/***************************************************************************
* Copyright (C) 2012 by H-Store Project *
* Brown University *
* Massachusetts Institute of Technology *
* Yale University *
* *
* http://hstore.cs.brown.edu/ *
* *
* Permission is hereby granted, free of charge, to any person obtaining *
* a copy of this software and associated documentation files (the *
* "Software"), to deal in the Software without restriction, including *
* without limitation the rights to use, copy, modify, merge, publish, *
* distribute, sublicense, and/or sell copies of the Software, and to *
* permit persons to whom the Software is furnished to do so, subject to *
* the following conditions: *
* *
* The above copyright notice and this permission notice shall be *
* included in all copies or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, *
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR *
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, *
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR *
* OTHER DEALINGS IN THE SOFTWARE. *
***************************************************************************/
package edu.brown.benchmark.auctionmark.util;
import java.util.Iterator;
import org.voltdb.utils.NotImplementedException;
import edu.brown.statistics.Histogram;
public class UserIdGenerator implements Iterator<UserId> {
private final int numClients;
private final Integer clientId;
private final Histogram<Long> users_per_item_count;
private final long min_count;
private final long max_count;
private UserId next = null;
private Long currentItemCount = null;
private long currentOffset;
private int currentPosition = 0;
/**
* Construct a new generator based on the given histogram.
* If clientId is not null, then this generator will only return UserIds that are mapped
* to that clientId based on the UserId's offset
* @param users_per_item_count
* @param numClients
* @param clientId
*/
public UserIdGenerator(Histogram<Long> users_per_item_count, int numClients, Integer clientId) {
if (numClients <= 0)
throw new IllegalArgumentException("numClients must be more than 0 : " + numClients);
if (clientId != null && clientId < 0)
throw new IllegalArgumentException("clientId must be more than or equal to 0 : " + clientId);
this.numClients = numClients;
this.clientId = clientId;
this.users_per_item_count = users_per_item_count;
this.min_count = users_per_item_count.getMinValue();
this.max_count = users_per_item_count.getMaxValue();
this.setCurrentItemCount(this.min_count);
}
public UserIdGenerator(Histogram<Long> users_per_item_count, int numClients) {
this(users_per_item_count, numClients, null);
}
public long getTotalUsers() {
return (this.users_per_item_count.getSampleCount());
}
public void setCurrentItemCount(long size) {
// It's lame, but we need to make sure that we prime total_ctr
// so that we always get the same UserIds back per client
this.currentPosition = 0;
for (long i = 0; i < size; i++) {
this.currentPosition += this.users_per_item_count.get(i, 0);
} // FOR
this.currentItemCount = size;
this.currentOffset = this.users_per_item_count.get(this.currentItemCount, 0);
}
public long getCurrentPosition() {
return (this.currentPosition);
}
public UserId seekToPosition(long position) {
assert(position <= this.getTotalUsers()) : String.format("%d < %d", position, this.getTotalUsers());
UserId user_id = null;
while (this.currentPosition < position) {
user_id = this.next();
} // WHILE
return (user_id);
}
private UserId findNextUserId() {
// Find the next id for this size level
Long found = null;
while (this.currentItemCount <= this.max_count) {
while (this.currentOffset > 0) {
long nextCtr = this.currentOffset--;
this.currentPosition++;
// If we weren't given a clientId, then we'll generate UserIds
// for all users in a given size level
if (this.clientId == null) {
found = nextCtr;
break;
}
// Otherwise we have to spin through and find one for our client
else if (this.currentPosition % this.numClients == this.clientId) {
found = nextCtr;
break;
}
} // WHILE
if (found != null) break;
this.currentItemCount++;
this.currentOffset = (int)this.users_per_item_count.get(this.currentItemCount, 0);
} // WHILE
if (found == null) return (null);
return (new UserId(this.currentItemCount.intValue(), found.intValue()));
}
@Override
public synchronized boolean hasNext() {
if (this.next == null) {
synchronized (this) {
if (this.next == null) this.next = this.findNextUserId();
}
}
return (this.next != null);
}
@Override
public synchronized UserId next() {
if (this.next == null) {
this.next = this.findNextUserId();
}
UserId ret = this.next;
this.next = null;
return (ret);
}
@Override
public void remove() {
throw new NotImplementedException("Cannot call remove!!");
}
}