v0.11

• Removed the following modules from Async_extra:

  • Cpu_usage

  • Dynamic_port_writer

  • File_tail

  • Persistent_singleton

  • Persistent_connection_intf

  • Sequencer_table (available at: http://github.com/janestreet/sequencer_table )

  • Tcp_file

  • Unpack_sequence

  • Versioned_typed_tcp

113.43.00

• Add the ability to specify the local source port to Async_extra.Tcp.

• Name the non-t arguments to Error.tag and similar functions to allow
  easier partial application.

• Name the non-t arguments to Error.tag and similar functions to allow
  easier partial application.

• Switched from:

  (** This signature is deliberately empty. *)

  to:

  (*_ This signature is deliberately empty. *)

  This causes the comment to not appear in documentation. We did not use:

  (* This signature is deliberately empty. *)

  because single-star comments, (* *), will be disallowed in signatures.
  We plan to disallow single-star comments to force the use of (** *) to
  indicate a doc comment and (*_ *) to indicate a non-doc comment.

• Update Async.Std.Schedule to allow use of Time_source.t other than wall_clock ().

  Time_source is a new abstraction for time progression that provides Clock and Time.now
  functionality driven by a time source other than the wall-clock. This can be useful for
  offline playback of historical events.

  Schedule was updatedso it can be used in these kinds of historical playback situations.

• Add functions to make it easy to start a tcp server that only listens on localhost
  The intention of this change is to make it both easy to bind to localhost and to make it clear in the mli
  that you bind to any with on_port.

• Allow passing in a socket to the tcp functions so that you can set socket options before a connection is established

• Make async_extra unit tests pass in 32bit

• Improve errors on exceptions raised inside Command.async'.

  A trivial use of Command.async' that raises:

  Before:

  (((pid 7781) (thread_id 0))
  ((human_readable 2016-04-22T19:11:26-0400)
  (int63_ns_since_epoch 1461366686545371364))
  "unhandled exception in Async scheduler"
  ("unhandled exception"
  ((monitor.ml.Error_
  ((exn (Failure "as;dfkj"))
  (backtrace
  ("Raised at file "pervasives.ml", line 30, characters 22-33"
  "Called from file "deferred1.ml", line 14, characters 63-68"
  "Called from file "job_queue.ml", line 160, characters 6-47" ""))
  (monitor
  (((name main) (here ()) (id 1) (has_seen_error true)
  (is_detached false))))))
  ((pid 7781) (thread_id 0)))))

  After:

  $ ./a.exe
  (monitor.ml.Error_
  ((exn (Failure "as;dfkj"))
  (backtrace
  ("Raised at file "pervasives.ml", line 30, characters 22-33"
  "Called from file "monitor.ml", line 214, characters 42-51"
  "Called from file "job_queue.ml", line 160, characters 6-47" ""))
  (monitor
  (((name Async.Std.Deferred.Or_error.try_with) (here ()) (id 2)
  (has_seen_error true) (is_detached true))))))

  After with ~extract_exn:true:

  $ ./a.exe
  (Failure "as;dfkj")

  The default can be changed for a project this way:

  module Command = struct
  include Command
  let async' = async' ~extract_exn:true
  let async_or_error' = async_or_error' ~extract_exn:true
  end

• Added module Async.Std.Require_explicit_time_source, so that one can
  require code to be explicit about what time source is used and not
  unintentionally use the wall clock. The idiom is to do:

  open! Require_explicit_time_source

  or, in an import.ml:

  include Require_explicit_time_source

• Don't wait for the full retry_delay before detecting close.

113.33.00

• Rename Async.Std.Schedule.every_{enter,tag_change} to
  Async.Std.Schedule.every_{enter,tag_change}_without_pushback and introduce
  Async.Std.Schedule.every_{enter,tag_change} with pushback behavior.

  The resulting functions are analogous to Pipe.iter_without_pushback and
  Pipe.iter.

