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Add support for nesting snapshots

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Former-commit-id: 5e6c37f388233cc3f2d204ad17ac2897d3333a21
This commit is contained in:
John Sully 2019-11-23 19:02:50 -05:00
parent 417388bd7a
commit b0278f5609
2 changed files with 102 additions and 43 deletions
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110
src/db.cpp
View File

@ -647,7 +647,7 @@ bool redisDbPersistentData::iterate(std::function<bool(const char*, robj*)> fn)
}
dictReleaseIterator(di);
if (m_pdbSnapshot != nullptr)
if (fResult && m_pdbSnapshot != nullptr)
{
fResult = m_pdbSnapshot->iterate([&](const char *key){
// Before passing off to the user we need to make sure it's not already in the
@ -671,7 +671,7 @@ bool redisDbPersistentData::iterate(std::function<bool(const char*, robj*)> fn)
bool redisDbPersistentData::iterate_threadsafe(std::function<bool(const char*, robj_roptr o)> fn) const
{
dictIterator *di = dictGetSafeIterator(m_pdict);
dictIterator *di = dictGetIterator(m_pdict);
dictEntry *de = nullptr;
bool fResult = true;
@ -685,7 +685,7 @@ bool redisDbPersistentData::iterate_threadsafe(std::function<bool(const char*, r
}
dictReleaseIterator(di);
if (m_pdbSnapshot != nullptr)
if (fResult && m_pdbSnapshot != nullptr)
{
fResult = m_pdbSnapshot->iterate_threadsafe([&](const char *key, robj_roptr o){
// Before passing off to the user we need to make sure it's not already in the
@ -707,7 +707,7 @@ bool redisDbPersistentData::iterate_threadsafe(std::function<bool(const char*, r
bool redisDbPersistentData::iterate(std::function<bool(const char*)> fn) const
{
dictIterator *di = dictGetSafeIterator(m_pdict);
dictIterator *di = dictGetIterator(m_pdict);
dictEntry *de = nullptr;
bool fResult = true;
while((de = dictNext(di)) != nullptr)
@ -720,7 +720,7 @@ bool redisDbPersistentData::iterate(std::function<bool(const char*)> fn) const
}
dictReleaseIterator(di);
if (m_pdbSnapshot != nullptr)
if (fResult && m_pdbSnapshot != nullptr)
{
fResult = m_pdbSnapshot->iterate([&](const char *key){
// Before passing off to the user we need to make sure it's not already in the
@ -740,14 +740,17 @@ bool redisDbPersistentData::iterate(std::function<bool(const char*)> fn) const
return fResult;
}
void keysCommandCore(client *c, const redisDbPersistentData *db, sds pattern)
client *createFakeClient(void);
void freeFakeClient(client *);
void keysCommandCore(client *cIn, const redisDbPersistentData *db, sds pattern)
{
int plen = sdslen(pattern), allkeys;
unsigned long numkeys = 0;
aeAcquireLock();
void *replylen = addReplyDeferredLenAsync(c);
aeReleaseLock();
client *c = createFakeClient();
c->flags |= CLIENT_FORCE_REPLY;
void *replylen = addReplyDeferredLen(c);
allkeys = (pattern[0] == '*' && pattern[1] == '\0');
db->iterate([&](const char *key)->bool {
@ -756,17 +759,28 @@ void keysCommandCore(client *c, const redisDbPersistentData *db, sds pattern)
if (allkeys || stringmatchlen(pattern,plen,key,sdslen(key),0)) {
keyobj = createStringObject(key,sdslen(key));
if (!keyIsExpired(c->db,keyobj)) {
aeAcquireLock();
addReplyBulkAsync(c,keyobj);
aeReleaseLock();
addReplyBulk(c,keyobj);
numkeys++;
}
decrRefCount(keyobj);
}
return true;
return !(cIn->flags.load(std::memory_order_relaxed) & CLIENT_CLOSE_ASAP);
});
setDeferredArrayLenAsync(c,replylen,numkeys);
setDeferredArrayLen(c,replylen,numkeys);
