presto-main/src/main/java/io/prestosql/server/remotetask/HttpRemoteTask.java/HttpRemoteTask/cancel
class HttpRemoteTask:    @Override
    public synchronized void cancel()
    {
        try (SetThreadName ignored = new SetThreadName("HttpRemoteTask-%s", taskId)) {
            TaskStatus taskStatus = getTaskStatus();
            if (taskStatus.getState().isDone()) {
                return;
            }

            // send cancel to task and ignore response
            HttpUriBuilder uriBuilder = getHttpUriBuilder(taskStatus).addParameter("abort", "false");
            Request request = prepareDelete()
                    .setUri(uriBuilder.build())
                    .build();
            scheduleAsyncCleanupRequest(createCleanupBackoff(), request, "cancel");
        }
    }