Add TusRetryingClient

src/main/java/io/tus/java/client/ProtocolException.java

@@ -1,11 +1,39 @@
 package io.tus.java.client;
 
+import java.io.IOException;
+import java.net.HttpURLConnection;
+
 /**
  * This exception is thrown if the server sends a request with an unexpected status code or
  * missing/invalid headers.
  */
 public class ProtocolException extends Exception {
+    private HttpURLConnection connection;
+
     public ProtocolException(String message) {
         super(message);
     }
+
+    public ProtocolException(String message, HttpURLConnection connection) {
+        super(message);
+        this.connection = connection;
+    }
+
+    public HttpURLConnection getCausingConnection() {
+        return connection;
+    }
+
+    public boolean shouldRetry() {
+        if(connection == null) {
+            return false;
+        }
+
+        try {
+            int responseCode = connection.getResponseCode();
+
+            return responseCode >= 500 && responseCode < 600;
+        } catch(IOException e) {
+            return false;
+        }
+    }
 }

src/main/java/io/tus/java/client/TusRetryingClient.java

@@ -0,0 +1,99 @@
+package io.tus.java.client;
+
+
+import java.io.IOException;
+
+public class TusRetryingClient extends TusClient {
+    private int maxRetries = 5;
+
+    public void setMaxRetries(int retries) {
+        maxRetries = retries;
+    }
+
+    @Override
+    public TusUploader createUpload(TusUpload upload) throws ProtocolException, IOException {
+        int attempt = 0;
+        while(true) {
+            attempt++;
+
+            try {
+                return super.createUpload(upload);
+            } catch(IOException e) {
+                if(attempt < maxRetries) {
+                    continue;
+                }
+
+                throw e;
+            } catch(ProtocolException e) {
+                if(e.shouldRetry()) {
+                    continue;
+                }
+
+                if(attempt < maxRetries) {
+                    continue;
+                }
+
+                throw e;
+            }
+        }
+    }
+
+    @Override
+    public TusUploader resumeUpload(TusUpload upload) throws FingerprintNotFoundException, ResumingNotEnabledException, ProtocolException, IOException {
+        int attempt = 0;
+        while(true) {
+            attempt++;
+
+            try {
+                return super.resumeUpload(upload);
+            } catch(IOException e) {
+                if(attempt < maxRetries) {
+                    continue;
+                }
+
+                throw e;
+            } catch(ProtocolException e) {
+                if(e.shouldRetry()) {
+                    continue;
+                }
+
+                if(attempt < maxRetries) {
+                    continue;
+                }
+
+                throw e;
+            }
+        }
+    }
+
+    @Override
+    public TusUploader resumeOrCreateUpload(TusUpload upload) throws IOException, ProtocolException {
+        int attempt = 0;
+        while(true) {
+            attempt++;
+
+            try {
+                return super.resumeOrCreateUpload(upload);
+            } catch(IOException e) {
+                if(attempt < maxRetries) {
+                    continue;
+                }
+
+                break;
+            } catch(ProtocolException e) {
+                if(e.shouldRetry()) {
+                    continue;
+                }
+
+                if(attempt < maxRetries) {
+                    continue;
+                }
+
+                break;
+            }
+        }
+
+        // Fall back to creating an upload if resuming failed for too long.
+        return createUpload(upload);
+    }
+}