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NOTE: Still in edit. Could contain some mistakes :) Hi everyone, I have been struggling a lot finding a working solution for the duplicate ObjectUID generation in the 18.104.22.168 version of the Epoch Mod. On my server I am using custom scripts like: Plot Management Snap Pro Vector Building And more... All these custom scripts require additional values in the Worldspace column of your database. In a lot of changes that I have seen, the dayz_objectUID2 function was adapted to to generate some kind of a unique value for each object in your database. This was never working well for me. My database had about 3000-4000 objects and we got sometimes 5-10 duplicates in it. So I decided to use my software coding skills and create a more robust solution which is clean and easy to implement. It does not matter how your worldspace looks like and if you are using several of the above mentioned custom scripts. The fix is using numerical 2 hashing alghorithms: MD5 and SHA1. Both are merged with a numerical transformation which provides a unique value. I will test the performance and release separated DLL's using only MD5 or SHA1 soon with some performance results for comparison. IMPORTANT: It is important not to have duplicate worldspace items in your database. Sometimes the server will spawn several vehicles at position 0,0 on the map. This will cause having same ObjectUID's. I have fixed this too and it is included in the instructions bellow. You will also need to clean your database. This can be done manually or with a tool that I provide with this solution. Also, make a backup of your database so you can avoid loosing changes. If anything goes wrong, you can go back and restore as it was before ;) ARMA2NET: First of all, you will need an additional MOD to include on your server. This does not affect your players and they will not need to download anything. I am using Arma2NET as a mod which allows me to create custom DLL's for Arma 2 OA. This DLL contains code to generate hashes of the Worldspace which are unique. Follow the tutorial on "How to Install and setup Arma2NET". https://bitbucket.org/Scott_NZ/arma2net/wiki/Home https://bitbucket.org/Scott_NZ/arma2net/wiki/Getting_started Download Arma2NET files from Armaholic's website: Click here to download. Arma2NET Directory: Go to your @Arma2NET directory in the root of Arma 2 OA. Go to the AddIns directory. Download the ZIP from this post and place the ObjectUID directory inside the AddIns folder. It should look like: @Arma2NET\AddIns\ObjectUID\ObjectUID.dll Epoch Server Changes: Go to your server's PBO file or folder and open server_functions.sqf. Now replace the dayz_objectUID2 and dayz_objectUID3 code with: function dayz_objectUID2 function dayz_objectUID3 function spawn_vehicles This is a fix for the 0-0 position spawn of vehicles. Find code: After the above line, place the following check: So end result will be: Database Fix: If you already have a database which is used and contains conflicted ObjectUID's, you will need to fix them manually by changing them before restart or you could use a simple tool I created for this. The tool will be posted here soon. I will make it configurable so you can use it to fix the ObjectUID's in your database. Credits: You are not allowed to change any of the above code or distribute this without my knowledge and permission. Download this resource only from this page to avoid hacked versions. Suggestions for improvements are welcome. Donations: Donations for my work are always welcome. You can donate at http://paypal.me/fp4p. Thank you! Downloads: - ObjectUID Fix - GitHub Download
So, as many will know, there is an issue in A2Epoch (possibily from DayZ) in the unique identifier generation not always producing unique identifiers. What is the unique identifier and how is it used ?. Epoch uses two object identifiers. ObjectID ObjectUID ObjectID is generated by the MySQL DB backend. ObjectUID is generated within the ARMA 2 game world via SQF code. Why two identifiers ?. For some reason... there is only one HiveExt.dll call to get the ObjectID for an object in the DB. This call is the one used to load all the DB objects in to ARMA. The offshoot of this is that when a new object is created and saved to the DB, the DB creates a unique objectID but this objectID cannot get back to the ARMA 2 game world until the ARMA 2 server process is restarted and all the objects are then read from the DB again. To get around this, the ObjectUID is created when a new object is created in the game world. This is used to reference the object in the game world and on the DB if the ARMA 2 engine does not know the DB assigned ObjectID. So, what is the problem ?. Whilst the code to generate a unique objectUID looks fairly good, it does not always create a unique ID. THis means that manipulation of any new objects that have not yet got an objectID in the game world (ie. created after the last server restart) but having an objectUID that matches the objectUID of an object currently in the DB will cause all sorts of problems. How is the objectUID calculated currently ?. There are three functions used to calculate the objectUID currently (all defined in server_functions.sqf). dayz_objectUID - No longer used it seems. dayz_objectUID2 - Used for objects objectUID generation. dayz_objectUID3 - Used for vehicle objectUID generation. dayz_objectUID just works out the required input parameters and then calls dayz_objectUID2. dayz_objectUID2 generates the objectUID for the object by applying the following calculation. x,y,z coords each multiplied by 10. Results made positive if required by multiplying by -10 and rounded to a whole number. 3 numbers are concatenated together (X + Y + Z). The objects direction (in degrees) after rounding is then concatenated to the result. dayz_objectUID3 does the same but adds the mission time (time in seconds since the ARMA 2 mission was started) to the direction value before adding it to the result for the x/y/x/ * 10 part. Worked example for dayz_objectUID2 Worldspace = [351.545[11079.8,11834.3,-0.380997]] = X = 11079.8 * 10 = 110798 Y = 11834.3 * 10 = 118343 Z = -0.380997 * 10 = -3.80997 * -10 (make positive) = 38.0997 round = 38 DIR = 351.545 rounded = 352 = concat 110798 + 118343 + 38 + 352 Calculated objectUID 11079811834338352 Stored ObjectUID 11079811834338352 So why is it not random ?. A set of coodinates ( [dir,[x,y,z]] ) for an object of [0,[1,1,10]] will produce the same result as a set of coordinates of [0,[1,10,1]]. The uniqueness plays on the probability of combination resulting in the same onjectUID being generated as unlikely. The more items you have in your DB then the more likely it is to happen. Ok, so what can we do about it ?. So this is the purpose of this thread. Both to highlight the issues to those who were not aware and to have a discussion on peoples thoughts on a better solution. I am curious as to why the code does not start at 0 and each time a objectUID is needed it just increments (possibly by 2 / 5 / 10). A server global variable could hold the current value and be populated on server restart by the highest objectUID found in the loaded objects. The only issue I can see is if multiple requests for a new objectUID resulted in the same objectUIDs being given out to multiple requestors as the global 'current objectUID' variable cannot be updated quickly enough. Presumabily that ould be managed by a basic schedualing system enforcing a FIFO queue so each request could be processed one at a time. Any other thoughts or observations ?. I am hoping we can all come up with a better solution that does not require any custom .dlls or DB table changes. Good news is that any new generation system should be pretty easy to plugin to Epoch. Over to you...