made LockFile reentrant (multiple locks on the same file can be acquired in the same JVM instance)

added argument file to JavaProcessBuilder

jwo-test/src/main/java/module-info.java

@@ -0,0 +1,6 @@
+module net.woggioni.jwo.lockfile.test {
+    requires net.woggioni.jwo;
+    requires static lombok;
+
+    exports net.woggioni.jwo.lockfile.test;
+}

jwo-test/src/main/java/net/woggioni/jwo/lockfile/test/LockFileTestMain.java

@@ -0,0 +1,42 @@
+package net.woggioni.jwo.lockfile.test;
+
+import lombok.SneakyThrows;
+import net.woggioni.jwo.LockFile;
+import net.woggioni.jwo.Run;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+
+public class LockFileTestMain {
+
+    @SneakyThrows
+    private static void run(
+        Path lockfilePath,
+        boolean shared,
+        boolean keep
+    ) {
+        Thread t = new Thread((Run)() -> {
+            try (AutoCloseable lockfile = LockFile.acquire(lockfilePath, shared)) {
+                while (keep) {
+                    Thread.sleep(1000);
+                }
+            }
+        });
+        t.start();
+        try (AutoCloseable lockfile = LockFile.acquire(lockfilePath, shared)) {
+            while (keep) {
+                Thread.sleep(1000);
+            }
+        }
+        t.join();
+    }
+
+    @SneakyThrows
+    public static void main(String[] args) {
+        Path lockfilePath = Paths.get(args[0]);
+        boolean shared = Boolean.parseBoolean(args[1]);
+        boolean keep = Boolean.parseBoolean(args[2]);
+        run(lockfilePath, shared, keep);
+    }
+}

jwo-test/src/test/java/module-info.java

@@ -1,4 +1,5 @@
 open module net.woggioni.jwo.unit.test {
+    requires org.slf4j;
     requires net.woggioni.jwo;
     requires net.woggioni.jwo.test.module;
     requires org.junit.jupiter.api;

