Subject: CVSup 13.4 is now available
Date: Thu, 12 Sep 1996 16:42:18 -0700
From: John Polstra <jdp>
Announcing CVSup 13.4
---------------------
Release 13.4 of CVSup, the CVS-aware network distribution system, is now
available.
Where to Get CVSup
- ------------------
CVSup is free software. It is available from the following FTP sites:
ftp://freefall.freebsd.org/pub/CVSup/
ftp://ftp.freebsd.org/pub/FreeBSD/incoming/
ftp://ftp.polstra.com/pub/FreeBSD/CVSup/ (slow; avoid if possible)
Full sources as well as FreeBSD binaries are available:
cvsup-bin-13.4.tar.gz FreeBSD binaries for the client
cvsupd-bin-13.4.tar.gz FreeBSD binaries for the server
cvsup-13.4.tar.gz Sources **
MD5 signatures for these files are:
MD5 (cvsup-bin-13.4.tar.gz) = d22feb17efbfbb53fbb1da03162216d5
MD5 (cvsupd-bin-13.4.tar.gz) = 0c5b90c7534e9a1591d99a93b236aa21
MD5 (cvsup-13.4.tar.gz) = d6c5aef96a01f657e7d884f6d2185232
An updated port will appear in the FreeBSD ports and packages
collections soon:
ftp:://ftp.freebsd.org/pub/FreeBSD/ports-current/net/cvsup/
ftp:://ftp.freebsd.org/pub/FreeBSD/packages-current/net/cvsup-13.4.tgz
** If you wish to build CVSup from the sources, be sure to read the
discussion further on in this announcement.
What Has Changed Since the Previous Release?
- --------------------------------------------
Detect and send changes to the RCS keyword expansion mode.
Formerly, these (rare) changes were ignored. That caused checksum
mismatches, which slowed down updates because the whole files had
to be sent as fixups.
Report 0-byte appends as what they really are, i.e., touches.
Add a new statistics line for them.
Make the command line option handling comply better with POSIX.
Fix supconv to handle recent changes to the example "ports-supfile"
in FreeBSD-current.
Add a timeout to kill a server process when it has been inactive
too long (15 minutes). This replaces the TCP keepalives that were
added in the previous release.
Add a hack to the server to make it easier to shut it down in a
controlled manner. If a file "cvsupd-HALT" exists in the directory
from which the server was started, and if it is newer than the
time when the server was started, then the server will reject
all new incoming connection requests.
Make some changes to the zlib interface to eliminate the potential for
an unsafe interaction with the garbage collector.
FreeBSD binary releases are now built with a new version of the
Modula-3 runtime that has a thread-safe version of malloc built
into it. This cures some vexing core dumps that had been happening
from time to time.
Add work-arounds for the worst of the problems associated with malloc
packages that are not thread-safe. These are not complete, however.
I will probably incorporate a (hopefully portable) thread-safe malloc
in the next release.
Eliminate several FreeBSD-specific constructs that caused
portability problems on other platforms. There is a good chance
now that this software will compile and run out-of-the-box on
most POSIX systems with standard SRC Modula-3 installations.
What Is CVSup?
- --------------
CVSup is a software package for distributing and updating collections
of files across a network. CVSup is specifically tailored to
distributing CVS repositories. By taking advantage of the special
properties of the files contained in CVS repositories, CVSup is
able to perform updates much faster than traditional systems. It is
especially valuable for people with slow Internet connections.
CVSup parses and understands the RCS files making up a CVS repository.
When updates occur, CVSup extracts new deltas directly from the RCS
files on the server and edits them into the client's RCS files.
Likewise, CVSup notes the addition of new symbolic tags to the files
on the server and sends only the new tags to the client.
CVSup is able to merge new deltas and tags from the server with deltas
and tags added locally on the client machine. This makes it possible
for the client to check local modifications into his repository
without their being obliterated by subsequent updates from the server.
Note: Although this feature is fully implemented in CVSup, it will
probably not be practical to use it until some small changes have been
made to CVS.
