Consolidate CMerkleBlock constructor into a single method

Incorporates feedback suggested by @sipa, @promag, @TheBlueMatt.

src/merkleblock.cpp

@@ -9,33 +9,8 @@
 #include "consensus/consensus.h"
 #include "utilstrencodings.h"
 
-CMerkleBlock::CMerkleBlock(const CBlock& block, CBloomFilter& filter)
-{
-    header = block.GetBlockHeader();
 
-    std::vector<bool> vMatch;
-    std::vector<uint256> vHashes;
-
-    vMatch.reserve(block.vtx.size());
-    vHashes.reserve(block.vtx.size());
-
-    for (unsigned int i = 0; i < block.vtx.size(); i++)
-    {
-        const uint256& hash = block.vtx[i]->GetHash();
-        if (filter.IsRelevantAndUpdate(*block.vtx[i]))
-        {
-            vMatch.push_back(true);
-            vMatchedTxn.push_back(std::make_pair(i, hash));
-        }
-        else
-            vMatch.push_back(false);
-        vHashes.push_back(hash);
-    }
-
-    txn = CPartialMerkleTree(vHashes, vMatch);
-}
-
-CMerkleBlock::CMerkleBlock(const CBlock& block, const std::set<uint256>& txids)
+CMerkleBlock::CMerkleBlock(const CBlock& block, CBloomFilter* filter, const std::set<uint256>* txids)
 {
     header = block.GetBlockHeader();
 
@@ -48,10 +23,14 @@ CMerkleBlock::CMerkleBlock(const CBlock& block, const std::set<uint256>& txids)
     for (unsigned int i = 0; i < block.vtx.size(); i++)
     {
         const uint256& hash = block.vtx[i]->GetHash();
-        if (txids.count(hash))
+        if (txids && txids->count(hash)) {
             vMatch.push_back(true);
-        else
+        } else if (filter && filter->IsRelevantAndUpdate(*block.vtx[i])) {
+            vMatch.push_back(true);
+            vMatchedTxn.emplace_back(i, hash);
+        } else {
             vMatch.push_back(false);
+        }
         vHashes.push_back(hash);
     }
 

src/merkleblock.h

@@ -131,8 +131,12 @@ public:
     CBlockHeader header;
     CPartialMerkleTree txn;
 
-public:
-    /** Public only for unit testing and relay testing (not relayed) */
+    /**
+     * Public only for unit testing and relay testing (not relayed).
+     *
+     * Used only when a bloom filter is specified to allow
+     * testing the transactions which matched the bloom filter.
+     */
     std::vector<std::pair<unsigned int, uint256> > vMatchedTxn;
 
     /**
@@ -140,10 +144,10 @@ public:
      * Note that this will call IsRelevantAndUpdate on the filter for each transaction,
      * thus the filter will likely be modified.
      */
-    CMerkleBlock(const CBlock& block, CBloomFilter& filter);
+    CMerkleBlock(const CBlock& block, CBloomFilter& filter) : CMerkleBlock(block, &filter, nullptr) { }
 
     // Create from a CBlock, matching the txids in the set
-    CMerkleBlock(const CBlock& block, const std::set<uint256>& txids);
+    CMerkleBlock(const CBlock& block, const std::set<uint256>& txids) : CMerkleBlock(block, nullptr, &txids) { }
 
     CMerkleBlock() {}
 
@@ -154,6 +158,10 @@ public:
         READWRITE(header);
         READWRITE(txn);
     }
+
+private:
+    // Combined constructor to consolidate code
+    CMerkleBlock(const CBlock& block, CBloomFilter* filter, const std::set<uint256>* txids);
 };
 
 #endif // BITCOIN_MERKLEBLOCK_H