versionbits: simplify state transitions

This removes the DEFINED->FAILED transition and changes the
STARTED->FAILED transition to only occur if signalling didn't pass the
threshold. This ensures that it is always possible for activation to
occur, no matter what settings are chosen, or the speed at which blocks
are found.

Github-Pull: #21377
Rebased-From: f054f6bcd2c2ce5fea84cf8681013f85a444e7ea

1 files changed, 3 insertions, 7 deletions

diff --git a/src/versionbits.cpp b/src/versionbits.cpp
index df666c963f..df2ec4e056 100644
--- a/src/versionbits.cpp
+++ b/src/versionbits.cpp
@@ -57,18 +57,12 @@ ThresholdState AbstractThresholdConditionChecker::GetStateFor(const CBlockIndex*
 
         switch (state) {
             case ThresholdState::DEFINED: {
-                if (pindexPrev->GetMedianTimePast() >= nTimeTimeout) {
-                    stateNext = ThresholdState::FAILED;
-                } else if (pindexPrev->GetMedianTimePast() >= nTimeStart) {
+                if (pindexPrev->GetMedianTimePast() >= nTimeStart) {
                     stateNext = ThresholdState::STARTED;
                 }
                 break;
             }
             case ThresholdState::STARTED: {
-                if (pindexPrev->GetMedianTimePast() >= nTimeTimeout) {
-                    stateNext = ThresholdState::FAILED;
-                    break;
-                }
                 // We need to count
                 const CBlockIndex* pindexCount = pindexPrev;
                 int count = 0;
@@ -80,6 +74,8 @@ ThresholdState AbstractThresholdConditionChecker::GetStateFor(const CBlockIndex*
                 }
                 if (count >= nThreshold) {
                     stateNext = ThresholdState::LOCKED_IN;
+                } else if (pindexPrev->GetMedianTimePast() >= nTimeTimeout) {
+                    stateNext = ThresholdState::FAILED;
                 }
                 break;
             }