How to use

GroupByContainerCount$TaskGroup

in

org.apache.samza.container.grouper.task

/**
 * Creates a list of empty {@link TaskGroup} instances for a range of container id's
 * from the start(inclusive) to end(exclusive) container id.
 *
 * @param startContainerId  the first container id for which a TaskGroup is needed.
 * @param endContainerId    the first container id AFTER the last TaskGroup that is needed.
 * @return                  a set of empty TaskGroup instances corresponding to the range
 *                          [startContainerId, endContainerId)
 */
private List<TaskGroup> createContainers(int startContainerId, int endContainerId) {
 List<TaskGroup> containers = new ArrayList<>(endContainerId - startContainerId);
 for (int i = startContainerId; i < endContainerId; i++) {
  TaskGroup taskGroup = new TaskGroup(String.valueOf(i), new ArrayList<String>());
  containers.add(taskGroup);
 }
 return containers;
}

/**
 * Assigns tasks from the specified list to containers that have fewer containers than indicated
 * in taskCountPerContainer.
 *
 * @param taskCountPerContainer the expected number of tasks for each container.
 * @param taskNamesToAssign     the list of tasks to assign to the containers.
 * @param containers            the containers (as {@link TaskGroup}) to which the tasks will be assigned.
 */
// TODO: Change logic from using int arrays to a Map<String, Integer> (id -> taskCount)
private void assignTasksToContainers(int[] taskCountPerContainer, List<String> taskNamesToAssign,
  List<TaskGroup> containers) {
 for (TaskGroup taskGroup : containers) {
  for (int j = taskGroup.size(); j < taskCountPerContainer[Integer.valueOf(taskGroup.getContainerId())]; j++) {
   String taskName = taskNamesToAssign.remove(0);
   taskGroup.addTaskName(taskName);
   log.info("Assigned task {} to container {}", taskName, taskGroup.getContainerId());
  }
 }
}

/**
 * Assigns tasks from the specified list to containers that have fewer containers than indicated
 * in taskCountPerContainer.
 *
 * @param taskCountPerContainer the expected number of tasks for each container.
 * @param taskNamesToAssign     the list of tasks to assign to the containers.
 * @param containers            the containers (as {@link TaskGroup}) to which the tasks will be assigned.
 */
// TODO: Change logic from using int arrays to a Map<String, Integer> (id -> taskCount)
private void assignTasksToContainers(int[] taskCountPerContainer, List<String> taskNamesToAssign,
  List<TaskGroup> containers) {
 for (TaskGroup taskGroup : containers) {
  for (int j = taskGroup.size(); j < taskCountPerContainer[Integer.valueOf(taskGroup.getContainerId())]; j++) {
   String taskName = taskNamesToAssign.remove(0);
   taskGroup.addTaskName(taskName);
   log.info("Assigned task {} to container {}", taskName, taskGroup.getContainerId());
  }
 }
}

/**
 * Creates a list of empty {@link TaskGroup} instances for a range of container id's
 * from the start(inclusive) to end(exclusive) container id.
 *
 * @param startContainerId  the first container id for which a TaskGroup is needed.
 * @param endContainerId    the first container id AFTER the last TaskGroup that is needed.
 * @return                  a set of empty TaskGroup instances corresponding to the range
 *                          [startContainerId, endContainerId)
 */
private List<TaskGroup> createContainers(int startContainerId, int endContainerId) {
 List<TaskGroup> containers = new ArrayList<>(endContainerId - startContainerId);
 for (int i = startContainerId; i < endContainerId; i++) {
  TaskGroup taskGroup = new TaskGroup(String.valueOf(i), new ArrayList<String>());
  containers.add(taskGroup);
 }
 return containers;
}

/**
 * Assigns tasks from the specified list to containers that have fewer containers than indicated
 * in taskCountPerContainer.
 *
 * @param taskCountPerContainer the expected number of tasks for each container.
 * @param taskNamesToAssign     the list of tasks to assign to the containers.
 * @param containers            the containers (as {@link TaskGroup}) to which the tasks will be assigned.
 */
// TODO: Change logic from using int arrays to a Map<String, Integer> (id -> taskCount)
private void assignTasksToContainers(int[] taskCountPerContainer, List<String> taskNamesToAssign,
  List<TaskGroup> containers) {
 for (TaskGroup taskGroup : containers) {
  for (int j = taskGroup.size(); j < taskCountPerContainer[Integer.valueOf(taskGroup.getContainerId())]; j++) {
   String taskName = taskNamesToAssign.remove(0);
   taskGroup.addTaskName(taskName);
   log.info("Assigned task {} to container {}", taskName, taskGroup.getContainerId());
  }
 }
}

