Do not store Merkle branches in the wallet. #6550

sipa · 2015-08-11T19:13:39Z

Assume that when a wallet transaction has a valid block hash and transaction position
in it, the transaction is actually there. We're already trusting wallet data in a
much more fundamental way anyway.

To prevent backward compatibility issues, a new record is used for storing the
block locator in the wallet. Old wallets will see a wallet file synchronized up
to the genesis block, and rescan automatically.

Fixes #6536 using a suggestion by @jonasschnelli to retain backward compatibility.

dcousens · 2015-08-12T00:53:59Z

utACK

dcousens · 2015-08-12T00:55:55Z

src/primitives/block.cpp

@@ -15,7 +15,7 @@ uint256 CBlockHeader::GetHash() const
    return SerializeHash(*this);
 }

-uint256 CBlock::BuildMerkleTree(bool* fMutated) const
+uint256 CBlock::ComputeMerkleRoot(bool* fMutated) const


Unrelated to this PR, but is there any reason we prefer the optional arguments compared to a tuple return value?

I'm not sure this is so much "preferred", it's how it happens to be written between two more-or-less equivalent ways to formulate it.

You're relying on an optional optimization allowed by the C++ standard (copy elision) to avoid constructing a tuple as a temporary and copying it to the return location. In C++11 it's better because you can explicitly indicate move semantics.

laanwj · 2015-08-12T07:37:36Z

Concept ACK.

jtimon · 2015-08-12T09:21:25Z

Concept ACK

sipa · 2015-08-12T18:42:24Z

This needs testing :)

jonasschnelli · 2015-08-12T18:46:19Z

Concept ACK. Started testing...

jonasschnelli · 2015-08-12T19:51:41Z

Tested ACK (lldb stepped; update of "old" wallet.dat works). Played around with some huge regtest wallets/chains. Moved wallet.dat back and forth from master bitcoin-core to master+this PR bitcoin-core.

I think this is a step forward. IMO it's totally sufficient to check if a wtx has a valid block in the active chain and the wtx transaction index matches the position in the block.

Next step could be to simplify the height calculation.
GetDepthInMainChainINTERNAL() is very ineffective and holds cs_main because it accesses mapBlockIndex. Calculating balance, UI listing of transactions will call GetDepthInMainChainINTERNAL() for each wallet transaction (! and it even gets called when the credit of a wtx is cached).

I think a height cache would perform better (together with a invalidating option down to a certain height in case of a reorg).

sipa · 2015-08-12T20:04:07Z

Thanks for testing!

@jonasschnelli No need for a height cache, just a cached chainActive.Tip() inside the wallet suffices (you can do ancestor-of checks without cs_main). I can do that, but it's not for this PR.

theuni · 2015-08-12T20:07:53Z

This will cause the merkle tree to be calculated at least 3x per accepted block, as far as I can see:
ProcessNewBlock -> CheckBlock
ProcessNewBlock -> AcceptBlock -> CheckBlock
ProcessNewBlock -> ActivateBestChain -> ... ConnectBlock -> CheckBlock

Is the calculation time significant enough to try to skip some of that?

sipa · 2015-08-12T20:09:11Z

@theuni Ugh, that's bad. No, it won't make up for that. We should avoid doing those duplicated checks.

theuni · 2015-08-12T20:37:03Z

@sipa If I'm reading correctly, it looks like the CheckBlock() in AcceptBlock() is safe to use !fCheckMerkleRoot since it's only ever called from ProcessNewBlock() where it's already been checked.

Same for the ConnectBlock() in ConnectTip(), since they're already checked before writing to disk. That seems a bit more risky, but surely a bad/corrupt read would be detected long before that point anyway?

sipa · 2015-08-13T16:20:18Z

I guess we want to verify the merkle root any time 1) we receive new block date 2) read block data back from this. If the functions who do that always verify, and there is no other way to construct a full CBlock, I think we're good.

sipa · 2015-08-15T21:34:16Z

@theuni It looks a bit more complicated, as currently we do a CheckBlock on blocks read from disk for validation, which would be harder to do if we want to avoid duplicate checks. I've made a much simpler (and slightly uglier) change for now here, which is to cache the result of CheckBlock in CBlock. That also avoids a few other checks that were being done 3 times before.

gmaxwell · 2015-09-06T08:33:55Z

Where does this stand right now? Should I spend cycles testing it as is?

sipa · 2015-09-07T16:17:04Z

@gmaxwell Test away.

