#@
#@ Dklab Realplexor: Comet server which handles 1000000+ parallel browser connections
#@ Author: Dmitry Koterov, dkLab (C)
#@ License: GPL 2.0
#@
#@ 2025-* Contributor: Alexxiy
#@ GitHub: http://github.com/alexxiy/
#@

BUILD A BINARY FROM C++ SOURCES
-------------------------------

Realplexor comes in two versions with exactly same functions and even exactly
same (shared) smoke tests code:

1. Perl version: treated as a prototype and development/debugging playground.
   It's quite slow and is not recommended in production.
2. C++ version: fast, but you should build it by yourself from sources,
   see cpp/ directory.

When you build a binary version of Realplexor, the binary is put to the current
directory; it will be used instead of Perl version automatically.


INSTALLATION ON LINUX
---------------------

Note that Realplexor works on Linux only, other OS (Windows, MacOS, FreeBSD)
are not known to be supported.

0. Build a binary file ./dklab_realplexor from C++ source code if you can
   (see cpp/ directory for instructions).

1. If you decide to use a Perl version, run ./dklab_realplexor.pl manually
   and check that all needed libraries are installed. If not, install them:
   - For RHEL (RedHat, CentOS, Fedora) - modern way, just packets:
     # dnf install perl-EV perl-Time-HiRes perl-Math-BigInt perl-FindBin perl-sigtrap
   - For RHEL (RedHat, CentOS, Fedora) - manually compilation of EV and dependent perl libs:
     # dnf install gcc perl-CPAN
     # perl -MCPAN -e "install EV"
   - For Debian (or Ubuntu):
     # apt-get install gcc
     # perl -MCPAN -e "install EV"

2. Copy Realplexor to /opt/dklab_realplexor (or you may create a symlink).
   # cp -a . /opt/dklab_realplexor
     - or -
   # ln -s `pwd` /opt/dklab_realplexor

3. Create /etc/dklab_realplexor.conf if you need a custom configuration.
   (You may create a symlink instead of creating the file.)

   # cat > /etc/dklab_realplexor.conf
   $CONFIG{WAIT_ADDR} = [ '1.2.3.4:80' ];  # your IP address and port
   $CONFIG{IN_ADDR} = [ '5.6.7.8:10010' ]; # for IN line
   return 1;
   ^D

     - or -

   # ln -s /path/to/your/config.conf /etc/dklab_realplexor.conf

4. Use bundled init-script to start Realplexor as a Linux service:
   # ln -s /opt/dklab_realplexor/contrib/dklab_realplexor.init /etc/init.d/dklab_realplexor
   Or for Systemd:
   # ln -s /opt/dklab_realplexor/contrib/dklab_realplexor.service /lib/systemd/system/dklab_realplexor.service

5. Tell your system to start Realplexor at boot:
   - For Systemd (modern RHEL, CentOS, Fedora, Ubuntu, Debian etc.):
     # systemctl enable dklab_realplexor
     # systemctl start dklab_realplexor
   - For old init.d for RHEL (RedHat, CentOS):
     # chkconfig --add dklab_realplexor
     # chkconfig dklab_realplexor on
   - For old rc.d Debian (or Ubuntu):
     # update-rc.d dklab_realplexor defaults
     # update-rc.d dklab_realplexor start


SYNOPSIS
--------

1. In JavaScript code, execute:
<script type="text/javascript" src="https://rpl.yoursite.com/?identifier=SCRIPT"></script>
var realplexor = new Dklab_Realplexor("https://rpl.yoursite.com/");
realplexor.subscribe("alpha", function(data) { alert("alpha: " + data) });
realplexor.subscribe("beta", function(data) { alert("beta: " + data) });
realplexor.execute();

2. In PHP code, execute:
require dirname(__FILE__) . '/Dklab/Realplexor.php';
$realplexor = new Dklab_Realplexor('127.0.0.1', 10010);
$realplexor->send(['alpha', 'beta'], 'hello!');

3. See more details in Realplexor documentation.


LOG MNEMONICS
-------------

pairs_by_fhs
  Number of active TCP connections on WAIT line (clients).

data_to_send
  Number of IDs with non-empty command queue.

connected_fhs
  Number of IDs which are listened by at least one client.

online_timers
  Number of "online" client identifiers. Client is treated as online if:
  - it has an active connection;
  - or it does not have a connection, but disconnected no more than
    OFFLINE_TIMEOUT seconds ago.

cleanup_timers
  Number of IDs which queue must be cleaned if no activity is present for
  a long time. This is a unused IDs garbage collector statistics.

events
  How many events (e.g. ONLINE/OFFLINE status changes) are collected
  by realplexor. Event queue is limited by size.