/**
 * Assigns tasks from the specified list to containers that have fewer containers than indicated
 * in taskCountPerContainer.
 *
 * @param taskCountPerContainer the expected number of tasks for each container.
 * @param taskNamesToAssign     the list of tasks to assign to the containers.
 * @param containers            the containers (as {@link TaskGroup}) to which the tasks will be assigned.
 */
// TODO: Change logic from using int arrays to a Map<String, Integer> (id -> taskCount)
private void assignTasksToContainers(int[] taskCountPerContainer, List<String> taskNamesToAssign,
  List<TaskGroup> containers) {
 for (TaskGroup taskGroup : containers) {
  for (int j = taskGroup.size(); j < taskCountPerContainer[Integer.valueOf(taskGroup.getContainerId())]; j++) {
   String taskName = taskNamesToAssign.remove(0);
   taskGroup.addTaskName(taskName);
   log.info("Assigned task {} to container {}", taskName, taskGroup.getContainerId());
  }
 }
}

/**
 * Converts the task->containerId map to an ordered list of {@link TaskGroup} instances.
 *
 * @param taskToContainerId a map from each task name to the containerId to which it is assigned.
 * @return                  a list of TaskGroups ordered ascending by containerId.
 */
private List<TaskGroup> getOrderedContainers(Map<String, String> taskToContainerId) {
 log.debug("Got task to container map: {}", taskToContainerId);
 // Group tasks by container Id
 HashMap<String, List<String>> containerIdToTaskNames = new HashMap<>();
 for (Map.Entry<String, String> entry : taskToContainerId.entrySet()) {
  String taskName = entry.getKey();
  String containerId = entry.getValue();
  List<String> taskNames = containerIdToTaskNames.get(containerId);
  if (taskNames == null) {
   taskNames = new ArrayList<>();
   containerIdToTaskNames.put(containerId, taskNames);
  }
  taskNames.add(taskName);
 }
 // Build container tasks
 List<TaskGroup> containerTasks = new ArrayList<>(containerIdToTaskNames.size());
 for (int i = 0; i < containerIdToTaskNames.size(); i++) {
  if (containerIdToTaskNames.get(String.valueOf(i)) == null) throw new IllegalStateException("Task mapping is missing container: " + i);
  containerTasks.add(new TaskGroup(String.valueOf(i), containerIdToTaskNames.get(String.valueOf(i))));
 }
 return containerTasks;
}

/**
 * Converts the task->containerId map to an ordered list of {@link TaskGroup} instances.
 *
 * @param taskToContainerId a map from each task name to the containerId to which it is assigned.
 * @return                  a list of TaskGroups ordered ascending by containerId.
 */
private List<TaskGroup> getOrderedContainers(Map<String, String> taskToContainerId) {
 log.debug("Got task to container map: {}", taskToContainerId);
 // Group tasks by container Id
 HashMap<String, List<String>> containerIdToTaskNames = new HashMap<>();
 for (Map.Entry<String, String> entry : taskToContainerId.entrySet()) {
  String taskName = entry.getKey();
  String containerId = entry.getValue();
  List<String> taskNames = containerIdToTaskNames.get(containerId);
  if (taskNames == null) {
   taskNames = new ArrayList<>();
   containerIdToTaskNames.put(containerId, taskNames);
  }
  taskNames.add(taskName);
 }
 // Build container tasks
 List<TaskGroup> containerTasks = new ArrayList<>(containerIdToTaskNames.size());
 for (int i = 0; i < containerIdToTaskNames.size(); i++) {
  if (containerIdToTaskNames.get(String.valueOf(i)) == null) throw new IllegalStateException("Task mapping is missing container: " + i);
  containerTasks.add(new TaskGroup(String.valueOf(i), containerIdToTaskNames.get(String.valueOf(i))));
 }
 return containerTasks;
}

/**
 * Converts the task->containerId map to an ordered list of {@link TaskGroup} instances.
 *
 * @param taskToContainerId a map from each task name to the containerId to which it is assigned.
 * @return                  a list of TaskGroups ordered ascending by containerId.
 */
private List<TaskGroup> getOrderedContainers(Map<String, String> taskToContainerId) {
 log.debug("Got task to container map: {}", taskToContainerId);
 // Group tasks by container Id
 HashMap<String, List<String>> containerIdToTaskNames = new HashMap<>();
 for (Map.Entry<String, String> entry : taskToContainerId.entrySet()) {
  String taskName = entry.getKey();
  String containerId = entry.getValue();
  List<String> taskNames = containerIdToTaskNames.get(containerId);
  if (taskNames == null) {
   taskNames = new ArrayList<>();
   containerIdToTaskNames.put(containerId, taskNames);
  }
  taskNames.add(taskName);
 }
 // Build container tasks
 List<TaskGroup> containerTasks = new ArrayList<>(containerIdToTaskNames.size());
 for (int i = 0; i < containerIdToTaskNames.size(); i++) {
  if (containerIdToTaskNames.get(String.valueOf(i)) == null) throw new IllegalStateException("Task mapping is missing container: " + i);
  containerTasks.add(new TaskGroup(String.valueOf(i), containerIdToTaskNames.get(String.valueOf(i))));
 }
 return containerTasks;
}

