Stratum v2 Template Provider common functionality

src/chainparamsbase.cpp

@@ -41,15 +41,15 @@ std::unique_ptr<CBaseChainParams> CreateBaseChainParams(const ChainType chain)
 {
     switch (chain) {
     case ChainType::MAIN:
-        return std::make_unique<CBaseChainParams>("", 8332);
+        return std::make_unique<CBaseChainParams>("", 8332, 8336);
     case ChainType::TESTNET:
-        return std::make_unique<CBaseChainParams>("testnet3", 18332);
+        return std::make_unique<CBaseChainParams>("testnet3", 18332, 18336);
     case ChainType::TESTNET4:
-        return std::make_unique<CBaseChainParams>("testnet4", 48332);
+        return std::make_unique<CBaseChainParams>("testnet4", 48332, 48336);
     case ChainType::SIGNET:
-        return std::make_unique<CBaseChainParams>("signet", 38332);
+        return std::make_unique<CBaseChainParams>("signet", 38332, 38336);
     case ChainType::REGTEST:
-        return std::make_unique<CBaseChainParams>("regtest", 18443);
+        return std::make_unique<CBaseChainParams>("regtest", 18443, 18447);
     }
     assert(false);
 }

src/chainparamsbase.h

@@ -22,13 +22,15 @@ class CBaseChainParams
 public:
     const std::string& DataDir() const { return strDataDir; }
     uint16_t RPCPort() const { return m_rpc_port; }
+    uint16_t Sv2Port() const { return m_sv2_port; }
 
     CBaseChainParams() = delete;
-    CBaseChainParams(const std::string& data_dir, uint16_t rpc_port)
-        : m_rpc_port(rpc_port), strDataDir(data_dir) {}
+    CBaseChainParams(const std::string& data_dir, uint16_t rpc_port, uint16_t sv2_port)
+        : m_rpc_port(rpc_port), m_sv2_port(sv2_port), strDataDir(data_dir) {}
 
 private:
     const uint16_t m_rpc_port;
+    const uint16_t m_sv2_port;
     std::string strDataDir;
 };
 

src/interfaces/mining.h

@@ -7,7 +7,7 @@
 
 #include <consensus/amount.h>       // for CAmount
 #include <interfaces/types.h>       // for BlockRef
-#include <node/types.h>             // for BlockCreateOptions
+#include <node/types.h>             // for BlockCreateOptions, BlockWaitOptions
 #include <primitives/block.h>       // for CBlock, CBlockHeader
 #include <primitives/transaction.h> // for CTransactionRef
 #include <stdint.h>                 // for int64_t
@@ -56,6 +56,19 @@ class BlockTemplate
      * @returns if the block was processed, independent of block validity
      */
     virtual bool submitSolution(uint32_t version, uint32_t timestamp, uint32_t nonce, CTransactionRef coinbase) = 0;
+
+    /**
+     * Waits for fees in the next block to rise, a new tip or the timeout.
+     *
+     * @param[in] options   Control the timeout (default forever) and by how much total fees
+     *                      for the next block should rise (default infinite).
+     *
+     * @returns a new BlockTemplate or nothing if the timeout occurs.
+     *
+     * On testnet this will additionally return a template with difficulty 1 if
+     * the tip is more than 20 minutes old.
+     */
+    virtual std::unique_ptr<BlockTemplate> waitNext(const node::BlockWaitOptions options = {}) = 0;
 };
 
 //! Interface giving clients (RPC, Stratum v2 Template Provider in the future)
@@ -76,20 +89,25 @@ class Mining
 
     /**
      * Waits for the connected tip to change. During node initialization, this will
-     * wait until the tip is connected.
+     * wait until the tip is connected (regardless of `timeout`).
      *
      * @param[in] current_tip block hash of the current chain tip. Function waits
      *                        for the chain tip to differ from this.
-     * @param[in] timeout     how long to wait for a new tip
-     * @returns               Hash and height of the current chain tip after this call.
+     * @param[in] timeout     how long to wait for a new tip (default is forever)
+     *
+     * @retval BlockRef hash and height of the current chain tip after this call.
+     * @retval std::nullopt if the node is shut down.
      */
-    virtual BlockRef waitTipChanged(uint256 current_tip, MillisecondsDouble timeout = MillisecondsDouble::max()) = 0;
+    virtual std::optional<BlockRef> waitTipChanged(uint256 current_tip, MillisecondsDouble timeout = MillisecondsDouble::max()) = 0;
 
