move-only: Move CBlockTreeDB to node/blockstorage

The block index (CBlockTreeDB) is required to write and read blocks, so
move it to blockstorage. This allows to drop the txdb.h include from
`node/blockstorage.h`.

Can be reviewed with:

--color-moved=dimmed-zebra  --color-moved-ws=ignore-all-space

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 +16,116 @@
 #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:
+// CBlockTreeDB::DB_TXINDEX_BLOCK{'T'};
+// CBlockTreeDB::DB_TXINDEX{'t'}
+// CBlockTreeDB::ReadFlag("txindex")
+
+bool CBlockTreeDB::ReadBlockFileInfo(int nFile, CBlockFileInfo &info) {
+    return Read(std::make_pair(DB_BLOCK_FILES, nFile), info);
+}
+
+bool CBlockTreeDB::WriteReindexing(bool fReindexing) {
+    if (fReindexing)
+        return Write(DB_REINDEX_FLAG, uint8_t{'1'});
+    else
+        return Erase(DB_REINDEX_FLAG);
+}
+
+void CBlockTreeDB::ReadReindexing(bool &fReindexing) {
+    fReindexing = Exists(DB_REINDEX_FLAG);
+}
+
+bool CBlockTreeDB::ReadLastBlockFile(int &nFile) {
+    return Read(DB_LAST_BLOCK, nFile);
+}
+
+bool CBlockTreeDB::WriteBatchSync(const std::vector<std::pair<int, const CBlockFileInfo*> >& fileInfo, int nLastFile, const std::vector<const CBlockIndex*>& blockinfo) {
+    CDBBatch batch(*this);
+    for (std::vector<std::pair<int, const CBlockFileInfo*> >::const_iterator it=fileInfo.begin(); it != fileInfo.end(); it++) {
+        batch.Write(std::make_pair(DB_BLOCK_FILES, it->first), *it->second);
+    }
+    batch.Write(DB_LAST_BLOCK, nLastFile);
+    for (std::vector<const CBlockIndex*>::const_iterator it=blockinfo.begin(); it != blockinfo.end(); it++) {
+        batch.Write(std::make_pair(DB_BLOCK_INDEX, (*it)->GetBlockHash()), CDiskBlockIndex(*it));
+    }
+    return WriteBatch(batch, true);
+}
+
+bool CBlockTreeDB::WriteFlag(const std::string &name, bool fValue) {
+    return Write(std::make_pair(DB_FLAG, name), fValue ? uint8_t{'1'} : uint8_t{'0'});
+}
+
+bool CBlockTreeDB::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 CBlockTreeDB::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);