Make jar extraction multi-process safe (#2552)

Author: IlyaMuravjov

utbot-core/src/main/kotlin/org/utbot/common/JarUtils.kt

@@ -4,18 +4,29 @@ import java.io.File
 import java.net.URL
 import java.nio.file.Files
 import java.nio.file.StandardCopyOption
+import java.util.*
 
 object JarUtils {
     private const val UNKNOWN_MODIFICATION_TIME = 0L
 
     fun extractJarFileFromResources(jarFileName: String, jarResourcePath: String, targetDirectoryName: String): File {
-        val targetDirectory =
-            Files.createDirectories(utBotTempDirectory.toFile().resolve(targetDirectoryName).toPath()).toFile()
-        return targetDirectory.resolve(jarFileName).also { jarFile ->
-            val resource = this::class.java.classLoader.getResource(jarResourcePath)
-                ?: error("Unable to find \"$jarResourcePath\" in resources, make sure it's on the classpath")
-            updateJarIfRequired(jarFile, resource)
+        val resource = this::class.java.classLoader.getResource(jarResourcePath)
+            ?: error("Unable to find \"$jarResourcePath\" in resources, make sure it's on the classpath")
+
+        val targetDirectory = utBotTempDirectory.toFile().resolve(targetDirectoryName).toPath()
+        fun extractToSubDir(subDir: String) =
+            Files.createDirectories(targetDirectory.resolve(subDir)).toFile().resolve(jarFileName).also { jarFile ->
+                updateJarIfRequired(jarFile, resource)
+            }
+
+        // We attempt to always extract jars to same locations, to avoid eating up drive space with
+        // every UtBot launch, but we may fail to do so if multiple processes are running in parallel.
+        repeat(10) { i ->
+            runCatching {
+                return extractToSubDir(i.toString())
+            }
         }
+        return extractToSubDir(UUID.randomUUID().toString())
     }
 
     private fun updateJarIfRequired(jarFile: File, resource: URL) {