CHANGELOG
---------

* Dklab Realplexor 2025-06-05: v2.0
  - [NEW] GCC 15.1 compatibility (compilation tested on Fedora 42, the latest on the moment),
          successful compilation against c++23 standards.
  - [NEW] Due to rounding issues with float-typed cursor, it was changed to INT:
          Example: 174860736061360005
                   [    A   ][B ][C ]
          A - timestamp, B - 1/10000 of second, C - event counter
  - [BUG] Fixed notify in Events.h(.pm): increment issue caused 'watch' consistency break for the first new event
  - [NEW] Fully rewritten PHP (tested on 8.4, strict types) and Python (tested on 3.13) API connectors.
          Method "send" now returns passed or newly created cursor(s) for destination ID(s).
  - [NEW] Got rid of IFRAME due to cross-frame limitations in modern browsers (see t/demo/README.txt)
  - [NEW] Add Systemd service unit, nginx config examples (see in contrib/)
  - [MIN] Updated autotests, demo

* Dklab Realplexor 2014-01-14: v1.41
  - [MIN] Brushed up C++ version, Ubuntu 12.04 build instructions.
  - [MIN] Banner comments added to source files.
  - [MIN] Tabs to spaces.
  - [BUG] GCC 4.7 compatibility & GCC bug work-around

* Dklab Realplexor 2011-07-28: v1.40
  - [NEW] Python API added (experimental)
  - [NEW] Added missed "return this" for chained JS calls.
  - [BUG] Firefox 4 bugfix against 'attempt to run compile-and-go script on a cleared scope'.
  - [BUG] Minor changes & better support for phpt tests.
  - [BUG] No OFFLINE event should be generated until the last connection with ID is disconnected.
  - [BUG] If no IDs are subscribed in JS, do not connect to the server with empty ID list.

* Dklab Realplexor 2010-08-11: v1.32
  - [SPD] When empty HTTP body is passed to IN connection, it is now ignored, no warnings generated.
  - [SPD] Remove old data from channels BEFORE data processing/sending.
  - [BUG] Use print instead of syswrite, because for large amount of data syswrite sometimes
    returns before all this data is transmitted.

* Dklab Realplexor 2010-04-16: v1.31
  - [BUG] Perl does not call flush() automatically before socket shutdown(). It
    sometimes (unstable!) causes unexpected SIGPIPEs and data loss. Fixed: now flush()
    is called manually.
  - [BUG] STATS command is not processed twice anymore.
  - [NEW] Ability to limit memory usage and auto-restart the daemon if it
    consumes too much memory. (Note that unsent data is lost during this restart.)
  - [NEW] PHP API: cmdOnlineWithCounters(): for each online ID also returns
    the number of browsers connected just now (it is NOT a "number of online
    users who listen this channel", but its approximation).
  - [BUG] Minor fixes in clean_old_data_for_id (bug is not reproduced,
    but now surrounding code is better).
  - [NEW] Visibility:hidden for IFRAME. It is good when BODY has relative position.
  - [BUG] Allow to pass a scalar to 2nd parameter of cmdWatch($fromPos, $idPrefixes).

* Dklab Realplexor 2010-02-27: v1.30
  - [SPD] Use EV library (http://search.cpan.org/~mlehmann/EV-3.9/EV.pm)
    instead of libevent. It is faster and has no memory leaks.

* Dklab Realplexor 2010-01-30: v1.24
  - [BUG] Avoid warnings in log on unexpected disconnect.
  - [NEW] Refactoring and profiler support.
  - [SPD] Do not create extra shell while calling ulimit.
  - [NEW] Support for per-config log facility.
  - [SPD] Profiler tool with IN line ignorance. Avoid BigFloat in events: 45% speedup. Apache ab patched utility.
  - [SPD] Keep channels pre-sorted after addition. It speedups 60%, because we need less cursor comparisions.
  - [SPD] STDOUT buffering in non-verbose mode. More verbosity levels. Logger speedup. Custom config for profiler script.

* Dklab Realplexor 2009-12-26: v1.23
  - [BUG] Empty identifier passed to IN line ("identifier=") caused warnings.
  - [SPD] Lower the number of useless debug lines and connection's name() calls.
  - [BUG] Improved init script: more time to restart and better signal handling.

* Dklab Realplexor 2009-12-24: v1.22
  - [BUG] SIGPIPE causes the script to restart on some unexpected client's disconnects.

* Dklab Realplexor 2009-12-22: v1.21
  - [NEW] ID queue is cleaned after CLEAN_ID_AFTER seconds when no data arrived
    (previously OFFLINE_TIMEOUT was used for that).
  - [NEW] To unsubscribe all callbacks from a channel: rpl.unsubscribe("channel", null).

* Dklab Realplexor 2009-12-16: v1.15
  - [NEW] When IDs list is long, JS API uses POST request instead of GET.
  - [NEW] IN line now fully supports HTTP POST.
  - [NEW] Non-200 responses from IN line are converted to exceptions.
  - [NEW] Content-Length verification in PHP API.
  - [NEW] Support for SSL in IN line for PHP API (use 443 port).
  - [BUG] If callback called execute(), extra request was performed.
  - [BUG] Referrer header was not ignored by server engine (bad if it contains IFRAME marker).