wallet: Track no-longer-spendable TXOs separately

achow101 commented at 6:40 pm on June 12, 2023: member

In #27286, the wallet keeps track of all of its transaction outputs, even if they are already spent or are otherwise unspendable. This TXO set is iterated for balance checking and coin selection preparation, which can still be slow for wallets that have had a lot of activity. This PR aims to improve the performance of such wallets by moving UTXOs that are definitely no longer spendable to a different map in the wallet so that far fewer TXOs need to be iterated for the aforementioned functions.

Unspendable TXOs (not to be confused with Unspent TXOs) are those which have a spending transaction that has been confirmed, or are no longer valid due to reorgs. TXOs that are spent in unconfirmed transactions remain in the primary TXO set, and are filtered out of balance and coin selection as before.

Depends on #27286

DrahtBot commented at 6:40 pm on June 12, 2023: contributor

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/27865.

Reviews

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Type	Reviewers
Concept ACK	remyers, murchandamus, jonatack

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Conflicts

Reviewers, this pull request conflicts with the following ones:

#33043 ([POC] wallet: Enable non-electronic (paper-based) wallet backup with codex32 by w0xlt)
#33034 (wallet: Store transactions in a separate sqlite table by achow101)
#32977 (wallet: Remove wallet version and several legacy related functions by w0xlt)
#32966 (Silent Payments: Receiving by Eunovo)
#32895 (wallet: Prepare for future upgrades by recording versions of last client to open and decrypt by achow101)
#32763 (wallet: Replace CWalletTx::mapValue and vOrderForm with explicit class members by achow101)
#32685 (wallet: Allow read-only database access for info and dump commands by PeterWrighten)
#32523 (wallet: Remove isminetypes by achow101)
#29278 (Wallet: Add maxfeerate wallet startup option by ismaelsadeeq)
#25722 (refactor: Use util::Result class for wallet loading by ryanofsky)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

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achow101 commented at 9:32 pm on September 7, 2023: member

@t-bast You may be interested in this for very large wallets.

t-bast commented at 12:26 pm on September 11, 2023: contributor

Neat, thanks @achow101, @remyers will give that a try and will review the related PRs!

remyers commented at 7:49 pm on September 12, 2023: contributor

Concept ACK - on a large synthetic test wallet I’m seeing a 250x speed up.

I created a large wallet in regtest with many fanout style transactions - 100,000 blocks each creating 1000 utxos. There are only 117 utxos currently, but the wallet.dat file is 370M.

Using the same wallet.dat file and (transaction history) fundrawtransaction saw a substantial speedup: ~5 seconds using v25.99.0-a36134fcc7b4 ~20 milliseconds using v25.99.0-d9c4dcfe68c5 (latest wallet-unspent-txos)

I will try to recreate my large test wallet.dat file tomorrow so I can confirm the steps to reproduce it. Is there anything in particular I can do to help? Would you like more testing? code review?

NB: I had to export my original wallet descriptors and re-import them to work around the issue fixed in #27920. Before the export/import the wallet.dat file was 1.1G, but the speed of fundrawtransaction was 5 sec both in the original file and the tested one created via importing descriptors.

achow101 commented at 8:55 pm on September 12, 2023: member

Is there anything in particular I can do to help? Would you like more testing? code review?

The prerequisite PR (#27286) will need review and testing before this can be merged. That should also provide some speed up.

remyers commented at 9:53 am on September 13, 2023: contributor

The prerequisite PR (#27286) will need review and testing before this can be merged. That should also provide some speed up.

Will do. I’m getting 400-500ms for the same test using just #27286, so indeed also ~100x speed-up.

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murchandamus commented at 7:47 pm on December 28, 2023: contributor

Concept ACK

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jonatack commented at 12:35 pm on November 26, 2024: member

Concept ACK, pending #27286, if this improves performance for wallets with many transactions.

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in src/wallet/test/util.cpp:26 in 9554a4d79a outdated

27-    }
28+    bilingual_str error;
29+    std::vector<bilingual_str> warnings;
30+    auto wallet = CWallet::Create(context, "", CreateMockableWalletDatabase(), WALLET_FLAG_DESCRIPTORS, error, warnings);
31+
32+    // Allow the fallback fee with it's default

maflcko commented at 7:17 am on June 2, 2025:

“with it’s default” -> “with its default” [“it’s” is a contraction of “it is,” but here the possessive “its” is required]

achow101 commented at 7:37 pm on June 2, 2025:

Fixed

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DrahtBot commented at 3:08 am on June 27, 2025: contributor

🚧 At least one of the CI tasks failed. Task lint: https://github.com/bitcoin/bitcoin/runs/44895352538 LLM reason (✨ experimental): The failure is caused by a Python lint error due to an unused variable in the wallet_backwards_compatibility.py test.

