[jboss-jira] [JBoss JIRA] Created: (JGRP-1066) Introduce dependencies for @Property annotations

[Richard Achmatowicz (JIRA)]

Introduce dependencies for @Property annotations
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                 Key: JGRP-1066
                 URL: https://jira.jboss.org/jira/browse/JGRP-1066
             Project: JGroups
          Issue Type: Feature Request
    Affects Versions: 2.8
            Reporter: Richard Achmatowicz
            Assignee: Richard Achmatowicz
            Priority: Minor
             Fix For: 2.8


When processing properties annotated by @Property in protocols, there is a need to reference one property when processing anoither; an example is that the setting of initial_hosts requires a list of host[port] entries, as well as a port_range value. Usually, this sort of property processing requirement forced delaying the processing of initial_hosts in the init() phase, after protocol property processing had completed. 

We introduce a dependency mechanism for @Property annotations:

1. @Properties have a name - it can either be explicitly specified in the annotation
@Property(name=X)
int i = 0 ;
or it can default to the variable name of a Field
@Property(desc=...)
int Y = 0 ;
ir it can default to the method name without the prefix set.
@Property(desc=...)
void setZ(int i)

2. You can specify a dependency on one or more properties (fields or methods) in the same protocol by specifying a comma separated list of @Property names in a dependsUpon attribte:
@Property(name="X", desc=..., dependsUpon="Y,Z")
int i = 0 ;
This ensures that properties Y and Z will be processed by their converters (default or specified) before property X is processed.

3. Which leads to the main reason for introducing dependscies: in this way, the converter for property X may refer to the converters for property Y and Z in its processing.

   public static class InitialHosts implements PropertyConverter{
       public Object convert(Protocol protocol, Class<?> propertyFieldType, Properties props, String propertyValue) throws Exception {
           int port_range = getPortRange(protocol) ;
           List<IpAddress> addresses = Util.parseCommaDelimitedHosts(propertyValue, port_range) ;               return addresses ;
       }
       private int getPortRange(Protocol protocol) {
           int port_range = 0 ;              try {
               Field f = protocol.getClass().getDeclaredField("port_range") ;
               port_range = ((Integer) Configurator.getField(f,protocol)).intValue() ;
           }
           catch(NoSuchFieldException e) {                  System.out.println("InitialHosts: no such field: port_range");
           }
           return port_range ;
       }
   }


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