Copyright (c) 2014-2019 The Monero Project

Copyright (c) 2017-2019, The Scala Project

Portions Copyright (c) 2012-2013, The Cryptonote developers

Portions Copyright (c) 2017 The Masari Project

• Development resources

• Introduction

• About this project

• Supporting the project

• License

• Scheduled software upgrades

• Release staging schedule and protocol

• Compiling Scala from source

• Dependencies

• Web: scalaproject.io

• Discord: https://discord.gg/QfCWRfx

• Mail: [email protected]

• GitHub: https://github.com/scala-network/scala

Scala is a private, secure, untraceable, decentralised digital currency. You are your bank, you control your funds, and nobody can trace your transfers unless you allow them to do so.

Privacy: Scala uses a cryptographically sound system to allow you to send and receive funds without your transactions being easily revealed on the blockchain (the ledger of transactions that everyone has). This ensures that your purchases, receipts, and all transfers remain absolutely private by default.

Security: Using the power of a distributed peer-to-peer consensus network, every transaction on the network is cryptographically secured. Individual wallets have a 25 word mnemonic seed that is only displayed once, and can be written down to backup the wallet. Wallet files are encrypted with a passphrase to ensure they are useless if stolen.

Untraceability: By taking advantage of ring signatures, a special property of a certain type of cryptography, Scala is able to ensure that transactions are not only untraceable, but have an optional measure of ambiguity that ensures that transactions cannot easily be tied back to an individual user or computer.

Decentralization: The utility of scala depends on its decentralised peer-to-peer consensus network - anyone should be able to run the scala software, validate the integrity of the blockchain, and participate in all aspects of the scala network using consumer-grade commodity hardware. Decentralization of the scala network is maintained by software development that minimizes the costs of running the scala software and inhibits the proliferation of specialized, non-commodity hardware.

Egalitarian: Scala has a very egalitarian proof-of-work allowing anyone with very simple hardware to participate in mining.

This is the core implementation of Scala. It is open source and completely free to use without restrictions, except for those specified in the license agreement below. There are no restrictions on anyone creating an alternative implementation of Scala that uses the protocol and network in a compatible manner.

As with many development projects, the repository on Github is considered to be the "staging" area for the latest changes. Before changes are merged into that branch on the main repository, they are tested by individual developers in their own branches, submitted as a pull request, and then subsequently tested by contributors who focus on testing and code reviews. That having been said, the repository should be carefully considered before using it in a production environment, unless there is a patch in the repository for a particular show-stopping issue you are experiencing. It is generally a better idea to use a tagged release for stability.

Anyone is welcome to contribute to Scala's codebase! If you have a fix or code change, feel free to submit it as a pull request directly to the "master" branch. In cases where the change is relatively small or does not affect other parts of the codebase it may be merged in immediately by any one of the collaborators. On the other hand, if the change is particularly large or complex, it is expected that it will be discussed at length either well in advance of the pull request being submitted, or even directly on the pull request.

Scala is a 100% community-sponsored endeavor. If you want to join our efforts, the easiest thing you can do is support the project financially. Both Scala and Bitcoin donations can be made to addresses given below.

The Scala donation address is: SEiTBcLGpfm3uj5b5RaZDGSUoAGnLCyG5aJjAwko67jqRwWEH26NFPd26EUpdL1zh4RTmTdRWLz8WCmk5F4umYaFByMtJT6RLjD6vzApQJWfi

The Bitcoin donation address is: 1XTLY5LqdBXRW6hcHtnuMU7c68mAyW6qm

If you would like to sponsor our project, please drop a twitter message at ScalaHQ or text us on discord

See LICENSE.

Scala uses a fixed-schedule software upgrade (hard fork) mechanism to implement new features. This means that users of Scala (end users and service providers) should run current versions and upgrade their software on a regular schedule. The required software for these upgrades will be available prior to the scheduled date. Please check the repository prior to this date for the proper Scala software version.

