Package com.yahoo.yolean.trace

Class TraceNode

java.lang.Object
com.yahoo.yolean.trace.TraceNode
public class TraceNode extends Object

This class represents a single node in a tree of TraceNodes. The trace forms a tree where there is a branch for each parallel execution, and a node within such a branch for each traced event. As each TraceNode may contain a payload of any type, the trace tree can be used to exchange any thread-safe state between producers and consumers in different threads, whether or not the shape of the trace tree is relevant to the particular information.

This class uses a ThreadRobustList for its children. That list allows multiple threads to inspect the hierarchy of a TraceNode tree while there are other threads concurrently modifying it, without incurring the cost of memory synchronization. The only caveat being that for each TraceNode there can never be more than exactly one writer thread. If multiple threads need to mutate a single TraceNode, then the writer threads need to synchronize their access on the TraceNode.

Since:
5.1.15
Author:
Steinar Knutsen, bratseth

  • Constructor Details

    • TraceNode

      public TraceNode(Object payload, long timestamp)

      Creates a new instance of this class.

      Parameters:
      payload - the payload to assign to this, may be null
      timestamp - the timestamp to assign to this

  • Method Details

    • add

      public TraceNode add(TraceNode child)

      Adds another TraceNode as a child to this.

      Parameters:
      child - the TraceNode to add
      Returns:
      this, to allow chaining
      Throws:
      IllegalArgumentException - if child is not a root TraceNode
      See Also:

    • descendants

      public <PAYLOADTYPE> Iterable<PAYLOADTYPE> descendants(Class<PAYLOADTYPE> payloadType)

      Returns a read-only iterable of all payloads that are instances of payloadType, in all its decendants. The payload of this TraceNode is ignored.

      The payloads are retrieved in depth-first, prefix order.

      Parameters:
      payloadType - the type of payloads to retrieve
      Returns:
      the payloads, never null

    • payload

      public Object payload()

      Returns the payload of this TraceNode, or null if none.

      Returns:
      the payload

    • timestamp

      public long timestamp()

      Returns the timestamp of this TraceNode.

      Returns:
      the timestamp

    • parent

      public TraceNode parent()

      Returns the parent TraceNode of this.

      Returns:
      the parent

    • children

      public Iterable<TraceNode> children()

      Returns the child TraceNodes of this.

      Returns:
      the children

    • isRoot

      public boolean isRoot()

      Returns whether or not this TraceNode is a root node (i.e. it has no parent).

      Returns:
      true if parent() returns null

    • root

      public TraceNode root()

      Returns the root TraceNode of the tree that this TraceNode belongs to.

      Returns:
      the root

    • accept

      public <T extends TraceVisitor> T accept(T visitor)

      Visits this TraceNode and all of its descendants in depth-first, prefix order.

      Parameters:
      visitor - The visitor to accept.
      Returns:
      The visitor parameter.

    • toString

      public String toString()
      Overrides:
      toString in class Object