Package org.spiderwiz.core

Class Resetter

java.lang.Object
org.spiderwiz.core.Resetter
public final class Resetter
extends Object
Data Object Resetting is the operation that takes place when a consumer of a specific data object type detects loss of data. This may happen when the application starts or when data is lost due to a communication problem. In this case, the consumer broadcasts a reset request, asking the producers of that object type to reset all missing objects to their most up-to-date state.

When receiving a reset request, the Spiderwiz framework creates a Resetter object and calls Main.onObjectReset() to give a chance to the application to fulfill the request programmatically. The method returns true when done this way.

If onObjectReset() returns false then the framework does automatic reset by fulfilling the request from the governed data object tree.

That parameter to onObjectReset() is an object of type Resetter that is documented here. It contains information about the requested object type. It also serves as a carrier to deliver objects back to the requester. As such, it facilitates efficient delivery by directing the reset items to the channel over which they were requested, as well as providing a mechanism for buffering the data and moderate its delivery to avoid network congestion in case of bulk delivery of a large amount of items. The class has few methods that can be used to control the delivery process.

Note that even if onObjectReset() returns false, the framework uses the same Resetter object that was provided to it for automatic object reset, therefore giving the method a chance to fine tune the Resetter object used for automatic reset.

  • Method Details

    • getObjectCode

      public String getObjectCode()
      Returns the Object Code of the data objects requested by this resetter.
      Returns:
      the Object Code of the data objects requested by this resetter.

    • resetObject

      public boolean resetObject​(DataObject object)
      Resets one item.

      Your reset procedure shall call this method for each item you want to reset. The method accepts as a parameter one data object that shall be of the same Object Code as the resetter object and buffers it for delivery to the reset requester.

      The method returns true if the operation is successful. It returns false in the following cases:

      • The type of the item to reset differs from this Resetter type.
      • The buffer is full and is not defined lossless.
      • This Resetter has been aborted.
      Parameters:
      object - the item to reset.
      Returns:
      true if and only if the reset object has been buffered for delivery successfully.

    • endOfData

      public void endOfData()
      Marks end of data.

      Call this method to mark the end of reset data. When the reset buffer is fully flushed for delivery Main.onResetCompleted() is called.

    • setMaxCapacity

      public void setMaxCapacity​(int capacity)
      Sets the maximum capacity of the resetter buffer.

      The resetter mechanism uses a buffer to moderate delivery rate. When the buffer gets full, if the resetter is set to lossless then further calls to resetObject() block until buffer space is freed, otherwise excess data is discarded and data is lost.

      Call this method to set the resetter buffer capacity. The default is 200K items.

      Parameters:
      capacity - Resetter buffer capacity in number of reset items.

    • setLossless

      public void setLossless​(boolean lossless)
      Sets lossless mode.

      The resetter mechanism uses a buffer to moderate delivery rate. When the buffer gets full, if the resetter is set to lossless then further calls to resetObject() block until buffer space is freed, otherwise excess data is discarded and data is lost.

      By default resetters are lossy. Call this method with lossless value set to true to make it lossless.

      Parameters:
      lossless - true to set a lossless resetter, false to set a lossy resetter.

    • setResetRate

      public void setResetRate​(int rate)
      Sets the reset rate in elements per minute.

      Calls this method to set reset rate to the given amount of elements per minute. A zero value eliminates the moderation effect, causing every element to be sent as soon as possible. A negative value (the default) tells the resetter to take the value from [stream rate] property of the application's configuration file. The default value, if that property does not exist, is 30,000 elements per minute.

      Parameters:
      rate - reset rate in elements per minute, zero to eliminate moderation and negative value to use the configured value.

    • getResetCount

      public final int getResetCount()
      Returns the number of items that were delivered by this resetter since it restarted.
      Returns:
      the number of items that were delivered by this resetter since it restarted.

    • getStartReset

      public final ZDate getStartReset()
      Returns the time reset was restarted.
      Returns:
      the time reset was restarted.

    • isAborted

      public boolean isAborted()
      Returns true if the current Resetter object is aborted by an overriding reset request.

      This happens when a new object reset request arrives from the same channel that previously requested a reset for the same object type and processing of that request has not finished yet. In this case the current object stops processing further resetObject() requests, but your implementation of onObjectReset() would not know it. You can call this method to check if resetting has been aborted and do something accordingly.

      Returns:
      true if and only if the current Resetter object is aborted by an overriding reset request.