FOSS gamedev and creative worlds

Hello I just Try out alternative Database Backens, namely the redis backend.
I created a new World, started it, open the world.mt and changed the backend setting to redis.
Started the geme anew and it tels me to put the redis_address and the redis_hash in the world_mt.
So I put the following lines in the world.mt redis_address = localhost, redis_hash = . Starting the Game gets me an empty world if I try redis_hash = backend norhing changes.
Where do I get this hash?
should not at least the redis_address be setted in the minetest.conf instead of the world.mt, because it is a client setting.
Thanks,
JPR

JPRuehmann wrote:Where do I get this hash?

Like I already said use any word you'd like.

JPRuehmann wrote:hould not at least the redis_address be setted in the minetest.conf instead of the world.mt, because it is a client setting.

The setting is not a client setting and is specific to the world.

In order to get redis support working (on linux - which is does). I had to :

1. Setup and properly configure a redis server. Go do that first or find a hosted one you can use.

2. Build the c library used to link to during minetest compiling and runtime:
a. git clone and build this: https://github.com/redis/hiredis

3. Next I had to build Minetest with redis support enabled:
cmake . -DRUN_IN_PLACE=1 -DBUILD_CLIENT=0 -DUSE_REDIS=1 -DREDIS_LIBRARY=/home/josh/hiredis/libhiredis.so -DREDIS_INCLUDE_DIR=/home/josh/hiredis/

These options are the special sauce:
-DUSE_REDIS=1 -DREDIS_LIBRARY=/home/josh/hiredis/libhiredis.so -DREDIS_INCLUDE_DIR=/home/josh/hiredis/
(Where the REDIS library and directory are correctly updated for your environment).

4. Make the hiredis library available during runtime.
Afterwards I copied the libhiredis.so library to the base of the minetest directory and created a sym link for the version specified via an 'ldd' on the resultant minetestserver binary:
libhiredis.so.0.11 -> libhiredis.so

5. Configure minetestserver to use the redis server
Update the world data storage by updating the world.mt as follows:
backend = redis
redis_address = 192.16.0.38
redis_port = 6379
redis_hash = minetest_dev

(The port and hash are optional parameters). The backend and server portal are REQUIRED.

I then launch minetestserver normally (from the root minetest directory: ./bin/minetestserver). If you missed anything it core dumps on start-up. Otherwise it acts just like a normal server but block data is stored in redis. Pure awesome! This was the steps needed for redis support in Linux. Your milage will vary and depending on the platform you're building for you might need to perform additional steps.

Hello
Sorry for my late reaction.
The Info that the hash is only the name for th Database on the Redis server was all i´ve needed, but thanks for all the other infos
backend = redis
redis_address = localhost
redis_hash = World
Works for me out of the box on a newly created minetest.
No configuration other than the World.mt needed.
Thanks,
JPR

Glad to hear it! :)

So to set up with redis from scratch now that redis "is supported", what should I do. I've tried the following, but I get the error "Unknown map backend"

Install Redis


Recompile minetest to support redis (see below for possible command line)

Start Redis


Edit world.mt to contain:-

Then run usual minetest and try an open the world
--> ERROR[main]: Some exception: "Unknown map backend"

OR I also tried:-

0.4.10 --> ERROR[main]: ERROR: An unhandled exception occurred: Unknown map backend
0.4.11 --> ERROR[main]: Migration to redis is not supported

Can anyone help?

Did you compile Minetest with Redis support?
If you didn't have Redis installed before you compiled Minetest, you may need to recompile Minetest to make it recognise Redis, but I don't really know what I'm talking about...

Amaz wrote:Did you compile Minetest with Redis support?

redis was already installed before I compiled both versions of minetest (I accidentally recompiled .10, then subsequently a new compile of .11 to see if that supported. For the compiles I used a modification of the one-line command from Calinou https://forum.minetest.net/viewtopic.php?f=42&t=3837



I have absolutely no idea what the following means, so didn't do this:-

4. Make the hiredis library available during runtime.
Afterwards I copied the libhiredis.so library to the base of the minetest directory and created a sym link for the version specified via an 'ldd' on the resultant minetestserver binary:
libhiredis.so.0.11 -> libhiredis.so

BTW does anyone know if redis is faster than just running an sqlite world from a ramdrive (which seems to be a heck of a lot easier). I wouldn't say the ramdisk was any faster than running MT from my normal system SSD, so had been hoping redis would be faster.
PS ramdrive commands were:
sudo mkdir /mnt/ramdisk
sudo mount -t tmpfs -o size=512m tmpfs /mnt/ramdisk
sudo ln -s /mnt/ramdisk /home/david/.minetest/worlds
cp -r /home/david/.minetest/worlds/myWorld/* /home/david/.minetest/worlds/ramdisk
Then just run it from minetest and copy back when finished

You may need to install hiredis, it's not part of the redis package. You don't have to copy the hiredis library anywhere though. I've tried the MT Redis backend on OS X and Arch last year and both worked fine.

