Merge bitcoin/bitcoin#23508: Add getdeploymentinfo RPC

a3809228917b8f750090c8bfec8e283391dbb524 Release notes for getdeploymentinfo rpc (Anthony Towns)
240cad09baefcf363cce36a4b2795122adfce27f rpc: getdeploymentinfo: include signalling info (Anthony Towns)
376c0c6dae2bebbb3e1352377e71fb1996d09f64 rpc: getdeploymentinfo: include block hash/height (Anthony Towns)
a7469bcd35692d56f57e91b3f21d30855bdf6531 rpc: getdeploymentinfo: change stats to always refer to current period (Anthony Towns)
7f15c1841b98de6931a7ac68e16635a05d3e96cf rpc: getdeploymentinfo: allow specifying a blockhash other than tip (Anthony Towns)
fd826130a0a4e67fdc26f8064f4ecb4ff79b3333 rpc: move softfork info from getblockchaininfo to getdeploymentinfo (Anthony Towns)

Pull request description:

  The aim of this PR is to improve the ability to monitor soft fork status. It first moves the softfork section from getblockchaininfo into a new RPC named getdeploymentinfo, which is then also able to query the status of forks at an arbitrary block rather than only at the tip. In addition, bip9 status is changed to indicate the status of the given block, rather than just for the next block, and an additional field is included to indicate whether each block in the signalling period signaled.

ACKs for top commit:
  laanwj:
    Code review and lightly tested ACK a3809228917b8f750090c8bfec8e283391dbb524
  Sjors:
    tACK a3809228917b8f750090c8bfec8e283391dbb524
  fjahr:
    tACK a3809228917b8f750090c8bfec8e283391dbb524

Tree-SHA512: 7417d733b47629f229c5128586569909250481a3e94356c52fe67a03fd42cd81745246e384b98c4115fb61587714c879e4bc3e5f5c74407d9f8f6773472a33cb

1 files changed, 20 insertions, 11 deletions

diff --git a/src/versionbits.cpp b/src/versionbits.cpp
index a9264e6116..36815fba17 100644
--- a/src/versionbits.cpp
+++ b/src/versionbits.cpp
@@ -98,29 +98,38 @@ ThresholdState AbstractThresholdConditionChecker::GetStateFor(const CBlockIndex*
     return state;
 }
 
-BIP9Stats AbstractThresholdConditionChecker::GetStateStatisticsFor(const CBlockIndex* pindex, const Consensus::Params& params) const
+BIP9Stats AbstractThresholdConditionChecker::GetStateStatisticsFor(const CBlockIndex* pindex, const Consensus::Params& params, std::vector<bool>* signalling_blocks) const
 {
     BIP9Stats stats = {};
 
     stats.period = Period(params);
     stats.threshold = Threshold(params);
 
-    if (pindex == nullptr)
-        return stats;
+    if (pindex == nullptr) return stats;
 
     // Find beginning of period
-    const CBlockIndex* pindexEndOfPrevPeriod = pindex->GetAncestor(pindex->nHeight - ((pindex->nHeight + 1) % stats.period));
-    stats.elapsed = pindex->nHeight - pindexEndOfPrevPeriod->nHeight;
+    int blocks_in_period = 1 + (pindex->nHeight % stats.period);
+
+    // Reset signalling_blocks
+    if (signalling_blocks) {
+        signalling_blocks->assign(blocks_in_period, false);
+    }
 
     // Count from current block to beginning of period
+    int elapsed = 0;
     int count = 0;
     const CBlockIndex* currentIndex = pindex;
-    while (pindexEndOfPrevPeriod->nHeight != currentIndex->nHeight){
-        if (Condition(currentIndex, params))
-            count++;
+    do {
+        ++elapsed;
+        --blocks_in_period;
+        if (Condition(currentIndex, params)) {
+            ++count;
+            if (signalling_blocks) signalling_blocks->at(blocks_in_period) = true;
+        }
         currentIndex = currentIndex->pprev;
-    }
+    } while(blocks_in_period > 0);
 
+    stats.elapsed = elapsed;
     stats.count = count;
     stats.possible = (stats.period - stats.threshold ) >= (stats.elapsed - count);
 
@@ -196,9 +205,9 @@ ThresholdState VersionBitsCache::State(const CBlockIndex* pindexPrev, const Cons
     return VersionBitsConditionChecker(pos).GetStateFor(pindexPrev, params, m_caches[pos]);
 }
 
-BIP9Stats VersionBitsCache::Statistics(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos)
+BIP9Stats VersionBitsCache::Statistics(const CBlockIndex* pindex, const Consensus::Params& params, Consensus::DeploymentPos pos, std::vector<bool>* signalling_blocks)
 {
-    return VersionBitsConditionChecker(pos).GetStateStatisticsFor(pindexPrev, params);
+    return VersionBitsConditionChecker(pos).GetStateStatisticsFor(pindex, params, signalling_blocks);
 }
 
 int VersionBitsCache::StateSinceHeight(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos)