package eio_linux

  1. Overview
  2. Docs
Eio implementation for Linux using io-uring


Dune Dependency






New features:

  • eio_posix: use directory FDs instead of realpath (@talex5 #694 #696, reviewed by @SGrondin).
    Using realpath was an old hack from the libuv days and subject to races. It was also slow.

  • Keep pool of systhreads for blocking operations (@SGrondin @talex5 #681).
    This is much faster than creating a new thread for each operation. It mainly benefits the eio_posix backend, as that uses lots of systhreads.

  • Make Switch.on_release thread-safe (@talex5 #684, requested by @art-w and @clecat).
    This allows resource pools to be shared between domains easily.

  • Add Eio.Path.read_link (@talex5 #686).

  • Add Eio_unix.Fd.is_open (@talex5 #690).

  • Include backtrace in systhread errors (@talex5 #688, reviewed by @SGrondin).
    Also, add Eio.Exn.empty_backtrace as a convenience.

  • eio.mock: add tracing support to mock backend (@talex5 #687).

  • Improve tracing (@talex5 #675 #683 #676, reviewed by @SGrondin).
    Update tracing section of README and trace more things (run_in_systhread, close, submit, traceln, cancellation and domain spawning).


  • Link to verification work in docs (@talex5 #682).

  • Add more trace diagrams to README (@talex5 #698).

  • Adjust COC contacts (@polytypic #685, reviewed by @Sudha247).

Bug fixes:

  • eio_linux: retry openat2 on EAGAIN (@talex5 #693, reviewed by @SGrondin).

  • eio_posix and eio_windows: check for IO periodically (@talex5 #674).

  • Handle EPERM when trying to initialise uring (@talex5 #691).
    This can happen when using a Docker container.

Build and tests:

  • Benchmark Eio_unix.run_in_systhread (@talex5 #678, reviewed by @SGrondin).

  • Enable lintcstubs for Eio_unix.Private too (@talex5 #689).

  • Stat benchmark: report cleanup time and optimise (@talex5 #692).

  • Make benchmarks start faster (@talex5 #673).

  • Update build for new eio-trace CLI (@talex5 #699).

  • Expect opam-repo-ci tests to fail on macos (@talex5 #672).


New features / API changes:

  • Add Eio.Executor_pool (@SGrondin #639, reviewed by @talex5).
    Provides an easy way to distribute jobs across domains.

  • Add Fiber.first ~combine and Fiber.n_any (@SGrondin @talex5 #587).
    Allows keeping both results in the case where multiple fibers succeed.

  • Add Eio_mock.Backend.run_full with auto-advancing mock clock (@talex5 #644, reviewed by @SGrondin).
    Simplifies testing of code using clocks.

  • Add Buf_write.printf (@SGrondin @talex5 #655).

  • Add Net.listening_addr (@mefyl #555, reviewed by @patricoferris @talex5).
    Useful to get the socket's address if the OS assigns it.

  • Add Promise.try_resolve (@talex5 #646).

  • Remove Cancel_hook_failed exception (@talex5 #640).
    Didn't seem to be used and broke dscheck.


  • Improve tracing (@TheLortex @patricoferris @talex5 #656).
    Trace cancellation contexts and OS operations, and simplify API.

  • Add labels to switches (@talex5 #661, reviewed by @SGrondin).

  • Fiber.all: use the parent fiber (@talex5 #665, reviewed by @SGrondin).
    Cleans up the traces a bit.


  • Faster and simpler Lf_queue (@talex5 #647, based on work by @polytypic).

  • Optimise Flow.copy with Buf_read.as_flow (@talex5 #663, reviewed by @SGrondin, reported by @leostera).

Bug fixes:

  • Fix handling of very long IO vectors (@talex5 #653, reported by @Cjen1).

  • eio_posix: use caml_enter_blocking_section in more places (@talex5 #654, reviewed by @SGrondin).

  • eio_posix: work around caml_unix_alloc_sockaddr bug (@talex5 #651).

  • Remove default backtrace from (@talex5 #664).


  • Organise eio.mli better (@talex5 #667).

  • Fix quoting of quotes in process error messages (@talex5 #666, reviewed by @SGrondin).

  • Mention Path module in File and Fs documentation (@talex5 #659, requested by @clecat).

