HDC (Hippo CMS7 Commons 3.1.0 API)

java.lang.Object
- org.hippoecm.hst.diagnosis.HDC

```
public class HDC
extends Object
```
Hierarchical Diagnostic Context.
This provides static methods to start, get and clean up diagnostic tasks.

This also allows to customize HDC by setting a system property, org.hippoecm.hst.diagnosis to a specific implementation class name. A custom HDC implementation may override the instance methods (#doXXX) to extend the functionality.

For example, suppose you want to extend HDC to report the duration of each task to an external performance measuring system. Then one example implementation could look like the following:
```
 public class CustomExternalApmIntegratedHDC extends HDC {

    // Suppose externalAPM is your external application performance monitoring system
    // at your hand to integrate with.
    private ExternalAPM externalAPM = ...;

    public CustomExternalApmIntegratedHDC() {
        super();
    }
```

Field Summary

Fields
Modifier and Type Field and Description

static Task NOOP_TASK

Fields
Modifier and Type	Field and Description
`static Task`	`NOOP_TASK`

Constructor Summary

Constructors
Modifier Constructor and Description

protected HDC()
Protected constructor which might be called by a child class.

Constructors
Modifier	Constructor and Description
`protected`	`HDC()` Protected constructor which might be called by a child class.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`static void`	`cleanUp()` Cleans up the HDC tasks and its context.
`protected void`	`doCleanUp()` Cleans up the HDC tasks and its context.
`protected Task`	`doCreateTask(String name)` Internally create a task instance by the name.
`protected Task`	`doGetCurrentTask()` Internally returns the task instance in the current thread context if available.
`protected Task`	`doGetRootTask()` Internally returns the root task instance if available.
`protected boolean`	`doIsStarted()` Internally check whether or not the root task was started.
`protected void`	`doSetCurrentTask(Task currentTask)` Internally sets the task instance in the current thread context.
`protected Task`	`doStart(String name)` Internally starts the root task by the name.
`static Task`	`getCurrentTask()` Returns the task in the current thread context.
`static Task`	`getRootTask()` Returns the root task.
`static boolean`	`isStarted()` Returns true if the root task was started.
`static void`	`setCurrentTask(Task currentTask)` Sets a task in the current thread context.
`static Task`	`start(String name)` Start the root task with the name.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - NOOP_TASK
```
public static final Task NOOP_TASK
```
- Constructor Detail
  - HDC
```
protected HDC()
```
    Protected constructor which might be called by a child class.
- Method Detail
  - start
```
public static Task start(String name)
```
    Start the root task with the name.
    
    Parameters:
    
    name - root task name
    
    Returns:
    
    root task instance
  - isStarted
```
public static boolean isStarted()
```
    Returns true if the root task was started.
    
    Returns:
    
    true if the root task was started
  - getRootTask
```
public static Task getRootTask()
```
    Returns the root task. Null otherwise.
    
    Returns:
    
    the root task if exists. Null, otherwise.
  - getCurrentTask
```
public static Task getCurrentTask()
```
    Returns the task in the current thread context. Null if not available.
    
    Returns:
    
    the task in the current thread context. Null if not available.
  - setCurrentTask
```
public static void setCurrentTask(Task currentTask)
```
    Sets a task in the current thread context.
    
    Parameters:
    
    currentTask - current task instance
  - cleanUp
```
public static void cleanUp()
```
    Cleans up the HDC tasks and its context.
  - doStart
```
protected Task doStart(String name)
```
    Internally starts the root task by the name.
    
    Parameters:
    
    name - root task name
    
    Returns:
    
    the root task instance
  - doCreateTask
```
protected Task doCreateTask(String name)
```
    Internally create a task instance by the name. This method is invoked by doStart(String), so a child class may override this method if it needs to override the default task implementation, DefaultTaskImpl, for instance.
    
    Parameters:
    
    name - task name
    
    Returns:
    
    internally created task instance
  - doIsStarted
```
protected boolean doIsStarted()
```
    Internally check whether or not the root task was started.
    
    Returns:
    
    returns if the root task was started
  - doGetRootTask
```
protected Task doGetRootTask()
```
    Internally returns the root task instance if available. Null otherwise.
    
    Returns:
    
    the root task instance if available. Null otherwise
  - doGetCurrentTask
```
protected Task doGetCurrentTask()
```
    Internally returns the task instance in the current thread context if available. Null otherwise.
    
    Returns:
    
    the task instance in the current thread context if available. Null otherwise
  - doSetCurrentTask
```
protected void doSetCurrentTask(Task currentTask)
```
    Internally sets the task instance in the current thread context.
    
    Parameters:
    
    currentTask - current task instance
  - doCleanUp
```
protected void doCleanUp()
```
    Cleans up the HDC tasks and its context.

Class HDC

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

NOOP_TASK

Constructor Detail

HDC

Method Detail

start

isStarted

getRootTask

getCurrentTask

setCurrentTask

cleanUp

doStart

doCreateTask

doIsStarted

doGetRootTask

doGetCurrentTask

doSetCurrentTask

doCleanUp