• Replaced Persistent_rpc_client with a successor Persistent_connection
  for maintaining persistent connections to all manner of services, not
  just rpc servers.

• Make Bus.pipe1_exn take a Source_position.t to be more consistent with
  first_exn and iter_exn. This also shows better debug sexps on Bus when
  multiple pipes are subscribed to the bus.

113.24.00

N.B. some changes happening for this release are not listed in this changelog
since they appear only as a consequence of changes in core or async_kernel.

• When Transfer.Writer.send* raises, send an error to the client.

• Add a new rpc that enables a "push" rather than a "poll" model.

• Switched to PPX.

• For connected UDP sockets, expose send in the same fashion as sendto.

• Tcp.Server is documented to refuse excess connections beyond
  max_connections + max_pending_connections, but it treats them as
  pending connections in our standard OS configuration. In fact,
  research indicates that the documented behavior is nearly impossible
  to obtain directly and consistently from listen.

  Clarify the name and role of the backlog argument to listen and
  rename and update documentation for max_pending_connections to
  clarify what it actually does, in light of some research:

  `listen` does not generally respect the backlog argument as an
  upper limit, but as a lower limit (mod `tcp_max_syn_backlog`) and,
  
  with `tcp_abort_on_overflow=0`, `listen` will ignore excess
  connections rather than actively refusing them.
  
  (With `syncookies=1`, this can look like an indefinite backlog.)
  

  Existing, working code can substitute max_pending_connections -> backlog and move on. The behavior is not changed.

  When possible, consider architecting applications so the server can
  simply accept and close excess connections, rather than relying on the
  listen backlog to return an active indication to the client that
  they won't be serviced. To make sure the client receives an RST
  rather than an orderly shutdown, you can set the linger time to 0
  before closing the socket. (Added to unit tests.)

  Direct Tcp.Server support for this paradigm is left for future work.

• Make Rpc_low_latency_transport treat disconnections as eof, like
  Async_unix.Reader does.

• Add an implementation of Mvars to Async

• Allow custom handling of missed async_rpc heartbeats.

• adds a configuration limit on the number of tokens that can be in-flight

• Replace an #include <sys/errno.h> by #include <errno.h>.

  Fixes janestreet/async_extra#4

• Added Tcp.Server.sexp_of_t

• Adds Rpc.Pipe_rpc.dispatch_iter, plus a bunch of additional types to support
  it. The main reason for this is to reduce space usage: Pipe_rpc.dispatch
  followed by Pipe.iter_without_pushback consumes ~105 words in the steady state
  (i.e., when no messages are coming in) while dispatch_iter consumes ~15. I'm
  sure dispatch can be improved a lot, but a pipe by itself is 46 words, so it
  can't possibly become as small as dispatch_iter.

  Both cases can be made smaller by making Connection.response_handler a GADT
  instead of a closure. I plan to do this later.

  One annoying property of the interface is that the only way to cancel
  a subscription is to use Pipe_rpc.abort, which has a terrible interface.
  The logical way to improve the interface is to return a record of
  a Pipe_rpc.t, a Connection.t, and a Query_id.t, which allocates an
  additional few words. I'd kind of like to do this but it seems counter to the
  goal of reducing space usage.

• Added Tcp.Server.listening_on_address, so that one can get the
  address a server is listening on, as compared with listening_on,
  which just returns the port.

• Marked Command.async_basic as deprecated using the appropriate ocaml attribute.

  @@ocaml.deprecated

  (http://caml.inria.fr/pub/docs/manual-ocaml/extn.html#sec241)

• Extend the interface of Persistent_rpc_client to make the "address"
  type - previously fixed as Host_and_port.t - abstract. This is
  helpful for integrating with libraries that have a different notion of
  an address, e.g. rpc_discovery_lib.

• Typed_tcp mutated a Hashtbl while iterating over it when closing.