jwo-test/src/test/java/net/woggioni/jwo/test/LockFileTest.java

@@ -0,0 +1,147 @@
+package net.woggioni.jwo.test;
+
+
+import lombok.RequiredArgsConstructor;
+import lombok.SneakyThrows;
+import net.woggioni.jwo.JavaProcessBuilder;
+import net.woggioni.jwo.LockFile;
+import net.woggioni.jwo.Run;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.channels.Channels;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.Arrays;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class LockFileTest {
+    private static Logger log = LoggerFactory.getLogger(LockFileTest.class);
+
+    @TempDir
+    public Path testDir;
+
+    private Path executablePath = Paths.get(System.getProperty("lockFileTest.executable.jar"));
+
+    @RequiredArgsConstructor
+    private static class LockFileTestMainArgs {
+        final Path lockFilePath;
+        final boolean shared;
+        final boolean keep;
+
+        public List<String> getArgs() {
+            return Arrays.asList(lockFilePath.toString(), Boolean.toString(shared), Boolean.toString(keep));
+        }
+    }
+
+    @SneakyThrows
+    private static void kill(Process p) {
+        if (p != null && p.isAlive()) p.destroyForcibly().waitFor();
+    }
+
+    @Test
+    @SneakyThrows
+    public void testExclusiveLockHeldOnFile() {
+        Path lockFilePath = Files.createFile(testDir.resolve("file.lock"));
+        // try to acquire an exclusive lock and check that the process returns immediately
+        JavaProcessBuilder javaProcessBuilder = new JavaProcessBuilder();
+        javaProcessBuilder.setExecutableJar(executablePath);
+        javaProcessBuilder.setCliArgs(new LockFileTestMainArgs(lockFilePath, false, false).getArgs());
+        Process process = javaProcessBuilder.build()
+                .inheritIO()
+                .start();
+        Assertions.assertTrue(process.waitFor(1, TimeUnit.SECONDS));
+        Assertions.assertEquals(0, process.exitValue());
+
+        Process sharedLockProcess = null;
+        Process anotherSharedLockProcess = null;
+        Process exclusiveLockProcess = null;
+        try {
+            // try to acquire and keep a shared lock on the file and check that the process does not exit
+            javaProcessBuilder.setCliArgs(new LockFileTestMainArgs(lockFilePath, true, true).getArgs());
+            sharedLockProcess = javaProcessBuilder.build()
+                    .inheritIO()
+                    .start();
+            Assertions.assertFalse(sharedLockProcess.waitFor(1000, TimeUnit.MILLISECONDS));
+
+            // try to acquire another shared lock on the file and check that the process is able to terminate
+            javaProcessBuilder.setCliArgs(new LockFileTestMainArgs(lockFilePath, true, false).getArgs());
+            anotherSharedLockProcess = javaProcessBuilder.build()
+                    .inheritIO()
+                    .start();
+            Assertions.assertTrue(anotherSharedLockProcess.waitFor(1, TimeUnit.SECONDS));
+
+            // try to acquire an exclusive lock on the file and check that process hangs
+            javaProcessBuilder.setCliArgs(new LockFileTestMainArgs(lockFilePath, false, false).getArgs());
+            exclusiveLockProcess = javaProcessBuilder.build()
+                    .inheritIO()
+                    .start();
+            Assertions.assertFalse(exclusiveLockProcess.waitFor(1, TimeUnit.SECONDS));
+            // kill the process holding the shared lock and check that the process holding the exclusive lock terminates
+            sharedLockProcess.destroyForcibly().waitFor();
+            Assertions.assertTrue(exclusiveLockProcess.waitFor(1, TimeUnit.SECONDS));
+            Assertions.assertEquals(0, exclusiveLockProcess.exitValue());
+        } finally {
+            kill(sharedLockProcess);
+            kill(anotherSharedLockProcess);
+            kill(exclusiveLockProcess);
+        }
+    }
+
+    @Test
+    @SneakyThrows
+    public void sameProcessTest(@TempDir Path testDir) {
+        ExecutorService executor = Executors.newThreadPerTaskExecutor(Thread::new);
+        Path lockfile = testDir.resolve("file.lock");
+        AtomicInteger readerRunning = new AtomicInteger(0);
+        AtomicBoolean writerRunning = new AtomicBoolean(false);
+        Run writerRunnable = () -> {
+            try(LockFile lock = LockFile.acquire(lockfile, false)) {
+                log.info("Writer start!!!!");
+                writerRunning.set(true);
+                FileChannel fileChannel = FileChannel.open(lockfile, EnumSet.of(StandardOpenOption.CREATE, StandardOpenOption.READ, StandardOpenOption.WRITE));
+                Writer writer = new OutputStreamWriter(Channels.newOutputStream(fileChannel));
+                writer.write("asdffdgkhjdhigsdfhuifg");
+                Thread.sleep(100);
+                log.info("Writer end!!!!");
+                writerRunning.set(false);
+                Assertions.assertEquals(0, readerRunning.get());
+            }
+        };
+        Run readerRunnable = () -> {
+            try(AutoCloseable lock = LockFile.acquire(lockfile, true)) {
+                readerRunning.incrementAndGet();
+                log.info("reader start");
+                Thread.sleep(100);
+                log.info("reader end");
+                readerRunning.decrementAndGet();
+                Assertions.assertEquals(false, writerRunning.get());
+            }
+        };
+        CompletableFuture<?> reader1 = CompletableFuture.runAsync(readerRunnable, executor);
+        CompletableFuture<?> reader2 = CompletableFuture.runAsync(readerRunnable, executor);
+        CompletableFuture<?> writer = CompletableFuture.runAsync(writerRunnable, executor);
+        try {
+            CompletableFuture.allOf(reader1, reader2, writer).get();
+        } catch (ExecutionException ee) {
+            throw ee.getCause();
+        }
+        log.info("FINISHED");
+    }
+}