package org.jgroups.util;
import org.jgroups.Global;
import org.jgroups.Header;
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 strings and the values Headers, and they're stored in an array in the format
* key-1 | header-1 | key-2 | header-2. The array is populated from left to right, so any null slots can terminate
* an interation, or signal empty slots.
* <br/>
* 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 <em>not</em> recommended for
* a large number of elements.
* <br/>
* This class is not synchronized
* @author Bela Ban
* @version $Id: Headers.java,v 1.15 2010/02/10 17:17:45 belaban Exp $
*/
public class Headers {
/** Used to store strings and headers, e.g: name-1 | header-1 | name-2 | header-2 | null | null | name-3 | header-3 */
private Object[] data;
/** Add space for 3 new elements when resizing */
private static final int RESIZE_INCR=6;
public Headers(int initial_capacity) {
data=new Object[initial_capacity << 1];
}
public Headers(Headers hdrs) {
data=new Object[hdrs.data.length];
System.arraycopy(hdrs.data, 0, this.data, 0, hdrs.data.length);
}
public Object[] getRawData() {
return data;
}
/**
* Returns the header associated with key
* @param key
* @return
*/
public Header getHeader(String key) {
for(int i=0; i < data.length; i+=2) {
if(data[i] == null)
return null;
if(data[i].equals(key))
return (Header)data[i+1];
}
return null;
}
public Map<String,Header> getHeaders() {
Map<String,Header> retval=new HashMap<String,Header>(data.length / 2);
for(int i=0; i < data.length; i+=2) {
if(data[i] != null)
retval.put((String)data[i], (Header)data[i+1]);
else
break;
}
return retval;
}
public String printHeaders() {
StringBuilder sb=new StringBuilder();
boolean first=true;
for(int i=0; i < data.length; i+=2) {
if(data[i] != null) {
if(first)
first=false;
else
sb.append(", ");
sb.append(data[i]).append(": ").append(data[i+1]);
}
else
break;
}
return sb.toString();
}
/** Puts a header given a key into the hashmap. Overwrites potential existing entry. */
public void putHeader(String key, Header hdr) {
_putHeader(key, hdr, 0, true);
}
/**
* Puts a header given a key into the map, only if the key doesn't exist yet
* @param key
* @param hdr
* @return the previous value associated with the specified key, or
* <tt>null</tt> if there was no mapping for the key.
* (A <tt>null</tt> return can also indicate that the map
* previously associated <tt>null</tt> with the key,
* if the implementation supports null values.)
*/
public Header putHeaderIfAbsent(String key, Header hdr) {
return _putHeader(key, hdr, 0, false);
}
/**
*
* @param key
* @return the header assoaicted with key
* @deprecated Use getHeader() instead. The issue with removing a header is described in
* http://jira.jboss.com/jira/browse/JGRP-393
*/
public Header removeHeader(String key) {
return getHeader(key);
}
public Headers copy() {
return new Headers(this);
}
public int marshalledSize() {
int retval=0;
for(int i=0; i < data.length; i+=2) {
if(data[i] != null) {
retval+=((String)data[i]).length() +2;
retval+=(Global.SHORT_SIZE); // 2 for magic number
retval+=((Header)data[i+1]).size();
}
else
break;
}
return retval;
}
public int size() {
int retval=0;
for(int i=0; i < data.length; i+=2) {
if(data[i] != null)
retval++;
else
break;
}
return retval;
}
public int capacity() {
return data.length / 2;
}
public String printObjectHeaders() {
StringBuilder sb=new StringBuilder();
for(int i=0; i < data.length; i+=2) {
if(data[i] != null)
sb.append(data[i]).append(": ").append(data[i+1]).append('\n');
else
break;
}
return sb.toString();
}
public String toString() {
return printHeaders();
}
/**
* Increases the capacity of the array and copies the contents of the old into the new array
*/
private void resize() {
int new_size=data.length + RESIZE_INCR;
Object[] new_data=new Object[new_size];
System.arraycopy(data, 0, new_data, 0, data.length);
data=new_data;
}
private Header _putHeader(String key, Header hdr, int start_index, boolean replace_if_present) {
int i=start_index;
while(i < data.length) {
if(data[i] == null) {
data[i]=key;
data[i+1]=hdr;
return null;
}
if(data[i].equals(key)) {
Header retval=(Header)data[i+1];
if(replace_if_present) {
data[i+1]=hdr;
}
return retval;
}
i+=2;
if(i >= data.length) {
resize();
}
}
throw new IllegalStateException("unable to add element " + key + ", index=" + i); // we should never come here
}
}