I think a RAM disk will not be much faster than an SSD. Why not use LevelDB? It's faster than SQLite, but you get more safety than Redis because the data is written to disk frequently. The main advantage of Redis over LevelDB is that you can run the Redis server on a different machine than the MT server.

Morn76 wrote:[...], but you get more safety than Redis because the data is written to disk frequently.

Redis also writes data to disk periodically, take a look into the redis config file.

I want maximum speed and the wiki page rates speed as: sqlite (acceptible) < leveldb (good) < redis (very good).

Morn76 wrote:You may need to install hiredis, it's not part of the redis package.

I did make it, it's buried in the command line):

I've tried running sudo make install from the hiredis dir, but I still get the same error from minetest:
ERROR[main]: Migration to redis is not supported

Can you create a brand new world with redis as the backend?

EDIT: change the setting in minetest.conf for backend when doing that.

I've tried copying libhiredis.so and creating a symlink to it in the same directory called libhiredis.so.0.11
In all of
/home/david/.minetest/minetest.conf (which is the one minetest modifies)
/home/david/minetest/minetest.conf
/usr/local/share/minetest/minetest.conf

I've also tried setting
backend = redis
in
/home/david/.minetest/minetest.conf (which is the one minetest modifies)
/home/david/minetest/minetest.conf
/usr/local/share/minetest/minetest.conf

None of these make any difference (they are totally ignored (no errors, and not changed in minetest.conf to backend = sqlite) and the world.mt file subsequently contains backend = sqlite and the directory a map.sqlite file

If I create a new world but don't enter it and manually add backend = redis, then opening the world fails with the error
ERROR[main]: Some exception: "Unknown map backend"

I also tried renaming .minetest so starting with only minetest_game mods and no worlds

Please can we see the output when you run the cmake command with a clean repository?

This is part 1/2 of the entire output to the terminal of the command line:-
I deleted ~/hiredis and ~/minetest and renamed ~/.minetest before running it:-

Part 2/2:-

I guess it is because you already did the symlink or whatever it is called?



There are no lines in CMake about Redis being found and enabled, nor about is being not found and disabled.

Looks like you need -DENABLE_REDIS=1 in the cmake command.



https://github.com/minetest/minetest/bl ... s.txt#L317

Brilliant!!!
Thanks, that's what I get for copying someone else (joshburt didn't mention an enable switch)
I've modified the post https://forum.minetest.net/viewtopic.php?p=169876#p169876 so the switches are now correct
and the instructions from https://forum.minetest.net/viewtopic.php?p=169869#p169869 also apply
There's no need to manually copy the hiredis stuff around either

BTW, why isn't minetest just compiled with redis enabled by default?

Is there a mod (or some other way) to have minetest start up and shut down the redis server if it's not already been started?
It's a bit of a pain having to browse to a bash script every time I want to run one (having said that the speed does seem to be worth it)

dgm5555 wrote:Is there a mod (or some other way) to have minetest start up and shut down the redis server if it's not already been started?
It's a bit of a pain having to browse to a bash script every time I want to run one (having said that the speed does seem to be worth it)

On Debian you can:


But that requires admin rights. Not helpful if you want minetest or a mod to automagically control.
You can use redis-cli from the command line to shutdown the running server without admin rights (at least on my machine):

I don't know if you can start the server from redis-cli though

Maybe that will inspire a workable solution for you?

You don't need to use sudo, the terminal commands are:-

I can easily do it by opening terminals, but I want to do it automatically.

True running redis-server without arguments does work without admin rights, but it uses the defaults instead of the redis.conf. Not sure about you, but mine is tuned for this machines capabilities.

I have toyed with the thought of writing a script to start and stop redis-server with a bash script, and it is quite possible. But I got lazy because I would need to make it fairly robust. I only use redis on one world. And I find myself turning it on an off often when I fire up various wolds. I have limited ram so I need redis shut down if not needed. Honestly I have no business messing with redis on this box. The speed boost is awesome at first, but soon the ram is consumed and then too much goes to swap.

I can't find redis database file for backup, after migrate in /worlds/world/ there are no new files or folders but server work with redis fine (i saw redis log and i deleted map.sqlite). Where is redis save database?

amadin wrote:I can't find redis database file for backup, after migrate in /worlds/world/ there are no new files or folders but server work with redis fine (i saw redis log and i deleted map.sqlite). Where is redis save database?

Depends on what you run for a OS.
Look in your redis.conf (maybe /etc/redis/redis.conf) file. It should point to the database location. I do know it will not be in your wold folder. It should be in a system directory.

Can't tell you for sure as I'm at work on a Windows machine.

Edit: I think it's in /var/redis/dump.rdp But please don't hold me to it.

Late answer: /var/lib/redis
Log is in /var/log/redis