indexes, refactor: Pass Chain interface instead of CChainState class to indexes

Passing abstract Chain interface will let indexes run in separate
processes.

This commit does not change behavior in any way.

Author: ryanofsky

src/index/base.cpp

@@ -4,7 +4,9 @@
 
 #include <chainparams.h>
 #include <index/base.h>
+#include <interfaces/chain.h>
 #include <node/blockstorage.h>
+#include <node/context.h>
 #include <node/interface_ui.h>
 #include <shutdown.h>
 #include <tinyformat.h>
@@ -49,6 +51,9 @@ void BaseIndex::DB::WriteBestBlock(CDBBatch& batch, const CBlockLocator& locator
     batch.Write(DB_BEST_BLOCK, locator);
 }
 
+BaseIndex::BaseIndex(std::unique_ptr<interfaces::Chain> chain)
+    : m_chain{std::move(chain)} {}
+
 BaseIndex::~BaseIndex()
 {
     Interrupt();
@@ -346,9 +351,11 @@ void BaseIndex::Interrupt()
     m_interrupt();
 }
 
-bool BaseIndex::Start(CChainState& active_chainstate)
+bool BaseIndex::Start()
 {
-    m_chainstate = &active_chainstate;
+    // m_chainstate member gives indexing code access to node internals. It is
+    // removed in followup https://github.com/bitcoin/bitcoin/pull/24230
+    m_chainstate = &m_chain->context()->chainman->ActiveChainstate();
     // Need to register this ValidationInterface before running Init(), so that
     // callbacks are not missed if Init sets m_synced to true.
     RegisterValidationInterface(this);

src/index/base.h

@@ -6,12 +6,16 @@
 #define BITCOIN_INDEX_BASE_H
 
 #include <dbwrapper.h>
+#include <interfaces/chain.h>
 #include <threadinterrupt.h>
 #include <validationinterface.h>
 
 class CBlock;
 class CBlockIndex;
 class CChainState;
+namespace interfaces {
+class Chain;
+} // namespace interfaces
 
 struct IndexSummary {
     std::string name;
@@ -79,6 +83,7 @@ class BaseIndex : public CValidationInterface
     virtual bool AllowPrune() const = 0;
 
 protected:
+    std::unique_ptr<interfaces::Chain> m_chain;
     CChainState* m_chainstate{nullptr};
 
     void BlockConnected(const std::shared_ptr<const CBlock>& block, const CBlockIndex* pindex) override;
@@ -110,6 +115,7 @@ class BaseIndex : public CValidationInterface
     void SetBestBlockIndex(const CBlockIndex* block);
 
 public:
+    BaseIndex(std::unique_ptr<interfaces::Chain> chain);
     /// Destructor interrupts sync thread if running and blocks until it exits.
     virtual ~BaseIndex();
 
@@ -124,7 +130,7 @@ class BaseIndex : public CValidationInterface
 
     /// Start initializes the sync state and registers the instance as a
     /// ValidationInterface so that it stays in sync with blockchain updates.
-    [[nodiscard]] bool Start(CChainState& active_chainstate);
+    [[nodiscard]] bool Start();
 
     /// Stops the instance from staying in sync with blockchain updates.
     void Stop();

src/index/blockfilterindex.cpp

@@ -94,9 +94,9 @@ struct DBHashKey {
 
 static std::map<BlockFilterType, BlockFilterIndex> g_filter_indexes;
 
-BlockFilterIndex::BlockFilterIndex(BlockFilterType filter_type,
+BlockFilterIndex::BlockFilterIndex(std::unique_ptr<interfaces::Chain> chain, BlockFilterType filter_type,
                                    size_t n_cache_size, bool f_memory, bool f_wipe)
-    : m_filter_type(filter_type)
+    : BaseIndex(std::move(chain)), m_filter_type(filter_type)
 {
     const std::string& filter_name = BlockFilterTypeName(filter_type);
     if (filter_name.empty()) throw std::invalid_argument("unknown filter_type");
@@ -467,12 +467,12 @@ void ForEachBlockFilterIndex(std::function<void (BlockFilterIndex&)> fn)
     for (auto& entry : g_filter_indexes) fn(entry.second);
 }
 
-bool InitBlockFilterIndex(BlockFilterType filter_type,
+bool InitBlockFilterIndex(std::function<std::unique_ptr<interfaces::Chain>()> make_chain, BlockFilterType filter_type,
                           size_t n_cache_size, bool f_memory, bool f_wipe)
 {
     auto result = g_filter_indexes.emplace(std::piecewise_construct,
                                            std::forward_as_tuple(filter_type),
-                                           std::forward_as_tuple(filter_type,
+                                           std::forward_as_tuple(make_chain(), filter_type,
                                                                  n_cache_size, f_memory, f_wipe));
     return result.second;
 }

src/index/blockfilterindex.h

@@ -55,7 +55,7 @@ class BlockFilterIndex final : public BaseIndex
 
 public:
     /** Constructs the index, which becomes available to be queried. */
-    explicit BlockFilterIndex(BlockFilterType filter_type,
+    explicit BlockFilterIndex(std::unique_ptr<interfaces::Chain> chain, BlockFilterType filter_type,
                               size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
 
