hardfork: allow per-fork voting thresholds

And setup the first fork to not vote

src/cryptonote_core/blockchain.cpp

@@ -72,23 +72,25 @@ DISABLE_VS_WARNINGS(4267)
 static const struct {
   uint8_t version;
   uint64_t height;
+  uint8_t threshold;
   time_t time;
 } mainnet_hard_forks[] = {
   // version 1 from the start of the blockchain
-  { 1, 1, 1341378000 },
+  { 1, 1, 0, 1341378000 },
 
-  // version 2 can start from block 1009827, setup on the 20th of september
+  // version 2 can start from block 1009827, setup on the 20th of september. No vote.
-  { 2, 1009827, 1442763710 },
+  { 2, 1009827, 0, 1442763710 },
 };
 static const uint64_t mainnet_hard_fork_version_1_till = 750000;
 
 static const struct {
   uint8_t version;
   uint64_t height;
+  uint8_t threshold;
   time_t time;
 } testnet_hard_forks[] = {
   // version 1 from the start of the blockchain
-  { 1, 1, 1341378000 },
+  { 1, 1, 0, 1341378000 },
 };
 static const uint64_t testnet_hard_fork_version_1_till = 540000;
 
@@ -252,13 +254,13 @@ bool Blockchain::init(BlockchainDB* db, const bool testnet)
     if (testnet) {
       m_hardfork = new HardFork(*db, 1, testnet_hard_fork_version_1_till);
       for (size_t n = 0; n < sizeof(testnet_hard_forks) / sizeof(testnet_hard_forks[0]); ++n)
-        m_hardfork->add(testnet_hard_forks[n].version, testnet_hard_forks[n].height, testnet_hard_forks[n].time);
+        m_hardfork->add(testnet_hard_forks[n].version, testnet_hard_forks[n].height, testnet_hard_forks[n].threshold, testnet_hard_forks[n].time);
     }
     else
     {
       m_hardfork = new HardFork(*db, 1, mainnet_hard_fork_version_1_till);
       for (size_t n = 0; n < sizeof(mainnet_hard_forks) / sizeof(mainnet_hard_forks[0]); ++n)
-        m_hardfork->add(mainnet_hard_forks[n].version, mainnet_hard_forks[n].height, mainnet_hard_forks[n].time);
+        m_hardfork->add(mainnet_hard_forks[n].version, mainnet_hard_forks[n].height, mainnet_hard_forks[n].threshold, mainnet_hard_forks[n].time);
     }
     m_hardfork->init();
 

src/cryptonote_core/hardfork.cpp

@@ -46,22 +46,22 @@ static uint8_t get_block_vote(const cryptonote::block &b)
   return b.minor_version;
 }
 
-HardFork::HardFork(cryptonote::BlockchainDB &db, uint8_t original_version, uint64_t original_version_till_height, time_t forked_time, time_t update_time, uint64_t window_size, int threshold_percent):
+HardFork::HardFork(cryptonote::BlockchainDB &db, uint8_t original_version, uint64_t original_version_till_height, time_t forked_time, time_t update_time, uint64_t window_size, uint8_t default_threshold_percent):
   db(db),
   original_version(original_version),
   original_version_till_height(original_version_till_height),
   forked_time(forked_time),
   update_time(update_time),
   window_size(window_size),
-  threshold_percent(threshold_percent)
+  default_threshold_percent(default_threshold_percent)
 {
   if (window_size == 0)
     throw "window_size needs to be strictly positive";
-  if (threshold_percent > 100)
+  if (default_threshold_percent > 100)
-    throw "threshold_percent needs to be between 0 and 100";
+    throw "default_threshold_percent needs to be between 0 and 100";
 }
 
-bool HardFork::add(uint8_t version, uint64_t height, time_t time)
+bool HardFork::add(uint8_t version, uint64_t height, uint8_t threshold, time_t time)
 {
   CRITICAL_REGION_LOCAL(lock);
 
@@ -76,10 +76,17 @@ bool HardFork::add(uint8_t version, uint64_t height, time_t time)
     if (time <= heights.back().time)
       return false;
   }
-  heights.push_back(Params(version, height, time));
+  if (threshold > 100)
+    return false;
+  heights.push_back(Params(version, height, threshold, time));
   return true;
 }
 
+bool HardFork::add(uint8_t version, uint64_t height, time_t time)
+{
+  return add(version, height, default_threshold_percent, time);
+}
+
 uint8_t HardFork::get_effective_version(uint8_t version) const
 {
   if (!heights.empty()) {
@@ -146,7 +153,6 @@ void HardFork::init()
   for (size_t n = 0; n < 256; ++n)
     last_versions[n] = 0;
   current_fork_index = 0;
-  vote_threshold = (uint32_t)ceilf(window_size * threshold_percent / 100.0f);
 