• Added Async.Bus.first_exn, which takes a bus and a function, and
  returns a deferred that becomes determined when the first event is
  published to the bus for which the function returns Some.

  This function is useful to reduce boilerplate for dealing with
  unsubscription.

• Reduced the number of threads required by tests in:

  async_extra/src/tcp.ml

• Added to the error message Bus.subscribe_exn called after first write
  the source-code position of the caller, in case there isn't a backtrace,
  to make the source of the problem clearer, and to avoid confusion with
  other source-code positions of subscribers already in the bus.

• Added to Bus.first_exn a Source_code_position.t argument, so that
  in the event of subscription failure, we can see who caused the
  subscription to the bus.

• Added to Tcp.Server.close an optional argument:

  ?close_existing_connections : bool

  This closes the sockets of all existing connections.

• Annotate errors returned by the async-rpc library with the name of the RPC for
  which the error was returned (if it's an rpc-level error) and a description of
  the remote side of the connection (the ip:host if connected via a network
  socket).

• Improved Async.Udp.bind's error message when it fails to
  mcast_join a multicast group.

• Change ~callback to ~f throughout the Bus interface

113.00.00

• Added Limiter module.

  Implements an async aware throttling rate limiter on top of Core.Limiter.

• Generalized Persistent_rpc_client to supports RPC connection types with
  additional information besides the Rpc.Connection.t itself.

  For instance: Persistent_rpc_client.Versioned has
  Versioned_rpc.Connection_with_menu.t as its connection type.

• Changed the Persistent_rpc_client.Make functor to not erase the type conn
  from its output module's signature.

  This way, the output of Make can be fed to functors or functions
  that expect a module matching Persistent_rpc_client.S.

• Moved Log from Async_extra to Async_unix, so that the scheduler can
  refer to it.

• Fixed a bug where Persistent_rpc_client.close would hang waiting for a
  connection to close.

112.35.00

• Added to Log a better mechanism for catching and handling background
  errors, via set_on_error and an on_error argument to create.

• Added Log.get_output : t -> Output.t list.

• Changed Monitor.try_with so that errors after the initial return are
  written to the global error log, rather than ignored.

• Added Monitor.try_with_or_error and try_with_join_or_error.

  try_with_or_error is intended to someday be renamed as try_with.
  It also omits some of try_with's optional arguments: run and
  rest. Different from try_with, try_with_or_error uses
  ~run:`Now, which we now believe is a more sensible behavior.

• Fixed a bug in Versioned_typed_tcp that causes spurious and repeated
  reconnects when user-level code disconnects.

• Added Tcp.Server.create_sock, to create TCP servers that don't use
  Reader and Writer.

• Changed Log.Level.arg to accept lowercase, uppercase, and
  capitalized words.

• Replaced Unpack_sequence.unpack* functions with unpack_into_pipe
  and unpack_iter, for reduced allocation.

    module Unpack_from : sig
      type t =
      | Pipe   of string Pipe.Reader.t
      | Reader of Reader.t
    end
  
    val unpack_into_pipe
      :  from  : Unpack_from.t
      -> using : ('a, 'b) Unpack_buffer.t
      -> 'a Pipe.Reader.t * ('a, 'b) Unpack_result.t Deferred.t
  
    val unpack_iter
      :  from  : Unpack_from.t
      -> using : ('a, 'b) Unpack_buffer.t
      -> f     : ('a -> unit)
      -> ('a, 'b) Unpack_iter_result.t Deferred.t
  

• Added to Log support for user-defined rotation schemes.

• Added Log.is_closed.

• Moved Async_extra.Rpc to its own library, Async_kernel_rpc, and
  abstracted its transport layer.

  Async_kernel_rpc depends only on Async_kernel. This allows
  Async_rpc to be used in javascript or to try transports tuned for
  different use cases. Versioned_rpc was moved to
  Async_rpc_kernel as well.

