org.jgroups.util.Headers Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
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;
/**
* Open addressing based implementation of a hashmap (not supporting the Map interface though) for message
* headers. The keys are shorts (IDs) and the values Headers, and they're stored in 2 arrays: an ID array and a headers
* array. The indices of the IDs array corespond with the headers array, e.g.
*
* IDs: id-1 | id-2 | id-3 | ... | id-n |
* Headers: hdr-1 | hdr-2 | hdr-3 | ... | hdr-n |
*
*
* The arrays are populated from left to right, and any 0 slots in 'ids' can terminate an interation, or signal empty slots.
*
* 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 short[] ids;
private Header[] hdrs;
/** Add space for 3 new elements when resizing */
private static final int RESIZE_INCR=3;
public Headers(int capacity) {
init(capacity);
}
protected Headers() {}
public short[] getRawIDs() {
return ids;
}
public Header[] getRawHeaders() {
return hdrs;
}
public synchronized Headers copy() {
if(ids == null || hdrs == null)
return new Headers();
Headers retval=new Headers(ids.length);
System.arraycopy(ids, 0, retval.ids, 0, ids.length);
System.arraycopy(hdrs, 0, retval.hdrs, 0, hdrs.length);
return retval;
}
/**
* Returns the header associated with an ID
* @param id The ID
* @return
*/
public Header getHeader(short id) {
for(int i=0; i < ids.length; i++) {
short current_id=ids[i];
if(current_id == 0)
return null;
if(current_id == id)
return hdrs[i];
}
return null;
}
public Map getHeaders() {
Map retval=new HashMap<>(ids.length);
for(int i=0; i < ids.length; i++) {
if(ids[i] > 0)
retval.put(ids[i], hdrs[i]);
else
break;
}
return retval;
}
public String printHeaders() {
StringBuilder sb=new StringBuilder();
boolean first=true;
for(int i=0; i < ids.length; i++) {
if(ids[i] > 0) {
if(first)
first=false;
else
sb.append(", ");
Class clazz=ClassConfigurator.getProtocol(ids[i]);
String name=clazz != null? clazz.getSimpleName() : Short.toString(ids[i]);
sb.append(name).append(": ").append(hdrs[i]);
}
else
break;
}
return sb.toString();
}
/** Puts a header given a key into the hashmap. Overwrites potential existing entry. */
public void putHeader(short id, Header hdr) {
_putHeader(id, hdr, 0, true);
}
/**
* Puts a header given a key into the map, only if the key doesn't exist yet
* @param id
* @param hdr
* @return the previous value associated with the specified id, or
* null if there was no mapping for the id.
* (A null return can also indicate that the map
* previously associated null with the id,
* if the implementation supports null values.)
*/
public Header putHeaderIfAbsent(short id, Header hdr) {
return _putHeader(id, hdr, 0, false);
}
public int marshalledSize() {
int retval=0;
for(int i=0; i < ids.length; i++) {
if(ids[i] > 0) {
retval+=Global.SHORT_SIZE *2; // for protocol ID and magic number
retval+=hdrs[i].size();
}
else
break;
}
return retval;
}
public int size() {
int retval=0;
for(int i=0; i < ids.length; i++) {
if(ids[i] > 0)
retval++;
else
break;
}
return retval;
}
public int size(short ... excluded_ids) {
int retval=0;
for(int i=0; i < ids.length; i++) {
if(ids[i] > 0) {
if(!Util.containsId(ids[i], excluded_ids))
retval++;
}
else
break;
}
return retval;
}
public int capacity() {
return ids.length;
}
public String printObjectHeaders() {
StringBuilder sb=new StringBuilder();
for(int i=0; i < ids.length; i++) {
if(ids[i] > 0)
sb.append(ids[i]).append(": ").append(hdrs[i]).append('\n');
else
break;
}
return sb.toString();
}
public String toString() {
return printHeaders();
}
protected void init(int length) {
ids=new short[length];
hdrs=new Header[length];
}
/**
* Increases the capacity of the array and copies the contents of the old into the new array
*/
private void resize() {
int new_capacity=ids.length + RESIZE_INCR;
short[] new_ids=new short[new_capacity];
Header[] new_hdrs=new Header[new_capacity];
System.arraycopy(ids, 0, new_ids, 0, ids.length);
System.arraycopy(hdrs, 0, new_hdrs, 0, hdrs.length);
ids=new_ids;
hdrs=new_hdrs;
}
private synchronized Header _putHeader(short id, Header hdr, int start_index, boolean replace_if_present) {
int i=start_index;
while(i < ids.length) {
if(ids[i] == 0) {
ids[i]=id;
hdrs[i]=hdr;
return null;
}
if(ids[i] == id) {
Header retval=hdrs[i];
if(replace_if_present || retval == null) {
hdrs[i]=hdr;
}
return retval;
}
i++;
if(i >= ids.length) {
resize();
}
}
throw new IllegalStateException("unable to add element " + id + ", index=" + i); // we should never come here
}
}