     BlockFilterType GetFilterType() const { return m_filter_type; }
@@ -88,7 +88,7 @@ void ForEachBlockFilterIndex(std::function<void (BlockFilterIndex&)> fn);
  * Initialize a block filter index for the given type if one does not already exist. Returns true if
  * a new index is created and false if one has already been initialized.
  */
-bool InitBlockFilterIndex(BlockFilterType filter_type,
+bool InitBlockFilterIndex(std::function<std::unique_ptr<interfaces::Chain>()> make_chain, BlockFilterType filter_type,
                           size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
 
 /**

src/index/coinstatsindex.cpp

@@ -102,7 +102,8 @@ struct DBHashKey {
 
 std::unique_ptr<CoinStatsIndex> g_coin_stats_index;
 
-CoinStatsIndex::CoinStatsIndex(size_t n_cache_size, bool f_memory, bool f_wipe)
+CoinStatsIndex::CoinStatsIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory, bool f_wipe)
+    : BaseIndex(std::move(chain))
 {
     fs::path path{gArgs.GetDataDirNet() / "indexes" / "coinstats"};
     fs::create_directories(path);

src/index/coinstatsindex.h

@@ -53,7 +53,7 @@ class CoinStatsIndex final : public BaseIndex
 
 public:
     // Constructs the index, which becomes available to be queried.
-    explicit CoinStatsIndex(size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
+    explicit CoinStatsIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
 
     // Look up stats for a specific block using CBlockIndex
     std::optional<kernel::CCoinsStats> LookUpStats(const CBlockIndex* block_index) const;

src/index/txindex.cpp

@@ -48,8 +48,8 @@ bool TxIndex::DB::WriteTxs(const std::vector<std::pair<uint256, CDiskTxPos>>& v_
     return WriteBatch(batch);
 }
 
-TxIndex::TxIndex(size_t n_cache_size, bool f_memory, bool f_wipe)
-    : m_db(std::make_unique<TxIndex::DB>(n_cache_size, f_memory, f_wipe))
+TxIndex::TxIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory, bool f_wipe)
+    : BaseIndex(std::move(chain)), m_db(std::make_unique<TxIndex::DB>(n_cache_size, f_memory, f_wipe))
 {}
 
 TxIndex::~TxIndex() = default;

src/index/txindex.h

@@ -31,7 +31,7 @@ class TxIndex final : public BaseIndex
 
 public:
     /// Constructs the index, which becomes available to be queried.
-    explicit TxIndex(size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
+    explicit TxIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
 
     // Destructor is declared because this class contains a unique_ptr to an incomplete type.
     virtual ~TxIndex() override;

src/init.cpp

@@ -1594,22 +1594,22 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
             return InitError(*error);
         }
 
-        g_txindex = std::make_unique<TxIndex>(cache_sizes.tx_index, false, fReindex);
-        if (!g_txindex->Start(chainman.ActiveChainstate())) {
+        g_txindex = std::make_unique<TxIndex>(interfaces::MakeChain(node), cache_sizes.tx_index, false, fReindex);
+        if (!g_txindex->Start()) {
             return false;
         }
     }
 
     for (const auto& filter_type : g_enabled_filter_types) {
-        InitBlockFilterIndex(filter_type, cache_sizes.filter_index, false, fReindex);
-        if (!GetBlockFilterIndex(filter_type)->Start(chainman.ActiveChainstate())) {
+        InitBlockFilterIndex([&]{ return interfaces::MakeChain(node); }, filter_type, cache_sizes.filter_index, false, fReindex);
+        if (!GetBlockFilterIndex(filter_type)->Start()) {
             return false;
         }
     }
 
     if (args.GetBoolArg("-coinstatsindex", DEFAULT_COINSTATSINDEX)) {
-        g_coin_stats_index = std::make_unique<CoinStatsIndex>(/* cache size */ 0, false, fReindex);
-        if (!g_coin_stats_index->Start(chainman.ActiveChainstate())) {
+        g_coin_stats_index = std::make_unique<CoinStatsIndex>(interfaces::MakeChain(node), /* cache size */ 0, false, fReindex);
+        if (!g_coin_stats_index->Start()) {
             return false;
         }
     }

src/interfaces/chain.h

@@ -304,6 +304,10 @@ class Chain
 
     //! Return true if an assumed-valid chain is in use.
     virtual bool hasAssumedValidChain() = 0;
+
+    //! Get internal node context. Useful for testing, but not
+    //! accessible across processes.
+    virtual node::NodeContext* context() { return nullptr; }
 };
 
 //! Interface to let node manage chain clients (wallets, or maybe tools for