Fix resume-of-reindex-after-restart

This more clearly uses fReindex vs fReset to make sure we're not
clearing our coinsdb needlessly when restarting after a reindex.
It also makes it so that restarting after shutting down mid-reindex
isn't treates specially at all during txdb loading code, as it
shouldn't be.

Author: TheBlueMatt

src/init.cpp

@@ -1400,9 +1400,9 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
                 delete pcoinscatcher;
                 delete pblocktree;
 
-                pblocktree = new CBlockTreeDB(nBlockTreeDBCache, false, fReindex);
+                pblocktree = new CBlockTreeDB(nBlockTreeDBCache, false, fReset);
 
-                if (fReindex) {
+                if (fReset) {
                     pblocktree->WriteReindexing(true);
                     //If we're reindexing in prune mode, wipe away unusable block files and all undo data files
                     if (fPruneMode)
@@ -1414,6 +1414,8 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
                 // LoadBlockIndex will load fTxIndex from the db, or set it if
                 // we're reindexing. It will also load fHavePruned if we've
                 // ever removed a block file from disk.
+                // Note that it also sets fReindex based on the disk flag!
+                // From here on out fReindex and fReset mean something different!
                 if (!LoadBlockIndex(chainparams)) {
                     strLoadError = _("Error loading block database");
                     break;
@@ -1448,7 +1450,7 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
                 // At this point we're either in reindex or we've loaded a useful
                 // block tree into mapBlockIndex!
 
-                pcoinsdbview = new CCoinsViewDB(nCoinDBCache, false, fReindex || fReindexChainState);
+                pcoinsdbview = new CCoinsViewDB(nCoinDBCache, false, fReset || fReindexChainState);
                 pcoinscatcher = new CCoinsViewErrorCatcher(pcoinsdbview);
 
                 // If necessary, upgrade from older database format.
@@ -1467,7 +1469,7 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
                 // The on-disk coinsdb is now in a good state, create the cache
                 pcoinsTip = new CCoinsViewCache(pcoinscatcher);
 
-                if (!fReindex && !fReindexChainState) {
+                if (!fReset && !fReindexChainState) {
                     // LoadChainTip sets chainActive based on pcoinsTip's best block
                     if (!LoadChainTip(chainparams)) {
                         strLoadError = _("Error initializing block database");
@@ -1476,7 +1478,7 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
                     assert(chainActive.Tip() != NULL);
                 }
 
-                if (!fReindex) {
+                if (!fReset) {
                     // Note that RewindBlockIndex MUST run even if we're about to -reindex-chainstate.
                     // It both disconnects blocks based on chainActive, and drops block data in
                     // mapBlockIndex based on lack of available witness data.
@@ -1487,7 +1489,7 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
                     }
                 }
 
-                if (!fReindex && !fReindexChainState) {
+                if (!fReset && !fReindexChainState) {
                     uiInterface.InitMessage(_("Verifying blocks..."));
                     if (fHavePruned && GetArg("-checkblocks", DEFAULT_CHECKBLOCKS) > MIN_BLOCKS_TO_KEEP) {
                         LogPrintf("Prune: pruned datadir may not have more than %d blocks; only checking available blocks",