An extremely rough but extremely damaging benchmark utility for memcached.

Does not use a client library, does not use threads (though it will). Uses
event based sockets via libevent.

Building
--------

$ (install libevent + headers)
$ ./compile

Usage
-----

Look in the conf/ directory for example configuration files.

$ ./mc-crusher ./conf/loadconf [host] [port]
defaults:
host: 127.0.0.1
port: 11211

Running
-------

This tool is extremely rough.

First, run it for a few seconds with a config like "conf/loadconf", this will
seed the instance with some values to fetch later. Now, kill it.

You can also use the bench-warmer.pl tool to preload some keys.

Pick a config file, and start it as above. You should start a fresh memcached,
and run the "sample" script that comes with mc-crusher. mc-crusher makes no
attempt to care about what it does. It flails tiredlessly against the fanged
defenses of the cache daemon.

Modify bench-sample to print what you are most interested in examining.

You can change the "default" destination ip/port by adding extra arguments:
$ ./mc-crusher ./conf/loadconf 192.168.1.1 11211

Configuration
-------------

mc-crusher reads a configuration file then executes. These configurations
describe a "type" of connection, one per line.

Each "type" can spawn N connections. This allows you to mix setters and
getters, getters of different sizes, binprot + asciiprot. It's very limited
right now, but I wanted to build this in as a base.

Config Options
--------------

send : defines what function to use to send requests to memcached
 - ascii_get : one get per request via asciiprot
 - ascii_set : one set per request via asciiprot
 - ascii_delete : one delete per request via asciiprot
 - ascii_mget : multiget test via asciiprot
 - bin_get : one get per req via binprot
 - bin_getq : endless streaming multiget from hell
 - bin_set : one set per req via binprot
 - bin_setq : unleash cthulu upon the cache_lock

recv : same, but for received data
 - blind_recv : mindlessly slurp any responses without inspecting them

mget_count : set this to the number of keys to fetch per get in ascii_mget

key_prefix : a string to prefix before each key's number (default 'foo')

value_size : size of the value to set

expire : the expiration value (default 0)

flags : client flags (raw number, default 0)

value : define a value by hand. Must be shortish and a string.

host : define a host to connect to

port : define a port to connect to

key_prealloc : pre-create key strings in memory to reduce bench cpu usage

key_count : number of keys to iterate across. use with key_prealloc=0 to
iterate over large numbers of keys

key_randomize : if using prealloc'ed keys, shuffle the list after generating

usleep : fire one write event (up to pipeline count) with a microsecond sleep
after. the sleep is per-connection (so conns=2 will write twice per usleep)

stop_after : stop all conns for this test after N writes have been made.

Caveats
-------

- I bundled the protocol_binary.h header. It will need to be copied from the
  primary repo for updates.

- Does not make any attempt to safely parse the config file. If you don't type
  it exactly right you will end up with bizarre failures.

- It only works well with small values

- It makes no attempt to reconcile with errors in the protocol, and can break
  if memcached throws errors. It will also stop if the connections are closed.

- It's a ton of fun!

Future Features
---------------

A short list of things I intend to change or add:

- Fix the command generators to have a *little* error handling

- Switch to writev and use iovectors + pregenerated keys for almost everything

- Add back some routines which are sprintf only, for doing tests with
  extremely wide keyspaces where performance is less of an issue.

- Add a "run_every" option which fires a conn every N microseconds instead of
  endlessly.

- Add a "timer" option which times the commands it runs and periodically dumps
  a histogram of response times. Mainly to be used with "run_every"

- Add missing protocol commands. *_incr, *_decr, *_delete, etc.

- Make the iteration loop per-connection, and randomizeable.

- Add commands to iterate over different value sizes

- Add multithreading to ease management.

- Allow running timer conns in their own thread (or just define if a conn
  template should use a thread, then define conns=1?)

- Bundle a better perl util for printing stats

- Write/bundle a better util for running iterative benchmarks.