Prepare toolchain/logs/master branch.

1 files changed, 0 insertions, 559 deletions

diff --git a/user/jkoenig/java/discussion.mdwn b/user/jkoenig/java/discussion.mdwn
deleted file mode 100644
index 352f6d62..00000000
--- a/user/jkoenig/java/discussion.mdwn
+++ /dev/null
@@ -1,559 +0,0 @@
-[[!meta copyright="Copyright © 2011 Free Software Foundation, Inc."]]
-
-[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
-id="license" text="Permission is granted to copy, distribute and/or modify this
-document under the terms of the GNU Free Documentation License, Version 1.2 or
-any later version published by the Free Software Foundation; with no Invariant
-Sections, no Front-Cover Texts, and no Back-Cover Texts.  A copy of the license
-is included in the section entitled [[GNU Free Documentation
-License|/fdl]]."]]"""]]
-
-[[!toc]]
-
-
-# General
-
-Some [[tschwinge]] comments regarding your proposal.  Which is very good, if I
-may say so again!  :-)
-
-Of course, everyone is invited to contribute here!
-
-I want to give the following methodology a try, instead of only having
-email/IRC discussions -- for the latter are again and again showing a tendency
-to be dumped and deposited into their respective archives, and be forgotten
-there.  Of course, email/IRC discussions have their usefulness too, so we're
-not going to replace them totally.  For example, for conducting discussions
-with a bunch of people (who may not even be following these pages here), email
-(or, as applicable, the even more interactive IRC) will still be the medium of
-choice.  (And then, the executive summary should be posted here, or
-incorporated into your proposal.)
-
-Also, if you disagree with this suggested procedure right away, or at some
-later point begin to feel that this thing doesn't work out, or simply takes too
-much time (I don't think so: writing emails takes time, too), just say so, and
-we can reconsider.
-
-Of course, as this wiki is a passive medium rather than an active one as IRC
-and email are, it is fine to send notices like: *I have updated the wiki page,
-please have a look*.
-
-One idea is that your proposal evolves alongside with the ongoing work, and
-represents (in more or less detail) what has been done and what will be done.
-Also, we can hopefully use parts of it for documentation purposes, or as
-recipes for similar work (enabling other programming languages on the Hurd, for
-example).
-
-For this, I suggest the following procedure: as applicable, you can either
-address any comments in here (for example, if they're wrong :-), or if they
-require further discussion; think: *email discussion*), or you can address them
-directly in your propoal and remove the comments from here at the same time
-(think: *bug fix*).
-
-Generally, you can assume that for things I didn't comment on (within some
-reasonable timeframe/upon asking me again) that I'm fine with them.  Otherwise,
-I might say: *I don't like this as is, but I'll need more time to think about
-it.*
-
-There is also a possibility that parts of your proposal will be split off; in
-cases where we think they're valuable to follow, but not at this time.  (As you
-know, your proposal is not really a trivial one, so it may just be too much for
-one person's summer.)  Such bits could be moved to [[open_issues]] pages,
-either new ones or existing ones, as applicable.
-
-
-# GSoC Site Discussion
-
-  * Discussion items from
-    <http://www.google-melange.com/gsoc/proposal/review/google/gsoc2011/jkoenig/1>
-    should be copied here:
-
-      * technical bits (obviously);
-
-      * also the *why do we want Java bindings* reasoning;
-
-      * CLISP findings should also be documented somewhere permanently.
-
-          * We should probaby open up a *languages for Hurd* section on the web
-            pages ([[!taglink open_issue_documentation]]).
-
-
-# Java Native Interface (JNI)
-
-  * <http://en.wikipedia.org/wiki/Java_Native_Interface>
-  * <http://download.oracle.com/javase/7/docs/technotes/guides/jni/>
-  * <http://java.sun.com/products/jdk/faq/jnifaq.html>
-  * <http://java.sun.com/docs/books/jni/>
-
-
-## Java Native Access (JNA)
-
-  * <http://jna.java.net/>
-  * <https://github.com/twall/jna#readme>
-
-This is a different approach, and *while some attention is paid to performance,
-correctness and ease of use take priority*.
-
-As we plan on only having a few native methods (for invoking `mach_msg`,
-essentially), JNA is probably the wrong approach: portability and ease of use
-is not important, but performance is.
