interfaces: refactor: move waitNext implementation to miner

- We now assert for a valid chainman and notifications once when
 invoking WaitAndCreateNewBlock function.

src/node/interfaces.cpp

@@ -935,87 +935,8 @@ public:
 
     std::unique_ptr<BlockTemplate> waitNext(BlockWaitOptions options) override
     {
-        // Delay calculating the current template fees, just in case a new block
+        auto new_template = WaitAndCreateNewBlock(chainman(), notifications(), m_node.mempool.get(), m_block_template, options, m_assemble_options);
-        // comes in before the next tick.
+        if (new_template) return std::make_unique<BlockTemplateImpl>(m_assemble_options, std::move(new_template), m_node);
-        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) {
-                        current_fees += fee;
-                    }
-                }
-
-                CAmount new_fees = 0;
-                for (CAmount fee : tmpl->m_block_template->vTxFees) {
-                    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;
     }
 
@@ -1023,7 +944,6 @@ public:
 
     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;

src/node/miner.cpp

@@ -16,11 +16,14 @@
 #include <consensus/validation.h>
 #include <deploymentstatus.h>
 #include <logging.h>
+#include <node/context.h>
+#include <node/kernel_notifications.h>
 #include <policy/feerate.h>
 #include <policy/policy.h>
 #include <pow.h>
 #include <primitives/transaction.h>
 #include <util/moneystr.h>
+#include <util/signalinterrupt.h>
 #include <util/time.h>
 #include <validation.h>
 
@@ -447,4 +450,93 @@ void AddMerkleRootAndCoinbase(CBlock& block, CTransactionRef coinbase, uint32_t
     block.nNonce = nonce;
     block.hashMerkleRoot = BlockMerkleRoot(block);
 }
+
+std::unique_ptr<CBlockTemplate> WaitAndCreateNewBlock(ChainstateManager& chainman,
+                                                      KernelNotifications& kernel_notifications,
+                                                      CTxMemPool* mempool,
+                                                      const std::unique_ptr<CBlockTemplate>& block_template,
+                                                      const BlockWaitOptions& options,
+                                                      const BlockAssembler::Options& assemble_options)
+{
+    // 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(kernel_notifications.m_tip_block_mutex, lock);
+            // Note that wait_until() checks the predicate before waiting
+            kernel_notifications.m_tip_block_cv.wait_until(lock, std::min(now + tick, deadline), [&]() EXCLUSIVE_LOCKS_REQUIRED(kernel_notifications.m_tip_block_mutex) {
+                AssertLockHeld(kernel_notifications.m_tip_block_mutex);
+                const auto tip_block{kernel_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 != 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 new_tmpl{BlockAssembler{
+                chainman.ActiveChainstate(),
+                mempool,
+                assemble_options}
+                              .CreateNewBlock()};
+
+            // If the tip changed, return the new template regardless of its fees.
+            if (tip_changed) return new_tmpl;
+
+            // Calculate the original template total fees if we haven't already
+            if (current_fees == -1) {
+                current_fees = 0;
+                for (CAmount fee : block_template->vTxFees) {
+                    current_fees += fee;
+                }
+            }
+
+            CAmount new_fees = 0;
+            for (CAmount fee : new_tmpl->vTxFees) {
+                new_fees += fee;
+                Assume(options.fee_threshold != MAX_MONEY);
+                if (new_fees >= current_fees + options.fee_threshold) return new_tmpl;
+            }
+        }
+
+        now = NodeClock::now();
+    } while (now < deadline);
+
+    return nullptr;
+}
 } // namespace node

src/node/miner.h

@@ -32,6 +32,8 @@ class ChainstateManager;
 namespace Consensus { struct Params; };
 
 namespace node {
+class KernelNotifications;
+
 static const bool DEFAULT_PRINT_MODIFIED_FEE = false;
 
 struct CBlockTemplate
@@ -232,6 +234,17 @@ void ApplyArgsManOptions(const ArgsManager& gArgs, BlockAssembler::Options& opti
 
 /* Compute the block's merkle root, insert or replace the coinbase transaction and the merkle root into the block */
 void AddMerkleRootAndCoinbase(CBlock& block, CTransactionRef coinbase, uint32_t version, uint32_t timestamp, uint32_t nonce);
+
+/**
+ * Return a new block template when fees rise to a certain threshold or after a
+ * new tip; return nullopt if timeout is reached.
+ */
+std::unique_ptr<CBlockTemplate> WaitAndCreateNewBlock(ChainstateManager& chainman,
+                                                      KernelNotifications& kernel_notifications,
+                                                      CTxMemPool* mempool,
+                                                      const std::unique_ptr<CBlockTemplate>& block_template,
+                                                      const BlockWaitOptions& options,
+                                                      const BlockAssembler::Options& assemble_options);
 } // namespace node
 
 #endif // BITCOIN_NODE_MINER_H