sipa · 2015-09-14T22:38:53Z

Ping

dcousens · 2015-09-14T22:46:13Z

src/main.cpp

@@ -2573,7 +2576,7 @@ bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bo
    // Check the merkle root.
    if (fCheckMerkleRoot) {
        bool mutated;
-        uint256 hashMerkleRoot2 = block.BuildMerkleTree(&mutated);
+        uint256 hashMerkleRoot2 = block.ComputeMerkleRoot(&mutated);


const what?

dcousens · 2015-09-14T22:46:41Z

re-utACK

Assume that when a wallet transaction has a valid block hash and transaction position in it, the transaction is actually there. We're already trusting wallet data in a much more fundamental way anyway. To prevent backward compatibility issues, a new record is used for storing the block locator in the wallet. Old wallets will see a wallet file synchronized up to the genesis block, and rescan automatically.

sipa · 2015-09-22T16:51:32Z

Rebased.

laanwj · 2015-09-23T16:39:43Z

src/primitives/block.h

@@ -78,7 +78,7 @@ class CBlock : public CBlockHeader
    std::vector<CTransaction> vtx;

    // memory only
-    mutable std::vector<uint256> vMerkleTree;
+    mutable bool fChecked;


Ideally we'd have this fChecked status (which isn't used in CBlock itself) on an administrative object that wraps a CBlock, instead of on CBlock itself.

Fully agree, I actually started implementing that as a follow-up, but didn't want to interfere with other refactorings.

OK, yes, I'm fine with keeping it like this for this pull

laanwj · 2015-09-23T17:35:32Z

Tested forward/backward compatibility of wallet with this code change.
ACK.

3b33ec8 Avoid duplicate CheckBlock checks (Pieter Wuille) 391dff1 Do not store Merkle branches in the wallet. (Pieter Wuille)

Backport of bitcoin#6550 Assume that when a wallet transaction has a valid block hash and transaction position in it, the transaction is actually there. We're already trusting wallet data in a much more fundamental way anyway. To prevent backward compatibility issues, a new record is used for storing the block locator in the wallet. Old wallets will see a wallet file synchronized up to the genesis block, and rescan automatically.

91b48c7 [Build] Add new merkle files to CMake lists (warrows) 48a3aff [Wallet] Ignore coinbase and zc tx "conflicts" (warrows) 3572354 [Wallet] Fix an error in tx depth computation (warrows) 6928369 [Tests] Enable abandonconflict functional test (warrows) 34cd496 Fix that CWallet::AbandonTransaction would only traverse one level (Ben Woosley) aba5b75 Fix calculation of balances and available coins. (Alex Morcos) 48d705f Remove stale wallet transactions on initial load. (presstab) 12985ae Flush wallet after abandontransaction (Alex Morcos) 8f87956 [Wallet] sort pending wallet transactions before reaccepting (dexX7) 9c2f445 [Wallet] Call notification signal when a transaction is abandoned (Jonas Schnelli) 778ebf3 Add new rpc call: abandontransaction (Alex Morcos) 0e86c3e Make wallet descendant searching more efficient (Alex Morcos) d0083a8 Make sure conflicted wallet tx's update balances (Alex Morcos) 6a50e03 [Wallet] Keep track of explicit wallet conflicts instead of using mempool (warrows) 7ccb2b5 [Wallet] Do not flush the wallet in AddToWalletIfInvolvingMe(..) (warrows) 47345be [Refactor] Move wallet functions out of header (warrows) ab9efb8 [Wallet] Switch to a constant-space Merkle root/branch algorithm (warrows) 5447622 [Wallet] Do not store Merkle branches in the wallet (warrows) Pull request description: This pull request is a happy melting pot of improvements regarding transactions handling. Most of them are backports from bitcoin. I advise reviewers to check the code of the different commits independently to understand them more easily. However, testing is probably better done all at once. I am making a single pull request because these changes are all entangled and introducing some of them without others would probably introduce temporary bugs. ## Commits details ## - 6c3e2ac backport of bitcoin#6550 - 5304fdf backport of bitcoin#6508 - c3eeeac simple code move from the header to the cpp file. It contains no functional change. - 6cc4d37 backport of bitcoin#4805 - 10be1db backport of bitcoin#7105 - 8a34c32 backport of bitcoin#7306 - 3caf123, 9e17178 and 240f5b4 are the backport for bitcoin#7312 - ad6d0b1 backport of bitcoin#5511 - fcc07c3 backport of bitcoin#9311 - 5ed5e26 is an update of #825 - 392d504 backport of bitcoin#7715 - 7199f3a backport of bitcoin#13652 - f09d999 enables and fixes the test from bitcoin#7312 - 4fd43c5 fixes an oversight in bitcoin#7105 backport ACKs for top commit: random-zebra: ACK 91b48c7 Fuzzbawls: ACK 91b48c7 Tree-SHA512: 2628cebe98805b8048b920b51ee26fd4f0c53643d78da9b8cb265aede52dfe1d40c8c19d34293c232c5c35be7f1ab89ff5b4a07073a4b27c371ea70eb8708669

Backport of bitcoin#6550 Assume that when a wallet transaction has a valid block hash and transaction position in it, the transaction is actually there. We're already trusting wallet data in a much more fundamental way anyway. To prevent backward compatibility issues, a new record is used for storing the block locator in the wallet. Old wallets will see a wallet file synchronized up to the genesis block, and rescan automatically.

