v0.13.1

Changed

• Allow _ as a dummy variable name [#1020] [#1061]
  • _ can be used in an assignment to effectively throw away a result
  • Unlike using a variable like dummy, _ acts as a wildcard from a type
    perspective, so that we can do _ = 3 and _ = "a", while if we attempt to
    use another dummy variable name we will get a type error as we try to assign
    it values with different types
• __self__ has been renamed to self [#1056]
  • it is a reference to the own actor and holds the "external" view, i.e. it
    can be passed to another actor as a reference to the local actor

Fixed

• Correct DB client comm thread to avoid potential deadlock [#1088]
  • Incorrect handling of error return status from select meant we could attempt
    to read on fds that had no data and thus the comm thread would deadlock.
  • Now we do proper error handling, always continuing for another spin &
    attempt at select in case we get an error back.
  • The (under development) garbage collector (GC) uses signals to instruct
    threads to pause for stop the world events and thus we end up interrupting
    the select loop a lot more frequently than before, thus surfacing this bug.
• Correct DB client comm thread to avoid busy waiting [#1089]
  • On Linux, using select() with a timeout, if the select is interrupted the
    timeout value will be modified to reflect the time not slept. Thus the next
    select in our comm thread loop would sleep for a shorter period of time.
    Depending on the timing of the interrupt, the sleep might be shortened to
    effectively form a busy wait.
  • The (under development) garbage collector (GC) uses signals to instruct
    threads to pause for stop the world events and thus we end up interrupting
    the select loop a lot more frequently than before, thus surfacing this bug.
  • Fixed by always resetting the timeout value in the loop.
• Make RTS DB clients stick to one partition [#1087]
  • Make sure RTS (a DB client) does not hop between different DB server
    partitions even if they learn about disjoint gossip views.
  • Prevents incorrect operation when DB servers are not aware of each other but
    are "joined" by a RTS that see all the servers.
  • This scenario is most easily reproduced by starting DB servers without
    specifying a seed, and so the DB servers won't see each other, and then let
    a RTS connect to the DB servers, which then sees a view of all 3 servers.
    • This is now rejected as invalid.
  • Using vector clocks to determine and reject invalid views. Very elegant =)
• Correct time.monotonic() [#1097]
  • It returned a wildly incorrect results as the nanoseconds part was not
    properly added up with seconds.
• Include argp-standalone library in libActonDeps [#1058]
  • No more external dependencies!
  • argp is available as part of the system on GNU/Linux but on MacOS we have
    relied on the argp-standalone package installed via brew. We now prefer to
    use our own on both Linux and MacOS.
• Acton system is now compiled with -Werror to improve code quality [#1060]
  • There are some exceptions to this but the overall goal is to be essentially
    free of compilation warnings
• Fix bug in truediv for int [#1076]
• Fix bad codegen of classname argument to isinstance() [#1055]
• Correct effect declaration to mut for some builtin protocols [#1053]
• Method decorators like @staticmethod now work [#1054]
• Added lost constraints inferred on target expressions [#1050]
• Avoid undefined behavior in builtin object hash [#1065]
• Clean up library include paths etc [#1068] [#1077] [#1080] [#1092]
  • Made possible by including all of our external dependencies in libActonDeps

Testing / CI

• Add back testing on Ubuntu 20.04 [#1093]
  • libxml2 requires a newer automake (1.16.3) than is available on Ubuntu 20.04
  • We fix this by hacking the configure.ac file to require the version
    available on Ubuntu 20.04 (1.16.1)