The following table summarizes the tools and libraries required to build. A

few of the libraries are also included in this repository (marked as

"Vendored"). By default, the build uses the library installed on the system,

and ignores the vendored sources. However, if no library is found installed on

the system, then the vendored source will be built and used. The vendored

sources are also used for statically-linked builds because distribution

packages often include only shared library binaries (.so) but not static

library archives (.a).

[1] On Debian/Ubuntu libgtest-dev only includes sources and headers. You must

build the library binary manually. This can be done with the following command sudo apt-get install libgtest-dev && cd /usr/src/gtest && sudo cmake . && sudo make && sudo mv libg* /usr/lib/

[2] libnorm-dev is needed if your zmq library was built with libnorm, and not needed otherwise

Install all dependencies at once on Debian/Ubuntu:

sudo apt update && sudo apt install build-essential cmake pkg-config libboost-all-dev libssl-dev libzmq3-dev libunbound-dev libsodium-dev libunwind8-dev liblzma-dev libreadline6-dev libldns-dev libexpat1-dev doxygen graphviz libpgm-dev

Install all dependencies at once on macOS with the provided Brewfile:

brew update && brew bundle --file=contrib/brew/Brewfile

FreeBSD one liner for required to build dependencies

pkg install git gmake cmake pkgconf boost-libs cppzmq libsodium

Clone recursively to pull-in needed submodule(s):

$ git clone --recursive https://github.com/scala-project/scala

If you already have a repo cloned, initialize and update:

$ cd scala && git submodule init && git submodule update

Scala uses the CMake build system and a top-level Makefile that

invokes cmake commands as needed.

• Install the dependencies

• Change to the root of the source code directory, change to the most recent release branch, and build:

cd scala

make

Optional: If your machine has several cores and enough memory, enable

parallel build by running make -j<number of threads> instead of make. For

this to be worthwhile, the machine should have one core and about 2GB of RAM

available per thread.

Note: If cmake can not find zmq.hpp file on macOS, installing zmq.hpp from

https://github.com/zeromq/cppzmq to /usr/local/include should fix that error.

Note: The instructions above will compile the most stable release of the

Scala software. If you would like to use and test the most recent software,

use git checkout master. The master branch may contain updates that are

both unstable and incompatible with release software, though testing is always

encouraged.

• The resulting executables can be found in build/release/bin

• Add PATH="$PATH:$HOME/scala/build/release/bin" to .profile

• Run Scala with scalad --detach

• Optional: build and run the test suite to verify the binaries:

make release-test

NOTE: core_tests test may take a few hours to complete.

• Optional: to build binaries suitable for debugging:

make debug

• Optional: to build statically-linked binaries:

make release-static

Dependencies need to be built with -fPIC. Static libraries usually aren't, so you may have to build them yourself with -fPIC. Refer to their documentation for how to build them.

• Optional: build documentation in doc/html (omit HAVE_DOT=YES if graphviz is not installed):

HAVE_DOT=YES doxygen Doxyfile

Tested on a Raspberry Pi Zero with a clean install of minimal Raspbian Stretch (2017-09-07 or later) from https://www.raspberrypi.org/downloads/raspbian/.

• apt-get update && apt-get upgrade to install all of the latest software

• Install the dependencies for Scala from the 'Debian' column in the table above.

• Increase the system swap size:

sudo /etc/init.d/dphys-swapfile stop

sudo nano /etc/dphys-swapfile

CONF_SWAPSIZE=2048

sudo /etc/init.d/dphys-swapfile start

• If using an external hard disk without an external power supply, ensure it gets enough power to avoid hardware issues when syncing, by adding the line "max_usb_current=1" to /boot/config.txt

• Clone scala and checkout the most recent release version:

git clone https://github.com/scala-project/scala.git

cd scala

• Build:

make release

• Wait 4-6 hours

• The resulting executables can be found in build/release/bin

• Add PATH="$PATH:$HOME/scala/build/release/bin" to .profile

• Run Scala with scalad --detach

• You may wish to reduce the size of the swap file after the build has finished, and delete the boost directory from your home directory

Binaries for Windows are built on Windows using the MinGW toolchain within

MSYS2 environment. The MSYS2 environment emulates a

POSIX system. The toolchain runs within the environment and cross-compiles

binaries that can run outside of the environment as a regular Windows

application.

