DanS
c1040028e4
An aborted or shutdown-interrupted rescan discarded all of its progress: nothing
advanced the on-disk best-block locator, so the next run started over. On a large
shielded wallet that is a multi-minute witness rebuild repeated from scratch.
Writes the locator ONCE, at the interrupt, rather than periodically through the
scan. That delivers the whole stated benefit -- "resume where it stopped" -- at
the cost of exactly one SetBestChain per interrupted scan. A periodic checkpoint
would additionally survive SIGKILL and power loss, a much weaker requirement, and
it is the part that carries all the cost: SetBestChainINTERNAL is O(whole wallet)
regardless of progress, so on the reported 5.3k-tx / 7.5k-note wallet a checkpoint
every 2500 blocks would plausibly cost more than the rebuild it was meant to save.
If someone later demonstrates a need for crash resilience mid-scan, add it then,
with a measured interval and fFlush=false -- not before.
Two guards, both necessary:
- CONTIGUITY. The RPC entry points (rescan / importprivkey / z_importkey /
z_importviewingkey) take a caller-supplied start height validated only against
chainActive.Height(), never against the wallet's own persisted locator. A scan
beginning above that locator must not checkpoint at all, or it would record
the skipped range as scanned and hide any funds in it. Logged once when it
applies, so an operator can see why an interrupt did not persist.
- MONOTONICITY. A checkpoint may only advance the locator, never move it back.
The locator points at the last FULLY PROCESSED block -- the parent of the block we
were about to scan -- so resume restarts one block early. CChain::GetLocator pushes
its argument first and FindForkInGlobalIndex returns that same block, so resume
begins AT it; the one-block overlap is deliberate and idempotent, since AddToWallet
only takes its merge path when the transaction is already present.
No witness work is done at the interrupt, which answers the two "//TODO: should we
update witness caches?" comments this replaces: witnesses are re-derived from each
note's own witnessHeight independently of the locator, and witnessRootValidated is
never serialized, so every note is revalidated against hashFinalSaplingRoot on the
next start. A mid-scan checkpoint does capture notes at mixed witnessHeights -- the
in-loop BuildWitnessCache(pindex, true) returns before the extension phase and only
seeds new notes at their own transaction's height -- but that state is recoverable:
the post-loop BuildWitnessCache(tip, false) levels every note, and it now occurs at
most once per scan instead of hundreds of times.
Uses SetBestChainNoFlush so the checkpoint does not trigger a full BDB
txn_checkpoint over the whole cache, and reports failure rather than silently
leaving the operator to discover the replay.
Depends on the fLastRescanCompleted gate in the previous commit: without it
init.cpp would overwrite this checkpoint with a tip locator immediately after the
scan returns.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FU87LdsJZiZkfq1eXubpeo
DragonX
A fully-private, RandomX CPU-mineable cryptocurrency.
| Introduction | Build | Run | Mine |
|---|---|---|---|
| What is DragonX? | Build from source | Run a node | CPU mining |
| Key facts | Install a release | Fastest sync | Wallets |
What is DragonX?
DragonX implements extreme privacy via blockchain technology. It is private from
genesis: every ordinary transaction is shielded (z2z), so your transaction metadata
stays private. DragonX is based on Bitcoin code with Zcash's zero-knowledge Sapling
cryptography, and its defining feature is RandomX Proof-of-Work — it is mined with a
CPU, not ASICs or GPUs.
DragonX has its own genesis block. Its lineage is Bitcoin → Zcash → Komodo → Hush → DragonX; it is a fork of the Hush full node, with the Proof-of-Work changed from Equihash to RandomX and privacy enforced from the very first block.
This software is the DragonX full node and command-line client. It downloads and stores the entire history of DragonX transactions; depending on your computer and network connection this can take a while, so most users start from the bootstrap snapshot.
DragonX is experimental software. Use at your own risk, just like Bitcoin.
Key facts
| Ticker | DRAGONX |
| Proof-of-Work | RandomX (CPU-mineable) |
| Privacy | fully private from genesis (ac_private=1, Sapling active at height 1) |
| Block time | 36 seconds |
| Block reward | 3 DRAGONX, halving every 3,500,000 blocks |
| Max block size | 4 MB |
| RPC port | 21769 |
| P2P port | 18030 |
| Data directory | ~/.hush/DRAGONX (Linux) |
| Config file | DRAGONX.conf |
| Binaries | dragonxd, dragonx-cli, dragonx-tx |
Fastest way to sync (bootstrap)
The quickest way to get a fully-synced node is the signed bootstrap snapshot, which installs a pre-built blockchain so you skip re-validating the whole chain from genesis:
# Stop dragonxd first if it is running, then:
./util/bootstrap-dragonx.sh
The script preserves your wallet.dat and DRAGONX.conf, verifies the download's
checksums and (once a release key is published) its cryptographic signature, then starts
you near the chain tip. If you prefer to sync from the network instead, a larger
-dbcache (e.g. -dbcache=2048) noticeably speeds up the initial block download.