  • Minor documentation updates (@SGrondin @talex5 #670).

Build / internals:

  • Allow closing synchronous streams (@talex5 #641, reviewed by @SGrondin).
    This isn't currently exposed in the public interface.

  • Fix non-idempotent tests (@SGrondin #662).

  • eio_windows: add explicit fmt dependency (@talex5 #643).


New features / API changes:

  • Add Flow.read_all (@SGrondin #596, reviewed by @talex5 @rbjorklin).

  • Add Path.stat (@patricoferris @talex5 @avsm #617 #618 #624 #620, reviewed by @SGrondin).

  • Add Path.rmtree (@talex5 #627 #628, reviewed by @SGrondin).

  • Add Path.mkdirs and Path.split (@patricoferris @talex5 #625).

  • Add Eio.File.{seek,sync,truncate} (@talex5 #626).

  • Add Eio.Path.{kind,is_file,is_directory} (@patricoferris @talex5 #623, reviewed by @avsm).

  • Switch from CTF to OCaml 5.1 runtime events (@TheLortex @patricoferris @talex5 #634 #635, reviewed by @avsm). This is a minimal initial version.


  • Document File.Stat record fields (@avsm @talex5 #621).

  • Update README section about env (@talex5 #614, reported by @jonsterling).

Build and test changes:

  • Add File.stat benchmark (@talex5 #616).

  • Add Path.stat benchmark (@patricoferris @talex5 #630).

  • eio_linux: mark as only available on Linux (@talex5 #629).

  • Make MDX tests idempotent (@SGrondin #601, reviewed by @talex5).

  • Allow trailing whitespace in (@talex5 #632).

  • Update minimum OCaml version to 5.1 (@talex5 #631).

  • Generate prototypes for C stubs from ml files (@talex5 #615).

  • Don't try to compile uring support on centos 7 (@talex5 #638, reported by @zenfey).


New features / API changes:

  • Replace objects with variants (@talex5 @patricoferris #553 #605 #608, reviewed by @avsm).
    Some potential users found object types confusing, so we now use an alternative scheme for OS resources. For users of the resources, the only thing that changes is the types:

    • Instead of taking an argument of type #foo, you should now take _ foo.

    • Instead of returning a value of type foo, you should now return foo_ty Eio.Resource.t.

    To provide your own implementation of an interface, you now provide a module rather than an object. For example, to provide your own source flow, use Eio.Flow.Pi.source (module My_source).

    If you want to define your own interfaces, see the Eio.Resource module documentation.

  • Add Eio.Pool (@talex5 @darrenldl #602, reviewed by @patricoferris).
    A lock-free pool of resources. This is similar to Lwt_pool.

  • Add Eio.Lazy (@talex5 #609, reviewed by @SGrondin).
    If one fiber tries to force a lazy value while another is already doing it, this will wait for the first one to finish rather than raising an exception (as Stdlib.Lazy does).

  • Add Eio.Path.native (@talex5 #603, reviewed by @patricoferris).
    This is useful when interacting with non-Eio libraries, for spawning sub-processes, and for displaying paths to users.

  • Add Flow.single_write (@talex5 #598).

  • Add Eio.Flow.Pi.simple_copy (@talex5 #611).
    Provides an easy way to implement the copy operation when making your own sink.

  • Eio_unix: add FD passing (@talex5 #522).
    Allows opening a file and passing the handle over a Unix-domain socket.

  • Add ?is_success to control definition of success (@SGrondin #586, reviewed by @talex5).

  • Add Eio_mock.Domain_manager (@talex5 #610).
    This mock domain manager runs everything in a single domain, allowing tests to remain deterministic.

  • Add Eio.Debug.with_trace_prefix (@talex5 #610). Allows prefixing all traceln output. The mock domain manager uses this to indicate which fake domain is running.

Bug fixes:

  • Fork actions must not allocate (@talex5 #593).
    When using multiple domains, child processes could get stuck if they forked while another domain held the malloc lock.

  • eio_posix: ignore some errors writing to the wake-up pipe (@talex5 #600).
    If the pipe is full or closed, the wake-up should simply be ignored.

Build/test fixes:

  • Fix some MDX problems on Windows (@polytypic #597).

