New hardfork class

This keeps track of voting via block version, in order to decide
when to enable a particular fork's code.

1 files changed, 266 insertions, 0 deletions

diff --git a/src/cryptonote_core/hardfork.cpp b/src/cryptonote_core/hardfork.cpp
new file mode 100644
index 000000000..c7a69dadb
--- /dev/null
+++ b/src/cryptonote_core/hardfork.cpp
@@ -0,0 +1,266 @@
+// Copyright (c) 2015, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// 
+// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
+
+#include <algorithm>
+#include <cstdio>
+
+#include "cryptonote_core/cryptonote_basic.h"
+#include "blockchain_db/blockchain_db.h"
+#include "hardfork.h"
+
+using namespace cryptonote;
+
+HardFork::HardFork(uint8_t original_version, time_t forked_time, time_t update_time, uint64_t max_history, int threshold_percent, uint64_t checkpoint_period):
+  original_version(original_version),
+  forked_time(forked_time),
+  update_time(update_time),
+  max_history(max_history),
+  threshold_percent(threshold_percent),
+  checkpoint_period(checkpoint_period)
+{
+  init();
+}
+
+bool HardFork::add(uint8_t version, uint64_t height, time_t time)
+{
+  CRITICAL_REGION_LOCAL(lock);
+
+  // add in order
+  if (version == 0)
+    return false;
+  if (!heights.empty()) {
+    if (version <= heights.back().version)
+      return false;
+    if (height <= heights.back().height)
+      return false;
+    if (time <= heights.back().time)
+      return false;
+  }
+  heights.push_back({version: version, height: height, time: time});
+  return true;
+}
+
+uint8_t HardFork::get_effective_version(const cryptonote::block &block) const
+{
+  uint8_t version = block.major_version;
+  if (!heights.empty()) {
+    uint8_t max_version = heights.back().version;
+    if (version > max_version)
+      version = max_version;
+  }
+  return version;
+}
+
+bool HardFork::do_check(const cryptonote::block &block) const
+{
+  return block.major_version >= heights[current_fork_index].version;
+}
+
+bool HardFork::check(const cryptonote::block &block) const
+{
+  CRITICAL_REGION_LOCAL(lock);
+  return do_check(block);
+}
+
+bool HardFork::add(const cryptonote::block &block, uint64_t height)
+{
+  CRITICAL_REGION_LOCAL(lock);
+
+  if (!do_check(block))
+    return false;
+
+  const uint8_t version = get_effective_version(block);
+
+  while (versions.size() >= max_history) {
+    const uint8_t old_version = versions.front();
+    last_versions[old_version]--;
+    assert(last_versions[old_version] >= 0);
+    versions.pop_front();
+  }
+
+  last_versions[version]++;
+  versions.push_back(version);
+
+  uint8_t voted = get_voted_fork_index(height);
+  if (voted > current_fork_index) {
+    for (int v = heights[current_fork_index].version + 1; v <= heights[voted].version; ++v) {
+      starting[v] = height;
+    }
+    current_fork_index = voted;
+  }
+
+  if (height % checkpoint_period == 0)
+    checkpoints.push_back(std::make_pair(height, current_fork_index));
+
+  return true;
+}
+
+void HardFork::init()
+{
+  CRITICAL_REGION_LOCAL(lock);
+  versions.clear();
+  for (size_t n = 0; n < 256; ++n)
+    last_versions[n] = 0;
+  for (size_t n = 0; n < 256; ++n)
+    starting[n] = std::numeric_limits<uint64_t>::max();
+  add(original_version, 0, 0);
+  for (size_t n = 0; n <= original_version; ++n)
+    starting[n] = 0;
+  checkpoints.clear();
+  current_fork_index = 0;
+  vote_threshold = (unsigned int)ceilf(max_history * threshold_percent / 100.0f);
+}
+
+bool HardFork::reorganize_from_block_height(const cryptonote::BlockchainDB *db, uint64_t height)
+{
+  CRITICAL_REGION_LOCAL(lock);
+  if (!db || height >= db->height())
+    return false;
+  while (!checkpoints.empty() && checkpoints.back().first > height)
+    checkpoints.pop_back();
+  versions.clear();
+
+  int v;
+  for (v = 255; v >= 0; --v) {
+    if (starting[v] <= height)
+      break;
+    if (starting[v] != std::numeric_limits<uint64_t>::max()) {
+      starting[v] = std::numeric_limits<uint64_t>::max();
+    }
+  }
+  for (current_fork_index = 0; current_fork_index < heights.size(); ++current_fork_index) {
+    if (heights[current_fork_index].version == v)
+      break;
+  }
+  for (size_t n = 0; n < 256; ++n)
+    last_versions[n] = 0;
+  const uint64_t rescan_height = height >= (max_history - 1) ? height - (max_history - 1) : 0;
+  for (uint64_t h = rescan_height; h <= height; ++h) {
+    cryptonote::block b = db->get_block_from_height(h);
+    const uint8_t v = get_effective_version(b);
+    last_versions[v]++;
+    versions.push_back(v);
+  }
+  const uint64_t bc_height = db->height();
+  for (uint64_t h = height + 1; h < bc_height; ++h) {
+    add(db->get_block_from_height(h), h);
+  }
+
+  return true;
+}
+
+bool HardFork::reorganize_from_chain_height(const cryptonote::BlockchainDB *db, uint64_t height)
+{
+  if (height == 0)
+    return false;
+  return reorganize_from_block_height(db, height - 1);
+}
+
+int HardFork::get_voted_fork_index(uint64_t height) const
+{
+  CRITICAL_REGION_LOCAL(lock);
+  unsigned int accumulated_votes = 0;
+  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) {
+      return n;
+    }
+  }
+  return current_fork_index;
+}
+
+HardFork::State HardFork::get_state(time_t t) const
+{
+  CRITICAL_REGION_LOCAL(lock);
+
+  // no hard forks setup yet
+  if (heights.size() <= 1)
+    return Ready;
+
+  time_t t_last_fork = heights.back().time;
+  if (t >= t_last_fork + forked_time)
+    return LikelyForked;
+  if (t >= t_last_fork + update_time)
+    return UpdateNeeded;
+  return Ready;
+}
+
+HardFork::State HardFork::get_state() const
+{
+  return get_state(time(NULL));
+}
+
+uint8_t HardFork::get(uint64_t height) const
+{
+  CRITICAL_REGION_LOCAL(lock);
+  for (size_t n = 1; n < 256; ++n) {
+    if (starting[n] > height)
+      return n - 1;
+  }
+  assert(false);
+  return 255;
+}
+
+uint64_t HardFork::get_start_height(uint8_t version) const
+{
+  CRITICAL_REGION_LOCAL(lock);
+  return starting[version];
+}
+
+uint8_t HardFork::get_current_version() const
+{
+  CRITICAL_REGION_LOCAL(lock);
+  return heights[current_fork_index].version;
+}
+
+uint8_t HardFork::get_ideal_version() const
+{
+  CRITICAL_REGION_LOCAL(lock);
+  return heights.back().version;
+}
+
+template<class archive_t>
+void HardFork::serialize(archive_t & ar, const unsigned int version)
+{
+  CRITICAL_REGION_LOCAL(lock);
+  ar & forked_time;
+  ar & update_time;
+  ar & max_history;
+  ar & threshold_percent;
+  ar & original_version;
+  ar & heights;
+  ar & last_versions;
+  ar & starting;
+  ar & current_fork_index;
+  ar & vote_threshold;
+  ar & checkpoint_period;
+  ar & checkpoints;
+}