-
-## Compiled Native Interface (CNI)
-
-  * <http://gcc.gnu.org/onlinedocs/gcj/About-CNI.html>
-  * <http://per.bothner.com/papers/UsenixJVM01/CNI01.pdf>
-
-Probably faster than JNI, but only usable with GCJ.
-
-> Given that we have very few JNI calls,
-> it might be interesting to take a "dual" approach
-> if CNI actually improves performance
-> when compiling to native code.
-> --[[jkoenig]] 2011-07-20
-
-# IRC, freenode, #hurd, 2011-07-13
-
-[[!tag open_issue_documentation]]
-
-    <jkoenig> Yes, I guess so. Maybe start investigating mig because it may
-      have repercussions on what the best approach would be for some aspects of
-      the Mach bindings.
-    <tschwinge> I still think that making MIG emit Java code is not too
-      difficult, once you have the required Java infrastructure (like what
-      you're writing at the moment).
-    <tschwinge> On the other hand, if there's another approach that you'd like
-      to use, I'm not trying to force using MIG.
-    <braunr> i still have a problem understanding your approach
-    <braunr> at which level are your bindings located ?
-    <jkoenig> I expect mig it will be the easiest route, but of course possibly
-      it won't.
-    <tschwinge> jkoenig: Yeah, be give some high-level to low-level overview?
-    <jkoenig> ok, so
-    <jkoenig> at the very core, low-level, we have a very thin amount of JNI
-      code to access (proper) system calls.
-    <jkoenig> by "proper" I mean things like mach_task_self, mach_msg and
-      mach_reply_port, which are actually system calls rather than RPCs to the
-      kernel.
-    <braunr> right
-    <jkoenig> at this level, we manipulate port names as integers, and the
-      message buffers for mach_msg are raw ByteBuffers (from the java.nio
-      package)
-    <jkoenig> actually, so-called /direct/ ByteBuffers, which are backed by
-      memory allocated outside of the Java heap, rather than as a byte[] array
-    <jkoenig> we can retreive the pointer from the JNI code and use the buffer
-      directly.
-    <jkoenig> (so, good for performance and it's also portable.)
-    <braunr> ok
-    <braunr> i'm more interested in the higher level bindings :)
-    <jkoenig> ok so, higher up.
-    <jkoenig> design goal from my proposal: "the memory safety of Java should
-      be maintained and extended to Mach primitives such as port names and
-      out-of-line memory regions"
-    <jkoenig> so integer port names are not "safe" in the sense that they can
-      be forged and misused in all kinds of way
-    <jkoenig> which is why I have a layer of Java code whose job is to wrap
-      this kind of low-level Mach stuff into safe abstractions
-    <jkoenig> and ideally the user should only use these safe abstractions.
-    <tschwinge> (Not to restrict the programmer, but to help him write correct
-      code.)
-    <jkoenig> right.
-    <braunr> so you can't use mach RPCs directly
-    <jkoenig> tschwinge, also to actually restrict them, in a Joe-E /
-      object-capability context, but that's not the primary concern right now
-      ;-)
-    <braunr> or you force your wrappers to have these abstractions as input
-    <jkoenig> braunr, well, actually at this level you still have Mach RPC
-    <jkoenig> but for instance, port names are encapsulated into "MachPort"
-      objects which ensure they are handled correcly
-    <tschwinge> As I understand it, you use these abstractions to prepare a
-      usual mach_msg message, and then invoke mach_msg.
-    <braunr> ok
-    <jkoenig> and message buffers are wrapped into "MachMsg" objects which both
-      help you write the messages into the ByteBuffer and prevent you from
-      doing funky stuff
-    <jkoenig> and ensure the ports which you send/receive/pseudo-receive after
-      an error/... are deallocated as required, etc.
-    <braunr> what's the interface to use IPC ?
-    <tschwinge> Is MIG doing that, too, I think?  (And antrik once found some
-      error there, which is still to be reviewed...)
-    <jkoenig> braunr, so basically as a user you would be free to use either
-      one of these layers, or to use MIG-generated classes which would
-      construct and exchange messages for you using the second (safe) layer.
