJ_MODULE) { + defragModule(db, de); + } else { + serverPanic("Unknown object type"); + } +} + +/* Defrag scan callback for the main db dictionary. */ +void defragScanCallback(void *privdata, const dictEntry *de) { + long long hits_before = server.stat_active_defrag_hits; + defragKey((redisDb*)privdata, (dictEntry*)de); + if (server.stat_active_defrag_hits != hits_before) + server.stat_active_defrag_key_hits++; + else + server.stat_active_defrag_key_misses++; + server.stat_active_defrag_scanned++; +} + +/* Utility function to get the fragmentation ratio from jemalloc. + * It is critical to do that by comparing only heap maps that belong to + * jemalloc, and skip ones the jemalloc keeps as spare. Since we use this + * fragmentation ratio in order to decide if a defrag action should be taken + * or not, a false detection can cause the defragmenter to waste a lot of CPU + * without the possibility of getting any results. */ +float getAllocatorFragmentation(size_t *out_frag_bytes) { + size_t resident, active, allocated; + zmalloc_get_allocator_info(&allocated, &active, &resident); + float frag_pct = ((float)active / allocated)*100 - 100; + size_t frag_bytes = active - allocated; + float rss_pct = ((float)resident / allocated)*100 - 100; + size_t rss_bytes = resident - allocated; + if(out_frag_bytes) + *out_frag_bytes = frag_bytes; + serverLog(LL_DEBUG, + "allocated=%zu, active=%zu, resident=%zu, frag=%.0f%% (%.0f%% rss), frag_bytes=%zu (%zu rss)", + allocated, active, resident, frag_pct, rss_pct, frag_bytes, rss_bytes); + return frag_pct; +} + +/* We may need to defrag other globals, one small allocation can hold a full allocator run. + * so although small, it is still important to defrag these */ +void defragOtherGlobals(void) { + + /* there are many more pointers to defrag (e.g. client argv, output / aof buffers, etc. + * but we assume most of these are short lived, we only need to defrag allocations + * that remain static for a long time */ + activeDefragSdsDict(evalScriptsDict(), DEFRAG_SDS_DICT_VAL_LUA_SCRIPT); + moduleDefragGlobals(); +} + +/* returns 0 more work may or may not be needed (see non-zero cursor), + * and 1 if time is up and more work is needed. */ +int defragLaterItem(dictEntry *de, unsigned long *cursor, long long endtime, int dbid) { + if (de) { + robj *ob = dictGetVal(de); + if (ob->type == OBJ_LIST) { + return scanLaterList(ob, cursor, endtime); + } else if (ob->type == OBJ_SET) { + scanLaterSet(ob, cursor); + } else if (ob->type == OBJ_ZSET) { + scanLaterZset(ob, cursor); + } else if (ob->type == OBJ_HASH) { + scanLaterHash(ob, cursor); + } else if (ob->type == OBJ_STREAM) { + return scanLaterStreamListpacks(ob, cursor, endtime); + } else if (ob->type == OBJ_MODULE) { + return moduleLateDefrag(dictGetKey(de), ob, cursor, endtime, dbid); + } else { + *cursor = 0; /* object type may have changed since we schedule it for later */ + } + } else { + *cursor = 0; /* object may have been deleted already */ + } + return 0; +} + +/* static variables serving defragLaterStep to continue scanning a key from were we stopped last time. */ +static sds defrag_later_current_key = NULL; +static unsigned long defrag_later_cursor = 0; + +/* returns 0 if no more work needs to be been done, and 1 if time is up and more work is needed. */ +int defragLaterStep(redisDb *db, long long endtime) { + unsigned int iterations = 0; + unsigned long long prev_defragged = server.stat_active_defrag_hits; + unsigned long long prev_scanned = server.stat_active_defrag_scanned; + long long key_defragged; + + do { + /* if we're not continuing a scan from the last call or loop, start a new one */ + if (!defrag_later_cursor) { + listNode *head = listFirst(db->defrag_later); + + /* Move on to next key */ + if (defrag_later_current_key) { + serverAssert(defrag_later_current_key == head->value); + listDelNode(db->defrag_later, head); + defrag_later_cursor = 0; + defrag_later_current_key = NULL; + } + + /* stop if we reached the last one. */ + head = listFirst(db->defrag_later); + if (!head) + return 0; + + /* start a new key */ + defrag_later_current_key = head->value; + defrag_later_cursor = 0; + } + + /* each time we enter this function we need to fetch the key from the dict again (if it still exists) */ + dictEntry *de = dictFind(db->dict, defrag_later_current_key); + key_defragged = server.stat_active_defrag_hits; + do { + int quit = 0; + if (defragLaterItem(de, &defrag_later_cursor, endtime,db->id)) + quit = 1; /* time is up, we didn't finish all the work */ + + /* Once in 16 scan iterations, 512 pointer reallocations, or 64 fields + * (if we have a lot of pointers in one hash bucket, or rehashing), + * check if we reached the time limit. */ + if (quit || (++iterations > 16 || + server.stat_active_defrag_hits - prev_defragged > 512 || + server.stat_active_defrag_scanned - prev_scanned > 64)) { + if (quit || ustime() > endtime) { + if(key_defragged != server.stat_active_defrag_hits) + server.stat_active_defrag_key_hits++; + else + server.stat_active_defrag_key_misses++; + return 1; + } + iterations = 0; + prev_defragged = server.stat_active_defrag_hits; + prev_scanned = server.stat_active_defrag_scanned; + } + } while(defrag_later_cursor); + if(key_defragged != server.stat_active_defrag_hits) + server.stat_active_defrag_key_hits++; + else + server.stat_active_defrag_key_misses++; + } while(1); +} + +#define INTERPOLATE(x, x1, x2, y1, y2) ( (y1) + ((x)-(x1)) * ((y2)-(y1)) / ((x2)-(x1)) ) +#define LIMIT(y, min, max) ((y)<(min)? min: ((y)>(max)? max: (y))) + +/* decide if defrag is needed, and at what CPU effort to invest in it */ +void computeDefragCycles(void) { + size_t frag_bytes; + float frag_pct = getAllocatorFragmentation(&frag_bytes); + /* If we're not already running, and below the threshold, exit. */ + if (!server.active_defrag_running) { + if(frag_pct < server.active_defrag_threshold_lower || frag_bytes < server.active_defrag_ignore_bytes) + return; + } + + /* Calculate the adaptive aggressiveness of the defrag */ + int cpu_pct = INTERPOLATE(frag_pct, + server.active_defrag_threshold_lower, + server.active_defrag_threshold_upper, + server.active_defrag_cycle_min, + server.active_defrag_cycle_max); + cpu_pct = LIMIT(cpu_pct, + server.active_defrag_cycle_min, + server.active_defrag_cycle_max); + /* We allow increasing the aggressiveness during a scan, but don't + * reduce it. */ + if (cpu_pct > server.active_defrag_running) { + server.active_defrag_running = cpu_pct; + serverLog(LL_VERBOSE, + "Starting active defrag, frag=%.0f%%, frag_bytes=%zu, cpu=%d%%", + frag_pct, frag_bytes, cpu_pct); + } +} + +/* Perform incremental defragmentation work from the serverCron. + * This works in a similar way to activeExpireCycle, in the sense that + * we do incremental work across calls. */ +void activeDefragCycle(void) { + static int current_db = -1; + static unsigned long cursor = 0; + static unsigned long expires_cursor = 0; + static redisDb *db = NULL; + static long long start_scan, start_stat; + unsigned int iterations = 0; + unsigned long long prev_defragged = server.stat_active_defrag_hits; + unsigned long long prev_scanned = server.stat_active_defrag_scanned; + long long start, timelimit, endtime; + mstime_t latency; + int quit = 0; + + if (!server.active_defrag_enabled) { + if (server.active_defrag_running) { + /* if active defrag was disabled mid-run, start from fresh next time. */ + server.active_defrag_running = 0; + if (db) + listEmpty(db->defrag_later); + defrag_later_current_key = NULL; + defrag_later_cursor = 0; + current_db = -1; + cursor = 0; + db = NULL; + goto update_metrics; + } + return; + } + + if (hasActiveChildProcess()) + return; /* Defragging memory while there's a fork will just do damage. */ + + /* Once a second, check if the fragmentation justfies starting a scan + * or making it more aggressive. */ + run_with_period(1000) { + computeDefragCycles(); + } + if (!server.active_defrag_running) + return; + + /* See activeExpireCycle for how timelimit is handled. */ + start = ustime(); + timelimit = 1000000*server.active_defrag_running/server.hz/100; + if (timelimit <= 0) timelimit = 1; + endtime = start + timelimit; + latencyStartMonitor(latency); + + dictDefragFunctions defragfns = {.defragAlloc = activeDefragAlloc}; + do { + /* if we're not continuing a scan from the last call or loop, start a new one */ + if (!cursor && !expires_cursor) { + /* finish any leftovers from previous db before moving to the next one */ + if (db && defragLaterStep(db, endtime)) { + quit = 1; /* time is up, we didn't finish all the work */ + break; /* this will exit the function and we'll continue on the next cycle */ + } + + /* Move on to next database, and stop if we reached the last one. */ + if (++current_db >= server.dbnum) { + /* defrag other items not part of the db / keys */ + defragOtherGlobals(); + + long long now = ustime(); + size_t frag_bytes; + float frag_pct = getAllocatorFragmentation(&frag_bytes); + serverLog(LL_VERBOSE, + "Active defrag done in %dms, reallocated=%d, frag=%.0f%%, frag_bytes=%zu", + (int)((now - start_scan)/1000), (int)(server.stat_active_defrag_hits - start_stat), frag_pct, frag_bytes); + + start_scan = now; + current_db = -1; + cursor = 0; + db = NULL; + server.active_defrag_running = 0; + + computeDefragCycles(); /* if another scan is needed, start it right away */ + if (server.active_defrag_running != 0 && ustime() < endtime) + continue; + break; + } + else if (current_db==0) { + /* Start a scan from the first database. */ + start_scan = ustime(); + start_stat = server.stat_active_defrag_hits; + } + + db = &server.db[current_db]; + cursor = 0; + } + + do { + /* before scanning the next bucket, see if we have big keys left from the previous bucket to scan */ + if (defragLaterStep(db, endtime)) { + quit = 1; /* time is up, we didn't finish all the work */ + break; /* this will exit the function and we'll continue on the next cycle */ + } + + /* Scan the keyspace dict unless we're scanning the expire dict. */ + if (!expires_cursor) + cursor = dictScanDefrag(db->dict, cursor, defragScanCallback, + &defragfns, db); + + /* When done scanning the keyspace dict, we scan the expire dict. */ + if (!cursor) + expires_cursor = dictScanDefrag(db->expires, expires_cursor, + scanCallbackCountScanned, + &defragfns, NULL); + + /* Once in 16 scan iterations, 512 pointer reallocations. or 64 keys + * (if we have a lot of pointers in one hash bucket or rehashing), + * check if we reached the time limit. + * But regardless, don't start a new db in this loop, this is because after + * the last db we call defragOtherGlobals, which must be done in one cycle */ + if (!(cursor || expires_cursor) || + ++iterations > 16 || + server.stat_active_defrag_hits - prev_defragged > 512 || + server.stat_active_defrag_scanned - prev_scanned > 64) + { + if (!cursor || ustime() > endtime) { + quit = 1; + break; + } + iterations = 0; + prev_defragged = server.stat_active_defrag_hits; + prev_scanned = server.stat_active_defrag_scanned; + } + } while((cursor || expires_cursor) && !quit); + } while(!quit); + + latencyEndMonitor(latency); + latencyAddSampleIfNeeded("active-defrag-cycle",latency); + +update_metrics: + if (server.active_defrag_running > 0) { + if (server.stat_last_active_defrag_time == 0) + elapsedStart(&server.stat_last_active_defrag_time); + } else if (server.stat_last_active_defrag_time != 0) { + server.stat_total_active_defrag_time += elapsedUs(server.stat_last_active_defrag_time); + server.stat_last_active_defrag_time = 0; + } +} + +#else /* HAVE_DEFRAG */ + +void activeDefragCycle(void) { + /* Not implemented yet. */ +} + +void *activeDefragAlloc(void *ptr) { + UNUSED(ptr); + return NULL; +} + +robj *activeDefragStringOb(robj *ob) { + UNUSED(ob); + return NULL; +} + +#endif |