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/*
D-Bus Java Implementation
Copyright (c) 2005-2006 Matthew Johnson
This program is free software; you can redistribute it and/or modify it
under the terms of either the GNU Lesser General Public License Version 2 or the
Academic Free Licence Version 2.1.
Full licence texts are included in the COPYING file with this program.
*/
package org.freedesktop.dbus;
/**
* Provides a long => MethodCall map which doesn't allocate objects
* on insertion/removal. Keys must be inserted in ascending order. */
class EfficientMap
{
private long[] kv;
private MethodCall[] vv;
private int start;
private int end;
private int init_size;
public EfficientMap(int initial_size)
{
init_size = initial_size;
shrink();
}
private void grow()
{
// create new vectors twice as long
long[] oldkv = kv;
kv = new long[oldkv.length*2];
MethodCall[] oldvv = vv;
vv = new MethodCall[oldvv.length*2];
// copy start->length to the start of the new vector
System.arraycopy(oldkv,start,kv,0,oldkv.length-start);
System.arraycopy(oldvv,start,vv,0,oldvv.length-start);
// copy 0->end to the next part of the new vector
if (end != (oldkv.length-1)) {
System.arraycopy(oldkv,0,kv,oldkv.length-start,end+1);
System.arraycopy(oldvv,0,vv,oldvv.length-start,end+1);
}
// reposition pointers
start = 0;
end = oldkv.length;
}
// create a new vector with just the valid keys in and return it
public long[] getKeys()
{
int size;
if (start < end) size = end-start;
else size = kv.length-(start-end);
long[] lv = new long[size];
int copya;
if (size > kv.length-start) copya = kv.length-start;
else copya = size;
System.arraycopy(kv,start,lv,0,copya);
if (copya < size) {
System.arraycopy(kv,0,lv,copya,size-copya);
}
return lv;
}
private void shrink()
{
if (null != kv && kv.length == init_size) return;
// reset to original size
kv = new long[init_size];
vv = new MethodCall[init_size];
start = 0;
end = 0;
}
public void put(long l, MethodCall m)
{
// put this at the end
kv[end] = l;
vv[end] = m;
// move the end
if (end == (kv.length-1)) end = 0; else end++;
// if we are out of space, grow.
if (end == start) grow();
}
public MethodCall remove(long l)
{
// find the item
int pos = find(l);
// if we don't have it return null
if (-1 == pos) return null;
// get the value
MethodCall m = vv[pos];
// set it as unused
vv[pos] = null;
kv[pos] = -1;
// move the pointer to the first full element
while (-1 == kv[start]) {
if (start == (kv.length-1)) start = 0; else start++;
// if we have emptied the list, shrink it
if (start == end) { shrink(); break; }
}
return m;
}
public boolean contains(long l)
{
// check if find succeeds
return -1 != find(l);
}
/* could binary search, but it's probably the first one */
private int find(long l)
{
int i = start;
while (i != end && kv[i] != l)
if (i == (kv.length-1)) i = 0; else i++;
if (i == end) return -1;
return i;
}
}
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