From e104f0fb7e464f8cadb4cbc99e8329d22c35c36a Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Tue, 25 Apr 2017 21:35:02 -0400
Subject: [PATCH] Move block writing out of AcceptBlock

---
 src/validation.cpp | 49 +++++++++++++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/src/validation.cpp b/src/validation.cpp
index 74e9671842..067e41495b 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -2759,7 +2759,7 @@ static bool ReceivedBlockTransactions(const CBlock &block, CValidationState& sta
     return true;
 }
 
-static bool FindBlockPos(CValidationState &state, CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeight, uint64_t nTime, bool fKnown = false)
+static bool FindBlockPos(CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeight, uint64_t nTime, bool fKnown = false)
 {
     LOCK(cs_LastBlockFile);
 
@@ -2808,7 +2808,7 @@ static bool FindBlockPos(CValidationState &state, CDiskBlockPos &pos, unsigned i
                 }
             }
             else
-                return state.Error("out of disk space");
+                return error("out of disk space");
         }
     }
 
@@ -3196,6 +3196,25 @@ bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidatio
     return true;
 }
 
+/** Store block on disk. If dbp is non-nullptr, the file is known to already reside on disk */
+static CDiskBlockPos SaveBlockToDisk(const CBlock& block, int nHeight, const CChainParams& chainparams, const CDiskBlockPos* dbp) {
+    unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
+    CDiskBlockPos blockPos;
+    if (dbp != nullptr)
+        blockPos = *dbp;
+    if (!FindBlockPos(blockPos, nBlockSize+8, nHeight, block.GetBlockTime(), dbp != nullptr)) {
+        error("%s: FindBlockPos failed", __func__);
+        return CDiskBlockPos();
+    }
+    if (dbp == nullptr) {
+        if (!WriteBlockToDisk(block, blockPos, chainparams.MessageStart())) {
+            AbortNode("Failed to write block");
+            return CDiskBlockPos();
+        }
+    }
+    return blockPos;
+}
+
 /** Store block on disk. If dbp is non-nullptr, the file is known to already reside on disk */
 static bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex, bool fRequested, const CDiskBlockPos* dbp, bool* fNewBlock)
 {
@@ -3257,19 +3276,13 @@ static bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidation
     if (!IsInitialBlockDownload() && chainActive.Tip() == pindex->pprev)
         GetMainSignals().NewPoWValidBlock(pindex, pblock);
 
-    int nHeight = pindex->nHeight;
-
     // Write block to history file
     try {
-        unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
-        CDiskBlockPos blockPos;
-        if (dbp != nullptr)
-            blockPos = *dbp;
-        if (!FindBlockPos(state, blockPos, nBlockSize+8, nHeight, block.GetBlockTime(), dbp != nullptr))
-            return error("AcceptBlock(): FindBlockPos failed");
-        if (dbp == nullptr)
-            if (!WriteBlockToDisk(block, blockPos, chainparams.MessageStart()))
-                AbortNode(state, "Failed to write block");
+        CDiskBlockPos blockPos = SaveBlockToDisk(block, pindex->nHeight, chainparams, dbp);
+        if (blockPos.IsNull()) {
+            state.Error(strprintf("%s: Failed to find position to write new block to disk", __func__));
+            return false;
+        }
         if (!ReceivedBlockTransactions(block, state, pindex, blockPos, chainparams.GetConsensus()))
             return error("AcceptBlock(): ReceivedBlockTransactions failed");
     } catch (const std::runtime_error& e) {
@@ -4037,15 +4050,11 @@ bool LoadGenesisBlock(const CChainParams& chainparams)
 
     try {
         CBlock &block = const_cast<CBlock&>(chainparams.GenesisBlock());
-        // Start new block file
-        unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
-        CDiskBlockPos blockPos;
-        CValidationState state;
-        if (!FindBlockPos(state, blockPos, nBlockSize+8, 0, block.GetBlockTime()))
-            return error("%s: FindBlockPos failed", __func__);
-        if (!WriteBlockToDisk(block, blockPos, chainparams.MessageStart()))
+        CDiskBlockPos blockPos = SaveBlockToDisk(block, 0, chainparams, nullptr);
+        if (blockPos.IsNull())
             return error("%s: writing genesis block to disk failed", __func__);
         CBlockIndex *pindex = AddToBlockIndex(block);
+        CValidationState state;
         if (!ReceivedBlockTransactions(block, state, pindex, blockPos, chainparams.GetConsensus()))
             return error("%s: genesis block not accepted", __func__);
     } catch (const std::runtime_error& e) {