  Async_extra still provides an Rpc module with the Unix-dependent
  part:

  • the Rpc.Transport module is augmented with
    Async_unix.{Reader,Writer} based transports

  • the Rpc.Connection module is augmented with helpers for TCP
    based connections

• In sexp-formatted Log messages, output the sexp on a single line
  rather than in multi-line "hum"an format.

  This makes it possible to, among other things, easily grep
  such logs.

• Fixed a (very small) space leak in Persistent_rpc_client.

  The fix was to use Deferred.choose and Deferred.choice instead
  of Deferred.any and >>|. The old implementation added
  a callback to the t.close_started ivar every time the connection
  transitioned from connected to disconnected.

• Added Persistent_rpc_client.create_generic, which is like create,
  but generic in the function used to connect.

• Fixed a race condition in the Versioned_typed_tcp interface that
  caused a worker to miss a Connect message if the box is under high
  load.

  Query_client.create is called from Worker_impl.create in
  a different async cycle than the following call to
  Query_client.listen (really, Tail.collect under the hood) which
  is made from Worker_impl.run.

  When the load on the box is heavy (many workers starting and
  connecting at the same time), the OS might take away the CPU from
  the worker process between the two async cycles. The TCP socket
  gets connected while the process is still waiting for its turn, and
  eventually, when it's the worker's turn to grab the CPU, Async
  scheduler might process the TCP event earlier than
  Worker_impl.run.

• Improved Udp.ready_iter to avoid intermediate exceptions by using
  Syscall_result.

  UDP loops use that, so will benefit.

  Adjust the implementation slightly as well: made the inner loop
  always exit on EAGAIN/EWOULDBLOCK to wait until ready, and give
  other Async jobs a chance to run after EAGAIN/EWOULDBLOCK in the
  outer loop.

112.24.00

• Changed Log to not eagerly run the rotation loop when an
  Output.Rotating_file is created.

• Changed Log.Output.combine to write log outputs in sequence rather than
  parallel, to give the correct semantics when the same output is included
  multiple times in Log.create.

  This fixed a test that was failing in lib_test/log_test.ml.

• Remove Log.Rotation.t_of_sexp.

• Made Command.async* functions flush stdout and stderr before calling
  shutdown, to avoid timeouts causing data to be dropped.

  For now, we're making this change in Command rather than Writer.
  Writer already has at_shutdown handlers. We've observed that they
  don't behave well for command-line programs w.r.t. stderr. So, the
  thinking of this feature is to try out a different at_shutdown
  behavior, just for Command executables and just for stdout and
  stderr. If it works out, maybe we move it into Writer proper.
  Putting the change in Command for now reduces the scope of what is
  affected by the experiment, and hopefully correlates well with where
  the change is likely to help.

• In Rpc, catch exceptions raised by blocking-RPC implementations.

• Added functionality to Versioned_typed_tcp.Repeater.

  Added to create an argument is_client_allowed : Client_name.t -> bool.

  Added to start an argument:

  on_connecting_error  : (client_name    : Client_name.t
                          -> server_name : Server_name.t
                          -> Error.t -> unit)
  

• Fixed a race in Versioned_typed_tcp in which a message can be dropped
  between Server.create and Server.listen

• Simplified the implementation of Rpc.

  Rpc has an internal Response_handler module, which is just a record containing
  a response-handling function and an already_removed boolean field. It turns
  out that this is unnecessary: already_removed is set to true when the
  function returns remove`, but if it returns remove` then it will also be
  removed from a hash table, and we only call the function immediately after
  looking it up in that hash table.

  This wasn't always pointless: this function used to return deferred values and
  run inside a throttle. The simplification is only possible because we made it
  synchronous a while ago.

• Added Tcp.Server.num_connections function.

• Added creation functions for Versioned_rpc menus, for use in clients of an
  RPC proxy.