  • The README depends on kcas (@talex5 #606).

  • Clarify configuration for lib_eio_linux and enable tests on other arches (@dra27 #592).

  • eio_linux tests: skip fixed buffer test if not available (@talex5 #604).

  • eio_windows: update available line to win32 (@talex5 #588 #591).


New features / API changes:

  • Extend Eio.Condition API (@talex5 #563).

    • loop_no_mutex is a simpler and more efficient way to way for a condition.

    • register_immediate allows integration with other IO libraries.

  • Expose Eio.Stdenv.backend_id (@bord-o #560, reviewed by @talex5).
    Useful in tests to report which backend is being used.

  • Remove deprecated features (@talex5 #552, reviewed by @avsm).
    These were all already marked as deprecated in v0.10 and are now gone completely:

    • Fiber.fork_sub

    • Eio_unix.{FD,Ipaddr,socketpair,getnameinfo}

    • Eio_linux.{FD,get_fd,get_fd_opt}

    • Eio_posix.Low_level.Fd

  • Allow calling close more than once (@talex5 #547, requested by @anmonteiro, reviewed by @patricoferris, @avsm).

  • Add close to socket type (@talex5 #549).
    Simplifies the type signatures a bit by avoiding having to mention this everywhere.

Bug fixes:

  • Fix handling of empty path strings (@talex5 #569, reported by @SGrondin).
    Using "" instead of "." in some places resulted in an error.

  • eio_posix: fix update to watched FDs on cancel (@talex5 #574, reported and reviewed by @quernd).
    Cancelling the last watcher of an FD didn't remove it from the set passed to poll, which could result in constant wake-ups.

  • eio_posix: fix pread at end-of-file (@talex5 #581, reported by @SGrondin).
    It tried to return 0 instead of End_of_file, triggering an assertion.

  • eio_posix: don't reap non-Eio child processes (@talex5 #562).
    This allows spawning processes with e.g. the stdlib or Lwt (but see for Lwt support).

  • Preserve backtraces across (@talex5 #571).

  • Correct the backend selection for Cygwin (@dra27 #557).
    Use eio_posix, not eio_windows in this case.

Other changes:

  • Simplify dune files with dune 3.9's build_if (@talex5 #582).

  • Remove Waiters from Eio_core (@talex5 #567).
    Eio.Switch no longer uses this so it can finally be removed.

  • Use Fmt.Dump.signal to format signals (@talex5, @MisterDA #543).


  • Add some notes about thread-safety in the documentation (@talex5 #568).


New features / API changes:

  • Add Eio.Process for cross-platform subprocess support (@patricoferris @talex5 #499, reviewed by @anmonteiro @avsm @haesbaert).

  • Add Eio_unix.Net module (@talex5 #516, reviewed by @avsm).
    The Unix network APIs have been cleaned up and moved here, and some missing datagram operations have been added. send now takes an iovec, not just a single buffer.

  • Add support for domain local await (@polytypic @talex5 #494 #503).
    Allows sharing e.g. kcas data-structures across Eio and Domainslib domains.

  • Add initial eio_windows backend (@patricoferris @talex5 #497 #530 #511 #523 #509, reviewed by @avsm @polytypic).

  • Remove eio_luv backend (@talex5 #485).
    It was only used on Windows, and has been replaced by eio_windows.

  • Unify Eio_linux.FD and Eio_posix.Fd as Eio_unix.Fd (@talex5 #491).
    Now that eio_luv is gone, there is no need for different backends to have different types for wrapped file descriptors.

  • Move Eio.Stdenv.t to Eio_unix.Stdenv.base (@talex5 #498).
    Note that the rest of Eio.Stdenv is still there; only the definition of a full Unix-like environment has moved.

  • Deprecation cleanups (@talex5 #508).
    Removed some APIs that were already marked as deprecated in Eio 0.8.

Bug fixes:

  • eio_linux: fall back to fork if clone3 is unavailable (@talex5 #524, reported by @smondet, reviewed by @avsm).
    Docker's default security policy blocks clone3.

  • Don't call accept_fork's error handler on cancellation (@talex5 #520).
    This isn't an error and should not be reported.

  • Fix eio_unix_is_blocking C stub (@patricoferris #505, reviewed by @talex5).