for (int i = 0; i < prevContainerCount; i++) {
 TaskGroup taskGroup = containers.get(i);
 while (taskGroup.size() > expectedTaskCountPerContainer[i]) {
  taskNamesToReassign.add(taskGroup.removeTask());

for (int i = 0; i < prevContainerCount; i++) {
 TaskGroup taskGroup = containers.get(i);
 while (taskGroup.size() > expectedTaskCountPerContainer[i]) {
  taskNamesToReassign.add(taskGroup.removeTask());

/**
 * Creates a list of empty {@link TaskGroup} instances for a range of container id's
 * from the start(inclusive) to end(exclusive) container id.
 *
 * @param startContainerId  the first container id for which a TaskGroup is needed.
 * @param endContainerId    the first container id AFTER the last TaskGroup that is needed.
 * @return                  a set of empty TaskGroup instances corresponding to the range
 *                          [startContainerId, endContainerId)
 */
private List<TaskGroup> createContainers(int startContainerId, int endContainerId) {
 List<TaskGroup> containers = new ArrayList<>(endContainerId - startContainerId);
 for (int i = startContainerId; i < endContainerId; i++) {
  TaskGroup taskGroup = new TaskGroup(String.valueOf(i), new ArrayList<String>());
  containers.add(taskGroup);
 }
 return containers;
}

for (int i = 0; i < prevContainerCount; i++) {
 TaskGroup taskGroup = containers.get(i);
 while (taskGroup.size() > expectedTaskCountPerContainer[i]) {
  taskNamesToReassign.add(taskGroup.removeTask());

/**
 * Creates a list of empty {@link TaskGroup} instances for a range of container id's
 * from the start(inclusive) to end(exclusive) container id.
 *
 * @param startContainerId  the first container id for which a TaskGroup is needed.
 * @param endContainerId    the first container id AFTER the last TaskGroup that is needed.
 * @return                  a set of empty TaskGroup instances corresponding to the range
 *                          [startContainerId, endContainerId)
 */
private List<TaskGroup> createContainers(int startContainerId, int endContainerId) {
 List<TaskGroup> containers = new ArrayList<>(endContainerId - startContainerId);
 for (int i = startContainerId; i < endContainerId; i++) {
  TaskGroup taskGroup = new TaskGroup(String.valueOf(i), new ArrayList<String>());
  containers.add(taskGroup);
 }
 return containers;
}

for (int i = 0; i < prevContainerCount; i++) {
 TaskGroup taskGroup = containers.get(i);
 while (taskGroup.size() > expectedTaskCountPerContainer[i]) {
  taskNamesToReassign.add(taskGroup.removeTask());

/**
 * Converts the task->containerId map to an ordered list of {@link TaskGroup} instances.
 *
 * @param taskToContainerId a map from each task name to the containerId to which it is assigned.
 * @return                  a list of TaskGroups ordered ascending by containerId.
 */
private List<TaskGroup> getOrderedContainers(Map<String, String> taskToContainerId) {
 log.debug("Got task to container map: {}", taskToContainerId);
 // Group tasks by container Id
 HashMap<String, List<String>> containerIdToTaskNames = new HashMap<>();
 for (Map.Entry<String, String> entry : taskToContainerId.entrySet()) {
  String taskName = entry.getKey();
  String containerId = entry.getValue();
  List<String> taskNames = containerIdToTaskNames.get(containerId);
  if (taskNames == null) {
   taskNames = new ArrayList<>();
   containerIdToTaskNames.put(containerId, taskNames);
  }
  taskNames.add(taskName);
 }
 // Build container tasks
 List<TaskGroup> containerTasks = new ArrayList<>(containerIdToTaskNames.size());
 for (int i = 0; i < containerIdToTaskNames.size(); i++) {
  if (containerIdToTaskNames.get(String.valueOf(i)) == null) throw new IllegalStateException("Task mapping is missing container: " + i);
  containerTasks.add(new TaskGroup(String.valueOf(i), containerIdToTaskNames.get(String.valueOf(i))));
 }
 return containerTasks;
}