Network upgrade activation mechanism

src/consensus/upgrades.h

@@ -0,0 +1,77 @@
+// 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.
+
+#ifndef ZCASH_CONSENSUS_UPGRADES_H
+#define ZCASH_CONSENSUS_UPGRADES_H
+
+#include "consensus/params.h"
+
+enum UpgradeState {
+    UPGRADE_DISABLED,
+    UPGRADE_PENDING,
+    UPGRADE_ACTIVE
+};
+
+struct NUInfo {
+    /** Branch ID (a random non-zero 32-bit value) */
+    uint32_t nBranchId;
+    /** User-facing name for the upgrade */
+    std::string strName;
+    /** User-facing information string about the upgrade */
+    std::string strInfo;
+};
+
+extern const struct NUInfo NetworkUpgradeInfo[];
+
+/**
+ * Checks the state of a given network upgrade based on block height.
+ * Caller must check that the height is >= 0 (and handle unknown heights).
+ */
+UpgradeState NetworkUpgradeState(
+    int nHeight,
+    const Consensus::Params& params,
+    Consensus::UpgradeIndex idx);
+
+/**
+ * Returns true if the given network upgrade is active as of the given block
+ * height. Caller must check that the height is >= 0 (and handle unknown
+ * heights).
+ */
+bool NetworkUpgradeActive(
+    int nHeight,
+    const Consensus::Params& params,
+    Consensus::UpgradeIndex idx);
+
+/**
+ * Returns the index of the most recent upgrade as of the given block height
+ * (corresponding to the current "epoch"). Consensus::BASE_SPROUT is the
+ * default value if no upgrades are active. Caller must check that the height
+ * is >= 0 (and handle unknown heights).
+ */
+int CurrentEpoch(int nHeight, const Consensus::Params& params);
+
+/**
+ * Returns the branch ID of the most recent upgrade as of the given block height
+ * (corresponding to the current "epoch"), or 0 if no upgrades are active.
+ * Caller must check that the height is >= 0 (and handle unknown heights).
+ */
+uint32_t CurrentEpochBranchId(int nHeight, const Consensus::Params& params);
+
+/**
+ * Returns true if the given block height is the activation height for the given
+ * upgrade.
+ */
+bool IsActivationHeight(
+    int nHeight,
+    const Consensus::Params& params,
+    Consensus::UpgradeIndex upgrade);
+
+/**
+ * Returns true if the given block height is the activation height for any upgrade.
+ */
+bool IsActivationHeightForAnyUpgrade(
+    int nHeight,
+    const Consensus::Params& params);
+
+#endif // ZCASH_CONSENSUS_UPGRADES_H