v0.12.0

Edvin's second birthday, only 10 minor releases behind Acton ;)

Added

• Zig is now used as the C compiler for Acton [#972]
  • Many parts of Acton, like the run time system, builtins and parts of the
    standard library are written in C
  • actonc compiles Acton programs into C which are then compiled into binary
    executables using a C compiler
  • zig is now used for both of these use cases
  • zig is bundled with Acton so that we know what version of zig we get, which
    is the same across Linux and MacOS
• Acton programs on Linux are now backwards compatible to GNU libc v2.28
  • Previously, acton programs would be built for the GNU libc version on the
    compiling computer, making it impossible to run on older distributions
  • Now compatible with for example Ubuntu 20.04 LTS & Debian 10
  • This is made possible by zigs incredible cross-compilation functionality,
    which isn't just about targetting other OS, CPUs but also older libc
    versions
  • v2.28 appears to be the oldest version we can practically target without
    code changes, even earlier versions fail compilation
  • We could reduce backwards compatible, for example by targetting glibc 2.31,
    if we find things that we would like access to, i.e. don't regard glibc 2.28
    compatibility as a hard promise
• Added --always-build to actonc [#988]
  • Used in test suite so that we always force compilation in order to ensure
    valid test results
• actonc argument parsing now done using sub-parsers, allowing greater freedom
  in constructing more complex commands [#976]
• All external library dependencies are combined in one .a archive [#849]
  • Decouples library dependency in builtins, RTS & stdlib from actonc compiler
    arguments
• All external library dependencies are now built from source [#984]
  • Allows us to compile them with zig, thus power to select target libc
• Add xml module [#835]
  • Offers simple encode() and decode() operations
  • Based on libxml2
• The int type now supports arbitrary precision [#146]
  • Add some big numbers!
  • The previous implementation of int was as a signed 64 bit integer, this is
    now available as the i64 type in Acton, although its use is currently
    quite limited.
  • Longer term, fixed size integers like i64 or u64 (for an unsigned) are
    available and can be chosen for high performance use cases. Developers
    familiar with this level of coding are likely able to make an informed
    choice about what integer type to choose. Using int for the arbitrary
    precision type is the safer choice which will make most users happy.
  • Using BSDNT library, which is a reasonably fast C implementation of
    arbitrary precision types and arithmetic operations. It is not as fast as
    MPL but has a more liberal license.

Fixed

• Fixed seed arg parsing in actondb [#900]
• Avoid crash during TCP client resume
• DB now using logging rather fprintf(stderr, ...)
• Reduce unprovoked CPS & 'rtail' bugs [#949]
• Update docs for --root & runacton [#950]
• file.ReadFile can now read arbitrarily large files [#955]
• RTS does proper error handling of DB interaction [#957]
  • This is a huge improvement!!!
  • The run time system now properly reads the return code from all DB query
    operations and acts appropriately. For example, lacking a quorum, the RTS
    will continuously retry an operation until quorum can be reached.
  • For some failures a larger chunk of operations needs to be retried, i.e. we
    can't just wrap up a small function in a retry loop but need a larger retry
    loop around a group of operations.
  • DB API now returns a minority status which the RTS can and does react on
    • Typical example is with 3 DB nodes and a commit goes through on 2, i.e.
      with a quorum and is thus considered a success, however the 3rd node
      rejected it because of a schema mismatch. The RTS can now be notified
      through the minority status and attempt to repair the schema.
      • A typical example of schema repairs necessary are for the queues, which
        are dynamic. Every actor gets a queue in the database, so when new
        actors are created, new queues also need to be created and if a
        particular DB server is not up when the queue is created, it will be
        missing and needs to be repaired later on.
      • We should have proper sync up between DB servers, so that they query
        each other and converge on the latest state. Until then, repair
        initiated from RTS is our way of fixing it.
• Notify gossip view to clients (RTS) from agreement round leader [#951]
  • For example, in this scenario:
    • db1 is started
    • RTS is started & connected to db1 but unable to progress due to no quorum
    • db2 is connected, gossips with db1 and we now have quorum
    • RTS continues to be stalled as it is never notified about db2 and thus
      unable to reach a quorum
• Avoid MacOS quarantine shenanigans that kills actonc [#971]
  • MacOS has some quarantine concept, so like if a file is downloaded from the
    Internet, it is marked as quarantine and the user is asked "Are you sure you
    want to run this" after which the quarantine flag, which is stored as a file
    system extended attribute, is cleared.
  • Somehow we trigger this quarantine, presumably by that we overwrite, through
    cp, a binary executable that macos has run and this triggers it to set the
    quarantine flag. The effect is that whenever we execute actonc, MacOS kills
    -9 it, which is obviously rather annoying.
  • By copying to a temporary file and then moving it in place, we avoid MacOS
    setting the quarantine flag. We already did this, though for other reasons,
    for actondb, so in a way this is a unification for the files in bin/

Testing / CI

• Simplify and clean up RTS DB test orchestrator [#941] [#973]
• Stop testing on Ubuntu 20.04
  • It's not possible to compile libxml2 on a stock Ubuntu 20.04 as a newer
    version of automake is required than is shipped
  • We mainly want to uphold run time compatibility with Ubuntu 20.04, like it
    should be possible to run Acton applications but utilizing Ubuntu 20.04 as a
    development platform for Acton is not a high priority target, thus dropping
    it is quite fine.
• Revamp Increase timeout
• Avoid kill -9 on macos [#969]
  • MacOS quarantine functionality thinks we are doing something fishy and kill
    -9 our process
  • Worked around by doing cp & mv instead of just a cp