Add convenience class for simple API calls.

bramble-core/src/main/java/org/briarproject/bramble/mailbox/SimpleApiCall.java

@@ -0,0 +1,40 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.Supplier;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
+import org.briarproject.bramble.mailbox.MailboxApi.TolerableFailureException;
+
+import java.io.IOException;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+/**
+ * Convenience class for making simple API calls that don't return values.
+ */
+@NotNullByDefault
+public abstract class SimpleApiCall implements Supplier<Boolean> {
+
+	private static final Logger LOG = getLogger(SimpleApiCall.class.getName());
+
+	abstract void callApi()
+			throws IOException, ApiException, TolerableFailureException;
+
+	@Override
+	public Boolean get() {
+		try {
+			callApi();
+			return false; // Succeeded, don't retry
+		} catch (IOException | ApiException e) {
+			logException(LOG, WARNING, e);
+			return true; // Failed, retry with backoff
+		} catch (TolerableFailureException e) {
+			logException(LOG, INFO, e);
+			return false; // Failed tolerably, don't retry
+		}
+	}
+}