fix the misleading exception throw on windows

- The file will be close before delete it
- Some refactoring of the downloader cache

Author: Mattia Bertorello

arduino-core/src/cc/arduino/utils/network/FileDownloader.java

@@ -148,12 +148,9 @@ private void downloadFile(boolean noResume) throws InterruptedException {
 
       final File settingsFolder = BaseNoGui.getPlatform().getSettingsFolder();
       final String cacheFolder = Paths.get(settingsFolder.getPath(), "cache").toString();
-      final FileDownloaderCache fileDownloaderCache =
-        new FileDownloaderCache(cacheFolder, downloadUrl);
+      final FileDownloaderCache fileDownloaderCache = FileDownloaderCache.getFileCached(cacheFolder, downloadUrl);
 
-      final boolean isChanged = fileDownloaderCache.checkIfTheFileIsChanged();
-
-      if (!isChanged) {
+      if (!fileDownloaderCache.isChange()) {
         try {
           final Optional<File> fileFromCache =
             fileDownloaderCache.getFileFromCache();
@@ -165,28 +162,26 @@ private void downloadFile(boolean noResume) throws InterruptedException {
         } catch (Exception e) {
           log.warn(
             "Cannot get the file from the cache, will be downloaded a new one ", e.getCause());
-
         }
       }
 
-      // Open file and seek to the end of it
-      randomAccessOutputFile = new RandomAccessFile(outputFile, "rw");
-      initialSize = randomAccessOutputFile.length();
-
+      initialSize = outputFile.length();
       if (noResume && initialSize > 0) {
         // delete file and restart downloading
-        Files.delete(outputFile.toPath());
+        Files.deleteIfExists(outputFile.toPath());
         initialSize = 0;
       }
-
+      // Open file and seek to the end of it
+      randomAccessOutputFile = new RandomAccessFile(outputFile, "rw");
       randomAccessOutputFile.seek(initialSize);
 
       final HttpURLConnection connection = new HttpConnectionManager(downloadUrl)
         .makeConnection((c) -> setDownloaded(0));
       final int resp = connection.getResponseCode();
 
       if (resp < 200 || resp >= 300) {
-        Files.delete(outputFile.toPath());
+        IOUtils.closeQuietly(randomAccessOutputFile);
+        Files.deleteIfExists(outputFile.toPath());
         throw new IOException("Received invalid http status code from server: " + resp);
       }
 

arduino-core/src/cc/arduino/utils/network/FileDownloaderCache.java

@@ -19,25 +19,28 @@
 
 public class FileDownloaderCache {
   private static Logger log = LoggerFactory.getLogger(FileDownloaderCache.class);
-  private final URL remoteURL;
   private final Path cacheFilePath;
-  // Will be initialized by call the checkIfTheFileIsChanged function
-  private String eTag;
+  private final String remoteETag;
+  private final String preferencesDataKey;
 
   // BaseNoGui.getSettingsFolder()
-  public FileDownloaderCache(String cacheFolder, URL remoteURL) {
-    this.remoteURL = remoteURL;
-    String[] splitPath = remoteURL.getPath().split("/");
+  private FileDownloaderCache(Path cacheFilePath, String remoteETag, String preferencesDataKey) {
+    this.cacheFilePath = cacheFilePath;
+    this.remoteETag = remoteETag;
+    this.preferencesDataKey = preferencesDataKey;
+  }
+
+  public static FileDownloaderCache getFileCached(String cacheFolder, URL remoteURL)
+    throws IOException, NoSuchMethodException, ScriptException, URISyntaxException {
+
+    final String[] splitPath = remoteURL.getPath().split("/");
+    final String preferencesDataKey = "cache.file." + remoteURL.getPath();
+    final Path cacheFilePath;
     if (splitPath.length > 0) {
-      this.cacheFilePath = Paths.get(cacheFolder, splitPath);
+      cacheFilePath = Paths.get(cacheFolder, splitPath);
     } else {
-      this.cacheFilePath = null;
+      cacheFilePath = null;
     }
-  }
-
-  public boolean checkIfTheFileIsChanged()
-    throws NoSuchMethodException, ScriptException, IOException,
-    URISyntaxException {
 
     final HttpURLConnection headRequest = new HttpConnectionManager(remoteURL)
       .makeConnection((connection) -> {
@@ -52,20 +55,30 @@ public boolean checkIfTheFileIsChanged()
     // Something bad is happening return a conservative true to try to download the file
     if (responseCode < 200 || responseCode >= 300) {
       log.warn("The head request return a bad response code " + responseCode);
-      return true;
+      // if something bad happend
+      return new FileDownloaderCache(cacheFilePath, null, preferencesDataKey);
     }
 
     final String remoteETag = headRequest.getHeaderField("ETag");
-    final String localETag = PreferencesData.get(getPreferencesDataKey());
+    String remoteETagClean = null;
+    if (remoteETag != null) {
+      remoteETagClean = remoteETag.trim().replace("\"", "");
+    }
+
+    return new FileDownloaderCache(cacheFilePath, remoteETagClean, preferencesDataKey);
+  }
+
+  public boolean isChange() {
+
+    final String localETag = PreferencesData.get(preferencesDataKey);
 
     // If the header doesn't exist or the local cache doesn't exist you need to download the file
-    if (remoteETag == null || localETag == null) {
+    if (cacheFilePath == null || remoteETag == null || localETag == null) {
       return true;
     }
-    eTag = remoteETag.trim().replace("\"", "");
 
     // If are different means that the file is change
-    return !eTag.equals(localETag);
+    return !remoteETag.equals(localETag);
   }
 
   public Optional<File> getFileFromCache() {
@@ -77,10 +90,10 @@ public Optional<File> getFileFromCache() {
   }
 
   public void fillCache(File fileToCache) throws Exception {
-    if (Optional.ofNullable(eTag).isPresent() &&
+    if (Optional.ofNullable(remoteETag).isPresent() &&
       Optional.ofNullable(cacheFilePath).isPresent()) {
 
-      PreferencesData.set(getPreferencesDataKey(), eTag);
+      PreferencesData.set(preferencesDataKey, remoteETag);
       // If the cache directory does not exist create it
       if (!Files.exists(cacheFilePath.getParent())) {
         Files.createDirectories(cacheFilePath.getParent());
@@ -89,7 +102,4 @@ public void fillCache(File fileToCache) throws Exception {
     }
   }
 
-  private String getPreferencesDataKey() {
-    return "cache.file." + remoteURL.getPath();
-  }
 }