Backport of bitcoin/bitcoin#6550 Assume that when a wallet transaction has a valid block hash and transaction position in it, the transaction is actually there. We're already trusting wallet data in a much more fundamental way anyway. To prevent backward compatibility issues, a new record is used for storing the block locator in the wallet. Old wallets will see a wallet file synchronized up to the genesis block, and rescan automatically.

Backport of bitcoin#6550 Assume that when a wallet transaction has a valid block hash and transaction position in it, the transaction is actually there. We're already trusting wallet data in a much more fundamental way anyway. To prevent backward compatibility issues, a new record is used for storing the block locator in the wallet. Old wallets will see a wallet file synchronized up to the genesis block, and rescan automatically.

Backport of bitcoin/bitcoin#6550 Assume that when a wallet transaction has a valid block hash and transaction position in it, the transaction is actually there. We're already trusting wallet data in a much more fundamental way anyway. To prevent backward compatibility issues, a new record is used for storing the block locator in the wallet. Old wallets will see a wallet file synchronized up to the genesis block, and rescan automatically.

Bitcoin 0.12 Merkle tree PRs Cherry-picked from the following upstream PRs: - bitcoin/bitcoin#6550 - bitcoin/bitcoin#6508

sipa mentioned this pull request Aug 11, 2015

Switch to a constant-space Merkle root/branch algorithm. #6508

Merged

dcousens reviewed Aug 12, 2015
View reviewed changes

laanwj added the Wallet label Aug 12, 2015

jonasschnelli mentioned this pull request Aug 20, 2015

listunspent running slowly (and also balance and transaction building) #6573

Closed

sipa force-pushed the nomerkle branch from 80a948f to dab5248 Compare September 7, 2015 16:15

sipa force-pushed the nomerkle branch from dab5248 to c7efe04 Compare September 7, 2015 16:47

dcousens reviewed Sep 14, 2015
View reviewed changes

sipa added 2 commits September 22, 2015 18:51

Avoid duplicate CheckBlock checks

3b33ec8

sipa force-pushed the nomerkle branch from c7efe04 to 3b33ec8 Compare September 22, 2015 16:51

laanwj reviewed Sep 23, 2015
View reviewed changes

laanwj merged commit 3b33ec8 into bitcoin:master Sep 23, 2015

laanwj added a commit that referenced this pull request Sep 23, 2015

Merge pull request #6550

5b77244

3b33ec8 Avoid duplicate CheckBlock checks (Pieter Wuille) 391dff1 Do not store Merkle branches in the wallet. (Pieter Wuille)

rnicoll mentioned this pull request Feb 21, 2016

Merge AuxPoW support from Namecore dogecoin/dogecoin#1332

Closed

dagurval mentioned this pull request Jun 13, 2018

Switch to a constant-space Merkle root/branch algorithm. bitcoinxt/bitcoinxt#452

Merged

Warrows mentioned this pull request Jul 30, 2019

[Wallet] Various transaction handling improvements PIVX-Project/PIVX#970

Merged

barton2526 mentioned this pull request Apr 5, 2021

consensus, refactor, test: Merkle gridcoin-community/Gridcoin-Research#2094

Merged

str4d mentioned this pull request Apr 20, 2021

Bitcoin 0.12 Merkle tree PRs zcash/zcash#5065

Merged

zkbot added a commit to zcash/zcash that referenced this pull request Apr 20, 2021

Auto merge of #5065 - str4d:merkle-backports, r=<try>

79c785d

Bitcoin 0.12 Merkle tree PRs Cherry-picked from the following upstream PRs: - bitcoin/bitcoin#6550 - bitcoin/bitcoin#6508

bitcoin locked as resolved and limited conversation to collaborators Sep 8, 2021

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Do not store Merkle branches in the wallet. #6550

Do not store Merkle branches in the wallet. #6550

sipa commented Aug 11, 2015

dcousens commented Aug 12, 2015

dcousens Aug 12, 2015

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laanwj commented Sep 23, 2015

Do not store Merkle branches in the wallet. #6550

Do not store Merkle branches in the wallet. #6550

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