Merge #16774: Avoid unnecessary "Synchronizing blockheaders" log messages

dcc448e Avoid unnecessary "Synchronizing blockheaders" log messages (Jonas Schnelli)

Pull request description:

  Fixes #16773

  I'm not entirely sure why 16773 happend, but probably due to headers fallback in a compact block.

  However, this PR should fix it and should have been included in #15615.

ACKs for top commit:
  ajtowns:
    ACK dcc448e ; code review only, haven't compiled or tested.
  promag:
    ACK dcc448e.
  TheBlueMatt:
    utACK dcc448e. Went and read how pindexBestHeader is handled and this code looks correct (worst case it breaks a LogPrint, so whatever). I also ran into this on #16762.
  fanquake:
    ACK dcc448e

Tree-SHA512: f8cac3b6eb9d4e8fab53a535b55f9ea9b058e3ab6ade64801ebc56439ede4f54b5fee36d5d2b316966ab987b65b13ab9dc18849f345d08b81ecdf2722a3f5f5a

Author: MarcoFalke

src/validation.cpp

@@ -2557,7 +2557,7 @@ bool CChainState::ActivateBestChainStep(CValidationState& state, const CChainPar
     return true;
 }
 
-static void NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
+static bool NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
     bool fNotify = false;
     bool fInitialBlockDownload = false;
     static CBlockIndex* pindexHeaderOld = nullptr;
@@ -2576,6 +2576,7 @@ static void NotifyHeaderTip() LOCKS_EXCLUDED(cs_main) {
     if (fNotify) {
         uiInterface.NotifyHeaderTip(fInitialBlockDownload, pindexHeader);
     }
+    return fNotify;
 }
 
 static void LimitValidationInterfaceQueue() LOCKS_EXCLUDED(cs_main) {
@@ -3396,8 +3397,7 @@ bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidatio
             }
         }
     }
-    NotifyHeaderTip();
-    {
+    if (NotifyHeaderTip()) {
         LOCK(cs_main);
         if (::ChainstateActive().IsInitialBlockDownload() && ppindex && *ppindex) {
             LogPrintf("Synchronizing blockheaders, height: %d (~%.2f%%)\n", (*ppindex)->nHeight, 100.0/((*ppindex)->nHeight+(GetAdjustedTime() - (*ppindex)->GetBlockTime()) / Params().GetConsensus().nPowTargetSpacing) * (*ppindex)->nHeight);