QML Load Snapshot Signet (160,000 height)

[D33r-Gee]

Open for review and testing only. Do not merge!

GUI Integration for UTXO Snapshot Loading

Overview

This PR adds initial GUI support for loading a signet UTXO snapshot at height 160,000, building on Bitcoin Core's assumeutxo infrastructure.

What This PR Does

1. Adds a basic GUI interface for loading UTXO snapshots via the Connection Settings panel
2. Implements non-blocking snapshot loading via QT Thread
3. Provides visual confirmation of snapshot activation
4. Adds a snapshot progress notifications accessible via a handler

Implementation Details

Core Components Modified

1. Node Interface (src/node/interfaces.cpp)

• Implements snapshotLoad() based on the loadtxoutset RPC
• Uses background QT thread for non-blocking operation

2. QML Integration (src/qml/models/nodemodel.cpp)

• Manages snapshot loading state and progress
• Introduces a worker class to manage snapshot metadata
• Uses Qt's thread system to prevent UI blocking
• Provides progress updates via Qt signals

3. UI Components (src/qml/components/SnapshotSettings.qml)

• File selection dialog
• Snapshot verification status
• Progress tracking and visualization

Key Design Decisions

1. Non-blocking Implementation

• Snapshot loading runs in separate QT thread
• UI remains responsive during load

2. Extensibility

• Interface designed to accommodate future assumeutxo changes
• Error handling framework in place

Testing Instructions

1. Build
2. Launch Bitcoin Core QML GUI
3. Navigate to Connection Settings (after onboarding is done)
4. Test with sample snapshot:

magnet:?xt=urn:btih:9da986cb27b3980ea7fd06b21e199b148d486880&dn=utxo-signet-160000.dat

6. Verify (see screenshots below):
   • "Snapshot Loaded" confirmation appears
   • Block clock shows ~50% progress
   • For errors, check debug.log for [snapshot] or [loadsnapshot] messages

Ubuntu 22.04 Screenshots

Expected Behavior

• File selection dialog works
• Success/failure state properly displayed
• Node becomes usable while background validation continues

Future Work

1. Error Handling

• Add user-facing error messages
• Implement recovery paths
• Add snapshot validation UI once background validation has completed

2. Integration

• Coordinate with upstream assumeutxo changes
• Add support for network-specific snapshots (testnet and mainnet)
• Integrate with initial setup wizard

Notes for Reviewers

Snapshot Compatibility

• Load option available after Onboarding in the Connections Settings page
• Currently only works with signet UTXO snapshot
• Limited to specific 160,000 height
• Validates against chain parameters m_assumeutxo_data
  (the changes there can be discarded once synced since m_assumeutxo_data is already hardcoded)

feedback welcome on the approach and implementation details.

[D33r-Gee]

With cb409e3 rebased and got rid off the extra options_mode settings which are not relevant for this evaluation.

Also deleted the extra loadsnapshot.cpp file and instead added the load snapshot function in src/node/interfaces.cpp

[yashrajd]

Should I be getting a binary specific for this issue? I tried loading a signet snapshot into the one for #421 but was unable to...

[D33r-Gee]

Should I be getting a binary specific for this issue?

Yes please download the artifact for your system here

I tried loading a signet snapshot into the one for #421 but was unable to...

That's correct behaviour, 421 is UI only and doesn't not have backend wiring

[D33r-Gee]

With b77f7c1 minor tweaks to the src/node/interfaces.cpp snapshotload() function.

It mimics the rpc call loadtxoutset from bitcoin/bitcoin repository

Next will connect the loading to the progress bar

[D33r-Gee]

with c59e557 Integrated the UI with the C++ backend, implementing a progress callback function to dynamically update the loading progress based on the number of coins processed.

Touched src/validation.h and src/validation.cpp to extract the coin loading progress.

Next: will update the "Loaded Snapshot" stack with the real info from the snapshot

[D33r-Gee]

With e3f8c70 moved the load snapshot functionality from nodeModel to optionsModel since it make it easier to store the snapshot info and reduces redundant variable declarations.

[jarolrod]

With e3f8c70 moved the load snapshot functionality from nodeModel to optionsModel since it make it easier to store the snapshot info and reduces redundant variable declarations.

e3f8c70 is a regression because optionsmodel is not an appropriate place for this, and we are now violating the role of settings.json to store the state of a process.