  In Menu:

  val create : Implementation.Description.t list -> t
  

  In Connection_with_menu:
  val create_directly : Connection.t -> Menu.t -> t

  These are for use in clients of an RPC proxy, which can't use the
  regular menu mechanism since they each need to have many menus (one
  for each potential target) but should only need to have one connection
  (to the proxy).

• Added to Rpc expert submodules, Implementations.Expert and Rpc.Expert,
  with low-level access for implementing a proxy that can handle queries without
  knowing their names, types, etc. in advance.

• Renamed Rpc.Implementation.Description as Rpc.Description.

• Added Rpc.{Rpc,Pipe_rpc,State_rpc}.description accessor functions.

• Added Rpc.Implementation.descriptions, which returns all RPCs in an
  Rpc.Implementations.t.
  This was needed for the rpc_discovery library: given an Implementations.t we want to advertise at

  prefix/<rpc_name>/<rpc_version>/host_and_port = <host_and_port>
  

• Added combinators to Rpc.Implementations: lift, add, add_exn.

112.17.00

• Modernized code style in Async_extra.

  This was mostly whitespace changes, plus deletions of unneeded
  module paths.

• Added with sexp_of to Tcp.Where_to_listen for debugging.

• In Versioned_typed_tcp, check that the writer on the other side is
  not closed in the Pass_on case.

• Added a new way to implement an RPC, where the implementation
  doesn't return a deferred.

  This "blocking" rpc implementation guarantees that the rpc will in
  fact be fully dispatched by the time the implementation returns.

  This can be used to skip the deserialization of the query, and
  instead operate directly in the message contents as received.

  Also, fixed a bug in which the query handler (and therefore the
  connection state) was being called before the internal async rpc
  handshake was finished.

• Added an optional job_tag argument to Sequencer_table.enqueue,
  to display for debugging.

• Added an optional argument to TCP-connection functions to control
  the local interface used to connect.

  To implement this this, extended Tcp.connect to work on a bound socket.

• Added with compare to Process.Output.t.

• Added Process.Output.Stable module.

• Exposed concrete rpc in Versioned_rpc.Both_convert.

• Changed Cpu_usage to take its first sample after waiting, rather
  than immediately.

  This fixes a problem where the first sample could be NAN or Inf.

• Made Log buffer-age be unlimited, to avoid exceptions when log
  writes are blocked for long periods.

• Improved Log.t_of_sexp's error message.

• Changed Rpc.Connection.client and with_client to raise some
  errors which had been dropped during RPC dispatch.

  Previously, errors dispatching Rpc.Rpc.t's were handled correctly
  and returned or raised by the relevant dispatch functions. However,
  errors that occurred in the middle of handling a Rpc.Pipe_rpc.t or
  Rpc.State_rpc.t were swallowed. This is because they happen after
  the dispatch functions have returned, and the dispatch interface
  doesn't allow for errors to occur in the middle of the pipe -- they
  must be raised to the monitor in effect when the Rpc.Connection.t
  is created. Errors could be raised to the effective monitor at the
  dispatch call, but the failure causes the entire connection to go
  into error, so the connection's monitor seems more appropriate.
  These errors weren't propagated to the caller because client and
  with_client both used Monitor.try_with without rest handling,
  causing /any/ errors caused while handling the connection (after the
  Connection.t has been returned to the user) to be dropped.

• In Rpc, exposed some optional parameters from the Tcp module:
  ?max_pending_connections and ?buffer_age_limit.

112.06.00

• In Log, exposed the raw message.

• Changed Rpc creators' connection_state to be a function that takes
  the connection and returns the state.

  This makes it possible for the connection state to actually get
  a handle on the connection itself, which simplifies a number of
  idioms for using RPC. In particular, it makes it easier to respond
  with an RPC back to a client over client's own connection.

• Fixed some nondeterministically failing tests.

• In Log, made logs discard messages when their output list is empty.

  Also, removed redundant tracking of current level.

