Merge #10758: Fix some chainstate-init-order bugs.

c0025d0 Fix segfault when shutting down before fully loading (Matt Corallo)
1385697 Order chainstate init more logically. (Matt Corallo)
ff3a219 Call RewindBlockIndex even if we're about to run -reindex-chainstate (Matt Corallo)
b0f3249 More user-friendly error message if UTXO DB runs ahead of block DB (Matt Corallo)
eda888e Fix some LoadChainTip-related init-order bugs. (Matt Corallo)

Pull request description:

  This does a number of things to clean up chainstate init order,
  fixing some issues as it goes:

  * Order chainstate init more logically - first all of the
    blocktree-related loading, then coinsdb, then
    pcoinsTip/chainActive. Only create objects as needed.

  * More clearly document exactly what is and isn't called in
    -reindex and -reindex-chainstate both with comments noting
    calls as no-ops and by adding if guards.

  * Move the writing of fTxIndex to LoadBlockIndex - this fixes a
    bug introduced in d6af06d68aae985436cbc942f0d11078041d121b where
    InitBlockIndex was writing to fTxIndex which had not yet been
    checked (because LoadChainTip hadn't yet initialized the
    chainActive, which would otherwise have resulted in
    InitBlockIndex being a NOP), allowing you to modify -txindex
    without reindex, potentially corrupting your chainstate!

  * Rename InitBlockIndex to LoadGenesisBlock, which is now a more
    natural name for it. Also check mapBlockIndex instead of
    chainActive, fixing a bug where we'd write the genesis block out
    on every start.

  * Move LoadGenesisBlock further down in init. This is a more logical
    location for it, as it is after all of the blockindex-related
    loading and checking, but before any of the UTXO-related loading
    and checking.

  * Give LoadChainTip a return value - allowing it to indicate that
    the UTXO DB ran ahead of the block DB. This just provides a nicer
    error message instead of the previous mysterious
    assert(!setBlockIndexCandidates.empty()) error.

  * Calls ActivateBestChain in case we just loaded the genesis
    block in LoadChainTip, avoiding relying on the ActivateBestChain
    in ThreadImport before continuing init process.

  * Move all of the VerifyDB()-related stuff into a -reindex +
    -reindex-chainstate if guard. It couldn't do anything useful
    as chainActive.Tip() would be null at this point anyway.

Tree-SHA512: 3c96ee7ed44f4130bee3479a40c5cd99a619fda5e309c26d60b54feab9f6ec60fabab8cf47a049c9cf15e88999b2edb7f16cbe6819e97273560b201a89d90762

1 files changed, 5 insertions, 4 deletions

diff --git a/src/validation.h b/src/validation.h
index 95c8e5b93e..b44b72d2d4 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -256,12 +256,13 @@ FILE* OpenBlockFile(const CDiskBlockPos &pos, bool fReadOnly = false);
 fs::path GetBlockPosFilename(const CDiskBlockPos &pos, const char *prefix);
 /** Import blocks from an external file */
 bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskBlockPos *dbp = NULL);
-/** Initialize a new block tree database + block data on disk */
-bool InitBlockIndex(const CChainParams& chainparams);
-/** Load the block tree and coins database from disk */
+/** Ensures we have a genesis block in the block tree, possibly writing one to disk. */
+bool LoadGenesisBlock(const CChainParams& chainparams);
+/** Load the block tree and coins database from disk,
+ * initializing state if we're running with -reindex. */
 bool LoadBlockIndex(const CChainParams& chainparams);
 /** Update the chain tip based on database information. */
-void LoadChainTip(const CChainParams& chainparams);
+bool LoadChainTip(const CChainParams& chainparams);
 /** Unload database information */
 void UnloadBlockIndex();
 /** Run an instance of the script checking thread */