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Cache serialized mapblocks during sending

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This reduces the
(absolute) time spent in Server::SendBlocks() from 700ms to 300ms
(relative) share of MapBlock::serialize() from 80% to 60%
in a test setup with 10 players and many block changes
This commit is contained in:
sfan5 2022-05-05 22:03:49 +02:00
parent 7fff9da71d
commit 1fa4f58080
2 changed files with 45 additions and 13 deletions
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44
src/server.cpp
View File

@ -2326,22 +2326,34 @@ void Server::sendMetadataChanged(const std::list<v3s16> &meta_updates, float far
}
void Server::SendBlockNoLock(session_t peer_id, MapBlock *block, u8 ver,
u16 net_proto_version)
u16 net_proto_version, SerializedBlockCache *cache)
{
/*
Create a packet with the block in the right format
*/
thread_local const int net_compression_level = rangelim(g_settings->getS16("map_compression_level_net"), -1, 9);
std::ostringstream os(std::ios_base::binary);
block->serialize(os, ver, false, net_compression_level);
block->serializeNetworkSpecific(os);
std::string s = os.str();
std::string s, *sptr = nullptr;
NetworkPacket pkt(TOCLIENT_BLOCKDATA, 2 + 2 + 2 + s.size(), peer_id);
if (cache) {
auto it = cache->find({block->getPos(), ver});
if (it != cache->end())
sptr = &it->second;
}
// Serialize the block in the right format
if (!sptr) {
std::ostringstream os(std::ios_base::binary);
block->serialize(os, ver, false, net_compression_level);
block->serializeNetworkSpecific(os);
s = os.str();
sptr = &s;
}
NetworkPacket pkt(TOCLIENT_BLOCKDATA, 2 + 2 + 2 + sptr->size(), peer_id);
pkt << block->getPos();
pkt.putRawString(s.c_str(), s.size());
pkt.putRawString(*sptr);
Send(&pkt);
// Store away in cache
if (cache && sptr == &s)
(*cache)[{block->getPos(), ver}] = std::move(s);
}
void Server::SendBlocks(float dtime)
@ -2351,7 +2363,7 @@ void Server::SendBlocks(float dtime)
std::vector<PrioritySortedBlockTransfer> queue;
u32 total_sending = 0;
u32 total_sending = 0, unique_clients = 0;
{
ScopeProfiler sp2(g_profiler, "Server::SendBlocks(): Collect list");
@ -2366,7 +2378,9 @@ void Server::SendBlocks(float dtime)
continue;
total_sending += client->getSendingCount();
const auto old_count = queue.size();
client->GetNextBlocks(m_env,m_emerge, dtime, queue);
unique_clients += queue.size() > old_count ? 1 : 0;
}
}
@ -2385,6 +2399,12 @@ void Server::SendBlocks(float dtime)
ScopeProfiler sp(g_profiler, "Server::SendBlocks(): Send to clients");
Map &map = m_env->getMap();
SerializedBlockCache cache, *cache_ptr = nullptr;
if (unique_clients > 1) {
// caching is pointless with a single client
cache_ptr = &cache;
}
for (const PrioritySortedBlockTransfer &block_to_send : queue) {
if (total_sending >= max_blocks_to_send)
break;
@ -2399,7 +2419,7 @@ void Server::SendBlocks(float dtime)
continue;
SendBlockNoLock(block_to_send.peer_id, block, client->serialization_version,
client->net_proto_version);
client->net_proto_version, cache_ptr);
client->SentBlock(block_to_send.pos);
total_sending++;

14
src/server.h
View File

@ -424,6 +424,16 @@ private:
std::unordered_set<session_t> waiting_players;
};
// the standard library does not implement std::hash for pairs so we have this:
struct SBCHash {
size_t operator() (const std::pair<v3s16, u16> &p) const {
return (((size_t) p.first.X) << 48) | (((size_t) p.first.Y) << 32) |
(((size_t) p.first.Z) << 16) | ((size_t) p.second);
}
};
typedef std::unordered_map<std::pair<v3s16, u16>, std::string, SBCHash> SerializedBlockCache;
void init();
void SendMovement(session_t peer_id);
@ -484,7 +494,9 @@ private:
float far_d_nodes = 100);
// Environment and Connection must be locked when called
void SendBlockNoLock(session_t peer_id, MapBlock *block, u8 ver, u16 net_proto_version);
// `cache` may only be very short lived! (invalidation not handeled)
void SendBlockNoLock(session_t peer_id, MapBlock *block, u8 ver,
u16 net_proto_version, SerializedBlockCache *cache = nullptr);
// Sends blocks to clients (locks env and con on its own)
void SendBlocks(float dtime);