Merge bitcoin/bitcoin#28195: blockstorage: Drop legacy -txindex check

fae405556d56f6f13ce57f69a06b9ec1e825422b scripted-diff: Rename CBlockTreeDB -> BlockTreeDB (MarcoFalke)
faf63039cce40f5cf8dea5a1d24945773c3433a1 Fixup style of moved code (MarcoFalke)
fa65111b99627289fd47dcfaa5197e0f09b8a50e move-only: Move CBlockTreeDB to node/blockstorage (MarcoFalke)
fa8685597e7302fc136f21b6dd3a4b187fa8e251 index: Drop legacy -txindex check (MarcoFalke)
fa69148a0a26c5054dbccdceeac8e117bf449275 scripted-diff: Use blocks_path where possible (MarcoFalke)

Pull request description:

  The only reason for the check was to print a warning about an increase in storage use. Now that 22.x is EOL and everyone should have migrated (or decided to not care about storage use), remove the check.

  Also, a move-only commit is included. (Rebased from https://github.com/bitcoin/bitcoin/pull/22242)

ACKs for top commit:
  TheCharlatan:
    ACK fae405556d56f6f13ce57f69a06b9ec1e825422b, though I lack historical context to really judge the second commit fa8685597e7302fc136f21b6dd3a4b187fa8e251.
  stickies-v:
    ACK fae405556d56f6f13ce57f69a06b9ec1e825422b

Tree-SHA512: 9da8f48767ae52d8e8e21c09a40c949cc0838794f1856cc5f58a91acd3f00a3bca818c8082242b3fdc9ca5badb09059570bb3870850d3807b75a8e23b5222da1

3 files changed, 142 insertions, 4 deletions

diff --git a/src/node/blockstorage.cpp b/src/node/blockstorage.cpp
index 01b4c36a8f..70f11be586 100644
--- a/src/node/blockstorage.cpp
+++ b/src/node/blockstorage.cpp
@@ -7,6 +7,7 @@
 #include <chain.h>
 #include <clientversion.h>
 #include <consensus/validation.h>
+#include <dbwrapper.h>
 #include <flatfile.h>
 #include <hash.h>
 #include <kernel/chainparams.h>
@@ -15,15 +16,125 @@
 #include <reverse_iterator.h>
 #include <signet.h>
 #include <streams.h>
+#include <sync.h>
 #include <undo.h>
 #include <util/batchpriority.h>
 #include <util/fs.h>
 #include <util/signalinterrupt.h>
+#include <util/translation.h>
 #include <validation.h>
 
 #include <map>
 #include <unordered_map>
 
+namespace kernel {
+static constexpr uint8_t DB_BLOCK_FILES{'f'};
+static constexpr uint8_t DB_BLOCK_INDEX{'b'};
+static constexpr uint8_t DB_FLAG{'F'};
+static constexpr uint8_t DB_REINDEX_FLAG{'R'};
+static constexpr uint8_t DB_LAST_BLOCK{'l'};
+// Keys used in previous version that might still be found in the DB:
+// BlockTreeDB::DB_TXINDEX_BLOCK{'T'};
+// BlockTreeDB::DB_TXINDEX{'t'}
+// BlockTreeDB::ReadFlag("txindex")
+
+bool BlockTreeDB::ReadBlockFileInfo(int nFile, CBlockFileInfo& info)
+{
+    return Read(std::make_pair(DB_BLOCK_FILES, nFile), info);
+}
+
+bool BlockTreeDB::WriteReindexing(bool fReindexing)
+{
+    if (fReindexing) {
+        return Write(DB_REINDEX_FLAG, uint8_t{'1'});
+    } else {
+        return Erase(DB_REINDEX_FLAG);
+    }
+}
+
+void BlockTreeDB::ReadReindexing(bool& fReindexing)
+{
+    fReindexing = Exists(DB_REINDEX_FLAG);
+}
+
+bool BlockTreeDB::ReadLastBlockFile(int& nFile)
+{
+    return Read(DB_LAST_BLOCK, nFile);
+}
+
+bool BlockTreeDB::WriteBatchSync(const std::vector<std::pair<int, const CBlockFileInfo*>>& fileInfo, int nLastFile, const std::vector<const CBlockIndex*>& blockinfo)
+{
+    CDBBatch batch(*this);
+    for (const auto& [file, info] : fileInfo) {
+        batch.Write(std::make_pair(DB_BLOCK_FILES, file), *info);
+    }
+    batch.Write(DB_LAST_BLOCK, nLastFile);
+    for (const CBlockIndex* bi : blockinfo) {
+        batch.Write(std::make_pair(DB_BLOCK_INDEX, bi->GetBlockHash()), CDiskBlockIndex{bi});
+    }
+    return WriteBatch(batch, true);
+}
+
+bool BlockTreeDB::WriteFlag(const std::string& name, bool fValue)
+{
+    return Write(std::make_pair(DB_FLAG, name), fValue ? uint8_t{'1'} : uint8_t{'0'});
+}
+
+bool BlockTreeDB::ReadFlag(const std::string& name, bool& fValue)
+{
+    uint8_t ch;
+    if (!Read(std::make_pair(DB_FLAG, name), ch)) {
+        return false;
+    }
+    fValue = ch == uint8_t{'1'};
+    return true;
+}
+
+bool BlockTreeDB::LoadBlockIndexGuts(const Consensus::Params& consensusParams, std::function<CBlockIndex*(const uint256&)> insertBlockIndex, const util::SignalInterrupt& interrupt)
+{
+    AssertLockHeld(::cs_main);
+    std::unique_ptr<CDBIterator> pcursor(NewIterator());
+    pcursor->Seek(std::make_pair(DB_BLOCK_INDEX, uint256()));
+
+    // Load m_block_index
+    while (pcursor->Valid()) {
+        if (interrupt) return false;
+        std::pair<uint8_t, uint256> key;
+        if (pcursor->GetKey(key) && key.first == DB_BLOCK_INDEX) {
+            CDiskBlockIndex diskindex;
+            if (pcursor->GetValue(diskindex)) {
+                // Construct block index object
+                CBlockIndex* pindexNew = insertBlockIndex(diskindex.ConstructBlockHash());
+                pindexNew->pprev          = insertBlockIndex(diskindex.hashPrev);
+                pindexNew->nHeight        = diskindex.nHeight;
+                pindexNew->nFile          = diskindex.nFile;
+                pindexNew->nDataPos       = diskindex.nDataPos;
+                pindexNew->nUndoPos       = diskindex.nUndoPos;
+                pindexNew->nVersion       = diskindex.nVersion;
+                pindexNew->hashMerkleRoot = diskindex.hashMerkleRoot;
+                pindexNew->nTime          = diskindex.nTime;
+                pindexNew->nBits          = diskindex.nBits;
+                pindexNew->nNonce         = diskindex.nNonce;
+                pindexNew->nStatus        = diskindex.nStatus;
+                pindexNew->nTx            = diskindex.nTx;
+
+                if (!CheckProofOfWork(pindexNew->GetBlockHash(), pindexNew->nBits, consensusParams)) {
+                    return error("%s: CheckProofOfWork failed: %s", __func__, pindexNew->ToString());
+                }
+
+                pcursor->Next();
+            } else {
+                return error("%s: failed to read value", __func__);
+            }
+        } else {
+            break;
+        }
+    }
+
+    return true;
+}
+} // namespace kernel
+
 namespace node {
 std::atomic_bool fReindex(false);
 