• Moved Udp.bind_to_interface_exn to Unix module in async_unix.

• Added Versioned_typed_tcp.Repeater.

  Repeater is used in the cases where we want to inspect and possibly
  alter the flow between a client and a server without having to
  change either the client or the server or the protocol between them.

112.01.00

• Changed Persistent_rpc_client.connected to avoid returning a
  connection that is closed at the time it was called.

• Optimized Rpc.implement so that if a server's implementation
  returns a determined deferred, then the output is immediately
  serialized and written out for the client.

  This reduces memory consumption, improves throughput and latency.
  Measurements with the pipe_rpc_test program showed that a server
  went from processing 600_000 msg/sec, to 2_200_000 msg/sec before
  pegging the CPU.

• Changed Log's output processor's batch size from 1_000 to 100.

• Added Persistent_rpc_client.close and close_finished.

• In Rpc.Connection.client and with_client, used the
  handshake_timeout as the timeout passed to Tcp.connect.

  handshake_timeout was previously used only for the Rpc module's
  handshake timeout.

• Changed Rpc.create's on_unknown_rpc argument, renaming
  \Ignoreas`Close_connection, and requiring `Callto return`Close_connectionor`Continue`.

  \Ignore` was renamed because it was a poor name, since in fact it
  closed the connection.

  Added a \Continue` option, whic allows one to keep the connection
  open.

  Changed \Callto return`Continueor`Close_connection, where the old unitreturn value meant`Close_connection`.

• In Versioned_typed_tcp, enabled the use of "credentials" in the
  "Hello" message.

  Propagate credentials to the user code when it arrives on the wire.

111.28.00

• Added to Versioned_rpc a non-functor interface.

• Added Log.level, which returns the last level passed to set_level.

• Enabled Async-RPC pushback in the Tcp_file protocol.

111.25.00

• Removed lazy from the core of Log.

• Made Log.Message.t have a stable bin_io.

  The Stable.V1 is the current serialization scheme, and Stable.V0
  is the serialization scheme in 111.18.00 and before, which is needed
  to talk to older systems.

• Changed Rpc to return Connection_closed if a connection ends
  before a response makes it to the caller.

  Previously, the dispatch output was never determined.

  Also, removed an unused field in one of the internal data structures
  of Async RPC.

• In Versioned_rpc, added version:int argument to implement_multi functions.

• In Versioned_rpc, the Pipe_rpc.Make functors now return an
  additional output functor.

  Register' is like Register but has in its input module:

  val response_of_model :
    Model.response Queue.t -> response Queue.t Deferred.t
  

  rather than

  val response_of_model : Model.response -> response
  

  This is analogous to Pipe.map' and Pipe.map.

• Added to Log a V2 stable format and better readers for
  time-varying formats.

• In Log, added an optional ?time:Time.t argument to allow callers
  to pass in the logged time of an event rather than relying on
  Time.now ().

111.21.00

• Added Sexp_hum Log.Output.format, which is useful for making logs
  more human readable.

• Added with compare to Rpc.Implementation.Description.

111.17.00

• Added module Persistent_rpc_client, an RPC client that attempts to
  reconnect when the connection is lost, until a new connection is
  established.

• Significantly sped up the Rpc module by removing Bigstring
  serialization.

  Performance of the two implementations was tested by building a
  simple client/server executable that would count major cycles.
  Sending 100 byte messages at a rate of 50k/second shows (on both
  sides of the RPC):

  original:

  • ~160 major cycles in 30s

  • CPU usage around 60%

  new:

  • ~10 major cycles in 30s

  • CPU usage <= 2%

• Enabled a version of Pipe_rpc and State_rpc where the consumer
  can pushback on the producer if it can't consume the contents of the
  pipe fast enough.

• Added Log.Level.arg : Log.Level.t Command.Spec.Arg_type.t for
  defining command lines that accept (and autocomplete) log levels.