    /**
-     * Construct a new block template
+     * Construct a new block template.
+     *
+     * During node initialization, this will wait until the tip is connected.
      *
      * @param[in] options options for creating the block
-     * @returns a block template
+     * @retval BlockTemplate a block template.
+     * @retval std::nullptr if the node is shut down.
      */
     virtual std::unique_ptr<BlockTemplate> createNewBlock(const node::BlockCreateOptions& options = {}) = 0;
 

src/ipc/capnp/mining.capnp

@@ -31,6 +31,7 @@ interface BlockTemplate $Proxy.wrap("interfaces::BlockTemplate") {
     getWitnessCommitmentIndex @7 (context: Proxy.Context) -> (result: Int32);
     getCoinbaseMerklePath @8 (context: Proxy.Context) -> (result: List(Data));
     submitSolution @9 (context: Proxy.Context, version: UInt32, timestamp: UInt32, nonce: UInt32, coinbase :Data) -> (result: Bool);
+    waitNext @10 (context: Proxy.Context, options: BlockWaitOptions) -> (result: BlockTemplate);
 }
 
 struct BlockCreateOptions $Proxy.wrap("node::BlockCreateOptions") {
@@ -39,6 +40,11 @@ struct BlockCreateOptions $Proxy.wrap("node::BlockCreateOptions") {
     coinbaseOutputMaxAdditionalSigops @2 :UInt64 $Proxy.name("coinbase_output_max_additional_sigops");
 }
 
+struct BlockWaitOptions $Proxy.wrap("node::BlockWaitOptions") {
+    timeout @0 : Float64 $Proxy.name("timeout");
+    feeThreshold @1 : Int64 $Proxy.name("fee_threshold");
+}
+
 # Note: serialization of the BlockValidationState C++ type is somewhat fragile
 # and using the struct can be awkward. It would be good if testBlockValidity
 # method were changed to return validity information in a simpler format.

src/key.h

@@ -204,6 +204,7 @@ class CKey
     ECDHSecret ComputeBIP324ECDHSecret(const EllSwiftPubKey& their_ellswift,
                                        const EllSwiftPubKey& our_ellswift,
                                        bool initiating) const;
+
     /** Compute a KeyPair
      *
      *  Wraps a `secp256k1_keypair` type.
@@ -220,6 +221,31 @@ class CKey
      *                               Merkle root of the script tree).
      */
     KeyPair ComputeKeyPair(const uint256* merkle_root) const;
+
+    /** Straight-forward serialization of key bytes (and compressed flag).
+     *  Use GetPrivKey() for OpenSSL compatible DER encoding.
+     */
+    template <typename Stream>
+    void Serialize(Stream& s) const
+    {
+        if (!IsValid()) {
+            throw std::ios_base::failure("invalid key");
+        }
+        s << fCompressed;
+        ::Serialize(s, Span{*this});
+    }
+
+    template <typename Stream>
+    void Unserialize(Stream& s)
+    {
+        s >> fCompressed;
+        MakeKeyData();
+        s >> Span{*keydata};
+        if (!Check(keydata->data())) {
+            ClearKeyData();
+            throw std::ios_base::failure("invalid key");
+        }
+    }
 };
 
 CKey GenerateRandomKey(bool compressed = true) noexcept;

src/node/context.h

@@ -25,6 +25,7 @@ class ChainstateManager;
 class ECC_Context;
 class NetGroupManager;
 class PeerManager;
+class Sv2TemplateProvider;
 namespace interfaces {
 class Chain;
 class ChainClient;

src/node/interfaces.cpp

@@ -82,6 +82,7 @@ using interfaces::Mining;
 using interfaces::Node;
 using interfaces::WalletLoader;
 using node::BlockAssembler;
+using node::BlockWaitOptions;
 using util::Join;
 
 namespace node {
@@ -877,7 +878,11 @@ class ChainImpl : public Chain
 class BlockTemplateImpl : public BlockTemplate
 {
 public:
-    explicit BlockTemplateImpl(std::unique_ptr<CBlockTemplate> block_template, NodeContext& node) : m_block_template(std::move(block_template)), m_node(node)
+    explicit BlockTemplateImpl(BlockAssembler::Options assemble_options,
+                               std::unique_ptr<CBlockTemplate> block_template,
+                               NodeContext& node) : m_assemble_options(std::move(assemble_options)),
+                                                    m_block_template(std::move(block_template)),
+                                                    m_node(node)
     {
         assert(m_block_template);
     }
@@ -942,9 +947,103 @@ class BlockTemplateImpl : public BlockTemplate
         return chainman().ProcessNewBlock(block_ptr, /*force_processing=*/true, /*min_pow_checked=*/true, /*new_block=*/nullptr);
     }
 
