release RPC recording memory early (#627)

previously the segment would call `clear()` on the `m_Entries` vector but this does not release the backing memory so we have to do the `swap` dance

1 files changed, 7 insertions, 2 deletions

diff --git a/src/zenutil/cache/rpcrecording.cpp b/src/zenutil/cache/rpcrecording.cpp
index b8f9d65ef..5e00e8852 100644
--- a/src/zenutil/cache/rpcrecording.cpp
+++ b/src/zenutil/cache/rpcrecording.cpp
@@ -425,7 +425,7 @@ RecordedRequestsSegmentWriter::EndWrite()
 		CbObjectWriter Cbo;
 		Cbo << "time_start" << m_StartTime << "time_end" << m_EndTime << "duration" << Duration;
 		Cbo << "segment_index" << m_SegmentIndex;
-		Cbo << "entry_count" << m_Entries.size() << "entry_size" << sizeof(RecordedRequest);
+		Cbo << "entry_count" << m_RequestCount << "entry_size" << sizeof(RecordedRequest);
 		Cbo << "block_size" << RecordedRequestBlockSize << "standalone_threshold" << StandaloneFileSizeThreshold;
 
 		Cbo.BeginObject("system_info");
@@ -446,7 +446,12 @@ RecordedRequestsSegmentWriter::EndWrite()
 	std::error_code Ec;
 	IndexFile.WriteAll(IndexBuffer, Ec);
 	IndexFile.Close();
-	m_Entries.clear();
+
+	// note that simply calling `.reset()` here will *not* release backing memory
+	// and it's important that we do because on high traffic servers this will use
+	// a lot of memory otherwise
+	std::vector<RecordedRequest> EmptyEntries;
+	swap(m_Entries, EmptyEntries);
 }
 
 uint64_t