• Added Command.async_or_error and renamed Command.async_basic to
  Command.async, leaving async_basic a deprecated alias for the
  new name.

  Command.async_or_error is similar to Command.basic and
  Command.async, but accepts a unit Or_error.t Deferred.t type.

• Added Persistent_rpc_connection.current_connection, so that one
  can detect whether one is currently connected.

  val current_connection : t -> Rpc.Connection.t option
  

111.13.00

• For Typed_tcp.create, added a Client_id.t argument to the auth
  callback.

111.11.00

• Made Log more fair with respect to other Async jobs, by working on
  fixed-length groups of incoming log messages.

  Previously, Log had processed everything available. The change
  gives other Async jobs more of a chance to run.

111.08.00

• Added Log.Message.add_tags, which extends a message with a list of
  key-value pairs.

    val add_tags : t -> (string * string) list -> t
  

111.06.00

• Added ?on_wouldblock:(unit -> unit) callback to
  Udp.recvmmsg_loop and recvmmsg_no_sources_loop.

• For functions that create Rpc connections, added optional
  arguments: ?max_message_size:int and
  ?handshake_timeout:Time.Span.t.

  These arguments were already available to Connection.create, but
  are now uniformly available to all functions that create
  connections.

111.03.00

• Add ?max_connections:int argument to Rpc.Connection.serve.

  max_connections is passed to Tcp.Server.create, and limits the
  number of connections that an Rpc server will accept.

• Improved Log.Rotation:

  • Made Log.Rotation.t abstract; use create rather than an
    explicit record.

  • Added a `Dated naming_scheme.

  • Add Log.Rotation.default, for getting a sensible default
    rotation scheme.

  • Added an optional (but discouraged) option to symlink the latest
    log file.

  • Every log rotation scheme has an associated Time.Zone.t.

  • Changed the internal representation of Log.Rotation.t, but
    t_of_sexp is backwards compatible, so existing config files will
    continue to work.

• Changed Udp.bind_any to use Socket.bind ~reuseaddr:false, to
  ensure a unique port.

• Added Tcp.Server.listening_socket, which returns the socket the
  server is listening on.

  Changed Tcp.Server so that if the listening socket is closed, the
  server is closed.

• Added to Udp.Config.t a max_ready : int field to prevent UDP
  receive loops from starving other async jobs.

• Improved File_tail to cut the number of fstat calls in half.

  File_tail uses a stat loop to monitor a file and continue reading
  it as it grows. We had made two fstat invocations per loop
  iteration, using Async.Std.Unix.with_file which constructs an
  Fd.t and therefore does it own fstat. Switching to
  Core.Std.Unix.with_file with In_thread.run eliminated the extra
  fstat.

110.01.00

• Added Cpu_usage.Sampler for directly sampling CPU usage.

• Fixed Log.rotate to never raise.

• Fixed two bugs in Log rotation.

  • Log rotation had used the wrong date when checking whether it
    should rotate.

  • Made Rotation.keep = \At_least` delete the oldest, rather than
    the newest, logs.

109.60.00

• Replaced Tcp_file.serve's ~port:int argument with
  Tcp.Where_to_listen.inet.

109.58.00

• Changed Cpu_usage to use Core.Percent instead of float where
  appropriate.

• Made Bus.unsubscribe check that the subscriber is subscribed to
  the given bus.

• Made Log.t support with sexp_of.

• Fixed Tcp.on_port 0 to return the port actually being listened on,
  like Tcp.on_port_chosen_by_os.

  Previously, a serverlistening on Tcp.on_port 0 would have its
  Tcp.Server.listening_on as 0, which of course is not the port
  the server is listening on.

109.55.00

• Added Udp.recvmmsg_no_sources_loop, a specialization of
  recvmmsg_loop for improved performance.

  This improvement was driven by profiling at high message rates.