-    <braunr> ok, let's just finish with the low level layer before going
-      further please
-    <jkoenig> tschwinge, MIG does some type checking on the received message
-      and saves you the trouble of constructing/parsing them yourself, but I'm
-      not sure about how mach_msg errors are handled
-    <braunr> what are the main methods of MachMsg for example ?
-    <jkoenig> braunr, you may want to have a look at
-      http://jk.fr.eu.org/hurd-java/doc/html/classorg_1_1gnu_1_1mach_1_1MachMsg.html
-    <braunr> right, sorry
-    <braunr> grabbed the code at work and forgot here
-    <jkoenig> and also
-      https://github.com/jeremie-koenig/hurd-java/blob/master/HelloMach.java
-      which uses it
-    <jkoenig> but roughly, you'd use setRemotePort, setLocalPort, setId to
-      write your message's header
-    <jkoenig> then use one of the putFoo() methods to add data items to the
-      message
-    <braunr> ok, the mapping with the low level C interface is very clear
-    <braunr> that's good for me
-    <jkoenig> the putFoo() methods would write the appropriate type
-      descriptors, then the actual data.
-    <braunr> we can go on with the MiG part if you want :)
-    <jkoenig> right,
-    <jkoenig> so here you may want to look at the UML class diagram from
-      http://www.bddebian.com/~hurd-web/user/jkoenig/java/proposal/
-    <jkoenig> so in the C case, mig generates 3 files
-    <jkoenig> a header file which has the prototypes of the mig-generated
-      stubs,
-    <jkoenig> a *User.c which has their actual implementation
-    <jkoenig> and a *Server.c which handles demultiplexing the incoming
-      messages and helps with implementing servers.
-    <jkoenig> so we would do something along these lines, more or less:
-    <jkoenig> mig would generate the code for a Java interface in lieu of the
-      *.h file.
-    <jkoenig> a generated FooUser class would implement this interface by doing
-      RPC
-    <jkoenig> (so basically you would pass a MachPort object to the
-      constructor, and then you could use the resulting object to do RPC with
-      whatever is on the other end)
-    <jkoenig> and the generated FooServer class would do the opposite,
-    <braunr> ok
-    <braunr> issues with threads ?
-    <jkoenig> you would pass an object implementing the Foo interface to the
-      constructor,
-    <braunr> i'm guessing the demux part may have to create threads, right ?
-    <jkoenig> and the resulting object would handle messages by using the
-      object you passed.
-    <jkoenig> braunr, right, so that would be more a libports kind of code,
-    <braunr> the libports-like library, i see
-    <jkoenig> to which you could pass Server objects (for instance the
-      FooServer above), and it would handle incoming messages.
-    <braunr> how is message content mapped to a java interface ?
-    <jkoenig> this would be determined from the .defs files and MIG would
-      generate the appropriate code, hopefully.
-    <braunr> so the demux part would handle rpc integer identifiers ?
-    <jkoenig> right.
-    <braunr> but hm
-    <jkoenig> also mapping .defs files to Java interfaces might prove to be
-      tricky. data types conversion and all
-    <antrik> tschwinge: my mamory is rather hazy. IIRC the issue was that the
-      MIG-generated stubs deallocate out-of-line port arrays after the
-      implementation returns, before returning to the dispatcher
-    <braunr> i'll just overlook this specific implementation detail
-    <jkoenig> but we could use some annotation-based system if we need to
-      provide more information to generate the java code.
-    <antrik> but the Hurd (or rather glibc) RPC handling also automatically
-      deallocates everything if an error occurs
-    <antrik> so I changed the MIG code to deallocate only when no error occurs
-    <braunr> jkoenig: ok, we'll talk about that when there is more progress and
-      you have a better view of the problem
-    <antrik> at that time I was pretty sure that this is a correctly working
-      solution, but it always seemed questionable conceptually... however, I
-      wasn't able to come up with a better one, and nobody else commented on it
-    <braunr> antrik: shouldn't the hurd be changed not to deallocate something
-      it didn't allocate in the first place ?
-    <antrik> braunr: no, the server has to deallocate stuff before returning to
-      the client. the request message is destroyed before returning the reply.
