1 files changed, 296 insertions, 0 deletions
diff --git a/src/consensus.cpp b/src/consensus.cpp
new file mode 100644
index 0000000..7749558
--- /dev/null
+++ b/src/consensus.cpp
@@ -0,0 +1,296 @@
+#include <cassert>
+#include <stack>
+
+#include "hotstuff/util.h"
+#include "hotstuff/consensus.h"
+
+#define LOG_INFO HOTSTUFF_LOG_INFO
+#define LOG_DEBUG HOTSTUFF_LOG_DEBUG
+#define LOG_WARN HOTSTUFF_LOG_WARN
+
+namespace hotstuff {
+
+/* The core logic of HotStuff, is farily simple :) */
+/*** begin HotStuff protocol logic ***/
+HotStuffCore::HotStuffCore(ReplicaID id,
+                            privkey_bt &&priv_key,
+                            int32_t parent_limit):
+        b0(new Block(true, 1)),
+        bqc(b0),
+        bexec(b0),
+        vheight(0),
+        priv_key(std::move(priv_key)),
+        tails{bqc},
+        id(id),
+        parent_limit(parent_limit),
+        storage(new EntityStorage()) {
+    storage->add_blk(b0);
+    b0->qc_ref = b0;
+}
+
+void HotStuffCore::sanity_check_delivered(const block_t &blk) {
+    if (!blk->delivered)
+        throw std::runtime_error("block not delivered");
+}
+
+block_t HotStuffCore::sanity_check_delivered(const uint256_t &blk_hash) {
+    block_t blk = storage->find_blk(blk_hash);
+    if (blk == nullptr || !blk->delivered)
+        throw std::runtime_error("block not delivered");
+    return std::move(blk);
+}
+
+bool HotStuffCore::on_deliver_blk(const block_t &blk) {
+    if (blk->delivered)
+    {
+        LOG_WARN("attempt to deliver a block twice");
+        return false;
+    }
+    blk->parents.clear();
+    for (const auto &hash: blk->parent_hashes)
+    {
+        block_t p = sanity_check_delivered(hash);
+        blk->parents.push_back(p);
+    }
+    blk->height = blk->parents[0]->height + 1;
+    for (const auto &cmd: blk->cmds)
+        cmd->container = blk;
+
+    if (blk->qc)
+    {
+        block_t _blk = storage->find_blk(blk->qc->get_blk_hash());
+        if (_blk == nullptr)
+            throw std::runtime_error("block referred by qc not fetched");
+        blk->qc_ref = std::move(_blk);
+    } // otherwise blk->qc_ref remains null
+
+    for (auto pblk: blk->parents) tails.erase(pblk);
+    tails.insert(blk);
+
+    blk->delivered = true;
+    LOG_DEBUG("delivered %.10s", get_hex(blk->get_hash()).c_str());
+    return true;
+}
+
+void HotStuffCore::check_commit(const block_t &_blk) {
+    const block_t &blk = _blk->qc_ref;
+    if (blk->qc_ref == nullptr) return;
+    if (blk->decision) return;
+    block_t p = blk->parents[0];
+    if (p == blk->qc_ref)
+    { /* commit */
+        std::vector<block_t> commit_queue;
+        block_t b;
+        for (b = p; b->height > bexec->height; b = b->parents[0])
+        { /* todo: also commit the uncles/aunts */
+            commit_queue.push_back(b);
+        }
+        if (b != bexec)
+            throw std::runtime_error("safety breached :(");
+        for (auto it = commit_queue.rbegin(); it != commit_queue.rend(); it++)
+        {
+            const block_t &blk = *it;
+            blk->decision = 1;
+#ifdef HOTSTUFF_ENABLE_LOG_PROTO
+            LOG_INFO("commit blk %.10s", get_hex10(blk->get_hash()).c_str());
+#endif
+            for (auto cmd: blk->cmds)
+                do_decide(cmd);
+        }
+        bexec = p;
+    }
+}
+
+bool HotStuffCore::update(const uint256_t &bqc_hash) {
+    block_t _bqc = sanity_check_delivered(bqc_hash);
+    if (_bqc->qc_ref == nullptr) return false;
+    check_commit(_bqc);
+    if (_bqc->qc_ref->height > bqc->qc_ref->height)
+        bqc = _bqc;
+    return true;
+}
+
+void HotStuffCore::on_propose(const std::vector<command_t> &cmds) {
+    size_t nparents = parent_limit < 1 ? tails.size() : parent_limit;
+    assert(tails.size() > 0);
+    block_t p = *tails.rbegin();
+    std::vector<block_t> parents{p};
+    tails.erase(p);
+    nparents--;
+    /* add the rest of tails as "uncles/aunts" */
+    while (nparents--)
+    {
+        auto it = tails.begin();
+        parents.push_back(*it);
+        tails.erase(it);
+    }
+    quorum_cert_bt qc = nullptr;
+    block_t qc_ref = nullptr;
+    if (p != b0 && p->voted.size() >= config.nmajority)
+    {
+        qc = p->self_qc->clone();
+        qc->compute();
+        qc_ref = p;
+    }
+    /* create a new block */
+    block_t bnew = storage->add_blk(
+        Block(
+            parents,
+            cmds,
+            p->height + 1,
+            std::move(qc), qc_ref,
+            nullptr
+        ));
