QUIC: Add memory_reduction_timeout configuration

api/envoy/config/core/v3/protocol.proto

@@ -57,7 +57,7 @@ message QuicKeepAliveSettings {
 }
 
 // QUIC protocol options which apply to both downstream and upstream connections.
-// [#next-free-field: 12]
+// [#next-free-field: 13]
 message QuicProtocolOptions {
   // Config for QUIC connection migration across network interfaces, i.e. cellular to WIFI, upon
   // network change events from the platform, i.e. the current network gets
@@ -173,6 +173,12 @@ message QuicProtocolOptions {
   // If absent, the feature will be disabled.
   // [#not-implemented-hide:]
   ConnectionMigrationSettings connection_migration = 11;
+
+  // Timeout for a QUIC connection to schedule memory reduction callback when the network has been idle for a while.
+  // This value should be smaller than the idle timeout to take effect.
+  // If not specified, memory reduction is set to infinite by QUIC connection (disabled).
+  google.protobuf.Duration memory_reduction_timeout = 12
+      [(validate.rules).duration = {gte {seconds: 1}}];
 }
 
 message UpstreamHttpProtocolOptions {

source/common/quic/envoy_quic_server_session.cc

@@ -214,6 +214,14 @@ void EnvoyQuicServerSession::setHttp3Options(
       }
     }
   }
+  if (http3_options.has_quic_protocol_options()) {
+    const uint64_t memory_reduction_timeout_ms = PROTOBUF_GET_MS_OR_DEFAULT(
+        http3_options.quic_protocol_options(), memory_reduction_timeout, 0);
+    if (memory_reduction_timeout_ms > 0) {
+      connection()->SetMemoryReductionTimeout(
+          quic::QuicTime::Delta::FromMilliseconds(memory_reduction_timeout_ms));
+    }
+  }
   set_allow_extended_connect(http3_options_->allow_extended_connect());
   if (http3_options_->disable_qpack()) {
     DisableHuffmanEncoding();