aeAcquireLock();
addReplyProtoAsync(cIn, c->buf, c->bufpos);
listIter li;
listNode *ln;
listRewind(c->reply, &li);
while ((ln = listNext(&li)) != nullptr)
{
clientReplyBlock *block = (clientReplyBlock*)listNodeValue(ln);
addReplyProtoAsync(cIn, block->buf(), block->used);
}
aeReleaseLock();
freeFakeClient(c);
}
int prepareClientToWrite(client *c, bool fAsync);
@ -2076,7 +2090,7 @@ void redisDbPersistentData::ensure(const char *sdsKey, dictEntry **pde)
dictEntry *deTombstone = dictFind(m_pdictTombstone, sdsKey);
if (deTombstone == nullptr)
{
auto itr = m_pdbSnapshot->find(sdsKey);
auto itr = m_pdbSnapshot->find_threadsafe(sdsKey);
if (itr == m_pdbSnapshot->end())
return; // not found
if (itr.val()->getrefcount(std::memory_order_relaxed) == OBJ_SHARED_REFCOUNT)
@ -2165,6 +2179,8 @@ void redisDbPersistentData::processChanges()
const redisDbPersistentData *redisDbPersistentData::createSnapshot(uint64_t mvccCheckpoint)
{
serverAssert(GlobalLocksAcquired());
serverAssert(m_refCount == 0); // do not call this on a snapshot
bool fNested = false;
if (m_spdbSnapshotHOLDER != nullptr)
{
if (mvccCheckpoint <= m_spdbSnapshotHOLDER->mvccCheckpoint)
@ -2173,14 +2189,15 @@ const redisDbPersistentData *redisDbPersistentData::createSnapshot(uint64_t mvcc
return m_spdbSnapshotHOLDER.get();
}
serverLog(LL_WARNING, "Nested snapshot created");
fNested = true;
}
auto spdb = std::unique_ptr<redisDbPersistentData>(new (MALLOC_LOCAL) redisDbPersistentData());
spdb->m_fAllChanged = false;
spdb->m_fTrackingChanges = 0;
spdb->m_pdict = m_pdict;
spdb->m_pdict->iterators++;
spdb->m_pdictTombstone = m_pdictTombstone;
spdb->m_pdict->iterators++; // fake an iterator so it doesn't rehash
spdb->m_spdbSnapshotHOLDER = std::move(m_spdbSnapshotHOLDER);
spdb->m_pdbSnapshot = m_pdbSnapshot;
spdb->m_refCount = 1;
@ -2191,6 +2208,8 @@ const redisDbPersistentData *redisDbPersistentData::createSnapshot(uint64_t mvcc
m_pdictTombstone = dictCreate(&dbDictType, this);
m_setexpire = new (MALLOC_LOCAL) expireset();
serverAssert(spdb->m_pdict->iterators == 1);
m_spdbSnapshotHOLDER = std::move(spdb);
m_pdbSnapshot = m_spdbSnapshotHOLDER.get();
@ -2234,14 +2253,18 @@ void redisDbPersistentData::endSnapshot(const redisDbPersistentData *psnapshot)
return;
}
// Alright we're ready to be free'd, but first dump all the refs on our child snapshots
if (m_spdbSnapshotHOLDER->m_refCount == 1)
recursiveFreeSnapshots(m_spdbSnapshotHOLDER.get());
m_spdbSnapshotHOLDER->m_refCount--;
if (m_spdbSnapshotHOLDER->m_refCount > 0)
return;
serverAssert(m_spdbSnapshotHOLDER->m_refCount == 0);
serverAssert((m_refCount == 0 && m_pdict->iterators == 0) || (m_refCount != 0 && m_pdict->iterators == 1));
// Alright we're ready to be free'd, but first dump all the refs on our child snapshots
recursiveFreeSnapshots(m_spdbSnapshotHOLDER.get());
serverAssert(m_spdbSnapshotHOLDER->m_pdict->iterators == 1); // All iterators should have been free'd except the fake one from createSnapshot
if (m_refCount == 0)
m_spdbSnapshotHOLDER->m_pdict->iterators--;
if (m_pdbSnapshot == nullptr)
@ -2311,9 +2334,15 @@ void redisDbPersistentData::endSnapshot(const redisDbPersistentData *psnapshot)
{
m_pdbSnapshot = nullptr;
}
// Fixup the about to free'd snapshots iterator count so the dtor doesn't complain
if (m_refCount)
m_spdbSnapshotHOLDER->m_pdict->iterators--;
m_spdbSnapshotHOLDER = std::move(m_spdbSnapshotHOLDER->m_spdbSnapshotHOLDER);