+    std::unique_ptr<BlockTemplate> waitNext(BlockWaitOptions options) override
+    {
+        // Delay calculating the current template fees, just in case a new block
+        // comes in before the next tick.
+        CAmount current_fees = -1;
+
+        // Alternate waiting for a new tip and checking if fees have risen.
+        // The latter check is expensive so we only run it once per second.
+        auto now{NodeClock::now()};
+        const auto deadline = now + options.timeout;
+        const MillisecondsDouble tick{1000};
+        const bool allow_min_difficulty{chainman().GetParams().GetConsensus().fPowAllowMinDifficultyBlocks};
+
+        do {
+            bool tip_changed{false};
+            {
+                WAIT_LOCK(notifications().m_tip_block_mutex, lock);
+                // Note that wait_until() checks the predicate before waiting
+                notifications().m_tip_block_cv.wait_until(lock, std::min(now + tick, deadline), [&]() EXCLUSIVE_LOCKS_REQUIRED(notifications().m_tip_block_mutex) {
+                    AssertLockHeld(notifications().m_tip_block_mutex);
+                    const auto tip_block{notifications().TipBlock()};
+                    // We assume tip_block is set, because this is an instance
+                    // method on BlockTemplate and no template could have been
+                    // generated before a tip exists.
+                    tip_changed = Assume(tip_block) && tip_block != m_block_template->block.hashPrevBlock;
+                    return tip_changed || chainman().m_interrupt;
+                });
+            }
+
+            if (chainman().m_interrupt) return nullptr;
+            // At this point the tip changed, a full tick went by or we reached
+            // the deadline.
+
+            // Must release m_tip_block_mutex before locking cs_main, to avoid deadlocks.
+            LOCK(::cs_main);
+
+            // On test networks return a minimum difficulty block after 20 minutes
+            if (!tip_changed && allow_min_difficulty) {
+                const NodeClock::time_point tip_time{std::chrono::seconds{chainman().ActiveChain().Tip()->GetBlockTime()}};
+                if (now > tip_time + 20min) {
+                    tip_changed = true;
+                }
+            }
+
+            /**
+             * We determine if fees increased compared to the previous template by generating
+             * a fresh template. There may be more efficient ways to determine how much
+             * (approximate) fees for the next block increased, perhaps more so after
+             * Cluster Mempool.
+             *
+             * We'll also create a new template if the tip changed during this iteration.
+             */
+            if (options.fee_threshold < MAX_MONEY || tip_changed) {
+                auto tmpl{std::make_unique<BlockTemplateImpl>(m_assemble_options,
+                                                              BlockAssembler{
+                                                                  chainman().ActiveChainstate(),
+                                                                  context()->mempool.get(),
+                                                                  m_assemble_options}
+                                                                  .CreateNewBlock(),
+                                                              m_node)};
+
+                // If the tip changed, return the new template regardless of its fees.
+                if (tip_changed) return tmpl;
+
+                // Calculate the original template total fees if we haven't already
+                if (current_fees == -1) {
+                    current_fees = 0;
+                    for (CAmount fee : m_block_template->vTxFees) {
+                        // Skip coinbase
+                        if (fee < 0) continue;
+                        current_fees += fee;
+                    }
+                }
+
+                CAmount new_fees = 0;
+                for (CAmount fee : tmpl->m_block_template->vTxFees) {
+                    // Skip coinbase
+                    if (fee < 0) continue;
+                    new_fees += fee;
+                    Assume(options.fee_threshold != MAX_MONEY);
+                    if (new_fees >= current_fees + options.fee_threshold) return tmpl;
+                }
+            }
+
+            now = NodeClock::now();
+        } while (now < deadline);
+
+        return nullptr;
+    }
+
+    const BlockAssembler::Options m_assemble_options;
+
     const std::unique_ptr<CBlockTemplate> m_block_template;
 
+    NodeContext* context() { return &m_node; }
     ChainstateManager& chainman() { return *Assert(m_node.chainman); }
+    KernelNotifications& notifications() { return *Assert(m_node.notifications); }
     NodeContext& m_node;
 };
 
@@ -971,27 +1070,44 @@ class MinerImpl : public Mining
         return BlockRef{tip->GetBlockHash(), tip->nHeight};
     }
 
