Merge #9571: RPC: getblockchaininfo returns BIP signaling statistics

557c9a6 RPC: getblockchaininfo: BIP9 stats (Matthew Zipkin)

Tree-SHA512: ecf0bf47f04f92becc77acc649fdfa270e768939acce42df39d30069398d40d9a30539862f7c307e08239f78d5c58c470ca5f6e717d2ab8e24db9be0dd7bec0c

5 files changed, 74 insertions, 3 deletions

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 9d72a23e6d..b4b160aac9 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -187,7 +187,7 @@ void RPCNotifyBlockChange(bool ibd, const CBlockIndex * pindex)
         latestblock.hash = pindex->GetBlockHash();
         latestblock.height = pindex->nHeight;
     }
-	cond_blockchange.notify_all();
+    cond_blockchange.notify_all();
 }
 
 UniValue waitfornewblock(const JSONRPCRequest& request)
@@ -1074,6 +1074,17 @@ static UniValue BIP9SoftForkDesc(const Consensus::Params& consensusParams, Conse
     rv.push_back(Pair("startTime", consensusParams.vDeployments[id].nStartTime));
     rv.push_back(Pair("timeout", consensusParams.vDeployments[id].nTimeout));
     rv.push_back(Pair("since", VersionBitsTipStateSinceHeight(consensusParams, id)));
+    if (THRESHOLD_STARTED == thresholdState)
+    {
+        UniValue statsUV(UniValue::VOBJ);
+        BIP9Stats statsStruct = VersionBitsTipStatistics(consensusParams, id);
+        statsUV.push_back(Pair("period", statsStruct.period));
+        statsUV.push_back(Pair("threshold", statsStruct.threshold));
+        statsUV.push_back(Pair("elapsed", statsStruct.elapsed));
+        statsUV.push_back(Pair("count", statsStruct.count));
+        statsUV.push_back(Pair("possible", statsStruct.possible));
+        rv.push_back(Pair("statistics", statsUV));
+    }
     return rv;
 }
 
@@ -1119,7 +1130,14 @@ UniValue getblockchaininfo(const JSONRPCRequest& request)
             "        \"bit\": xx,             (numeric) the bit (0-28) in the block version field used to signal this softfork (only for \"started\" status)\n"
             "        \"startTime\": xx,       (numeric) the minimum median time past of a block at which the bit gains its meaning\n"
             "        \"timeout\": xx,         (numeric) the median time past of a block at which the deployment is considered failed if not yet locked in\n"
-            "        \"since\": xx            (numeric) height of the first block to which the status applies\n"
+            "        \"since\": xx,           (numeric) height of the first block to which the status applies\n"
+            "        \"statistics\": {        (object) numeric statistics about BIP9 signalling for a softfork (only for \"started\" status)\n"
+            "           \"period\": xx,       (numeric) the length in blocks of the BIP9 signalling period \n"
+            "           \"threshold\": xx,    (numeric) the number of blocks with the version bit set required to activate the feature \n"
+            "           \"elapsed\": xx,      (numeric) the number of blocks elapsed since the beginning of the current period \n"
+            "           \"count\": xx,        (numeric) the number of blocks with the version bit set in the current period \n"
+            "           \"possible\": xx      (boolean) returns false if there are not enough blocks left in this period to pass activation threshold \n"
+            "        }\n"
             "     }\n"
             "  }\n"
             "}\n"
diff --git a/src/validation.cpp b/src/validation.cpp
index 73466b9df7..89358f9603 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3935,6 +3935,12 @@ ThresholdState VersionBitsTipState(const Consensus::Params& params, Consensus::D
     return VersionBitsState(chainActive.Tip(), params, pos, versionbitscache);
 }
 
+BIP9Stats VersionBitsTipStatistics(const Consensus::Params& params, Consensus::DeploymentPos pos)
+{
+    LOCK(cs_main);
+    return VersionBitsStatistics(chainActive.Tip(), params, pos);
+}
+
 int VersionBitsTipStateSinceHeight(const Consensus::Params& params, Consensus::DeploymentPos pos)
 {
     LOCK(cs_main);
diff --git a/src/validation.h b/src/validation.h
index 743a2973f8..b19c3ff4f7 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -339,6 +339,9 @@ std::string FormatStateMessage(const CValidationState &state);
 /** Get the BIP9 state for a given deployment at the current tip. */
 ThresholdState VersionBitsTipState(const Consensus::Params& params, Consensus::DeploymentPos pos);
 