Preparing the build environment

• Download and install the MSYS2 installer, either the 64-bit or the 32-bit package, depending on your system.

• Open the MSYS shell via the MSYS2 Shell shortcut

• Update packages using pacman:

pacman -Syu

• Exit the MSYS shell using Alt+F4

• Edit the properties for the MSYS2 Shell shortcut changing "msys2_shell.bat" to "msys2_shell.cmd -mingw64" for 64-bit builds or "msys2_shell.cmd -mingw32" for 32-bit builds

• Restart MSYS shell via modified shortcut and update packages again using pacman:

pacman -Syu

• Install dependencies:

To build for 64-bit Windows:

pacman -S mingw-w64-x86_64-toolchain make mingw-w64-x86_64-cmake mingw-w64-x86_64-boost mingw-w64-x86_64-openssl mingw-w64-x86_64-zeromq mingw-w64-x86_64-libsodium mingw-w64-x86_64-hidapi

To build for 32-bit Windows:

pacman -S mingw-w64-i686-toolchain make mingw-w64-i686-cmake mingw-w64-i686-boost mingw-w64-i686-openssl mingw-w64-i686-zeromq mingw-w64-i686-libsodium mingw-w64-i686-hidapi

• Open the MingW shell via MinGW-w64-Win64 Shell shortcut on 64-bit Windows

or MinGW-w64-Win64 Shell shortcut on 32-bit Windows. Note that if you are

running 64-bit Windows, you will have both 64-bit and 32-bit MinGW shells.

Cloning

• To git clone, run:

git clone https://github.com/scala-project/scala.git

Building

• Change to the cloned directory, run:

cd scala

• If you are on a 64-bit system, run:

make release-static-win64

• If you are on a 32-bit system, run:

make release-static-win32

• The resulting executables can be found in build/release/bin

• Optional: to build Windows binaries suitable for debugging on a 64-bit system, run:

make debug-static-win64

• Optional: to build Windows binaries suitable for debugging on a 32-bit system, run:

make debug-static-win32

• The resulting executables can be found in build/debug/bin

By default, in either dynamically or statically linked builds, binaries target the specific host processor on which the build happens and are not portable to other processors. Portable binaries can be built using the following targets:

• make release-static-linux-x86_64 builds binaries on Linux on x86_64 portable across POSIX systems on x86_64 processors

• make release-static-linux-i686 builds binaries on Linux on x86_64 or i686 portable across POSIX systems on i686 processors

• make release-static-linux-armv8 builds binaries on Linux portable across POSIX systems on armv8 processors

• make release-static-linux-armv7 builds binaries on Linux portable across POSIX systems on armv7 processors

• make release-static-linux-armv6 builds binaries on Linux portable across POSIX systems on armv6 processors

• make release-static-win64 builds binaries on 64-bit Windows portable across 64-bit Windows systems

• make release-static-win32 builds binaries on 64-bit or 32-bit Windows portable across 32-bit Windows systems

You can also cross-compile static binaries on Linux for Windows and macOS with the depends system.

• make depends target=x86_64-linux-gnu for 64-bit linux binaries.

• make depends target=x86_64-w64-mingw32 for 64-bit windows binaries.

• Requires: python3 g++-mingw-w64-x86-64 wine1.6 bc

• make depends target=x86_64-apple-darwin11 for macOS binaries.

• Requires: cmake imagemagick libcap-dev librsvg2-bin libz-dev libbz2-dev libtiff-tools python-dev

• make depends target=i686-linux-gnu for 32-bit linux binaries.

