# Controllers

Istio has a variety of [controllers](https://kubernetes.io/docs/concepts/architecture/controller/), which basically watch some inputs and do something.
This can be reading from Kubernetes and writing other objects back, writing to proxies over XDS, etc.

Unfortunately, writing controllers is very error prone, even for seemingly simple cases.
To work around this, Istio has a variety of abstractions meant to make writing controllers easier.

## Clients

**Here's why we have this policy:** We want to focus on the work that benefits
the whole community, e.g., fixing bugs and adding features. Individual support
should be sought on Stack Overflow or other non-GitHub channels. It helps us to

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Environment (please complete the following information):**
 - OS: [e.g. Windows 10]
 - Version [e.g. 13.5.0]

**Additional context**

    if (obj == this) {
      return true;
    }
    if (!(obj instanceof ElementOrder)) {
      return false;
    }

    ElementOrder<?> other = (ElementOrder<?>) obj;
    return (type == other.type) && Objects.equal(comparator, other.comparator);
  }

  @Override
  public int hashCode() {
    return Objects.hashCode(type, comparator);
  }

  @Override
  public String toString() {

    if (obj == this) {
      return true;
    }
    if (!(obj instanceof ElementOrder)) {
      return false;
    }

    ElementOrder<?> other = (ElementOrder<?>) obj;
    return (type == other.type) && Objects.equal(comparator, other.comparator);
  }

  @Override
  public int hashCode() {
    return Objects.hashCode(type, comparator);
  }

  @Override
  public String toString() {

 *     this.entry = entry;
 *   }
 *   public E getEntry() { return entry; }
 *   public int compareTo(FIFOEntry<E> other) {
 *     int res = entry.compareTo(other.entry);
 *     if (res == 0 && other.entry != this.entry)
 *       res = (seqNum < other.seqNum ? -1 : 1);
 *     return res;
 *   }
 * }</pre>
 *
 * @author Doug Lea
 * @author Justin T. Sampson

TF_CAPI_EXPORT extern void TFE_ContextClearCaches(TFE_Context* ctx);

// Sets a thread-local device placement policy. After this call, other calls to
// TFE_Execute in the same thread will use the device policy specified here
// instead of the device policy used to construct the context. This has no
// effect on the device policy used by other program threads.
TF_CAPI_EXPORT extern void TFE_ContextSetThreadLocalDevicePlacementPolicy(

API changes and other small changes to the standard library go here....

   *
   * @param formal The type whose type variables or itself is mapped to other type(s). It's almost
   *     always a bug if {@code formal} isn't a type variable and contains no type variable. Make
   *     sure you are passing the two parameters in the right order.
   * @param actual The type that the formal type variable(s) are mapped to. It can be or contain yet
   *     other type variables, in which case these type variables will be further resolved if

 * with any other implementation of this interface.
 *
 * <p>If you have your own graph implementation based around a custom node type {@code MyNode},
 * which has a method {@code getParents()} that retrieves its predecessors in a graph:
 *
 * <pre>{@code
 * someGraphAlgorithm(startNode, MyNode::getParents);
 * }</pre>
 *