-    <tschwinge> jkoenig, braunr: That's what I had in mind where MIG might be a
-      bit awkward.  Then we can indeed either add annotations to the .defs
-      files, or reproduce them in some other format.  That's some work, but
-      it's mostly a one-time work.
-    <tschwinge> After all, the RPC interface is a binary one, and there may be
-      more than one API for creating these messages, etc.
-    <antrik> jkoenig: actually, at least in the Hurd, server-side and
-      client-side headers are separate -- so MIG actually creates four files
-    <jkoenig> tschwinge, wrt to annotations I was more thinking about Java
-      ones, such as: @MIGDefsFile("mach/task.defs") @MIGCType("task_t") public
-      interface Task { }
-    <jkoenig> antrik, oh, ok, it makes sense.
-    <braunr> jkoenig: anything else ?
-    <jkoenig> braunr, nothing that I can think of
-    <braunr> ok
-    <antrik> tschwinge: I think it would be a *very* bad idea to introduce
-      redundancy regarding RPC definitions
-    <braunr> thanks for the tour :)
-    <antrik> (the _request.defs/_reply.defs mess is bad enough...)
-    <jkoenig> did I speak about the "Unsafe" pseudo-exception? that's
-      interesting :-)
-    <tschwinge> jkoenig: Also, virtual memory abstractions?
-    <braunr> jkoenig: you didn't
-    <tschwinge> antrik: Well, then we could create some other super-format.
-      But that's just a detail IMO.
-    <jkoenig> ok, so wrt virtual memory, a page we received can be wrapped with
-      some JNI help into a (direct) ByteBuffer object.
-    <jkoenig> deallocating sent pages will be tricky, though.
-    <tschwinge> antrik: To put it this way: for me the .defs files are just one
-      way of expressing the RPC interfaces' contracts.  (At the same time, they
-      happen to be the actual reference for these, too.  But the specification
-      itself could just as well be a textual one.) 
-    <jkoenig> on approach I've been thinking about would be to "wrap" the
-      ByteBuffer object into an object which has the sole reference to it, so
-      that when it's deallocated the reference can be replaced with "null", and
-      further attempts to access the buffer would throw exceptions.
-    <braunr> sounds reasonable
-    <jkoenig> but that's still in flux in my head, we may end up needing our
-      own implementation of ByteBuffer-like objects.
-    <tschwinge> The problem being that there is no mechanism to ``revoke'' an
-      object once a reference to it has been shared.
-    <jkoenig> right.
-    <tschwinge> A wrapper is one possibility indeed.
-    <antrik> tschwinge: they are called interface *definitions* for a reason
-      :-)
-    <tschwinge> This is a very similar problem as with capabilities when there
-      is no revoke operation for these, too.
-    <tschwinge> antrik: Yes, because they define MIG's input.  :-P
-    <tschwinge> Isn't that what is called a membrane in the capability world?
-    <antrik> I do not say that we have to consider the format of the .defs to
-      be set in stone; but I do insist on using a canonical machine-parsable
-      source for all language bindings
-    <tschwinge> attenuation
-    <jkoenig> tschwinge, you mean the revokable proxy contruct ? (It's the same
-      principle indeed)
-    <tschwinge>     A common design pattern in object-capability systems: given
-      one reference of an object, create another reference for a proxy object
-      with certain security restrictions, such as only permitting read-only
-      access or allowing revocation. The proxy object performs security checks
-      on messages that it receives and passes on any that are allowed. Deep
-      attenuation refers to the case where the same attenuation is applied
-      transitively to any
-    <tschwinge>     objects obtained via the original attenuated object,
-      typically by use of a "membrane".
-    <tschwinge> http://en.wikipedia.org/wiki/Object-capability_model
-    <tschwinge> Yes.
-    <tschwinge> Good.  I understood something.  ;-)
-    <tschwinge> antrik: OKAY!  :-P
-    <tschwinge> jkoenig: And hopefully the JVM will optimize away all the
-      additional indirection...  :-D
-    <tschwinge> jkoenig: Is there anything more to say about the VM layer?
-    <jkoenig> tschwinge, "hopefully", yes :-)
-    <tschwinge> Like, the data that I'm sharing -- is it untyped, isn't it?
-    <jkoenig> tschwinge, you mean that within the received/sent pages ?
-    <tschwinge> Yes.
