From 9d6dcc52c6cb0cdcda220fddccaabb0ffd40068d Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Sun, 24 Feb 2019 12:07:10 -0800
Subject: Abstract EraseBlockData out of RewindBlockIndex

Note that the former 'else' branch in RewindBlockIndex is now
dealt with more naturally inside the EraseBlockData call (by
checking whether the parent needs to be re-added as candidate
after deleting a child).
---
 src/validation.cpp | 67 ++++++++++++++++++++++++++++++++----------------------
 1 file changed, 40 insertions(+), 27 deletions(-)

(limited to 'src/validation.cpp')

diff --git a/src/validation.cpp b/src/validation.cpp
index 1806bc1268..d1872c961c 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -206,8 +206,10 @@ private:
     CBlockIndex* FindMostWorkChain() EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     void ReceivedBlockTransactions(const CBlock& block, CBlockIndex* pindexNew, const CDiskBlockPos& pos, const Consensus::Params& consensusParams) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
-
     bool RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs, const CChainParams& params) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
+
+    //! Mark a block as not having block data
+    void EraseBlockData(CBlockIndex* index) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 } g_chainstate;
 
 /**
@@ -4168,6 +4170,42 @@ bool ReplayBlocks(const CChainParams& params, CCoinsView* view) {
     return g_chainstate.ReplayBlocks(params, view);
 }
 
+//! Helper for CChainState::RewindBlockIndex
+void CChainState::EraseBlockData(CBlockIndex* index)
+{
+    AssertLockHeld(cs_main);
+    assert(!chainActive.Contains(index)); // Make sure this block isn't active
+
+    // Reduce validity
+    index->nStatus = std::min<unsigned int>(index->nStatus & BLOCK_VALID_MASK, BLOCK_VALID_TREE) | (index->nStatus & ~BLOCK_VALID_MASK);
+    // Remove have-data flags.
+    index->nStatus &= ~(BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO);
+    // Remove storage location.
+    index->nFile = 0;
+    index->nDataPos = 0;
+    index->nUndoPos = 0;
+    // Remove various other things
+    index->nTx = 0;
+    index->nChainTx = 0;
+    index->nSequenceId = 0;
+    // Make sure it gets written.
+    setDirtyBlockIndex.insert(index);
+    // Update indexes
+    setBlockIndexCandidates.erase(index);
+    std::pair<std::multimap<CBlockIndex*, CBlockIndex*>::iterator, std::multimap<CBlockIndex*, CBlockIndex*>::iterator> ret = mapBlocksUnlinked.equal_range(index->pprev);
+    while (ret.first != ret.second) {
+        if (ret.first->second == index) {
+            mapBlocksUnlinked.erase(ret.first++);
+        } else {
+            ++ret.first;
+        }
+    }
+    // Mark parent as eligible for main chain again
+    if (index->pprev && index->pprev->IsValid(BLOCK_VALID_TRANSACTIONS) && index->pprev->HaveTxsDownloaded()) {
+        setBlockIndexCandidates.insert(index->pprev);
+    }
+}
+
 bool CChainState::RewindBlockIndex(const CChainParams& params)
 {
     LOCK(cs_main);
@@ -4219,32 +4257,7 @@ bool CChainState::RewindBlockIndex(const CChainParams& params)
         // rewind all the way.  Blocks remaining on chainActive at this point
         // must not have their validity reduced.
         if (IsWitnessEnabled(pindexIter->pprev, params.GetConsensus()) && !(pindexIter->nStatus & BLOCK_OPT_WITNESS) && !chainActive.Contains(pindexIter)) {
-            // Reduce validity
-            pindexIter->nStatus = std::min<unsigned int>(pindexIter->nStatus & BLOCK_VALID_MASK, BLOCK_VALID_TREE) | (pindexIter->nStatus & ~BLOCK_VALID_MASK);
-            // Remove have-data flags.
-            pindexIter->nStatus &= ~(BLOCK_HAVE_DATA | BLOCK_HAVE_UNDO);
-            // Remove storage location.
-            pindexIter->nFile = 0;
-            pindexIter->nDataPos = 0;
-            pindexIter->nUndoPos = 0;
-            // Remove various other things
-            pindexIter->nTx = 0;
-            pindexIter->nChainTx = 0;
-            pindexIter->nSequenceId = 0;
-            // Make sure it gets written.
-            setDirtyBlockIndex.insert(pindexIter);
-            // Update indexes
-            setBlockIndexCandidates.erase(pindexIter);
-            std::pair<std::multimap<CBlockIndex*, CBlockIndex*>::iterator, std::multimap<CBlockIndex*, CBlockIndex*>::iterator> ret = mapBlocksUnlinked.equal_range(pindexIter->pprev);
-            while (ret.first != ret.second) {
-                if (ret.first->second == pindexIter) {
-                    mapBlocksUnlinked.erase(ret.first++);
-                } else {
-                    ++ret.first;
-                }
-            }
-        } else if (pindexIter->IsValid(BLOCK_VALID_TRANSACTIONS) && pindexIter->HaveTxsDownloaded()) {
-            setBlockIndexCandidates.insert(pindexIter);
+            EraseBlockData(pindexIter);
         }
     }
 
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