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Choose sync peer other than leader when possible #2041

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Merged
cead22 merged 3 commits into from
Dec 31, 2024
Merged

Choose sync peer other than leader when possible #2041

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5ba847e
adding logic to skip leader
danieldoglas Dec 24, 2024
a16718b
Merge branch 'dsilva_blockingCommandPortWhenNotCaughtUp' into dsilva_…
danieldoglas Dec 24, 2024
a92f259
addressing comments
danieldoglas Dec 31, 2024
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14 changes: 14 additions & 0 deletions sqlitecluster/SQLiteNode.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2201,6 +2201,7 @@ void SQLiteNode::_updateSyncPeer()
{
SQLitePeer* newSyncPeer = nullptr;
uint64_t commitCount = _db.getCommitCount();
bool isLeaderValidPeer = false;
for (auto peer : _peerList) {
// If either of these conditions are true, then we can't use this peer.
if (!peer->loggedIn || peer->commitCount <= commitCount) {
Expand All @@ -2212,6 +2213,13 @@ void SQLiteNode::_updateSyncPeer()
continue;
}

// We want to sync, if possible, from a peer that is not the leader. So at this point, skip choosing it
// as the newSyncPeer.
if (peer == _leadPeer) {
isLeaderValidPeer = true;
continue;
}

// Any peer that makes it to here is a usable peer, so it's by default better than nothing.
if (!newSyncPeer) {
newSyncPeer = peer;
Expand All @@ -2234,6 +2242,12 @@ void SQLiteNode::_updateSyncPeer()
}
}

// If we reached this point, it means that there are no other available peers to sync from, but leader
// was a valid choice. In this case, let's use it as the newSyncPeer.
if (!newSyncPeer && isLeaderValidPeer) {
newSyncPeer = _leadPeer;
}

// Log that we've changed peers.
if (_syncPeer != newSyncPeer) {
string from, to;
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