109.53.00

• Added module Bus, which is an intraprocess "broadcast"
  communication mechanism.

• Added Tcp.to_inet_address and to_unix_address.

• Added Tcp.to_socket which creates a Tcp.where_to_connect from a
  Socket.Address.Inet.t.

• Module Weak_hashtbl is now implemented as a wrapper around
  Core.Weak_hashtbl.

  No intended change in behavior.

109.52.00

• Added module Cpu_usage, which publishes CPU-usage statistics for
  the running process.

• Fixed Sequencer_table.enqueue so that there is no deferred between
  finding the state and calling the user function.

109.47.00

• Added with sexp to Log.Output.machine_readable_format and format.

109.45.00

• Added ?abort:unit Deferred.t argument to
  Lock_file.waiting_create, Lock_file.Nfs.waiting_create and
  critical_section.

109.44.00

• Fixed a time-based race condition in Log rotation.

109.42.00

• Fixed Log.Blocking so that when async is running it writes the message in syslog before failing with an exception.

109.40.00

• Added to Udp.Config the ability to stop early, via stop : unit Deferred.t.

109.38.00

• In Rpc, exposed accessors for binary protocol values.

  For example, this allows one to write a wrapper for Pipe_rpc that
  allows for the easy re cording and replaying of values the come over
  the pipe.

109.35.00

• Added module Async.Udp, aimed at high-performance UDP
  applications.

• Added module Lock_file.Nfs, which wraps the functions in
  Core.Std.Lock_file.Nfs.

109.33.00

• Change Log.Global to by default send all output, including `Info,
  to stderr.

  Replaced Log.Output.screen with Log.Output.stderr. There is now
  also and Log.Output.stdout.

109.32.00

• Added Dynamic_port_writer.

  Dynamic_port_writer solves the problem of communicating a
  dynamically selected tcp port from a child process to its parent.

109.28.00

• Fixed an error message in Versioned_rpc that was swapping which
  versions were supported by the caller and the callee.

109.27.00

• Added function Versioned_typed_tcp.Client.shutdown.

• Added new module Sequencer_table, which is a table of
  Throttle.Sequencer's indexed by keys.

109.24.00

• Made the Caller_converts interface in Versioned_rpc use the
  Connection_with_menu idea introduced in Both_convert.

109.19.00

• Added function Versioned_typed_tcp.Client.flushed : t -> [ Flushed | Pending of Time.t Deferred.t ].

  This exposes whether the underlying Writer.t has been flushed.

109.17.00

• Added an option to Async.Log.Rotation to include the date in
  logfile names.

  This is mostly for archiving purposes.

• Made Versioned_rpc.Callee_converts.Pipe_rpc.implement_multi agree
  with Rpc.Pipe_rpc.implement on the type of pipe rpc
  implementations.

• Improved the performance of Versioned_typed_tcp.

  Avoided creating deferreds while reading the incoming messages.

109.15.00

• In Rpc.client and Rpc.with_client, allowed the client to
  implement the rpcs.

  Added a new optional argument: ?implementations:_ Client_implementations.t.

• Added new module Versioned_rpc.Both_convert to allow the caller
  and callee to independently upgrade to a new rpc.

  This is a new flavor of Versioned_rpc in which both sides do some
  type coercions.

109.12.00

• Made explicit the equivalence between type Async.Command.t and type Core.Command.t.

109.11.00

• Exposed a version function in Pipe_rpc and State_rpc.

109.10.00

• Fixed a race condition in Pipe_rpc and State_rpc. This race
  could cause an exception to be raised on connection closing.

109.08.00

• Added module Async.Command
  This is Core.Command with additional async functions. In particular
  it contains a function async_basic that is exactly the same as
  Core.Command.basic, except that the function it wraps returns
  unit Deferred.t, instead of unit. async_basic will also start the
  async scheduler before the wrapped function is run, and will stop the
  scheduler when the wrapped function returns.