   // restore state from DB
   uint64_t height = db.height();
@@ -274,7 +280,8 @@ int HardFork::get_voted_fork_index(uint64_t height) const
   for (unsigned int n = heights.size() - 1; n > current_fork_index; --n) {
     uint8_t v = heights[n].version;
     accumulated_votes += last_versions[v];
-    if (height >= heights[n].height && accumulated_votes >= vote_threshold) {
+    uint32_t threshold = (window_size * heights[n].threshold + 99) / 100;
+    if (height >= heights[n].height && accumulated_votes >= threshold) {
       return n;
     }
   }
@@ -340,7 +347,7 @@ bool HardFork::get_voting_info(uint8_t version, uint32_t &window, uint32_t &vote
   votes = 0;
   for (size_t n = version; n < 256; ++n)
       votes += last_versions[n];
-  threshold = vote_threshold;
+  threshold = (window * heights[current_version].threshold + 99) / 100;
   assert((votes >= threshold) == enabled);
   voting = heights.back().version;
   return enabled;

src/cryptonote_core/hardfork.h

@@ -48,7 +48,7 @@ namespace cryptonote
     static const time_t DEFAULT_FORKED_TIME = 31557600; // a year in seconds
     static const time_t DEFAULT_UPDATE_TIME = 31557600 / 2;
     static const uint64_t DEFAULT_WINDOW_SIZE = 10080; // supermajority window check length - a week
-    static const int DEFAULT_THRESHOLD_PERCENT = 80;
+    static const uint8_t DEFAULT_THRESHOLD_PERCENT = 80;
 
     /**
      * @brief creates a new HardFork object
@@ -57,9 +57,21 @@ namespace cryptonote
      * @param forked_time the time in seconds before thinking we're forked
      * @param update_time the time in seconds before thinking we need to update
      * @param window_size the size of the window in blocks to consider for version voting
-     * @param threshold_percent the size of the majority in percents
+     * @param default_threshold_percent the size of the majority in percents
      */
-    HardFork(cryptonote::BlockchainDB &db, uint8_t original_version = 1, uint64_t original_version_till_height = DEFAULT_ORIGINAL_VERSION_TILL_HEIGHT, time_t forked_time = DEFAULT_FORKED_TIME, time_t update_time = DEFAULT_UPDATE_TIME, uint64_t window_size = DEFAULT_WINDOW_SIZE, int threshold_percent = DEFAULT_THRESHOLD_PERCENT);
+    HardFork(cryptonote::BlockchainDB &db, uint8_t original_version = 1, uint64_t original_version_till_height = DEFAULT_ORIGINAL_VERSION_TILL_HEIGHT, time_t forked_time = DEFAULT_FORKED_TIME, time_t update_time = DEFAULT_UPDATE_TIME, uint64_t window_size = DEFAULT_WINDOW_SIZE, uint8_t default_threshold_percent = DEFAULT_THRESHOLD_PERCENT);
+
+    /**
+     * @brief add a new hardfork height
+     *
+     * returns true if no error, false otherwise
+     *
+     * @param version the major block version for the fork
+     * @param height The height the hardfork takes effect
+     * @param threshold The threshold of votes needed for this fork (0-100)
+     * @param time Approximate time of the hardfork (seconds since epoch)
+     */
+    bool add(uint8_t version, uint64_t height, uint8_t threshold, time_t time);
 
     /**
      * @brief add a new hardfork height
@@ -199,23 +211,23 @@ namespace cryptonote
     time_t forked_time;
     time_t update_time;
     uint64_t window_size;
-    int threshold_percent;
+    uint8_t default_threshold_percent;
 
     uint8_t original_version;
     uint64_t original_version_till_height;
 
     struct Params {
       uint8_t version;
+      uint8_t threshold;
       uint64_t height;
       time_t time;
-      Params(uint8_t version, uint64_t height, time_t time): version(version), height(height), time(time) {}
+      Params(uint8_t version, uint64_t height, uint8_t threshold, time_t time): version(version), threshold(threshold), height(height), time(time) {}
     };
     std::vector<Params> heights;
 
     std::deque<uint8_t> versions; /* rolling window of the last N blocks' versions */
     unsigned int last_versions[256]; /* count of the block versions in the last N blocks */
     uint32_t current_fork_index;
-    uint32_t vote_threshold;
 
     mutable epee::critical_section lock;
   };

tests/unit_tests/hardfork.cpp

@@ -352,6 +352,34 @@ TEST(voting, threshold)
   }
 }
 
+TEST(voting, different_thresholds)
+{
+  for (int threshold = 87; threshold <= 88; ++threshold) {
+    TestDB db;
+    HardFork hf(db, 1, 0, 1, 1, 4, 50); // window size 4
+
+    //                 v  h  t
+    ASSERT_TRUE(hf.add(1, 0, 0));
+    ASSERT_TRUE(hf.add(2, 5, 0, 1)); // asap
+    ASSERT_TRUE(hf.add(3, 10, 100, 2)); // all votes
+    ASSERT_TRUE(hf.add(4, 15, 3)); // default 50% votes
+    hf.init();
+
+    //                                           0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5  6  7  8  9
+    static const uint8_t block_versions[] =    { 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4 };
+    static const uint8_t expected_versions[] = { 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4 };
+
+    for (uint64_t h = 0; h < sizeof(block_versions) / sizeof(block_versions[0]); ++h) {
+      db.add_block(mkblock(block_versions[h]), 0, 0, 0, crypto::hash());
+      bool ret = hf.add(db.get_block_from_height(h), h);
+      ASSERT_EQ(ret, true);
+    }
+    for (uint64_t h = 0; h < sizeof(expected_versions) / sizeof(expected_versions[0]); ++h) {
+      ASSERT_EQ(hf.get(h), expected_versions[h]);
+    }
+  }
+}
+
 TEST(new_blocks, denied)
 {
     TestDB db;