  • Fix Condition.await bug when cancelling (@polytypic @talex5 #487).

  • Buf_write: fix flush returning too early (@talex5 #539, reported by @cometkim).

  • Ignore ENOTCONN errors on socket shutdown (@avsm #533, reported by @patricoferris, reviewed by @talex5).


  • Link to developer meetings information (@talex5 @Sudha247 #515).

  • Adopt OCaml Code of Conduct (@Sudha247 #501).

  • Add README links to Meio and Lambda Capabilities blog post (@talex5 #496).

  • Document mirage Ipaddr conversion (@RyanGibb @patricoferris @talex5 #492).

  • Document how to use Domainslib from Eio (@talex5 #489, reviewed by @polytypic @patricoferris).

Other changes:

  • Run benchmarks with current-bench (@Sudha247 @talex5 #500).

  • Fix MDX tests on OCaml 5.1 (@talex5 #526).

  • Add stress test for spawning processes (@talex5 #519).
    This was an attempt to track down the signals bug.

  • Eio.Process.pp_status should be polymorphic (@talex5 #518).

  • eio_posix: probe for existence of some flags (@talex5 #507, reported by @hannesm).
    FreeBSD 12 didn't have O_DSYNC. Also, add O_RESOLVE_BENEATH and O_PATH if available.

  • Fix race in ctf tests (@talex5 #493).


New features:

  • Add eio_posix backend (@talex5 @haesbaert #448 #477, reviewed by @avsm @patricoferris @polytypic).
    This replaces eio_luv on all platforms except Windows (which will later switch to its own backend). It is a lot faster, provides access to more modern features (such as openat), and can safely share OS resources between domains.

  • Add subprocess support (@patricoferris @talex5 #461 #464 #472, reviewed by @haesbaert @avsm).
    This is the low-level API support for eio_linux and eio_posix. A high-level cross-platform API will be added in the next release.

  • Add Fiber.fork_seq (@talex5 #460, reviewed by @avsm).
    This is a light-weight alternative to using a single-producer, single-consumer, 0-capacity stream, similar to a Python generator function.

Bug fixes:

  • eio_linux: make it safe to share FDs across domains (@talex5 #440, reviewed by @haesbaert).
    It was previously not safe to share file descriptors between domains because if one domain used an FD just as another was closing it, and the FD got reused, then the original operation could act on the wrong file.

  • eio_linux: release uring if Linux is too old (@talex5 #476).
    Avoids a small resource leak.

  • eio_linux: improve error handling creating pipes and sockets (@talex5 #474, spotted by @avsm).
    If we get an error (e.g. too many FDs) then report it to the calling fiber, instead of exiting the event loop.

  • eio_linux: wait for uring to finish before exiting (@talex5 #470, reviewed by @avsm).
    If the main fiber raised an exception then it was possible to exit while a cancellation operation was still in progress.

  • eio_main: make EIO_BACKEND handling more uniform (@talex5 #447).
    Previously this environment variable was only used on Linux. Now all platforms check it.

  • Tell dune about EIO_BACKEND (@talex5 #442).
    If this changes, dune needs to re-run the tests.

  • eio_linux: add some missing close-on-execs (@talex5 #441).

  • eio_linux: read_exactly fails to update file offset (@talex5 #438).

  • Work around dune enabled_if bug on non-Linux systems (@polytypic #475, reviewed by @talex5).

  • Use raw system call of getrandom for glibc versions before 2.25 (@zenfey #482).


  • Add with hints for working on Eio (@talex5 #443, reviewed by @avsm @polytypic).

  • Improve worker pool example (@talex5 #454).

  • Add more Conditions documentation (@talex5 #436, reviewed by @haesbaert).
    This adds a discussion of conditions to the README and provides examples using them to handle signals.

  • Condition: fix the example in the docstring (@avsm #468).


  • Add a network benchmark using an HTTP-like protocol (@talex5 #478, reviewed by @avsm @patricoferris).

  • Add a benchmark for reading from /dev/zero (@talex5 #439).

Other changes:

  • Add CI for macOS (@talex5 #452).

  • Add tests for pread, pwrite and readdir (@talex5 #451).

  • eio_linux: split into multiple files (@talex5 #465 #466, reviewed by @avsm).