-    <tschwinge> But that'S how it is, indeed.
-    <jkoenig> well actually the type descriptor should indicate what they
-      contain.
-    <tschwinge> I cannot trust anything I receive from externally.
-    <jkoenig> it's most often used for MACH_MSG_TYPE_CHAR items I guess, and it
-      will be type checked when retreive
-    <tschwinge> Yeah, and that then just *is* arbitrary data, like a block read
-      from a disk file.
-    <jkoenig> you would have something like: ByteBuffer
-      MachMsg.getBuffer(MachMsg.Type expected), and MachMsg would check the
-      type descriptor against that which you specified
-    <tschwinge> Or a packet transmitted over the network.
-    <tschwinge> OK, yes.
-    <antrik> jkoenig: in theory ints should be used quite often too. the whole
-      purpose of the type descriptors is to allow byte order swapping when
-      messages are passed between hosts with different architecture...
-    <jkoenig> tschwinge, right, except for out-of-line port arrays, which need
-      to be handled differently obviously.
-    <antrik> (which is totally irrelevat for our purposes -- especially since
-      the actual network IPC code doesn't exist anymore ;-) )
-    <jkoenig> antrik, oh, interesting
-    <tschwinge> Yes, that was one original idea.
-    <jkoenig> actually my litmus test for what the bindings should be, is you
-      should be able to implement such a proxy in Java :-)
-    <tschwinge> antrik: And hey, you now have processors that can switch
-      between different modes during runtime...  :-)
-    <jkoenig> (although arguably that's a little bit ambitious)
-    <braunr> tschwinge: there should be bits in page tables to indicate the
-      endianness to use on a page .. :)
-    <tschwinge> Hehe!
-    <tschwinge> jkoenig: Don't worry -- you're already known for ambitious
-      projects.  One more can't hurt.
-    <jkoenig> Also, actually the word size is not something that I've been able
-      to abstract so far, so I'll be hardcoding little-endian 32 bits for now.
-    <braunr> why is that ?
-    <antrik> some of the Hurd RPC break the idea anyways BTW
-    <jkoenig> the org.vmmagic package (from Jikes RVM and JNode) could help
-      with that, but GCJ does not support it unfortunately (not sure about
-      OpenJDK)
-    <jkoenig> braunr, Java does not allow us to define new unboxed types
-    <braunr> jkoenig: does it have its own definition of the word size ?
-    <jkoenig> braunr, nope.
-    <jkoenig> (although, maybe, and also we could use JNI to query it)
-    <braunr> even if virtual, i'd expect a machine to have such a defnition
-    <jkoenig> braunr, maybe it has, but basically in Java nothing depends on
-      the word size
-    <jkoenig> 'int' is 32 bits, 'long' is 64 and that's it.
-    <braunr> oh right, i remember most types are fixed size, right ?
-    <jkoenig> right.
-    <braunr> if not all
-    <jkoenig> now Jikes RVM's "org.vmmagic" provides an interface to defined
-      new unboxed types which can depend on the actual word size, but Jikes RVM
-      is its own JVM so obviously they can use and provide whatever extensions
-      they need :-)
-    <jkoenig> (but maybe they've implemented them in OpenJDK for bootstrap
-      purposes, I'm not sure)
-    <tschwinge> I'm missing this detail: where does the word size come into
-      play here?
-    <jkoenig> anyway, I _could_ indiscriminately use 'long' for port names, and
-      sparkle the code with word size tests but that would be very clumsy
-    <braunr> jkoenig: port names are actually ints :/
-    <jkoenig> tschwinge, the actual format of the message header and type
-      descriptors, for instance.
-    <braunr> jkoenig: ok, got your point
-    <jkoenig> braunr, by 'long' I mean 64-bits integers (which they are on
-      64-bits machines I think?)
-    <braunr> :)
-    <braunr> jkoenig: port names are as large as the word size
-    <braunr> but in C at least, they're int, not long
-    <braunr> it doesn't change many things, but you get lots of warnings if you
-      try with a long :)
-    <tschwinge> What is the reason that port names are an
-      architecture-dependent word size's width, and not simply 32 bit?
-    <jkoenig> "4 billions of port names should be enough for everyone" :-)
-    <braunr> tschwinge: an optimization is to use them as pointers in the
-      kernel
-    <antrik> tschwinge: the machine's native word size is what it can process
-      most efficiently, and what should be used for most normal
-      operations... it makes sense to define stuff as int, except for network
-      communication
-    <tschwinge> jkoenig: Well, yeah, but if you want to communicate with a
-      peer, you have to agree on the maximum number anyway (not for port names,
-      though, which are local).
-    <braunr> antrik: int isn't the word size everywhere
-    <braunr> antrik: the most common type matching the word size is long, at
-      least on ILP32/LP64 data models
-    <antrik> braunr: that's just because some idiots assumed int would always
-      be 32 bits, and consequently when 64 architectures came up the compiler
-      guys chickened out ;-)
-    <braunr> without int, you wouldn't have a 32 bits type
-    <antrik> that's not true for all architectures and/or operating systems
-      though AFAIK
-    <braunr> or a 16 bits one
-    <braunr> antrik: windows guys got even more scared, so windows 64 is LLP64
-    <antrik> BTW, I haven't checked, but it's quite possible that 32 bit
-      numbers are actually preferable even on AMD64...
-    <tschwinge> jkoenig: So, back on track.  :-)
-    <tschwinge> jkoenig: You didn't find anything yet in Mach's VM interfaces
-      as well a MemoryObject, etc., that can't be used/implemented in the Java
-      world?
-    <braunr> antrik: they consume less memory, but don't have much effect on
-      performance
-    <jkoenig> tschwinge, once we have the basic system calls and the
-      corresponding abstractions in place, I don't think anything else
-      fundamentally problematic could possibly show up
-    <antrik> braunr: if you really *need* a type of a certain bit size, you
-      should use stdint types. so not having a 16 or 32 bit type in the
-      short/int/long canon is *not* an excuse
-    <tschwinge> jkoenig: That speaks for the Mach designers!
-    <braunr> antrik: right
-    <jkoenig> tschwinge, on trick is that for instance, mach_task_self would
-      still be unsafe even if it returned a nicely wrapped Task object, because
-      you could still wreck your own address space and threads with it. So we
-      would need the "attenuation" pattern mentionned above to provide a safe
-      one.
-    <jkoenig> (which would disallow thinks such as the port/thread/vm calls)
-    <braunr> jkoenig: you mentioned the unsafe pseudo exception earlier
-    <jkoenig> braunr, right, so the issue is with distinguishing safe from
-      unsafe methods
-    <antrik> braunr: BTW, the Windows guys actually broke a lot of stuff by
-      fixing long at 32 bits -- this way long doesn't match size_t and pointer
-      types anymore, which was an assumption that was true for pretty much any
-      system so far...
-    <tschwinge> jkoenig: Yes.  (And again hope for the JVM to optim...)
-    <braunr> antrik: that's right :)
-    <braunr> antrik: that's LLP64
-    <braunr> antrik: long long and pointers
-    <jkoenig> braunr, so basically the idea is that unsafe methods are declared
-      as "throws Unsafe"
-    <jkoenig> the effect is that if you use such a method you must either
-      "throw Unsafe" yourself,
-    <jkoenig> or if you're building a safe abstraction on top of Unsafe
-      methods, you'll "catch" the "exception" in question to tell the compiler
-      that it's okay.
-    <jkoenig> it's more or less inspired from the "semantic regimes" idea from
-      the org.vmmagic paper which is referenced in my original proposal,
-    <jkoenig> only implementing by hijacking the exception checking machinery,
-      which has a behaviour similar to what we want.
-    <braunr> ok
-    <braunr> but hmm this seems pretty normal, what's the tricky part ? :)
-    <tschwinge> braunr: The idea is that the programmer explicitly has to
-      acknowledge if he'S using an unsafe interface.
-    <braunr> tschwinge: sounds pretty normal too
-    <jkoenig> braunr, the trick is that you would not usually declare
-      exceptions which are never actually thrown (and actually since the
-      compiler does not know it's never thrown, I need to work around it in a
-      few places)
-    <braunr> oh, ok
-    <braunr> jkoenig: that's interesting indeed
-    <jkoenig> braunr, the org.vmmagic paper provides an example which uses some
-      annotations called @UncheckedMemoryAccess and @AssertSafe to the same
-      effect (which is kind of cleaner), but it would be a headache to
-      implement without help from the compiler I think (as far as I can tell
-      the annotation processor would have to inspect the bytecode)
-    <braunr> but hm
-    <braunr> what's the true problem about this ?