-    BlockRef waitTipChanged(uint256 current_tip, MillisecondsDouble timeout) override
+    std::optional<BlockRef> waitTipChanged(uint256 current_tip, MillisecondsDouble timeout) override
     {
+        Assume(timeout >= 0ms); // No internal callers should use a negative timeout
+        if (timeout < 0ms) timeout = 0ms;
         if (timeout > std::chrono::years{100}) timeout = std::chrono::years{100}; // Upper bound to avoid UB in std::chrono
+        auto deadline{std::chrono::steady_clock::now() + timeout};
         {
             WAIT_LOCK(notifications().m_tip_block_mutex, lock);
-            notifications().m_tip_block_cv.wait_for(lock, timeout, [&]() EXCLUSIVE_LOCKS_REQUIRED(notifications().m_tip_block_mutex) {
-                // We need to wait for m_tip_block to be set AND for the value
-                // to differ from the current_tip value.
-                return (notifications().TipBlock() && notifications().TipBlock() != current_tip) || chainman().m_interrupt;
+            // For callers convenience, wait longer than the provided timeout
+            // during startup for the tip to be non-null. That way this function
+            // always returns valid tip information when possible and only
+            // returns null when shutting down, not when timing out.
+            notifications().m_tip_block_cv.wait(lock, [&]() EXCLUSIVE_LOCKS_REQUIRED(notifications().m_tip_block_mutex) {
+                return notifications().TipBlock() || chainman().m_interrupt;
+            });
+            if (chainman().m_interrupt) return {};
+            // At this point TipBlock is set, so continue to wait until it is
+            // different then `current_tip` provided by caller.
+            notifications().m_tip_block_cv.wait_until(lock, deadline, [&]() EXCLUSIVE_LOCKS_REQUIRED(notifications().m_tip_block_mutex) {
+                return Assume(notifications().TipBlock()) != current_tip || chainman().m_interrupt;
             });
         }
-        // Must release m_tip_block_mutex before locking cs_main, to avoid deadlocks.
-        LOCK(::cs_main);
-        return BlockRef{chainman().ActiveChain().Tip()->GetBlockHash(), chainman().ActiveChain().Tip()->nHeight};
+
+        if (chainman().m_interrupt) return {};
+
+        // Must release m_tip_block_mutex before getTip() locks cs_main, to
+        // avoid deadlocks.
+        return getTip();
     }
 
     std::unique_ptr<BlockTemplate> createNewBlock(const BlockCreateOptions& options) override
     {
+        // Ensure m_tip_block is set so consumers of BlockTemplate can rely on that.
+        if (!waitTipChanged(uint256::ZERO, MillisecondsDouble::max())) return {};
+
         BlockAssembler::Options assemble_options{options};
         ApplyArgsManOptions(*Assert(m_node.args), assemble_options);
-        return std::make_unique<BlockTemplateImpl>(BlockAssembler{chainman().ActiveChainstate(), context()->mempool.get(), assemble_options}.CreateNewBlock(), m_node);
+        return std::make_unique<BlockTemplateImpl>(assemble_options, BlockAssembler{chainman().ActiveChainstate(), context()->mempool.get(), assemble_options}.CreateNewBlock(), m_node);
     }
 
     NodeContext* context() override { return &m_node; }

src/node/types.h

@@ -13,9 +13,11 @@
 #ifndef BITCOIN_NODE_TYPES_H
 #define BITCOIN_NODE_TYPES_H
 
+#include <consensus/amount.h>
 #include <cstddef>
 #include <policy/policy.h>
 #include <script/script.h>
+#include <util/time.h>
 
 namespace node {
 enum class TransactionError {
@@ -61,6 +63,28 @@ struct BlockCreateOptions {
      */
     CScript coinbase_output_script{CScript() << OP_TRUE};
 };
+
+struct BlockWaitOptions {
+    /**
+     * How long to wait before returning nullptr instead of a new template.
+     * Default is to wait forever.
+     */
+    MillisecondsDouble timeout{MillisecondsDouble::max()};
+
+    /**
+     * The wait method will not return a new template unless it has fees at
+     * least fee_threshold sats higher than the current template, or unless
+     * the chain tip changes and the previous template is no longer valid.
+     *
+     * A caller may not be interested in templates with higher fees, and
+     * determining whether fee_threshold is reached is also expensive. So as
+     * an optimization, when fee_threshold is set to MAX_MONEY (default), the
+     * implementation is able to be much more efficient, skipping expensive
+     * checks and only returning new templates when the chain tip changes.
+     */
+    CAmount fee_threshold{MAX_MONEY};
+};
+
 } // namespace node
 
 #endif // BITCOIN_NODE_TYPES_H