Try to run the tests locally, according to the documentation. However, a CI failure may still happen due to a number of reasons, for example:

Possibly due to a silent merge conflict (the changes in this pull request being incompatible with the current code in the target branch). If so, make sure to rebase on the latest commit of the target branch.
A sanitizer issue, which can only be found by compiling with the sanitizer and running the affected test.
An intermittent issue.

Leave a comment here, if you need help tracking down a confusing failure.

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in src/wallet/transaction.h:225 in 25a16d0a25 outdated

214@@ -215,6 +215,11 @@ class CWalletTx
215      * CWallet::ComputeTimeSmart().
216      */
217     unsigned int nTimeSmart;
218+    /**
219+     * For every isminetype, we want to track whether the transaction spends any
220+     * inputs that match that isminetype.
221+     */
222+    std::optional<bool> m_from_me;

w0xlt commented at 0:26 am on July 3, 2025:

Why is it optional instead of false by default?

achow101 commented at 8:50 pm on July 9, 2025:

Using a default value has the potential very problematic because its value is expected to be correct. By using an optional, we can detect when there is a programming error that did not set the value.

DrahtBot added the label Needs rebase on Jul 7, 2025

wallet: Store the TxState in each WalletTXO as well cb1ac025b9

wallet: Get the depth in main chain for a TxState f034b26ca0

wallet: Get the coinbase maturity state for a TXO and TxState bceddd7d52

wallet: Use WalletTXO stored state and coinbase rather than wtx 61e4211636

walletdb: Move ReorderTransactions to immediately after loading txs

Perform the transaction reorder upgrade immediately after loading txs
instead of waiting for the end of loading.

b5e21abf48

wallet: Add m_from_me to cache "from me" status

m_from_me is used to track whether a transaction is "from me", i.e. has
any inputs which belong to the wallet.

a1031b4ca6

wallet: Replace CachedTxIsFromMe with direct m_from_me lookup

Instead of looking at the cached amounts or searching every input of a
transaction each time we want to determine whether it is "from me", use
m_from_me  which stores this value for us.

dbe4d7df3f

wallet: Store a copy of m_from_me in WalletTXOs and use for "from me"

Since we need to know whether the transaction that creates a WalletTXO
is "from me", we should store this state in the WalletTXO too, copied
from its parent CWalletTx.

69be4f07a7

wallet: Have WalletTXOs also store parent tx time

WalletTXOs need to know their parent tx's timestamp for AvailableCoins
to work.

515964be76

wallet: Make CWalletTx::m_state private with {get,set}ters 2d54d7febd

wallet: have CWalletTx also be aware of it's WalletTXOs 849040457d

wallet: Also update a CWalletTx's WalletTXOs states

When the state of a CWalletTx changes, we need to change the state in
the WalletTXOs too.

c77685d4ae

wallet: Remove unused WalletTXO::GetWalletTx() bf6481c33c

wallet: Have IsSpent take a min_conf

A min_conf parameter is added to IsSpent so that it can set a
confirmation threshold for whether something is considered spent.

179fdb4cd6

wallet: Iterate block txs in reverse on blockDisconnected

When a block is disconnected, we need to process the transactions in
reverse order so that the wallet's TXO set is updated in the correct
order.

7ac7b2362a

wallet, tests: Have CreateSyncedWallet use CWallet::Create

CWallet::Create will properly connect the wallet to the chain, so we
should be doing that rather than ad-hoc chain connection.

7aa62bbdd7

wallet: Move definintely unusable TXOs to a separate container

Definitely unusable TXOs are those that are spent by a confirmed
transaction or were produced by a now conflicted transaction. However,
we still need them for GetDebit, so we store them in a separate
m_unusable_txos container. MarkConflicted, AbandonTransaction, and
loading (via PruneSpentTXOs) will ensure that these unusable TXOs are
properly moved.

3c56e99057

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Zeegaths commented at 0:54 am on August 1, 2025: none

Performance Testing Results

Tested this PR against master using regtest with high-activity wallets.

Test Setup:

Ubuntu 22.04, CMake build
Fresh regtest environment for both branches
1,110 transactions (200 initial coinbase + 500 small sends + 100 coinbase + 300 large sends + 10 final coinbase)
Identical test patterns on both branches

Results:

Operation	Master	PR Branch	Performance Change
`getwalletinfo`	0.008s	0.011s	+38% slower
`getbalance`	0.009s	0.010s	+11% slower
`listunspent`	0.051s	0.035s	-31% faster
`sendtoaddress`	0.036s	0.037s	+3% slower

Observations:

The TXO separation optimization shows its intended benefit in listunspent (31% improvement), which makes sense given that this operation iterates through unspent outputs - exactly what the PR optimizes. Other operations show minimal performance differences within expected measurement variance.

Results suggest the optimization is working as designed for the primary use case.

wallet: Track no-longer-spendable TXOs separately #27865

Code Coverage & Benchmarks

Reviews

Conflicts

Performance Testing Results

Test Setup:

Results:

Observations: