[Click] Click 2.0 RELEASED

[Eddie Kohler]

Hi all,

See subject.  Thanks!

Best,
Eddie


Version 2.0   16.Jul.2011

* New elements: AdjustTimestamp, BlockThread, ClickyInfo, EtherVLANEncap,
   HandlerTask, ICMPIPEncap, NullTask, SetVLANAnno, StoreUDPTimeSeqRecord,
   StripDSRHeader, StripEtherVLANHeader, TCPFragmenter, UDPIP6Encap,
   UnstripDSRHeader.

* Improved elements: ARPQuerier, AddressInfo, BandwidthRatedSplitter,
   BandwidthRatedUnqueue, CheckLength, DRRSched, FromDevice linuxmodule,
   FromDevice userlevel, FromHost userlevel, FromIPSummaryDump,
   FromSimDevice, FromUserDevice, GetIPAddress, HostEtherFilter, IPFilter
   ("ether" comparisons, faster initialization), InfiniteSource, KernelTun,
   LinkUnqueue, RandomSource, RatedSource, RatedSplitter, RatedUnqueue,
   Script, SetIPAddress, SetTimestamp, TCPIPSend, TimeSortedSched, ToDevice
   userlevel, ToUserDevice, Truncate, Unqueue2, and others.

* Element and tool bug fixes: CheckTCPHeader, CheckUDPHeader, DSRRouteTable
   DelayUnqueue, FastUDPSourceIP6, FromHost, FromUserDevice, IP6Encap,
   IPAddrRewriter, IPFilter and other classifiers, KernelFilter,
   RadiotapDecap, RadixIPLookup, SetIP6DSCP, Socket, ThreadSafeQueue,
   TimeSortedSched, ToUserDevice, UDPIPEncap, WifiDecap, click-align,
   click-undead, and others.

* Performance improvements

** Tasks: A simplified reschedule implementation and streamlined driver
    loop is both faster and less error prone (now calling fast_reschedule()
    outside of Element::run_task() is safe).

** Tasks: If a task does no work, delay re-running it.  This simple change
    improves performance on many configurations, particularly those mixing
    file descriptor or timer access and Tasks.

** Timers: A 4-heap improves performance with very large numbers of timers.

** User-level: Device elements default to libpcap even on Linux, offering
    improved performance depending on how libpcap was compiled (e.g. packet
    mmap support).  A packet memory pool suggested by Luigi Rizzo offers
    much better performance for packet allocation and freeing.

** The round-robin scheduler (--disable-stride) works again.

** New configure option --enable-bound-port-transfer slightly optimizes
    push() and pull() calls (Cliff Frey).

* Language changes

** New "require(library FILE)" allows one Click script to include another
    (Christian Kreibich).

** Many-to-one, one-to-many, and many-to-many connections cleanly express
    some connection patterns.  For example, "c :: Classifier => a1, a2, a3"
    means the same as "c :: Classifier; c [0] -> a1; c [1] -> a2; c [2] ->
    a3".

** Element groups cleanly express short detours from a connection path.
    For example, this:

         c :: Classifier(00/01);
         x -> c -> y;
         c [1] -> Paint(1) -> y;

    can be expressed like this:

         x -> c :: Classifier(00/01) => (
             [0] -> [0]; [1] -> Paint(1) -> [0]
         ) -> y;

* Multithreading

** Many performance and stability improvements to multithreaded
    configurations, particularly at userlevel.

** Lazy Task rescheduling reduces opportunities for bugs.

** Each thread gains its own sets of Timers (and, at user level, selector
    file descriptors).  An element's Timers are initially scheduled on the
    same thread as its Tasks.  This should simplify reasoning about
    Task/Timer conflicts, and can help improve performance.

* Linuxmodule

** Patchless installs are on by default.  Click installs and works without
    a patch on many versions of Linux up to 2.6.38.

* Clicky changes

** Per-router styles: ClickyInfo elements let a script specify how it
    should be drawn.

** "Run" and "Stop" buttons can execute a configuration.

* Internals

** Args: This new class and its helpers support concise, easy-to-use,
    type-safe argument parsing and are strongly preferred to cp_va_kparse in
    new code.

** TokenBucket: This new template class supports fast, flexible,
    integer-based token bucket rate management.

** Timestamps default to nanosecond precision on many platforms.

** Element::simple_action() can be used for multi-port elements.

** On some platforms, set environment variable CLICK_BACKTRACE to 1 and get
    a useful stack backtrace if Click crashes (Cliff Frey).

** Other improvements: more flexible handlers, simple_action, type traits,
    faster multi-precision arithmetic, better IPv6 address unparsing.

* Acknowledgements

** Thanks to Cliff Frey for extensive discussion, multithreaded debugging,
    802.1Q elements, TokenBucket, TCPFragmenter, bound port transfer, and
    others.

** Thanks to Joonwoo Park for Linux kernel module patches.

** Thanks to Jimmy Kjällman and Pekka Nikander for FreeBSD kernel module
    support.

** Thanks to Johan Bergs, Jesse Brown, Roman Chertov, Beyers Cronje, Jens
    De Wit, Kevin Paul Herbert, Sascha Alexander Jopen, Christian Kreibich,
    Bobby Longpocket, Ruben Merz, Derrick Pallas, Roberto Riggio, Luigi
    Rizzo, Jim Roewe, Ian Rose, Harald Schiöberg, Florian Sesser, Lalith
    Suresh, and Wim Vandenberghe for patches, bug fixes, and new elements.

** Thanks to Dan Aguayo, Mark Allman, Manel Bourguiba, Bart Braem, Lars
    Bro, Dmitriy Bubnov, Rémi Clavier, Jonathan Kirchhoff, Dan Levin, José
    Pedro Oliveira, Kostas Pelechrinis, Sami Ruponen, Robert Shanks, Robert
    Sombrutzki, Patrick Verkaik, Nicholas Weaver, Xianghua Xiao, and
    xuhui122000 gmail com for bug reports.

** Thanks to everyone else who supports and uses Click.