conr2d / daml

The DAML smart contract language

Copyright 2020 Digital Asset (Switzerland) GmbH and/or its affiliates. All Rights Reserved. SPDX-License-Identifier: Apache-2.0

Welcome to the DAML repository!

This repository hosts all code for the DAML smart contract language and SDK, originally created by Digital Asset. DAML is an open-source smart contract language for building future-proof distributed applications on a safe, privacy-aware runtime. The DAML SDK is a set of tools to help you develop applications based on DAML.

Using DAML

To download DAML, follow the installation instructions. Once installed, to try it out, follow the quickstart guide.

If you have questions about how to use DAML or how to build DAML-based solutions, please ask them on StackOverflow using the daml tag.

Contributing to DAML

We warmly welcome contributions. If you are looking for ideas on how to contribute, please browse our issues. To build and test DAML:

1. Clone this repository

git clone [email protected]:digital-asset/daml.git
cd daml

2. Set up the development dependencies

Our builds require various development dependencies (e.g. Java, Bazel, Python), provided by a tool called dev-env.

Linux and Mac

On Linux and Mac dev-env can be installed with:

1. Install Nix by running: bash <(curl -sSfL https://nixos.org/nix/install)
2. Enter dev-env by running: eval "$(dev-env/bin/dade assist)"

If you don't want to enter dev-env manually each time using eval "$(dev-env/bin/dade assist)", you can also install direnv. This repo already provides a .envrc file, with an option to add more in a .envrc.private file.

Windows

On Windows you need to enable long file paths by running the following command in an admin powershell:

Set-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem' -Name LongPathsEnabled -Type DWord -Value 1

Then start dev-env from PowerShell with:

.\dev-env\windows\bin\dadew.ps1 install
.\dev-env\windows\bin\dadew.ps1 sync
.\dev-env\windows\bin\dadew.ps1 enable

In all new PowerShell processes started, you need to repeat the enable step.

3. First build and test

We have a single script to build most targets and run the tests. On Linux and Mac run ./build.sh. On Windows run .\build.ps1. Note that these scripts may take over an hour the first time.

To just build do bazel build //..., and to just test do bazel test //.... To read more about Bazel and how to use it, see the Bazel site.

On Mac if building is causing trouble complaining about missing nix packages, you can try first running nix-build -A tools -A cached nix repeatedly until it completes without error.

4. Installing a local copy

On Linux and Mac run daml-sdk-head which installs a version of the SDK with version number 0.0.0. Set the version: field in any DAML project to 0.0.0 and it will use the locally installed one.

On Windows:

bazel build //release:sdk-release-tarball
tar -vxf .\bazel-bin\release\sdk-release-tarball.tar.gz
cd sdk-*
daml\daml.exe install . --activate

That should tell you what to put in the path, something along the lines of C:\Users\admin\AppData\Roaming\daml\bin. Note that the Windows build is not yet fully functional.

Caching: build speed and disk space considerations

Bazel has a lot of nice properties, but they come at the cost of frequently rebuilding "the world". To make that bearable, we make extensive use of caching. Most artifacts should be cached in our CDN, which is configured in .bazelrc in this project.

However, even then, you may end up spending a lot of time (and bandwidth!) downloading artifacts from the CDN. To alleviate that, by default, our build will create a subfolder .bazel-cache in this project and keep an on-disk cache. This can take about 10GB at the time of writing.

To disable the disk cache, remove the following lines:

build:linux --disk_cache=.bazel-cache
build:darwin --disk_cache=.bazel-cache

from the .bazelrc file.

If you work with multiple copies of this repository, you can point all of them to the same disk cache by overwriting these configs in either a .bazelrc.local file in each copy, or a ~/.bazelrc file in your home directory.

Shared memory segment issues

On macOS at least, it looks like our setup does not always properly close the resources PostgreSQL uses. After a number of test runs, you may encounter an error message along the lines of:

FATAL:  could not create shared memory segment: No space left on device
DETAIL:  Failed system call was shmget(key=5432001, size=56, 03600).
HINT:  This error does *not* mean that you have run out of disk space. It occurs either if all available shared memory IDs have been taken, in which case you need to raise the SHMMNI parameter in your kernel, or because the system's overall limit for shared memory has been reached.
        The PostgreSQL documentation contains more information about shared memory configuration.
child process exited with exit code 1

In this case, this is a memory leak, so increasing SHMNI (or SHMALL etc.) as suggested will only delay the issue. You can look at the existing shared memory segments on your system by running ipcs -mcopt; this will print a line per segment, indicating the process ID of the last process to connect to the segment as well as the last access time and the number of currently connected processes.

If you identify segments with no connected processes, and you are confident you can remove them, you can do so with ipcrm $sid, where $sid is the process ID displayed (as the second column) by ipcs. Not many macOS applications use shared memory segments; if you have verified that all the existing memory segments on your machine need to be deleted, e.g. because they have all been created by PostgreSQL instances that are no longer running, here is a Bash invocation you can use to remove all shared memory segments from your system.

This is a dangerous command. Make sure you understand what it does before running it.

for shmid in $(ipcs -m | sed 1,3d | awk '{print $2}' | sed '$d'); do ipcrm -m $shmid; done

Haskell profiling builds

To build Haskell executables with profiling enabled, pass -c dbg to Bazel, e.g. bazel build -c dbg damlc. If you want to build the whole SDK with profiling enabled use daml-sdk-head --profiling.