org.jgroups.util.Headers Maven / Gradle / Ivy
package org.jgroups.util;
import org.jgroups.Global;
import org.jgroups.Header;
import org.jgroups.conf.ClassConfigurator;
import java.util.HashMap;
import java.util.Map;
/**
* Helper class providing functions to manipulate the {@link org.jgroups.Message#headers} array. The headers are stored
* in the array as follows:
*
* Headers: hdr-1 | hdr-2 | hdr-3 | ... | hdr-n |
*
*
* The arrays are populated from left to right, and any empty slot in 'headers' can terminate an interation
* (e.g. a getHeader())
*
* It is assumed that we only have a few headers, 3-4 on average. Note that getting a header for a given key and
* putting a new key/header are operations with O(n) cost, so this implementation is not recommended for
* a large number of elements.
*
* This class is synchronized for writes (put(), resize()), but not for reads (size(), get())
* @author Bela Ban
*/
public class Headers {
private static final int RESIZE_INCR=3;
/**
* Returns the header associated with an ID
* @param id The ID
* @return
*/
public static Header getHeader(final Header[] hdrs, short id) {
if(hdrs == null)
return null;
for(Header hdr: hdrs) {
if(hdr == null)
return null;
if(hdr.getProtId() == id)
return hdr;
}
return null;
}
public static Map getHeaders(final Header[] hdrs) {
if(hdrs == null)
return new HashMap<>();
Map retval=new HashMap<>(hdrs.length);
for(Header hdr: hdrs) {
if(hdr == null)
break;
retval.put(hdr.getProtId(), hdr);
}
return retval;
}
public static String printHeaders(final Header[] hdrs) {
if(hdrs == null)
return "";
StringBuilder sb=new StringBuilder();
boolean first=true;
for(Header hdr: hdrs) {
if(hdr == null)
break;
short id=hdr.getProtId();
if(first)
first=false;
else
sb.append(", ");
Class clazz=ClassConfigurator.getProtocol(id);
String name=clazz != null? clazz.getSimpleName() : Short.toString(id);
sb.append(name).append(": ").append(hdr);
}
return sb.toString();
}
/**
* Adds hdr at the next available slot. If none is available, the headers array passed in will be copied and the copy
* returned
* @param headers The headers array
* @param id The protocol ID of the header
* @param hdr The header
* @param replace_if_present Whether or not to overwrite an existing header
* @return A new copy of headers if the array needed to be expanded, or null otherwise
*/
public static Header[] putHeader(final Header[] headers, short id, Header hdr, boolean replace_if_present) {
int i=0;
Header[] hdrs=headers;
boolean resized=false;
while(i < hdrs.length) {
if(hdrs[i] == null) {
hdrs[i]=hdr;
return resized? hdrs: null;
}
short hdr_id=hdrs[i].getProtId();
if(hdr_id == id) {
if(replace_if_present || hdrs[i] == null)
hdrs[i]=hdr;
return resized? hdrs : null;
}
i++;
if(i >= hdrs.length) {
hdrs=resize(hdrs);
resized=true;
}
}
throw new IllegalStateException("unable to add element " + id + ", index=" + i); // we should never come here
}
/**
* Increases the capacity of the array and copies the contents of the old into the new array
*/
public static Header[] resize(final Header[] headers) {
int new_capacity=headers.length + RESIZE_INCR;
Header[] new_hdrs=new Header[new_capacity];
System.arraycopy(headers, 0, new_hdrs, 0, headers.length);
return new_hdrs;
}
public static Header[] copy(final Header[] headers) {
if(headers == null)
return new Header[0];
Header[] retval=new Header[headers.length];
System.arraycopy(headers, 0, retval, 0, headers.length);
return retval;
}
public static String printObjectHeaders(final Header[] hdrs) {
if(hdrs == null)
return "";
StringBuilder sb=new StringBuilder();
for(Header hdr: hdrs) {
if(hdr == null)
break;
sb.append(hdr.getProtId()).append(": ").append(hdr).append('\n');
}
return sb.toString();
}
public static int marshalledSize(final Header[] hdrs) {
int retval=0;
if(hdrs == null)
return retval;
for(Header hdr: hdrs) {
if(hdr == null)
break;
retval+=Global.SHORT_SIZE *2; // for protocol ID and magic number
retval+=hdr.size();
}
return retval;
}
public static int size(Header[] hdrs) {
int retval=0;
if(hdrs == null)
return retval;
for(Header hdr: hdrs) {
if(hdr == null)
break;
retval++;
}
return retval;
}
public static int size(Header[] hdrs, short... excluded_ids) {
int retval=0;
if(hdrs == null)
return retval;
for(Header hdr: hdrs) {
if(hdr == null)
break;
if(!Util.containsId(hdr.getProtId(), excluded_ids))
retval++;
}
return retval;
}
}