• Requires: g++-multilib bc

• make depends target=i686-w64-mingw32 for 32-bit windows binaries.

• Requires: python3 g++-mingw-w64-i686

• make depends target=arm-linux-gnueabihf for armv7 binaries.

• Requires: g++-arm-linux-gnueabihf

• make depends target=aarch64-linux-gnu for armv8 binaries.

• Requires: g++-aarch64-linux-gnu

The required packages are the names for each toolchain on apt. Depending on your distro, they may have different names.

Using depends might also be easier to compile Scala on Windows than using MSYS. Activate Windows Subsystem for Linux (WSL) with a distro (for example Ubuntu), install the apt build-essentials and follow the depends steps as depicted above.

The produced binaries still link libc dynamically. If the binary is compiled on a current distribution, it might not run on an older distribution with an older installation of libc. Passing -DBACKCOMPAT=ON to cmake will make sure that the binary will run on systems having at least libc version 2.17.

The build places the binary in bin/ sub-directory within the build directory

from which cmake was invoked (repository root by default). To run in

foreground:

./bin/scalad

To list all available options, run ./bin/scalad --help. Options can be

specified either on the command line or in a configuration file passed by the

--config-file argument. To specify an option in the configuration file, add

a line with the syntax argumentname=value, where argumentname is the name

of the argument without the leading dashes, for example log-level=1.

To run in background:

./bin/scalad --log-file scalad.log --detach

To run as a systemd service, copy

scalad.service to /etc/systemd/system/ and

scalad.conf to /etc/. The [example

service](utils/systemd/scalad.service) assumes that the user scala exists

and its home is the data directory specified in the [example

config](utils/conf/scalad.conf).

If you're on Mac, you may need to add the --max-concurrency 1 option to

scala-wallet-cli, and possibly scalad, if you get crashes refreshing.

This section contains general instructions for debugging failed installs or problems encountered with Scala. First, ensure you are running the latest version built from the Github repo.

We generally use the tool gdb (GNU debugger) to provide stack trace functionality, and ulimit to provide core dumps in builds which crash or segfault.

• To use gdb in order to obtain a stack trace for a build that has stalled:

Run the build.

Once it stalls, enter the following command:

gdb /path/to/scalad `pidof scalad`

Type thread apply all bt within gdb in order to obtain the stack trace

• If however the core dumps or segfaults:

Enter ulimit -c unlimited on the command line to enable unlimited filesizes for core dumps

Enter echo core | sudo tee /proc/sys/kernel/core_pattern to stop cores from being hijacked by other tools

Run the build.

When it terminates with an output along the lines of "Segmentation fault (core dumped)", there should be a core dump file in the same directory as scalad. It may be named just core, or core.xxxx with numbers appended.

You can now analyse this core dump with gdb as follows:

gdb /path/to/scalad /path/to/dumpfile`

Print the stack trace with bt

Type gdb /path/to/scalad

Pass command-line options with --args followed by the relevant arguments

Type run to run scalad

There are two tools available:

Configure Scala with the -D SANITIZE=ON cmake flag, eg:

cd build/debug && cmake -D SANITIZE=ON -D CMAKE_BUILD_TYPE=Debug ../..

You can then run the scala tools normally. Performance will typically halve.

Install valgrind and run as valgrind /path/to/scalad. It will be very slow.

Instructions for debugging suspected blockchain corruption as per @HYC

There is an mdb_stat command in the LMDB source that can print statistics about the database but it's not routinely built. This can be built with the following command:

cd  ~/scala/external/db_drivers/liblmdb && make

The output of mdb_stat -ea <path to blockchain dir> will indicate inconsistencies in the blocks, block_heights and block_info table.

The output of mdb_dump -s blocks <path to blockchain dir> and mdb_dump -s block_info <path to blockchain dir> is useful for indicating whether blocks and block_info contain the same keys.

These records are dumped as hex data, where the first line is the key and the second line is the data.