In addition to distributing the RCS files themselves, CVSup is able to
distribute specific checked-out versions. The client can specify a
symbolic tag, a date, or both and CVSup will extract the appropriate
versions from the server's CVS repository. Checked-out versions do
not need to be stored on the server since CVSup can extract any
version directly from the CVS repository.
If the client has an existing checked-out tree, CVSup will apply the
appropriate edits to update the tree or transform it into the
requested version. Only the differences between the existing version
and the desired version are sent across the network.
CVSup uses lightweight processes (threads) to implement a streaming
protocol across the network. This completely eliminates the delays
associated with the lock-step, request-reply form of communication
used by many existing protocols, such as sup and NNTP. Information
is transferred at the full available speed of the network in both
directions at once. Network latency and server response delays
are rendered practically irrelevant.
CVSup uses the "zlib" compression package to optionally compress all
communications. This provides an additional 65-75% compression, on
top of the diff-based compression already built into CVSup.
For efficiency, all processing is built into the CVSup package
itself. Neither the client nor the server executes any other
programs.
For further information about how CVSup works, see the "Blurb"
document
in the CVSup distribution.
Using CVSup to Maintain FreeBSD Sources
- ---------------------------------------
CVSup servers are currently running at the following FreeBSD mirror
sites:
USA:
cvsup.freebsd.org
cvsup2.freebsd.org
The Netherlands:
cvsup.nl.freebsd.org
Using CVSup, you can easily receive or update any of the standard
FreeBSD source releases, namely, "cvs", "current", and
"stable".
The manual page for cvsup(1) describes how to do that.
If all goes well, additional servers will come on-line soon.
Building CVSup from the Sources
- -------------------------------
CVSup is written in Modula-3, a modern, compiled, object-oriented
language. Modula-3 integrates threads, exceptions, and garbage
collection, providing an ideal vehicle for this sort of application.
Without Modula-3, CVSup would almost certainly not exist today.
If you wish to build CVSup from the sources, you will first need
to install the free Modula-3 compiler and runtime libraries from
DEC SRC. A port is available in the FreeBSD ports collection, in
"lang/modula-3". The corresponding package is, of course, available
in the packages collection.
You will also need version 1.0.4 or later of the "zlib" library.
In recent versions of FreeBSD-2.2-current, this library has been
incorporated into the system sources, in "src/sys/lib/libz". Prior
to that, a FreeBSD port was available in "devel/libz" of the FreeBSD
ports collection. For other sources of this library, see the
"Install"
file. Do not try to use versions earlier than 1.0.4.
You will also need Poul-Henning Kamp's "libmd" library. It is a
standard library on FreeBSD systems.
Portability Issues
- ------------------
I intend for CVSup to be portable to most POSIX systems. The
present release has only been tested under FreeBSD versions 2.1
and later. Primarily because of packaging problems, this release
of CVSup probably won't build out-of-the-box on other systems.
Among other things, it relies on Poul-Henning Kamp's "libmd"
encapsulation of the MD5 subroutines. The library itself appears
to be quite portable, but its Makefiles are BSD-specific. There
are probably some other FreeBSD-specific things in CVSup that have
not been found yet.
Anybody who succeeds in porting CVSup to other systems is encouraged
to send his changes to <cvsup-bugs@polstra.com>. As long as the
changes are reasonably palatable, they will be incorporated into
future CVSup releases.
CVSup uses several POSIX-specific functions which may make it more
of an effort to port the package to non-POSIX systems such as Win32.
These functions include mmap, fork, syslog, stat, and chmod, among
others.
Status of this Release
- ----------------------
CVSup has been in alpha testing since mid-May. This should be
considered a beta release. Please be prepared to find bugs --
without a doubt, there are some. Please report bugs to
<cvsup-bugs@polstra.com>.
John Polstra, <jdp@polstra.com>
Copyright 1996 John D. Polstra
$Id: Announce,v 1.9 1996/09/12 22:43:05 jdp Exp $
$Name: REL_13_4 $