Network upgrade activation mechanism

src/consensus/upgrades.cpp

@@ -0,0 +1,94 @@
+// Copyright (c) 2018 The Zcash developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "consensus/upgrades.h"
+
+/**
+ * General information about each network upgrade.
+ * Ordered by Consensus::UpgradeIndex.
+ */
+const struct NUInfo NetworkUpgradeInfo[Consensus::MAX_NETWORK_UPGRADES] = {
+    {
+        /*.nBranchId =*/ 0,
+        /*.strName =*/ "Sprout",
+        /*.strInfo =*/ "The Zcash network at launch",
+    }
+};
+
+UpgradeState NetworkUpgradeState(
+    int nHeight,
+    const Consensus::Params& params,
+    Consensus::UpgradeIndex idx)
+{
+    assert(nHeight >= 0);
+    assert(idx >= Consensus::BASE_SPROUT && idx < Consensus::MAX_NETWORK_UPGRADES);
+    auto nActivationHeight = params.vUpgrades[idx].nActivationHeight;
+
+    if (nActivationHeight == Consensus::NetworkUpgrade::NO_ACTIVATION_HEIGHT) {
+        return UPGRADE_DISABLED;
+    } else if (nHeight >= nActivationHeight) {
+        // From ZIP ???:
+        //
+        // ACTIVATION_HEIGHT
+        //     The block height at which the network upgrade rules will come into effect.
+        //
+        //     For removal of ambiguity, the block at height ACTIVATION_HEIGHT - 1 is
+        //     subject to the pre-upgrade consensus rules.
+        return UPGRADE_ACTIVE;
+    } else {
+        return UPGRADE_PENDING;
+    }
+}
+
+bool NetworkUpgradeActive(
+    int nHeight,
+    const Consensus::Params& params,
+    Consensus::UpgradeIndex idx)
+{
+    return NetworkUpgradeState(nHeight, params, idx) == UPGRADE_ACTIVE;
+}
+
+int CurrentEpoch(int nHeight, const Consensus::Params& params) {
+    for (auto idxInt = Consensus::MAX_NETWORK_UPGRADES - 1; idxInt >= Consensus::BASE_SPROUT; idxInt--) {
+        if (NetworkUpgradeActive(nHeight, params, Consensus::UpgradeIndex(idxInt))) {
+            return idxInt;
+        }
+    }
+}
+
+uint32_t CurrentEpochBranchId(int nHeight, const Consensus::Params& params) {
+    return NetworkUpgradeInfo[CurrentEpoch(nHeight, params)].nBranchId;
+}
+
+bool IsActivationHeight(
+    int nHeight,
+    const Consensus::Params& params,
+    Consensus::UpgradeIndex idx)
+{
+    assert(idx >= Consensus::BASE_SPROUT && idx < Consensus::MAX_NETWORK_UPGRADES);
+
+    // Don't count Sprout as an activation height
+    if (idx == Consensus::BASE_SPROUT) {
+        return false;
+    }
+
+    return nHeight >= 0 && nHeight == params.vUpgrades[idx].nActivationHeight;
+}
+
+bool IsActivationHeightForAnyUpgrade(
+    int nHeight,
+    const Consensus::Params& params)
+{
+    if (nHeight < 0) {
+        return false;
+    }
+
+    // Don't count Sprout as an activation height
+    for (int idx = Consensus::BASE_SPROUT + 1; idx < Consensus::MAX_NETWORK_UPGRADES; idx++) {
+        if (nHeight == params.vUpgrades[idx].nActivationHeight)
+            return true;
+    }
+
+    return false;
+}