+    const uint256_t bnew_hash = bnew->get_hash();
+    bnew->self_qc = create_quorum_cert(bnew_hash);
+    on_deliver_blk(bnew);
+    update(bnew_hash);
+    Proposal prop(id, bqc->get_hash(), bnew, nullptr);
+#ifdef HOTSTUFF_ENABLE_LOG_PROTO
+    LOG_INFO("propose %s", std::string(*bnew).c_str());
+#endif
+    /* self-vote */
+    on_receive_vote(
+        Vote(id, bqc->get_hash(), bnew_hash,
+            create_part_cert(*priv_key, bnew_hash), this));
+    on_propose_(bnew);
+    /* boradcast to other replicas */
+    do_broadcast_proposal(prop);
+}
+
+void HotStuffCore::on_receive_proposal(const Proposal &prop) {
+    if (!update(prop.bqc_hash)) return;
+#ifdef HOTSTUFF_ENABLE_LOG_PROTO
+    LOG_INFO("got %s", std::string(prop).c_str());
+#endif
+    block_t bnew = prop.blk;
+    sanity_check_delivered(bnew);
+    bool opinion = false;
+    if (bnew->height > vheight)
+    {
+        block_t pref = bqc->qc_ref;
+        block_t b;
+        for (b = bnew;
+            b->height > pref->height;
+            b = b->parents[0]);
+        opinion = b == pref;
+        vheight = bnew->height;
+    }
+#ifdef HOTSTUFF_ENABLE_LOG_PROTO
+    LOG_INFO("now state: %s", std::string(*this).c_str());
+#endif
+    do_vote(prop.proposer,
+        Vote(id,
+            bqc->get_hash(),
+            bnew->get_hash(),
+            (opinion ?
+                create_part_cert(*priv_key, bnew->get_hash()) :
+                nullptr),
+            nullptr));
+}
+
+void HotStuffCore::on_receive_vote(const Vote &vote) {
+    if (!update(vote.bqc_hash)) return;
+#ifdef HOTSTUFF_ENABLE_LOG_PROTO
+    LOG_INFO("got %s", std::string(vote).c_str());
+    LOG_INFO("now state: %s", std::string(*this).c_str());
+#endif
+
+    block_t blk = sanity_check_delivered(vote.blk_hash);
+    if (vote.cert == nullptr) return;
+    if (!vote.verify())
+    {
+        LOG_WARN("invalid vote");
+        return;
+    }
+    if (!blk->voted.insert(vote.voter).second)
+    {
+        LOG_WARN("duplicate votes");
+        return;
+    }
+    size_t qsize = blk->voted.size();
+    if (qsize <= config.nmajority)
+    {
+        blk->self_qc->add_part(vote.voter, *vote.cert);
+        if (qsize == config.nmajority)
+            on_qc_finish(blk);
+    }
+}
+/*** end HotStuff protocol logic ***/
+
+void HotStuffCore::prune(uint32_t staleness) {
+    block_t start;
+    /* skip the blocks */
+    for (start = bexec; staleness; staleness--, start = start->parents[0])
+        if (!start->parents.size()) return;
+    std::stack<block_t> s;
+    start->qc_ref = nullptr;
+    s.push(start);
+    while (!s.empty())
+    {
+        auto &blk = s.top();
+        if (blk->parents.empty())
+        {
+            storage->try_release_blk(blk);
+            s.pop();
+            continue;
+        }
+        blk->qc_ref = nullptr;
+        s.push(blk->parents.back());
+        blk->parents.pop_back();
+    }
+}
+
+int8_t HotStuffCore::get_cmd_decision(const uint256_t &cmd_hash) {
+    auto cmd = storage->find_cmd(cmd_hash);
+    return cmd != nullptr ? cmd->get_decision() : 0;
+}
+
+void HotStuffCore::add_replica(ReplicaID rid, const NetAddr &addr,
+                                pubkey_bt &&pub_key) {
+    config.add_replica(rid, 
+            ReplicaInfo(rid, addr, std::move(pub_key)));
+    b0->voted.insert(rid);
+}
+
+promise_t HotStuffCore::async_qc_finish(const block_t &blk) {
+    if (blk->voted.size() >= config.nmajority)
+        return promise_t([](promise_t &pm) {
+            pm.resolve();
+        });
+    auto it = qc_waiting.find(blk);
+    if (it == qc_waiting.end())
+        it = qc_waiting.insert(std::make_pair(blk, promise_t())).first;
+    return it->second;
+}
+
+void HotStuffCore::on_qc_finish(const block_t &blk) {
+    auto it = qc_waiting.find(blk);
+    if (it != qc_waiting.end())
+    {
+        it->second.resolve();
+        qc_waiting.erase(it);
+    }
+}
+
+promise_t HotStuffCore::async_wait_propose() {
+    return propose_waiting;
+}
+
+void HotStuffCore::on_propose_(const block_t &blk) {
+    auto t = std::move(propose_waiting);
+    propose_waiting = promise_t();
+    t.resolve(blk);
+}
+
+HotStuffCore::operator std::string () const {
+    DataStream s;
+    s << "<hotstuff "
+      << "bqc=" << get_hex10(bqc->get_hash()) << " "
+      << "bexec=" << get_hex10(bqc->get_hash()) << " "
+      << "vheight=" << std::to_string(vheight) << " "
+      << "tails=" << std::to_string(tails.size()) << ">";
+    return std::string(std::move(s));
+}
+
+}