Add removable drive manager with placeholder task implementations.

bramble-api/src/main/java/org/briarproject/bramble/api/Consumer.java

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface Consumer<T> {
+
+	void accept(T t);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/FileConstants.java

@@ -1,4 +1,4 @@
-package org.briarproject.bramble.api.plugin;
+package org.briarproject.bramble.api.plugin.file;
 
 public interface FileConstants {
 

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/RemovableDriveConstants.java

@@ -1,4 +1,6 @@
-package org.briarproject.bramble.api.plugin;
+package org.briarproject.bramble.api.plugin.file;
+
+import org.briarproject.bramble.api.plugin.TransportId;
 
 public interface RemovableDriveConstants {
 

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/RemovableDriveManager.java

@@ -0,0 +1,40 @@
+package org.briarproject.bramble.api.plugin.file;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.File;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public interface RemovableDriveManager {
+
+	/**
+	 * Returns the currently running reader task for the given contact,
+	 * or null if no task is running.
+	 */
+	@Nullable
+	RemovableDriveTask getCurrentReaderTask(ContactId c);
+
+	/**
+	 * Returns the currently running writer task for the given contact,
+	 * or null if no task is running.
+	 */
+	@Nullable
+	RemovableDriveTask getCurrentWriterTask(ContactId c);
+
+	/**
+	 * Starts and returns a reader task for the given contact, reading from
+	 * the given file. If a reader task for the contact is already running,
+	 * it will be returned and the file argument will be ignored.
+	 */
+	RemovableDriveTask startReaderTask(ContactId c, File f);
+
+	/**
+	 * Starts and returns a writer task for the given contact, writing to
+	 * the given file. If a writer task for the contact is already running,
+	 * it will be returned and the file argument will be ignored.
+	 */
+	RemovableDriveTask startWriterTask(ContactId c, File f);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/RemovableDriveTask.java

@@ -0,0 +1,34 @@
+package org.briarproject.bramble.api.plugin.file;
+
+import org.briarproject.bramble.api.event.EventExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.File;
+
+@NotNullByDefault
+public interface RemovableDriveTask {
+
+	/**
+	 * Returns the file that this task is reading from or writing to.
+	 */
+	File getFile();
+
+	/**
+	 * Adds an observer to the task.
+	 */
+	void addObserver(Observer o);
+
+	/**
+	 * Removes an observer from the task.
+	 */
+	void removeObserver(Observer o);
+
+	interface Observer {
+
+		@EventExecutor
+		void onProgress(long written, long total);
+
+		@EventExecutor
+		void onCompletion(boolean success);
+	}
+}