Build from source
Building uses 3 build processes by default; you need ~2GB of RAM for each.
Debian or Ubuntu
sudo apt-get install build-essential pkg-config libc6-dev m4 g++-multilib \
autoconf libtool ncurses-dev unzip git zlib1g-dev wget \
bsdmainutils automake curl unzip nano libsodium-dev cmake
git clone https://git.dragonx.is/DragonX/dragonx
cd dragonx
./build.sh -j3
Arch
sudo pacman -S gcc libsodium lib32-zlib unzip wget git python rust curl autoconf cmake
git clone https://git.dragonx.is/DragonX/dragonx
cd dragonx
./build.sh -j3
Fedora
sudo dnf install make automake gcc gcc-c++ kernel-devel cmake libtool ncurses-devel patch -y
git clone https://git.dragonx.is/DragonX/dragonx
cd dragonx
./build.sh -j3
macOS
Install Xcode Command Line Tools and Homebrew, then:
xcode-select --install
brew install gcc autoconf automake pkgconf libtool cmake curl
# Install Rust (needed for librustzcash on macOS Sequoia+)
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
source "$HOME/.cargo/env"
git clone https://git.dragonx.is/DragonX/dragonx
cd dragonx
# Make sure libtool gnubin and cargo are on PATH
export PATH="$HOME/.cargo/bin:/usr/local/opt/libtool/libexec/gnubin:$PATH"
./build.sh -j3
For a release build:
export PATH="$HOME/.cargo/bin:/usr/local/opt/libtool/libexec/gnubin:$PATH"
./build.sh --mac-release -j$(sysctl -n hw.ncpu)
Windows (cross-compiled on Linux)
sudo apt-get install \
build-essential pkg-config libc6-dev m4 g++-multilib libdb++-dev \
autoconf libtool ncurses-dev unzip git zip \
zlib1g-dev wget bsdmainutils automake mingw-w64 cmake libsodium-dev
git clone https://git.dragonx.is/DragonX/dragonx
cd dragonx
./util/build-win.sh -j$(nproc)
ARM (Raspberry Pi)
Any ARMv7 machine cannot build this repo because the underlying zk-SNARK library does not
support that instruction set. You need an ARMv8-based board (Raspberry Pi 4 or newer). Either
install an aarch64 release package (see below) or cross-compile from amd64.
Installing DragonX binaries
- Download a release with a
.debextension. - Install it, substituting the version you downloaded:
sudo dpkg -i dragonx-VERSION-amd64.deb(or-aarch64.debon ARM). - Run with:
dragonxd.
Running a node
Start the daemon:
./src/dragonxd
It stores data in ~/.hush/DRAGONX and reads ~/.hush/DRAGONX/DRAGONX.conf. Query it with
./src/dragonx-cli, for example:
./src/dragonx-cli getinfo
To run DragonX as a background service, see doc/dragonxd-systemd.md.
CPU mining (RandomX)
DragonX is CPU-mineable via RandomX (the same algorithm family as Monero); ASICs and GPUs do not apply. To mine with your node, enable generation and choose how many threads to use:
# mine with 4 CPU threads
./src/dragonxd -gen=1 -genproclimit=4
or add to DRAGONX.conf:
gen=1
genproclimit=4
Mining rewards arrive as transparent coinbase, which is directly spendable; you can optionally
move it into the shielded pool with z_shieldcoinbase (see
doc/shield-coinbase.md). For more on the algorithm and its tuning
options, see doc/randomx.md.
Wallets
The DragonX full node includes a built-in wallet, managed via dragonx-cli (see
doc/wallet-backup.md and doc/seed-phrase.md).
Graphical and mobile wallets:
- ObsidianDragon — desktop wallet, available in both full-node and light-wallet modes.
- SilentDragonXAndroid — wallet for Android devices.
DragonX light and mobile wallets use BIP39 seed phrases that are compatible with the full node — see doc/seed-phrase.md.
Support and links
- Website: https://dragonx.is
- Source code: https://git.dragonx.is/DragonX
- Block explorer: https://explorer.dragonx.is
- Issues / bounties: https://git.dragonx.is/DragonX/dragonx/issues
- Telegram: https://dragonx.is/tg
- Matrix: https://dragonx.is/matrix
- Twitter / X: https://twitter.com/DragonXchain
License
For license information see the file COPYING.