Alloy API resulting in java.lang.UnsatisfiedLinkError

Question

I'm currently using the Alloy Analyzer API to build a program, and getting some peculiar behavior. Specifically, if I open a file and parse it (using CompUtil.parseEverything), then make a new Command and call TranslateAlloyToKodkod.execute_command on the parsed file and newly created command using MiniSat with UNSAT core, it runs fine. However, later in execution, my program parses a second input file (also using CompUtil.parseEverything), gets another world, makes a new command, and then I try to call TranslateAlloyToKodkod.execute_command again, it throws the following error:

ERROR: class edu.mit.csail.sdg.alloy4.ErrorFatal: The required JNI library cannot be found: java.lang.UnsatisfiedLinkError: no minisatproverx5 in java.library.path edu.mit.csail.sdg.alloy4compiler.translator.TranslateAlloyToKodkod.execute_command(TranslateAlloyToKodkod.java:390)

Does anyone have any idea why this is thrown the second time, but not the first?

To summarize, I have something similar to the following:

Module someWorld = CompUtil.parseEverything_fromFile(rep, null, "someFile.als");
//For the following, "sig" is a sig in someWorld.getAllReachableSigs();
Command command = sig.not();
A4Options options = new A4Options();
options.solver = A4Options.SatSolver.MiniSatProverJNI;
A4Solution ans = 
    TranslateAlloyToKodkod.execute_command(rep, someWorld, command, options);
//No thrown error
Module someOtherWorld = CompUtil.parseEverything_fromFile(rep, null, "someOtherFile.als");
//For the following, "sig" is a sig in someOtherWorld.getAllReachableSigs();
Command commandTwo = sig.not();
A4Solution ansTwo = 
    TranslateAlloyToKodkod.execute_command(rep, someOtherWorld, commandTwo, options);
//Thrown error above. Why?

Answer 1

I tried to reproduce this behavior, but I couldn't. If I don't add MiniSat binaries to the LD_LIBRARY_PATH environment variable, I get the exception you mentioned the very first time I invoke execute_command. After configuring LD_LIBRARY_PATH, the exception doesn't happen.

To configure LD_LIBRARY_PATH:

(1) if using Eclipse, you can right-click on one of your source folders, choose Build Path -> Configure Build Path, then on the "Source" tab make sure that "Native library location" points to a folder in which MiniSat binaries reside.

(2) if running from the shell, just add the path to a folder with MiniSat binaries to LD_LIBRARY_PATH, e.g., something like export LD_LIBARRY_PATH=alloy/extra/x86-linux:$LD_LIBRARY_PATH.

Here is the exact code that I was running, and everything worked

public static void main(String[] args) throws Exception {
    A4Reporter rep = new A4Reporter();

    A4Options options = new A4Options();
    options.solver = A4Options.SatSolver.MiniSatProverJNI;

    Module someWorld = CompUtil.parseEverything_fromFile(rep, null, "someFile.als");
    Command command = someWorld.getAllCommands().get(0);
    A4Solution ans = TranslateAlloyToKodkod.execute_command(rep, someWorld.getAllReachableSigs(), command, options);
    System.out.println(ans);

    Module someOtherWorld = CompUtil.parseEverything_fromFile(rep, null, "someOtherFile.als");
    Command commandTwo = someOtherWorld.getAllCommands().get(0);
    A4Solution ansTwo = TranslateAlloyToKodkod.execute_command(rep, someOtherWorld.getAllReachableSigs(), commandTwo, options);
    System.out.println(ansTwo);
}

with "someFile.als" being

sig A {}
run { some A } for 4

and "someOtherFile.als"

sig A {}
run { no A } for 4

Answer 2

I use alloy4.2.jar as a library in my eclipse plugin project.

A4Reporter rep = new A4Reporter();
Module world = CompUtil.parseEverything_fromFile(rep, null, "civi.als");
A4Options options = new A4Options();
options.solver = A4Options.SatSolver.SAT4J;
options.skolemDepth = 1;

When I use SAT4J, the default solver, the problem mentioned here will not show up. But another exception comes out. The reason is that my civi.als file need Integer model, which located in alloy4.2.jar under the folder /models/util/. But when I run the application, it tries to find the file util/Integer.als directly. That causes the exception. Is it possible to fix that problem?

Besides, I also tried to put the alloy4.2.jar in eclipse plugin project and run my application as an eclipse application (running my application as a plugin). With the default solver, the application has no problem at all. But when I switch to MiniSatProverJNI, the problem mentioned here comes out (I have set the alloy4.2.jar as classpath).