NodeModel and AppMode are more appropriate places for this information. But the entire approach here is still a concept NACK as we are performing unecessary changes to validation and chainparams.

[yashrajd]

Ok I tested artefact#235 and functionality & UI seems to work.

Didn't see block clock so couldn't verify easily. Adding some UI feedback below:

• fix list item width

• fix list item width
• fix icon size

• blockHeight is accurate
• the date in the copy above it seems right
• didn't check hash accuracy
• hash value is overflowing as you can see, I'd probably wrap it over 2-3 lines, perhaps add copy functionality

[D33r-Gee]

with 90dc0dd rebased over main and addressed @jarolrod concerns by reverting back to just a minimal integration of the loading snapshot functionality.

@yashrajd I will address the UI issues next

As a follow up will investigate how to access the snapshot verification progress

Also looking into how to make the snapshot data persist and be available for display (i.e. snapshot block height, date, and merkle hash)

[D33r-Gee]

But the entire approach here is still a concept NACK as we are performing unecessary changes to validation and chainparams.

For the chainparams the changes there are only temporary for evaluating and testing within this repo. I checked upstream and the signet snapshot has already been hardcoded so once our repo is synced the changes in chainparams.cpp can be discarded.

[D33r-Gee]

with 85592f5 made the snapshot activation persist on node restart by making use of the interface with chain->hasAssumedValidChain

Also changed the green-check icon size to 30 pix

Next looking into how to extract the progress from the ActivateSnapshot process

[D33r-Gee]

with 955c65d modified the snapshotLoad() function in src/node/interfaces.cpp and the initializeSnapshot() function in nodemodel.cpp to extract progress information using regular expressions.

This design decision aimed to keep snapshot loading mechanisms self-contained.

However, it looks like the use of std::stod is triggering some lint failures... will look into how to address that.

Perhaps the way to go is to use the handler in src/node/interfaces_ui ... will explore that path then update

[D33r-Gee]

with 0eba513 reverted back to minimal snapshot load functionality.

Snapshot loading progress is still not were I want it to be so in the meantime replaced the progress bar with placeholder text.

Also updated the snapshot info display. once successfully loaded, and I'm using the hardcoded info in chainparams since if the snapshot has loaded successfully it means the info there has been validated.
This is make the info persistent and not rely on the snapshot.dat file (in case it gets deleted)

[D33r-Gee]

With cd2ec69 added a section to keep track of snapshot loading, it is not ideal so will look for better ways to achieve it.

Since the core functionality is there will ask for "pre-reviews" before un-drafting

[D33r-Gee]

with 5d0756c updated SnapshotSettings.qml with comments documenting the loading process.

with 262bb03 updated nodemodel by adding the m_snapshot_loading bool so that the "Snapshot Loading" page persist if the user navigates away from it.

Next looking into how to finesse the snapshot loading progress...

[D33r-Gee]

With 68efab5 this PR is ready to transition from draft status.

The changes are separated into two distinct commits:

1. Core functionality changes intended for upstream integration into bitcoin/bitcoin (bd0f120)

2. QML-specific implementations and adaptations (68efab5)

[D33r-Gee]

109cf42 rebased over main

[D33r-Gee]

with cad966e rebased over main.

Keeping this PR as draft until we get closer to the sync with upstream...

[D33r-Gee]

with 6c25cd7 :

• rebased with main
• updated the qml pages to behave more like the designers feedback in [DRAFT] WIP QML Generate Snapshot Signet #446
• Also updated some of the cpp code to enable the UI changes

Will keep this as draft until we get closer to the sync with upstream

[D33r-Gee]

4e43df9 updates the following:

• Introduce isIBDComplete bool in qml/nodemodel
• Update ConnectionsSettings.qml to reflect the change

Once the CI completes will undraft since we are not exactly sure when the sync with upstream will happen. And this feature will be demoed at upcoming events.

Feedback welcomed!

[D33r-Gee]

With bbbbf42 adds error page to handle when a invalid snapshot gets used, this is based on @GBKS feedback in #449

Feedback welcomed!

[hebasto]

Based on #421.

This is confusing, given that #421 is closed.

[D33r-Gee]

e02f382 rebased over main