  • Update Dockerfile (@talex5 #471).

  • Use dune.3.7.0 (@patricoferris #457).

  • Mint exclusive IDs across domains (@TheLortex #480, reported by @haesbaert, reviewed by @talex5).
    The tracing currently only works with a single domain anyway, but this will change when OCaml 5.1 is released.


Some build fixes:

  • Fix build on various architectures (@talex5 #432).

    • Work around dune %{system} bug.

    • eio_luv: fix max_luv_buffer_size on 32-bit platforms.

  • Add missing test-dependency on MDX (@talex5 #430).


New features:

  • Add Eio.Net.run_server (@bikallem @talex5 #408).
    Runs an accept loop in one or more domains, with cancellation and graceful shutdown, and an optional maximum number of concurrent connections.

  • Add Buf_read.BE and LE parsers (@Cjen1 #399).
    Parse numbers in various binary formats.

  • Add Eio.Buf_read.uint8 (@talex5 #418).


  • Make Eio.Condition lock-free (@talex5 #397 #381).
    In addition to being faster, this allows using conditions in signal handlers.

  • Make Eio.Semaphore lock-free (@talex5 @polytypic #398).

  • Make Eio.Stream lock-free when the capacity is zero (@talex5 #413 #411).

  • Make Eio.Promise lock-free (@talex5 #401).

Bug fixes:

  • eio_linux: call Uring.submit as needed (@talex5 @bikallem #428).
    Previously, we could fail to submit a job promptly because the SQE queue was full.

  • Fix luv signals (@haesbaert #412).
    libuv automatically retries polling if it gets EINTR, without giving OCaml signal handlers a chance to run.

  • eio_luv: fix some resource leaks (@talex5 @patricoferris #421).

  • eio_luv: fix "unavailable signal" error on Windows (@talex5 #420, reported by @nojb).

  • Fix Buf_write.BE.uint48 and LE.uint48 (@adatario #418).


  • Add example programs (@talex5 #389).

  • Update network examples to use run_server (@talex5 #417).

  • Add a warning to the tutorial about Fiber.first (@talex5 #394).

  • Clarify the epoch used for (@bikallem #395).

  • Describe secure_random as an infinite source (@patricoferris #426).

  • Update README for OCaml 5 release (@talex5 #384 #391 #393).

Other changes:

  • Delay setting SIGPIPE handler until the run function is called (@talex5 #420).

  • Remove debug-level logging (@talex5 #403).

  • eio-luv: improve test (@smondet #414).

  • Update to Dune 3 (@talex5 #410).

  • Remove test dependency on Astring (@talex5 #402 #404).

  • Simplify cancellation logic (@talex5 #396).

  • time: Mtime.Spand.to_s has been deprecated in mtime 2.0.0 (@bikallem #385).


API changes:

  • Unify IO errors as Eio.Io (@talex5 #378).
    This makes it easy to catch and log all IO errors if desired. The exception payload gives the type and can be used for matching specific errors. It also allows attaching extra information to exceptions, and various functions were updated to do this.

  • Add Time.Mono for monotonic clocks (@bikallem @talex5 #338).
    Using the system clock for timeouts, etc can fail if the system time is changed during the wait.

  • Allow datagram sockets to be created without a source address (@bikallem @haesbaert #360).
    The kernel will allocate an address in this case. You can also now control the reuse_addr and reuse_port options.

  • Add File.stat and improve Path.load (@haesbaert @talex5 #339).
    Path.load now uses the file size as the initial buffer size.

  • Add Eio_unix.pipe (@patricoferris #350).
    This replaces Eio_linux.pipe.

  • Avoid short reads from getrandom(2) (@haesbaert #344).
    Guards against buggy user code that might not handle this correctly.

  • Rename to Flow.single_read (@talex5 #353).
    This is a low-level function and it is easy to use it incorrectly by ignoring the possibility of short reads.

Bug fixes:

  • Eio_luv: Fix non-tail-recursive continue (@talex5 #378).
    Affects the Socket_of_fd and Socketpair effects.

  • Eio_linux: UDP sockets were not created close-on-exec (@talex5 #360).

  • Eio_linux: work around io_uring non-blocking bug (@haesbaert #327 #355).
    The proper fix should be in Linux 6.1.

