Fix critical issue with open file handle leak on user guide folder

dmp-backend/web/src/main/java/eu/eudat/controllers/UserGuideController.java

@@ -20,6 +20,7 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.List;
+import java.util.Objects;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -41,32 +42,36 @@ public class UserGuideController {
 
 	@RequestMapping(path = "{lang}", method = RequestMethod.GET )
 	public ResponseEntity getUserGuide(@PathVariable(name = "lang") String lang) throws IOException {
-		long files = Files.list(Paths.get(this.environment.getProperty("userguide.path"))).count();
-		metricsManager.calculateValue(MetricNames.LANGUAGES, (int) files, null);
-		Stream<Path> walk = Files.walk(Paths.get(this.environment.getProperty("userguide.path")));
-		List<String> result = walk.filter(Files::isRegularFile)
-								  .map(Path::toString).collect(Collectors.toList());
-
-		String fileName =  result.stream().filter(guide -> guide.contains("_" + lang)).findFirst().orElse(null);
-		if (fileName == null) {
-			fileName = result.stream().filter(guide -> guide.contains("_en")).findFirst().get();
+		long files = 0;
+		try (Stream<Path> paths = Files.list(Paths.get(Objects.requireNonNull(this.environment.getProperty("userguide.path"))))) {
+			files = paths.count();
 		}
-		InputStream is = new FileInputStream(fileName);
+			metricsManager.calculateValue(MetricNames.LANGUAGES, (int) files, null);
+		try (Stream<Path> paths = Files.walk(Paths.get(Objects.requireNonNull(this.environment.getProperty("userguide.path"))))) {
+			List<String> result = paths.filter(Files::isRegularFile)
+					.map(Path::toString).collect(Collectors.toList());
+
+			String fileName = result.stream().filter(guide -> guide.contains("_" + lang)).findFirst().orElse(null);
+			if (fileName == null) {
+				fileName = result.stream().filter(guide -> guide.contains("_en")).findFirst().get();
+			}
+			InputStream is = new FileInputStream(fileName);
 
-		Path path = Paths.get(fileName);
+			Path path = Paths.get(fileName);
 
-		HttpHeaders responseHeaders = new HttpHeaders();
-		responseHeaders.setContentLength(is.available());
-		responseHeaders.setContentType(MediaType.TEXT_HTML);
-		responseHeaders.set("Content-Disposition", "attachment;filename=" + path.getFileName().toString());
-		responseHeaders.set("Access-Control-Expose-Headers", "Content-Disposition");
-		responseHeaders.get("Access-Control-Expose-Headers").add("Content-Type");
+			HttpHeaders responseHeaders = new HttpHeaders();
+			responseHeaders.setContentLength(is.available());
+			responseHeaders.setContentType(MediaType.TEXT_HTML);
+			responseHeaders.set("Content-Disposition", "attachment;filename=" + path.getFileName().toString());
+			responseHeaders.set("Access-Control-Expose-Headers", "Content-Disposition");
+			responseHeaders.get("Access-Control-Expose-Headers").add("Content-Type");
 
-		byte[] content = new byte[is.available()];
-		is.read(content);
-		is.close();
+			byte[] content = new byte[is.available()];
+			is.read(content);
+			is.close();
 
-		return new ResponseEntity<>(content, responseHeaders, HttpStatus.OK);
+			return new ResponseEntity<>(content, responseHeaders, HttpStatus.OK);
+		}
 
 	}
 

dmp-backend/web/src/main/java/eu/eudat/logic/managers/MetricsManager.java

@@ -17,15 +17,13 @@ import javax.annotation.PostConstruct;
 import javax.transaction.Transactional;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.time.LocalDate;
 import java.time.ZoneId;
-import java.util.Collections;
-import java.util.Date;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -179,8 +177,10 @@ public class MetricsManager {
         calculateValue(MetricNames.USERS, (int) userManager.countActiveUsers().intValue(), MetricNames.LOGGEDIN);
         calculateValue(MetricNames.USERS, (int) userManager.countAllUsers().intValue(), MetricNames.TOTAL);
 
-        long files = Files.list(Paths.get(this.environment.getProperty("userguide.path"))).count();
-        calculateValue(MetricNames.LANGUAGES, (int) files, null);
+        try (Stream<Path> paths = Files.list(Paths.get(Objects.requireNonNull(this.environment.getProperty("userguide.path"))))) {
+            long files = paths.count();
+            calculateValue(MetricNames.LANGUAGES, (int) files, null);
+        }
 
         calculateValue(MetricNames.INSTALLATIONS, 1, null);
         calculateValue(MetricNames.NEXUS + MetricNames.INSTALLATIONS, 1, null);