private DataKey* LookupKey(DataKey* rqs, bool deleteKey = false)
{
var level = 0;
var he = _htable + (rqs->hash & _hashMask);
do
{
if (he->IsList)
{
DataKey* cp = he->List, nx;
for (DataKey* wx = null; cp != null; wx = cp, cp = nx)
{
nx = cp->next;
// check eviction opportunities.
if (IsExpired(cp))
{
var expired = DataKey.Equal(cp, rqs);
he->Pop(wx);
DeleteKey(cp);
if (expired) break;
cp = wx;
continue;
}
// check if we have a clean match.
if (DataKey.Equal(cp, rqs))
{
if (!deleteKey)
return LruUpdate(cp);
he->Pop(wx);
DeleteKey(cp);
return null;
}
}
}
else
{
var htp = _hashBits + iHSubBits * level++;
htp = (int)(rqs->hash >> htp) & iHSubMask;
he = he->Htab + htp;
continue;
}
// if command can append to cache, request entry will be consumed.
if (!ReqsAdds.Has(rqs->opcode) || deleteKey)
return null;
Stats.CurrentItems++;
// create new data key for the request.
var nk = GetDk(rqs->KeySize);
_copy_with_key(nk, rqs);
// add new key to the head of LRU list.
var head = _lruHead;
nk->lrup = null;
if (head != null) { nk->lrux = head; head->lrup = nk; }
else _lruTail = nk;
var hmax = he->Push(_lruHead = nk);
if (hmax > 8 && hmax > 8 + level * 2 && level < 3)
he->Split(GetBucket(), _hashBits + level * iHSubBits, iHSubMask);
return nk;
} while (true);
}
private DataKey* LruUpdate(DataKey* cp)
{
if (_lruHead != cp)
{
DataKey* prev = cp->lrup, lx = cp->lrux;
prev->lrux = lx;
if (lx != null) lx->lrup = prev;
else _lruTail = prev;
cp->lrup = null; cp->lrux = _lruHead;
_lruHead->lrup = cp;
_lruHead = cp;
}
return cp;
}
private byte* ParsePacket(byte* cp, byte* ep)
{
var left = (int)(ep - cp);
if (left < SizeofPacket)
return SaveIntoSplit(cp, left);
var cr = (Packet*)cp;
if (cr->magic != 0x80)
throw new SerializationException("magic byte");
if (_ce == null)
{
// create new datakey and add it to the list.
_ce = GetDk(cr);
if (_clist == null) _clist = _ce;
else _clast->next = _ce;
_clast = _ce;
}
int xsz = cr->extlen, xks = xsz + _ce->KeySize;
// buffer may split on extras or key part.
if (xks > left - SizeofPacket)
return SaveIntoSplit(cp, left);
// copy key and extras bytes into place.
cp += sizeof(Packet);
_set_key(_ce, cp + xsz);
if (xsz > 0) _ce->SetExtras(cp, xsz);
return cp + xks;
}
private void DeleteKey(DataKey* dk)
{
// remove entry from LRU list.
DataKey* prev = dk->lrup, next = dk->lrux;
if (next == null)
if ((_lruTail = prev) != null)
prev->lrux = null;
else _lruHead = null;
else
{
next->lrup = prev;
if (prev != null) prev->lrux = next;
else _lruHead = next;
}
// free key-mem and release val-mem.
FreeDk(dk);
}
public override int ParseExecuteRequest()
{
if (_stackSize > 512 * 1024)
throw new InvalidOperationException("request-too-big");
// allocate space on stack for request headers and keys.
_clist = _clast = _ce = null;
byte* sp = stackalloc byte[_stackSize + iDataKeyLimit];
_split = _ep = sp + _stackSize;
_cp = sp;
// parse storage data into request entries.
var bytesIn = _data.ContentSize;
ParseRequests(_data);
if (_ce != null)
throw new SerializationException("corrupt memcached byte stream");
// run requests through cache instance, copy results into storage and release values.
try
{
_cache.ExecuteBatch(_clist, bytesIn);
OutputResponse(_data.Reset());
}
finally
{
_cache.ReleaseValues(_clist, (uint)_data.ContentSize);
_stackSize = 0;
}
return 0;
}