  • Eio_mock.Backend: preserve backtraces from main (@talex5 #349).

  • Don't lose backtrace in Switch.run_internal (@talex5 #369).


  • Use a proper HTTP response in the README example (@talex5 #377).

  • Document that read_dir excludes "." and ".." (@talex5 #379).

  • Warn about both operations succeeding in Fiber.first (@talex5 #358, reported by @iitalics).

  • Update README for OCaml 5.0.0~beta2 (@talex5 #375).

Backend-specific changes:

  • Eio_luv: add low-level process support (@patricoferris #359).
    A future release will add Eio_linux support and a cross-platform API for this.

  • Expose Eio_luv.Low_level.Stream.write (@patricoferris #359).

  • Expose Eio_luv.Low_level.get_loop (@talex5 #371).
    This is needed if you want to create resources directly and then use them with Eio_luv.

  • Eio_linux.Low_level.openfile is gone (@talex5 #378).
    It was just left-over test code.



  • Update to OCaml 5.0.0~beta1 (@anmonteiro @talex5 #346).

  • Add API for seekable read/writes (@nojb #307).

  • Add Flow.write (@haesbaert #318).
    This provides an optimised alternative to copy in the case where you are writing from a buffer.

  • Add Net.with_tcp_connect (@bikallem #302).
    Convenience function for opening a TCP connection.

  • Add Eio.Time.Timeout (@talex5 #320).
    Makes it easier to pass timeouts around.

  • Add Eio_mock.Clock (@talex5 #328).
    Control time in tests.

  • Add Buf_read.take_while1 and skip_while1 (@bikallem #309).
    These fail if no characters match.

  • Make the type parameter for Promise.t covariant (@anmonteiro #300).

  • Move list functions into a dedicated submodule (@raphael-proust #315).

  • Direct implementation of Flow.source_string (@c-cube #317).
    Slightly faster.

Bug fixes:

  • Condition.broadcast must interlock as well (@haesbaert #324).

  • Split the reads into no more than 2^32-1 for luv (@haesbaert @talex5 @EduardoRFS #343).
    Luv uses a 32 bit int for buffer sizes and wraps if the value passed is too big.

  • eio_luv: allow Net.connect to be cancelled (@talex5 @nojb #311).

  • eio_main: Use dedicated log source (@anmonteiro #326).

  • linux_eio: fix kernel version number in log message (@talex5 @nojb #314).

  • Account for stack differences in the socketpair test (issue #312) (@haesbaert #313).


  • Add Best Practices section to README (@talex5 #299).

  • Documentation improvements (@talex5 #295 #337).


New features:

  • Add Eio.Condition (@TheLortex @talex5 #277).
    Allows a fiber to wait for some condition to become true.

  • Add Eio.Net.getaddrinfo and getnameinfo (@bikallem @talex5 #278 #288 #291).
    Convert between host names and addresses.

  • Add Eio.Debug (@talex5 #276).
    Currently, this allows overriding the traceln function.

  • Buf_write.create: make switch optional (@talex5 #283).
    This makes things easier for people porting code from Faraday.

Bug fixes:

  • Allow sharing of libuv poll handles (@patricoferris @talex5 #279).
    Luv doesn't allow two callers to watch the same file handle, so we need to handle that in Eio.

Other changes:

  • Upgrade to uring 0.4 (@talex5 #290).

  • Mention Mutex, Semaphore and Condition in the README (@talex5 #281).


Note: Eio 0.4 drops compatibility with OCaml 4.12+domains. Use OCaml 5.0.0~alpha1 instead.

API changes:

  • Eio.Dir has gone. Use Eio.Path instead (@talex5 #266 #270).

  • Eio_unix.FD.{take,peek} were renamed to take_opt/peek_opt to make way for non-optional versions.

New features:

  • Fiber-local storage (@SquidDev #256).
    Attach key/value bindings to fibers. These are inherited across forks.

  • Eio.Path.{unlink,rmdir,rename} (@talex5 #264 #265).

  • can now return a value (@talex5 #263).
    This is useful for e.g. cmdliner.

  • Eio_unix.socketpair (@talex5 #260).

  • Fiber.fork_daemon (@talex5 #252).
    Create a helper fiber that does not prevent the switch from exiting.