serverAssert(m_spdbSnapshotHOLDER != nullptr || m_pdbSnapshot == nullptr);
serverAssert(m_pdbSnapshot == m_spdbSnapshotHOLDER.get() || m_pdbSnapshot == nullptr);
serverAssert((m_refCount == 0 && m_pdict->iterators == 0) || (m_refCount != 0 && m_pdict->iterators == 1));
}
redisDbPersistentData::~redisDbPersistentData()
@ -2321,8 +2350,51 @@ redisDbPersistentData::~redisDbPersistentData()
serverAssert(m_spdbSnapshotHOLDER == nullptr);
serverAssert(m_pdbSnapshot == nullptr);
serverAssert(m_refCount == 0);
serverAssert(m_pdict->iterators == 0);
dictRelease(m_pdict);
if (m_pdictTombstone)
dictRelease(m_pdictTombstone);
delete m_setexpire;
}
dict_iter redisDbPersistentData::random()
{
if (size() == 0)
return dict_iter(nullptr);
if (m_pdbSnapshot != nullptr && m_pdbSnapshot->size() > 0)
{
dict_iter iter(nullptr);
double pctInSnapshot = (double)m_pdbSnapshot->size() / (size() + m_pdbSnapshot->size());
double randval = (double)rand()/RAND_MAX;
if (randval <= pctInSnapshot)
{
iter = m_pdbSnapshot->random_threadsafe();
ensure(iter.key());
dictEntry *de = dictFind(m_pdict, iter.key());
return dict_iter(de);
}
}
dictEntry *de = dictGetRandomKey(m_pdict);
if (de != nullptr)
ensure((const char*)dictGetKey(de), &de);
return dict_iter(de);
}
dict_iter redisDbPersistentData::random_threadsafe() const
{
if (size() == 0)
return dict_iter(nullptr);
if (m_pdbSnapshot != nullptr && m_pdbSnapshot->size() > 0)
{
dict_iter iter(nullptr);
double pctInSnapshot = (double)m_pdbSnapshot->size() / (size() + m_pdbSnapshot->size());
double randval = (double)rand()/RAND_MAX;
if (randval <= pctInSnapshot)
{
return m_pdbSnapshot->random_threadsafe();
}
}
serverAssert(dictSize(m_pdict) > 0);
dictEntry *de = dictGetRandomKey(m_pdict);
return dict_iter(de);
}

33
src/server.h
View File

@ -1229,28 +1229,7 @@ public:
return find(szFromObj(key));
}
dict_iter random()
{
if (size() == 0)
return dict_iter(nullptr);
if (m_pdbSnapshot != nullptr && m_pdbSnapshot->size() > 0)
{
dict_iter iter(nullptr);
double pctInSnapshot = (double)m_pdbSnapshot->size() / (size() + m_pdbSnapshot->size());
double randval = (double)rand()/RAND_MAX;
if (randval <= pctInSnapshot)
{
iter = m_pdbSnapshot->random();
ensure(iter.key());
dictEntry *de = dictFind(m_pdict, iter.key());
return dict_iter(de);
}
}
dictEntry *de = dictGetRandomKey(m_pdict);
if (de != nullptr)
ensure((const char*)dictGetKey(de), &de);
return dict_iter(de);
}
dict_iter random();
const expireEntry &random_expire()
{
@ -1309,6 +1288,14 @@ private:
void storeKey(const char *key, size_t cchKey, robj *o);
void recursiveFreeSnapshots(redisDbPersistentData *psnapshot);
// These do not call ENSURE and so may have a NULL object
dict_iter random_threadsafe() const;
dict_iter find_threadsafe(const char *key) const
{
dictEntry *de = dictFind(m_pdict, key);
return dict_iter(de);
}
// Keyspace
dict *m_pdict = nullptr; /* The keyspace for this DB */
dict *m_pdictTombstone = nullptr; /* Track deletes when we have a snapshot */
@ -1324,7 +1311,7 @@ private:
// These two pointers are the same, UNLESS the database has been cleared.
// in which case m_pdbSnapshot is NULL and we continue as though we weren'
// in a snapshot
redisDbPersistentData *m_pdbSnapshot = nullptr;
const redisDbPersistentData *m_pdbSnapshot = nullptr;
std::unique_ptr<redisDbPersistentData> m_spdbSnapshotHOLDER;
int m_refCount = 0;
};