[net processing] Remove QueuedBlock.fValidatedHeaders

Since headers-first syncing, we only ever request a block if we've already validated its headers.
Therefore QueuedBlock.fValidatedHeaders is always set to true. Remove it.

Author: jnewbery

src/net_processing.cpp

@@ -159,10 +159,12 @@ static constexpr size_t MAX_ADDR_TO_SEND{1000};
 namespace {
 /** Blocks that are in flight, and that are in the queue to be downloaded. */
 struct QueuedBlock {
+    /** Block hash */
     uint256 hash;
-    const CBlockIndex* pindex;                               //!< Optional.
-    bool fValidatedHeaders;                                  //!< Whether this block has validated headers at the time of request.
-    std::unique_ptr<PartiallyDownloadedBlock> partialBlock;  //!< Optional, used for CMPCTBLOCK downloads
+    /** BlockIndex. We must have this since we only request blocks when we've already validated the header. */
+    const CBlockIndex* pindex;
+    /** Optional, used for CMPCTBLOCK downloads */
+    std::unique_ptr<PartiallyDownloadedBlock> partialBlock;
 };
 
 /**
@@ -764,8 +766,8 @@ bool PeerManagerImpl::MarkBlockAsReceived(const uint256& hash)
     if (itInFlight != mapBlocksInFlight.end()) {
         CNodeState *state = State(itInFlight->second.first);
         assert(state != nullptr);
-        state->nBlocksInFlightValidHeaders -= itInFlight->second.second->fValidatedHeaders;
-        if (state->nBlocksInFlightValidHeaders == 0 && itInFlight->second.second->fValidatedHeaders) {
+        state->nBlocksInFlightValidHeaders -= 1;
+        if (state->nBlocksInFlightValidHeaders == 0) {
             // Last validated block on the queue was received.
             nPeersWithValidatedDownloads--;
         }
@@ -803,9 +805,9 @@ bool PeerManagerImpl::MarkBlockAsInFlight(NodeId nodeid, const CBlockIndex* pind
     MarkBlockAsReceived(hash);
 
     std::list<QueuedBlock>::iterator it = state->vBlocksInFlight.insert(state->vBlocksInFlight.end(),
-            {hash, pindex, pindex != nullptr, std::unique_ptr<PartiallyDownloadedBlock>(pit ? new PartiallyDownloadedBlock(&m_mempool) : nullptr)});
+            {hash, pindex, std::unique_ptr<PartiallyDownloadedBlock>(pit ? new PartiallyDownloadedBlock(&m_mempool) : nullptr)});
     state->nBlocksInFlight++;
-    state->nBlocksInFlightValidHeaders += it->fValidatedHeaders;
+    state->nBlocksInFlightValidHeaders += 1;
     if (state->nBlocksInFlight == 1) {
         // We're starting a block download (batch) from this peer.
         state->m_downloading_since = GetTime<std::chrono::microseconds>();