  • Add Fiber.{iter,map,filter,fiter_map} (@talex5 #248 #250).
    These are concurrent versions of the corresponding operations in List.

Bug fixes:

  • Fix scheduling fairness in luv backend (@talex5 #269).

  • Implement remaining shutdown commands for luv (@talex5 #268).

  • Fix IPv6 support with uring backend (@haesbaert #261 #262).

  • Use Eio.Net.Connection_reset exception in more places (@talex5 #257).

  • Report use of closed FDs better (@talex5 #255).
    Using a closed FD could previously cause the whole event loop to exit.

  • Some fixes for cancellation (@talex5 #254).

  • Ensure Buf_write still flushes if an exception is raised (@talex5 #246).

  • Do not allow close on accept_fork socket (@talex5 #245).


  • Document integrations with Unix, Lwt and Async (@talex5 #247).

  • Add a Dockerfile for easy testing (@talex5 #224).


API changes:

  • Net.accept_sub is deprecated in favour of accept_fork (@talex5 #240).
    Fiber.fork_on_accept, which it used internally, has been removed.

  • Allow short writes in Read_source_buffer (@talex5 #239).
    The reader is no longer required to consume all the data in one go. Also, add Linux_eio.Low_level.writev_single to expose this behaviour directly.

  • Eio.Unix_perm is now Eio.Dir.Unix_perm.

New features:

  • Add Eio.Mutex (@TheLortex @talex5 #223).

  • Add Eio.Buf_write (@talex5 #235).
    This is a buffered writer for Eio sinks, based on Faraday.

  • Add Eio_mock library for testing (@talex5 #228).
    At the moment it has mock flows and networks.

  • Add Eio_mock.Backend (@talex5 #237 #238).
    Allows running tests without needing a dependency on eio_main. Also, as it is single-threaded, it can detect deadlocks in test code instead of just hanging.

  • Add Buf_read.{of_buffer, of_string, parse_string{,_exn}, return} (@talex5 #225).

  • Add <*> combinator to Buf_read.Syntax (@talex5 #227).

  • Add Eio.Dir.read_dir (@patricoferris @talex5 #207 #218 #219)


  • Add Buf_read benchmark and optimise it a bit (@talex5 #230).

  • Inline Buf_read.consume to improve performance (@talex5 #232).

Bug fixes / minor changes:

  • Allow IO to happen even if a fiber keeps yielding (@TheLortex @talex5 #213).

  • Fallback for traceln without an effect handler (@talex5 #226).
    traceln now works outside of an event loop too.

  • Check for cancellation when creating a non-protected child context (@talex5 #222).

  • eio_linux: handle EINTR when calling getrandom (@bikallem #212).

  • Update to cmdliner.1.1.0 (@talex5 #190).


  • Add support for UDP (@patricoferris #171).

  • Rename Fibre to Fiber (@talex5 #195). This is to match the compiler's spelling.

  • Switch to luv backend if uring can't be used (@talex5 #203). Useful on Windows with WSL, and also in Docker containers on older systems.

  • Eio_linux: cope with lack of fixed chunks (@talex5 #200).

    • If we run out of fixed memory, just use regular memory instead of waiting (which might deadlock).

    • If we try to allocate a fixed buffer and fail, we now just log a warning and continue without one.

  • Add support for FD passing with Eio_linux (@talex5 #199).

  • Add Eio_unix.FD.as_socket (@talex5 #193). Useful for working with existing libraries that provide a Unix.file_descr, or for receiving FDs from elsewhere (e.g. socket activation). Also, the Luv.{File,Handle}.of_luv functions now allow controlling whether to close the wrapped FD.

  • Add Eio_unix.sleep (@talex5 #188). Based on feedback that some people don't want to treat time as a capability. Possibly also useful for debugging race conditions.

  • Tidy up forking API (@talex5 #192). Moves some common code out the the individual backends.

  • Improve documentation (@talex5 #197 #194 #186 #185). In particular, explain more low-level details about how cancellation works.

  • Add an example Eio_null backend (@talex5 #189). This supports creating fibers, promises and cancellation, but provides no IO operations.

  • Effect.eff is now Effect.t in OCaml trunk (@talex5 #201).


  • Initial release.


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