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Unshare object to avoid LRU/LFU being messed up. #250

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merged 3 commits into from
Jun 1, 2024
Merged

Unshare object to avoid LRU/LFU being messed up. #250

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16e60ff
Unshare object to avoid LRU/LFU being messed up.
CharlesChen888 Apr 7, 2024
a590629
Move canUseSharedObject to server.h.
CharlesChen888 May 6, 2024
43584f9
Add test for unsharing object.
CharlesChen888 May 6, 2024
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4 changes: 4 additions & 0 deletions src/db.c
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Original file line number Diff line number Diff line change
Expand Up @@ -122,6 +122,10 @@ robj *lookupKey(serverDb *db, robj *key, int flags) {
server.current_client->cmd->proc != touchCommand)
flags |= LOOKUP_NOTOUCH;
if (!hasActiveChildProcess() && !(flags & LOOKUP_NOTOUCH)) {
if (!canUseSharedObject() && val->refcount == OBJ_SHARED_REFCOUNT) {
val = dupStringObject(val);
kvstoreDictSetVal(db->keys, getKeySlot(key->ptr), de, val);
}
if (server.maxmemory_policy & MAXMEMORY_FLAG_LFU) {
updateLFU(val);
} else {
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6 changes: 4 additions & 2 deletions src/object.c
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Expand Up @@ -647,8 +647,10 @@ robj *tryObjectEncodingEx(robj *o, int try_trim) {
* Note that we avoid using shared integers when maxmemory is used
* because every object needs to have a private LRU field for the LRU
* algorithm to work well. */
if ((server.maxmemory == 0 || !(server.maxmemory_policy & MAXMEMORY_FLAG_NO_SHARED_INTEGERS)) && value >= 0 &&
value < OBJ_SHARED_INTEGERS) {
if (canUseSharedObject() &&
value >= 0 &&
value < OBJ_SHARED_INTEGERS)
{
decrRefCount(o);
return shared.integers[value];
} else {
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3 changes: 3 additions & 0 deletions src/server.h
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Expand Up @@ -2852,6 +2852,9 @@ int collateStringObjects(const robj *a, const robj *b);
int equalStringObjects(robj *a, robj *b);
unsigned long long estimateObjectIdleTime(robj *o);
void trimStringObjectIfNeeded(robj *o, int trim_small_values);
static inline int canUseSharedObject(void) {
return server.maxmemory == 0 || !(server.maxmemory_policy & MAXMEMORY_FLAG_NO_SHARED_INTEGERS);
}
#define sdsEncodedObject(objptr) (objptr->encoding == OBJ_ENCODING_RAW || objptr->encoding == OBJ_ENCODING_EMBSTR)

/* Synchronous I/O with timeout */
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15 changes: 15 additions & 0 deletions tests/unit/maxmemory.tcl
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Expand Up @@ -168,6 +168,21 @@ start_server {tags {"maxmemory external:skip"}} {
r config set maxmemory 0
}

test "Shared integers are unshared with maxmemory and LRU policy" {
r set a 1
r set b 1
assert_refcount_morethan a 1
assert_refcount_morethan b 1
r config set maxmemory 1073741824
r config set maxmemory-policy allkeys-lru
r get a
assert_refcount 1 a
r config set maxmemory-policy volatile-lru
r get b
assert_refcount 1 b
r config set maxmemory 0
}

foreach policy {
allkeys-random allkeys-lru allkeys-lfu volatile-lru volatile-lfu volatile-random volatile-ttl
} {
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