diff --git a/src/node/blockstorage.h b/src/node/blockstorage.h
index 0180124a79..c79fd2c6a1 100644
--- a/src/node/blockstorage.h
+++ b/src/node/blockstorage.h
@@ -7,17 +7,25 @@
 
 #include <attributes.h>
 #include <chain.h>
+#include <dbwrapper.h>
 #include <kernel/blockmanager_opts.h>
 #include <kernel/chainparams.h>
 #include <kernel/cs_main.h>
 #include <protocol.h>
 #include <sync.h>
-#include <txdb.h>
 #include <util/fs.h>
+#include <util/hasher.h>
 
 #include <atomic>
 #include <cstdint>
+#include <functional>
+#include <limits>
+#include <map>
+#include <memory>
+#include <set>
+#include <string>
 #include <unordered_map>
+#include <utility>
 #include <vector>
 
 class BlockValidationState;
@@ -36,7 +44,26 @@ namespace util {
 class SignalInterrupt;
 } // namespace util
 
+namespace kernel {
+/** Access to the block database (blocks/index/) */
+class BlockTreeDB : public CDBWrapper
+{
+public:
+    using CDBWrapper::CDBWrapper;
+    bool WriteBatchSync(const std::vector<std::pair<int, const CBlockFileInfo*>>& fileInfo, int nLastFile, const std::vector<const CBlockIndex*>& blockinfo);
+    bool ReadBlockFileInfo(int nFile, CBlockFileInfo& info);
+    bool ReadLastBlockFile(int& nFile);
+    bool WriteReindexing(bool fReindexing);
+    void ReadReindexing(bool& fReindexing);
+    bool WriteFlag(const std::string& name, bool fValue);
+    bool ReadFlag(const std::string& name, bool& fValue);
+    bool LoadBlockIndexGuts(const Consensus::Params& consensusParams, std::function<CBlockIndex*(const uint256&)> insertBlockIndex, const util::SignalInterrupt& interrupt)
+        EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
+};
+} // namespace kernel
+
 namespace node {
+using kernel::BlockTreeDB;
 
 /** The pre-allocation chunk size for blk?????.dat files (since 0.8) */
 static const unsigned int BLOCKFILE_CHUNK_SIZE = 0x1000000; // 16 MiB
@@ -185,7 +212,7 @@ public:
      */
     std::multimap<CBlockIndex*, CBlockIndex*> m_blocks_unlinked;
 
-    std::unique_ptr<CBlockTreeDB> m_block_tree_db GUARDED_BY(::cs_main);
+    std::unique_ptr<BlockTreeDB> m_block_tree_db GUARDED_BY(::cs_main);
 
     bool WriteBlockIndexDB() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
     bool LoadBlockIndexDB() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
diff --git a/src/node/chainstate.cpp b/src/node/chainstate.cpp
index 0828f64856..ae1457a87e 100644
--- a/src/node/chainstate.cpp
+++ b/src/node/chainstate.cpp
@@ -37,10 +37,10 @@ static ChainstateLoadResult CompleteChainstateInitialization(
     const ChainstateLoadOptions& options) EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
 {
     auto& pblocktree{chainman.m_blockman.m_block_tree_db};
-    // new CBlockTreeDB tries to delete the existing file, which
+    // new BlockTreeDB tries to delete the existing file, which
     // fails if it's still open from the previous loop. Close it first:
     pblocktree.reset();
-    pblocktree = std::make_unique<CBlockTreeDB>(DBParams{
+    pblocktree = std::make_unique<BlockTreeDB>(DBParams{
         .path = chainman.m_options.datadir / "blocks" / "index",
         .cache_bytes = static_cast<size_t>(cache_sizes.block_tree_db),
         .memory_only = options.block_tree_db_in_memory,