-    <jkoenig> (the paper advocates "high-level low-level programming" and is a
-      very interesting read I think,
-      http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.151.5253&rep=rep1&type=pdf,
-      for what it's worth)
-    <braunr> what's wrong if you just declare your methods unsafe and don't
-      alter anything else ?
-    <tschwinge> Yes, I read it and it is interesting.  Unfortunately, it seems
-      I forgot most of it again...
-    <jkoenig> braunr, declare? alter?
-    <jkoenig> you mean just tag them with an annotation?
-    <braunr> just stating a method "throws Unsafe"
-    <jkoenig> braunr, well some compiler will output a warning because they can
-      tell there's no way the method is going to throw such an exception.
-    <jkoenig> and then some other compiler will complain that my
-      @SuppressWarnings("unused") does not serve any purpose to them :-)
-    <jkoenig> also, when initializing final fields, I need to work around the
-      fact that the compiler thinks "Unsafe" might be thrown.
-    <jkoenig> see for instance MachPort.DEAD
-    <braunr> jkoenig: ok
-    <jkoenig> braunr, but I'm more than willing to accept this in exchange for
-      a clear, compiler-enforced materialization of the border between safe an
-      unsafe code.
-    <jkoenig> actually another question I have is the amount of static typing I
-      should add to the safe version, for instance should I subclass MachPort
-      into MachSendRight, MachReceiveRight and so on. I don't want to depart
-      from the C inteface too much but it could be useful.
-    <braunr> jkoenig: can't answer that :)
-    <braunr> jkoenig: keep them in mind for later i think
-    <tschwinge> jkoenig: What's the safety concern w.r.t. having MachPort (not)
-      final?
-    <jkoenig> tschwinge, actually I'm partly wrong in that we only need name()
-      and a couple other methods to be final
-    <tschwinge> jkoenig: That's what I was thinking.  :-)
-    <tschwinge> I though I'm missing something here.
-    <jkoenig> tschwinge, the idea is that the user (ie., the adversary :-)
-      could extend MachPort and inject their own fake port name into messages
-    <jkoenig> by overriding name() or clear()
-    <tschwinge> Yeah, but if these are final, that's not possible.
-    <jkoenig> right.
-    <tschwinge> And that *should* be enough, I think.
-    <tschwinge> Unless I'm missing something.
-    <jkoenig> I don't think so. Also I hope it is, because as mentionned above
-      there might be some value in subclassing MachPort.
-    <tschwinge> Yep.
-    <jkoenig> incidentally, declaring the class or the method final will allow
-      the JVM to inline them I think.
-    <tschwinge> It will help the JVM, yes.  It can also figure that out without
-      final, though.  (And may have to de-optimize the code again in case there
-      are additional classes loaded during run-time.)
-    <tschwinge> jkoenig: The reference counting in MachPort.  I think I'm
-      beginning to understand this.
-    <jkoenig> oh ok
-    <jkoenig> tschwinge, yes the javadoc is maybe a bit obscure so far.
-    <jkoenig> but basically you don't want the port name you acquire to become
-      invalid before you're done using it.
-    <tschwinge> But how is this different from the C world?
-    <jkoenig> here my goal is to provide some guarantees if you use only safe
-      methods
-    <jkoenig> like, you can't forge a port name and things like that
-    <jkoenig> so basically it should never be possible to include an invalid
-      port name in a message if you use only safe methods.
-    <tschwinge> Ah, I see!
-    <tschwinge> Now that does make sense.
-    <jkoenig> but the mechanism in itself is similar to the Hurd port cells and
-      user_link structures
-    <tschwinge> It's again ``only'' helping the programmer.
-    <jkoenig> right, no object-capability ulterior motives :-)
-    <jkoenig> another assumption which the javadoc does not state yet it that
-      basically there should be exactly one MachPort object for each mach-level
-      port name reference (in the sense of mach_port_mod_refs)
-    <tschwinge> Yes, I figured out that bit.