QML Snapshot Load

[D33r-Gee]

This is an re-opened PR based on #424 and #449. It's an alternate to #485 that uses a different /bitcoin branch instead of a patch.

UTXO Snapshot Loading

Overview

This PR enables loading UTXO snapshots both during and after the initial onboarding process.

What This PR Does

1. Adds a basic GUI interface for loading UTXO snapshots via the Connection Settings panel
2. Enables snapshot selection during onboarding, with loading when headers are synced
3. Implements non-blocking snapshot loading via QT Thread
4. Provides visual confirmation of snapshot activation
5. Adds a snapshot progress notifications accessible via a handler

Implementation Details

Core Components Modified

1. CPP Backend (qml/models/nodemodel.cpp)

• Manages snapshot loading state and progress
• Uses Qt's thread system to prevent UI blocking
• Provides progress updates via Qt signals
• Adds support for storing snapshot file path during onboarding
• Implements automatic snapshot loading once headers are synced

2. UI Components (qml/components/SnapshotLoadSettings.qml, src/qml/components/ConnectionSettings.qml)

• File selection dialog with onboarding awareness
• Snapshot verification status
• Progress tracking and visualization
• Updated visibility conditions to enable loading during onboarding

3. Snapshot Qml Model (qml/models/snapshotqml.cpp)

• Introduces a worker class to manage snapshot metadata

Key Design Decisions

1. Onboarding Integration

• Allows users to select snapshot during setup
• Delayed loading until headers are synced
• Proper state handling between onboarding and regular modes

Testing Instructions

1. Build
2. Launch Bitcoin Core QML GUI
3. Navigate to Connection Settings
4. Test with different snapshots:

mainnet: magnet:?xt=urn:btih:559bd78170502971e15e97d7572e4c824f033492&dn=utxo-880000.dat&tr=udp%3A%2F%2Ftracker.bitcoin.sprovoost.nl%3A6969

alternatively, you can use the following link to download the mainnet snapshot: https://bitcoin-snapshots.jaonoctus.dev/

signet: https://drive.google.com/file/d/1VJeeGQncrs4xZhh6kU5IwkyatXVM4SOm/view?usp=sharing

7. Test onboarding flow:

   • Select a snapshot file during initial setup
   • Verify it loads automatically after headers sync

8. Verify (see screenshots below):

   • "Snapshot Loaded" confirmation appears
   • For errors, check debug.log for [snapshot]

Ubuntu 22.04 Screenshots

Expected Behavior

• File selection dialog works
• Node becomes usable while background validation continues
• When selected during onboarding, snapshot loads after headers sync

Success/failure state properly displayed

feedback welcome on the approach and implementation details.

[pinheadmz]

I don't know why CI is able to build, I am failing locally which makes sense because .gitmodules is still pointing at bitcoin core:

--> cat .gitmodules 
[submodule "bitcoin"]
	path = bitcoin
	url = https://github.com/bitcoin/bitcoin

but your commit is not part of that repo, so I get:

--> git submodule update --init
Submodule 'bitcoin' (https://github.com/bitcoin/bitcoin) registered for path 'bitcoin'
Cloning into '/Users/matthewzipkin/Desktop/work/gui-qml/bitcoin'...
fatal: transport 'file' not allowed
fatal: Fetched in submodule path 'bitcoin', but it did not contain c29a5df51402b85fb335b0d16e3016e984224d90. Direct fetching of that commit failed.

I am still trying to figure out what the "file" protocol message is about but otherwise I sort of expected to see this error in CI as well. ChatGPT suspects that the github "checkout" action may have access to some huge github-wide cache and is somehow able to look up c29a... even though it actually lives in https://github.com/D33r-Gee/bitcoin/tree/interface-load-snapshot

[pinheadmz]

The fix for me locally which I think should be part of the PR is:

diff --git a/.gitmodules b/.gitmodules
index fabdfe506..03c475675 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "bitcoin"]
        path = bitcoin
-       url = https://github.com/bitcoin/bitcoin
+       url = https://github.com/D33r-Gee/bitcoin

Then I executed:

git submodule sync
git submodule update --init

This tells git to re-read .gitmodules so it sees the new repo, then the update command pulls that and can fetch the specified commit:

Submodule path 'bitcoin': checked out 'c29a5df51402b85fb335b0d16e3016e984224d90'

[pinheadmz]

concept and tested ACK, no code review yet

--> bitcoin-cli -datadir=/Users/matthewzipkin/Desktop/asutxo/ gettxoutsetinfo
{
  "height": 880355,
  "bestblock": "000000000000000000027d56fb62e21d05bc0626334ece51e780bc68b5e7e1ea",
  "txouts": 184590802,
  "bogosize": 14352668388,
  "hash_serialized_3": "fd3028844649c086e0223880e3b1f8b271775a549598c22ad12792c27553c98f",
  "total_amount": 19813391.91492533,
  "transactions": 128585770,
  "disk_size": 12552553130
}

[D33r-Gee]

concept and tested ACK, no code review yet

Thanks for testing @pinheadmz !

As you saw currently updating the upstream portion which will impact code review here.

Ultimately, the snapshot processing (path → file & metadata) will be moved there. Once the flow is more solid in that location, I’ll update the code here accordingly by removing the models/snapshotqml files and updating the snapshot info retrieval method.