net_processing: Clean up INVENTORY_BROADCAST_MAX constants

Author: ajtowns

src/net_processing.cpp

@@ -147,8 +147,12 @@ static constexpr auto OUTBOUND_INVENTORY_BROADCAST_INTERVAL{2s};
 /** Maximum rate of inventory items to send per second.
  *  Limits the impact of low-fee transaction floods. */
 static constexpr unsigned int INVENTORY_BROADCAST_PER_SECOND = 7;
+/** Target number of tx inventory items to send per transmission. */
+static constexpr unsigned int INVENTORY_BROADCAST_TARGET = INVENTORY_BROADCAST_PER_SECOND * count_seconds(INBOUND_INVENTORY_BROADCAST_INTERVAL);
 /** Maximum number of inventory items to send per transmission. */
-static constexpr unsigned int INVENTORY_BROADCAST_MAX = INVENTORY_BROADCAST_PER_SECOND * count_seconds(INBOUND_INVENTORY_BROADCAST_INTERVAL);
+static constexpr unsigned int INVENTORY_BROADCAST_MAX = 1000;
+static_assert(INVENTORY_BROADCAST_MAX >= INVENTORY_BROADCAST_TARGET, "INVENTORY_BROADCAST_MAX too low");
+static_assert(INVENTORY_BROADCAST_MAX <= MAX_PEER_TX_ANNOUNCEMENTS, "INVENTORY_BROADCAST_MAX too high");
 /** Average delay between feefilter broadcasts in seconds. */
 static constexpr auto AVG_FEEFILTER_BROADCAST_INTERVAL{10min};
 /** Maximum feefilter broadcast delay after significant change. */
@@ -5630,7 +5634,7 @@ bool PeerManagerImpl::SendMessages(CNode* pto)
         std::vector<CInv> vInv;
         {
             LOCK(peer->m_block_inv_mutex);
-            vInv.reserve(std::max<size_t>(peer->m_blocks_for_inv_relay.size(), INVENTORY_BROADCAST_MAX));
+            vInv.reserve(std::max<size_t>(peer->m_blocks_for_inv_relay.size(), INVENTORY_BROADCAST_TARGET));
 
             // Add blocks
             for (const uint256& hash : peer->m_blocks_for_inv_relay) {
@@ -5707,8 +5711,8 @@ bool PeerManagerImpl::SendMessages(CNode* pto)
                     // especially since we have many peers and some will draw much shorter delays.
                     unsigned int nRelayedTransactions = 0;
                     LOCK(tx_relay->m_bloom_filter_mutex);
-                    size_t broadcast_max{INVENTORY_BROADCAST_MAX + (tx_relay->m_tx_inventory_to_send.size()/1000)*5};
-                    broadcast_max = std::min<size_t>(1000, broadcast_max);
+                    size_t broadcast_max{INVENTORY_BROADCAST_TARGET + (tx_relay->m_tx_inventory_to_send.size()/1000)*5};
+                    broadcast_max = std::min<size_t>(INVENTORY_BROADCAST_MAX, broadcast_max);
                     while (!vInvTx.empty() && nRelayedTransactions < broadcast_max) {
                         // Fetch the top element from the heap
                         std::pop_heap(vInvTx.begin(), vInvTx.end(), compareInvMempoolOrder);