+/** Get the numerical statistics for the BIP9 state for a given deployment at the current tip. */
+BIP9Stats VersionBitsTipStatistics(const Consensus::Params& params, Consensus::DeploymentPos pos);
+
 /** Get the block height at which the BIP9 deployment switched into the state for the block building on the current tip. */
 int VersionBitsTipStateSinceHeight(const Consensus::Params& params, Consensus::DeploymentPos pos);
 
diff --git a/src/versionbits.cpp b/src/versionbits.cpp
index 8a7cce7485..80786233f5 100644
--- a/src/versionbits.cpp
+++ b/src/versionbits.cpp
@@ -3,7 +3,6 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "versionbits.h"
-
 #include "consensus/params.h"
 
 const struct BIP9DeploymentInfo VersionBitsDeploymentInfo[Consensus::MAX_VERSION_BITS_DEPLOYMENTS] = {
@@ -105,6 +104,36 @@ ThresholdState AbstractThresholdConditionChecker::GetStateFor(const CBlockIndex*
     return state;
 }
 
+// return the numerical statistics of blocks signalling the specified BIP9 condition in this current period
+BIP9Stats AbstractThresholdConditionChecker::GetStateStatisticsFor(const CBlockIndex* pindex, const Consensus::Params& params) const
+{
+    BIP9Stats stats;
+
+    stats.period = Period(params);
+    stats.threshold = Threshold(params);
+
+    if (pindex == NULL)
+        return stats;
+
+    // Find beginning of period
+    const CBlockIndex* pindexEndOfPrevPeriod = pindex->GetAncestor(pindex->nHeight - ((pindex->nHeight + 1) % stats.period));
+    stats.elapsed = pindex->nHeight - pindexEndOfPrevPeriod->nHeight;
+
+    // Count from current block to beginning of period
+    int count = 0;
+    const CBlockIndex* currentIndex = pindex;
+    while (pindexEndOfPrevPeriod->nHeight != currentIndex->nHeight){
+        if (Condition(currentIndex, params))
+            count++;
+        currentIndex = currentIndex->pprev;
+    }
+
+    stats.count = count;
+    stats.possible = (stats.period - stats.threshold ) >= (stats.elapsed - count);
+
+    return stats;
+}
+
 int AbstractThresholdConditionChecker::GetStateSinceHeightFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const
 {
     const ThresholdState initialState = GetStateFor(pindexPrev, params, cache);
@@ -167,6 +196,11 @@ ThresholdState VersionBitsState(const CBlockIndex* pindexPrev, const Consensus::
     return VersionBitsConditionChecker(pos).GetStateFor(pindexPrev, params, cache.caches[pos]);
 }
 
+BIP9Stats VersionBitsStatistics(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos)
+{
+    return VersionBitsConditionChecker(pos).GetStateStatisticsFor(pindexPrev, params);
+}
+
 int VersionBitsStateSinceHeight(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache)
 {
     return VersionBitsConditionChecker(pos).GetStateSinceHeightFor(pindexPrev, params, cache.caches[pos]);
diff --git a/src/versionbits.h b/src/versionbits.h
index 7a929266aa..f1d31ea0af 100644
--- a/src/versionbits.h
+++ b/src/versionbits.h
@@ -37,6 +37,14 @@ struct BIP9DeploymentInfo {
     bool gbt_force;
 };
 
+struct BIP9Stats {
+    int period;
+    int threshold;
+    int elapsed;
+    int count;
+    bool possible;
+};
+
 extern const struct BIP9DeploymentInfo VersionBitsDeploymentInfo[];
 
 /**
@@ -51,6 +59,7 @@ protected:
     virtual int Threshold(const Consensus::Params& params) const =0;
 
 public:
+    BIP9Stats GetStateStatisticsFor(const CBlockIndex* pindex, const Consensus::Params& params) const;
     // Note that the functions below take a pindexPrev as input: they compute information for block B based on its parent.
     ThresholdState GetStateFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const;
     int GetStateSinceHeightFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const;
@@ -64,6 +73,7 @@ struct VersionBitsCache
 };
 
 ThresholdState VersionBitsState(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
+BIP9Stats VersionBitsStatistics(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos);
 int VersionBitsStateSinceHeight(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos pos, VersionBitsCache& cache);
 uint32_t VersionBitsMask(const Consensus::Params& params, Consensus::DeploymentPos pos);