Package com.sas.services.util

Class WaitPolicy

java.lang.Object
com.sas.services.util.WaitPolicy
public class WaitPolicy extends Object
Defines a wait policy. This class defines a wait policy. Typically a consumer using an API will specify a wait policy (construct an object of this class) if API uses a resource which needs to be locked. The API implementer will use the wait policy in conjunction with the Waiter class to determine how frequently to test for the availability of the resource.

A wait policy of WaitPolicy.TYPE.NONE implies the consumer does not want to wait. An API implementer when encountering a locked resource should notify the consumer that the operation could not be performed since the consumer has requested that waiting not be done.

A wait policy of WaitPolicy.TYPE.FINITE implies the consumer is prepared to wait a finite amount of time. An API implementer when encountering a locked resource will poll it at the intervals specified in this policy using Waiter.sleep(). If at the end of the time specified by the consumer, the resource is still locked behavior is similar to the WaitPolicy.TYPE.NONE case encountering a locked resource.

A wait policy of WaitPolicy.TYPE.INFINITE implies the consumer is prepared to wait an infinite amount of time. An API implementer when encountering a locked resource will poll it at the intervals specified in this policy using Waiter.sleep(). Since no time limit has been specified the polling is only stopped once the resource is unlocked.

The values specified for initialWait, waitIncrement, minimumWait, maximumWait and totalWait dictate the behavior of the Waiter.sleep(). initialWait sets the time for the first sleep. waitIncrement can be either positive or negative and subsequent sleep periods are adjusted by waitIncrement subject to the bounds imposed by minimumWait and maximumWait. totalWait is only used in the WaitPolicy.TYPE.FINITE case.

  • Field Details

  • Constructor Details

    • WaitPolicy

      public WaitPolicy(WaitPolicy.TYPE type) throws ServiceException
      Construct a wait policy using default values. This method is typically used to construct a policy of WaitPolicy.TYPE.NONE. For other types of policies the values used will be static fields ending with the "_N" suffix defined by this class.
      Parameters:
      type - the type of the policy
      Throws:
      ServiceException

    • WaitPolicy

      public WaitPolicy(WaitPolicy.TYPE type, int initialWait, int waitIncrement, int minimumWait, int maximumWait, long totalWait) throws ServiceException
      Construct a wait policy using the values specified. If the type desired is WaitPolicy.TYPE.NONE values specified for the other parameters are ignored. If the type desired is WaitPolicy.TYPE.INFINITE the value for totalWait is ignored. The units for the value of all parameters except type is milliseconds.
      Parameters:
      type - the type of the policy
      initialWait - the duration of the first wait
      waitIncrement - the change (positive or negative) in wait time for subsequent waits
      minimumWait - the lower bound on the wait time
      maximumWait - the upper bound on the wait time
      totalWait - the total time to wait
      Throws:
      ServiceException

  • Method Details

    • getType

      public WaitPolicy.TYPE getType()

    • getInitialWait

      public int getInitialWait()

    • getWaitIncrement

      public int getWaitIncrement()

    • getMinimumWait

      public int getMinimumWait()

    • getMaximumWait

      public int getMaximumWait()

    • getTotalWait

      public long getTotalWait()

    • getDefaultWaitPolicy

      public static WaitPolicy getDefaultWaitPolicy(WaitPolicy.TYPE type, String prefix) throws ServiceException
      Gets the default wait policy. Constructs a WaitPolicy whose type is that specified by the type parameter and values obtained from the environment. The values it uses for the constructor are the values obtained using the prefix parameter, a known suffix and the System.getProperty() method.

      An example is used to illustrate the process. If the prefix parameter has a value of "com.sas.mypackage", then the initial wait value obtained by appending a dot and INITIAL_WAIT_KEY (whose value is "InitialWait") to the prefix results in a key of "com.sas.mypackage.InitialWait" which is used in a call to System.getProperty(). The default value used if there is no such property defined is the value of INITIAL_WAIT_VALUE_S.

      If the type requested is WaitPolicy.TYPE.NONE, no attempt is made to obtain values.

      If the type requested is WaitPolicy.TYPE.INFINITE, no attempt is made to obtain the total wait value which is not needed.

      If a null or an empty prefix is supplied the key used is just the name - "InitialWait" in the example described above.

      Parameters:
      type - the type of the policy
      prefix - prefix without the trailing dot used to find property value
      Returns:
      Throws:
      ServiceException - if invalid values are specified