memory usage estimation for memcached entries (#586)

* do a more accurate memory usage estimation for memcached entries
* early exit when checking memcache usage

1 files changed, 24 insertions, 5 deletions

diff --git a/src/zenserver/cache/cachedisklayer.cpp b/src/zenserver/cache/cachedisklayer.cpp
index 2c344dd1d..05eb9658b 100644
--- a/src/zenserver/cache/cachedisklayer.cpp
+++ b/src/zenserver/cache/cachedisklayer.cpp
@@ -209,6 +209,9 @@ namespace {
 			zen::Sleep(100);
 		} while (true);
 	}
+
+	uint64_t EstimateMemCachePayloadMemory(uint64_t PayloadSize) { return 8u + 32u + RoundUp(PayloadSize, 8u); }
+
 }  // namespace
 
 namespace fs = std::filesystem;
@@ -1289,14 +1292,26 @@ ZenCacheDiskLayer::CacheBucket::MemCacheTrim(GcClock::TimePoint ExpireTime)
 	GcClock::Tick ExpireTicks = ExpireTime.time_since_epoch().count();
 
 	RwLock::ExclusiveLockScope _(m_IndexLock);
+	if (m_MemCachedPayloads.empty())
+	{
+		return;
+	}
 	for (const auto& Kv : m_Index)
 	{
-		if (m_AccessTimes[Kv.second] < ExpireTicks)
+		size_t		   Index   = Kv.second;
+		BucketPayload& Payload = m_Payloads[Index];
+		if (!Payload.MemCached)
+		{
+			continue;
+		}
+		if (m_AccessTimes[Index] < ExpireTicks)
 		{
-			BucketPayload& Payload = m_Payloads[Kv.second];
 			RemoveMemCachedData(Payload);
 		}
 	}
+	m_MemCachedPayloads.shrink_to_fit();
+	m_FreeMemCachedPayloads.shrink_to_fit();
+	m_FreeMetaDatas.shrink_to_fit();
 }
 
 void
@@ -1305,6 +1320,10 @@ ZenCacheDiskLayer::CacheBucket::GetUsageByAccess(GcClock::TimePoint		TickStart,
 												 std::vector<uint64_t>& InOutUsageSlots)
 {
 	RwLock::SharedLockScope _(m_IndexLock);
+	if (m_MemCachedPayloads.empty())
+	{
+		return;
+	}
 	for (const auto& It : m_Index)
 	{
 		size_t		   Index   = It.second;
@@ -2630,7 +2649,7 @@ ZenCacheDiskLayer::CacheBucket::SetMemCachedData(BucketPayload& Payload, IoBuffe
 		{
 			Payload.MemCached = MemCachedIndex(gsl::narrow<uint32_t>(m_MemCachedPayloads.size()));
 			m_MemCachedPayloads.push_back(MemCachedData);
-			AddMemCacheUsage(PayloadSize);
+			AddMemCacheUsage(EstimateMemCachePayloadMemory(PayloadSize));
 			m_MemoryWriteCount++;
 		}
 	}
@@ -2639,7 +2658,7 @@ ZenCacheDiskLayer::CacheBucket::SetMemCachedData(BucketPayload& Payload, IoBuffe
 		Payload.MemCached = m_FreeMemCachedPayloads.back();
 		m_FreeMemCachedPayloads.pop_back();
 		m_MemCachedPayloads[Payload.MemCached] = MemCachedData;
-		AddMemCacheUsage(PayloadSize);
+		AddMemCacheUsage(EstimateMemCachePayloadMemory(PayloadSize));
 		m_MemoryWriteCount++;
 	}
 }
@@ -2650,7 +2669,7 @@ ZenCacheDiskLayer::CacheBucket::RemoveMemCachedData(BucketPayload& Payload)
 	if (Payload.MemCached)
 	{
 		size_t PayloadSize = m_MemCachedPayloads[Payload.MemCached].GetSize();
-		RemoveMemCacheUsage(PayloadSize);
+		RemoveMemCacheUsage(EstimateMemCachePayloadMemory(PayloadSize));
 		m_MemCachedPayloads[Payload.MemCached] = IoBuffer{};
 		m_FreeMemCachedPayloads.push_back(Payload.MemCached);
 		Payload.MemCached = {};