Refactor incoming packet (rxQueue/fragmentQueue) to eliminate variable length queues and merge queues. This is both faster and saves memory.

node/DeferredPackets.cpp

@@ -26,8 +26,6 @@ namespace ZeroTier {
 
 DeferredPackets::DeferredPackets(const RuntimeEnvironment *renv) :
 	RR(renv),
-	_readPtr(0),
-	_writePtr(0),
 	_waiting(0),
 	_die(false)
 {
@@ -37,39 +35,45 @@ DeferredPackets::~DeferredPackets()
 {
 	_q_m.lock();
 	_die = true;
-	while (_waiting > 0) {
-		_q_m.unlock();
+	_q_m.unlock();
+
+	for(;;) {
 		_q_s.post();
+
 		_q_m.lock();
+		if (_waiting <= 0) {
+			_q_m.unlock();
+			break;
+		} else {
+			_q_m.unlock();
+		}
 	}
 }
 
 bool DeferredPackets::enqueue(IncomingPacket *pkt)
 {
-	_q_m.lock();
-	const unsigned long p = _writePtr % ZT_DEFFEREDPACKETS_MAX;
-	if (_q[p]) {
-		_q_m.unlock();
-		return false;
-	} else {
-		_q[p].setToUnsafe(pkt);
-		++_writePtr;
-		_q_m.unlock();
-		_q_s.post();
-		return true;
+	{
+		Mutex::Lock _l(_q_m);
+		if (_q.size() >= ZT_DEFFEREDPACKETS_MAX)
+			return false;
+		_q.push_back(*pkt);
 	}
+	_q_s.post();
+	return true;
 }
 
 int DeferredPackets::process()
 {
-	SharedPtr<IncomingPacket> pkt;
+	std::list<IncomingPacket> pkt;
 
 	_q_m.lock();
+
 	if (_die) {
 		_q_m.unlock();
 		return -1;
 	}
-	while (_readPtr == _writePtr) {
+
+	while (_q.empty()) {
 		++_waiting;
 		_q_m.unlock();
 		_q_s.wait();
@@ -80,10 +84,16 @@ int DeferredPackets::process()
 			return -1;
 		}
 	}
-	pkt.swap(_q[_readPtr++ % ZT_DEFFEREDPACKETS_MAX]);
+
+	// Move item from _q list to a dummy list here to avoid copying packet
+	pkt.splice(pkt.end(),_q,_q.begin());
+
 	_q_m.unlock();
 
-	pkt->tryDecode(RR,true);
+	try {
+		pkt.front().tryDecode(RR,true);
+	} catch ( ... ) {} // drop invalids
+
 	return 1;
 }