std::pair<const MockMc::Item*, uint64_t> MockMc::gets(folly::StringPiece key) {
auto it = findUnexpired(key);
if (it == citems_.end() || it->second.state != CacheItem::CACHE) {
return std::make_pair<Item*, uint64_t>(nullptr, 0);
}
return std::make_pair(&it->second.item, it->second.casToken);
}
/**
* @return: (item, 0) On a hit.
* (stale_item, token) On a miss.
* (stale_item, 1) On a hot miss (another lease outstanding).
*/
std::pair<MockMc::Item*, uint64_t> MockMc::leaseGet(folly::StringPiece key) {
auto it = findUnexpired(key);
if (it == citems_.end()) {
/* Lease get on a non-existing item: create a new empty item and
put it in TLRU with valid token */
it = citems_.insert(
std::make_pair(key.str(),
CacheItem(Item(folly::IOBuf::copyBuffer(""))))).first;
it->second.state = CacheItem::TLRU;
it->second.updateToken();
}
auto& citem = it->second;
switch (citem.state) {
case CacheItem::CACHE:
/* Regular hit */
return std::make_pair(&citem.item, 0);
case CacheItem::TLRU:
/* First lease-get for a TLRU item, return with a valid token */
citem.state = CacheItem::TLRU_HOT;
return std::make_pair(&citem.item, citem.token);
case CacheItem::TLRU_HOT:
/* TLRU item with other lease-gets pending, return a hot miss token
(special value 1). Note: in real memcached this state would
revert to TLRU after a timeout. */
return std::make_pair(&citem.item, 1);
}
CHECK(false);
}
MockMc::Item* MockMc::get(folly::StringPiece key) {
auto it = findUnexpired(key);
if (it == citems_.end() || it->second.state != CacheItem::CACHE) {
return nullptr;
}
return &it->second.item;
}
bool MockMc::append(folly::StringPiece key, Item suffix) {
auto it = findUnexpired(key);
if (it == citems_.end() || it->second.state != CacheItem::CACHE) {
return false;
}
auto& item = it->second.item;
item.value->appendChain(std::move(suffix.value));
return true;
}
bool MockMc::touch(folly::StringPiece key, int32_t newExptime) {
auto it = findUnexpired(key);
if (it == citems_.end() || it->second.state != CacheItem::CACHE) {
return false;
}
it->second.item.exptime = newExptime != 0 && newExptime <= 60 * 60 * 24 * 30
? newExptime + time(nullptr)
: newExptime;
return true;
}
std::pair<bool, int64_t> MockMc::arith(folly::StringPiece key, int64_t delta) {
auto it = findUnexpired(key);
if (it == citems_.end() || it->second.state != CacheItem::CACHE) {
return std::make_pair(false, 0);
}
auto oldval = folly::to<uint64_t>(coalesceAndGetRange(it->second.item.value));
auto newval = folly::to<std::string>(oldval + delta);
it->second.updateCasToken();
it->second.item.value = folly::IOBuf::copyBuffer(newval);
return std::make_pair(true, oldval + delta);
}
MockMc::CasResult
MockMc::cas(folly::StringPiece key, Item item, uint64_t token) {
auto it = findUnexpired(key);
if (it == citems_.end() || it->second.state != CacheItem::CACHE) {
return CasResult::NOT_FOUND;
}
if (it->second.casToken != token) {
return CasResult::EXISTS;
}
set(key, std::move(item));
return CasResult::STORED;
}
bool MockMc::del(folly::StringPiece key) {
auto it = findUnexpired(key);
if (it != citems_.end()) {
bool deleted = false;
/* Delete moves items from CACHE to TLRU, and always bumps lease tokens */
if (it->second.state == CacheItem::CACHE) {
deleted = true;
it->second.state = CacheItem::TLRU;
}
it->second.updateToken();
return deleted;
}
return false;
}
MockMc::LeaseSetResult
MockMc::leaseSet(folly::StringPiece key, Item item, uint64_t token) {
auto it = findUnexpired(key);
if (it == citems_.end()) {
/* Item doesn't exist in cache or TLRU */
return LeaseSetResult::NOT_STORED;
}
auto& citem = it->second;
if (citem.state == CacheItem::CACHE || citem.leaseToken == token) {
/* Either the item is a hit, or the token is valid. Regular set */
set(key, std::move(item));
return LeaseSetResult::STORED;
} else {
/* The token is not valid (expired or wrong), but the value is in TLRU.
Update the value but don't promote to cache. */
citem.item = std::move(item);
return LeaseSetResult::STALE_STORED;
}
}
