ID2Count.java revision 7a0b4fed1cfa0934091355444cc4bc2fb48997ac
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at legal-notices/CDDLv1_0.txt.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information:
* Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*
* Copyright 2015 ForgeRock AS
*/
/**
* Store a counter associated to a key. Counter value is sharded amongst multiple keys to allow concurrent
* update without contention (at the price of a slower read).
*/
final class ID2Count extends AbstractTree
{
/**
* Must be a power of 2 @see <a href="http://en.wikipedia.org/wiki/Modulo_operation#Performance_issues">Performance
* issues</a>
*/
private static final long SHARD_COUNT = 4096;
{
super(name);
}
{
{
}
{
{
}
});
}
/**
* Updates the counter associated with the given key, but does not update the total count.
* <p>
* Implementation note: this method accepts a {@code null} entryID in order to eliminate null checks in client code.
* In particular, client code has to deal with the special case where a target entry does not have a parent because
* the target entry is a base entry within the backend.
*
* @param txn storage transaction
* @param entryID The entryID identifying to the counter, which may be
* {@code null} in which case calling this method has no effect.
* @param delta The value to add. Can be negative to decrease counter value.
*/
{
}
}
/**
* Updates the total count which should be the sum of all counters.
* @param txn storage transaction
* @param delta The value to add. Can be negative to decrease counter value.
*/
}
{
{
{
}
});
}
{
}
{
}
{
if (delta != 0)
{
}
}
{
}
{
}
{
}
{
return (keyID == TOTAL_COUNT_ENTRY_ID.longValue() ? "Total Children Count" : keyID) + "#" + shardBucket;
}
{
}
{
return entryID.toByteString();
}
/**
* Get the counter value for the specified key
* @param txn storage transaction
* @param entryID The entryID identifying to the counter
* @return Value of the counter. 0 if no counter is associated yet.
*/
{
long counterValue = 0;
{
}
}
return counterValue;
}
}
}
/**
* Get the total counter value. The total counter maintain the sum of all
* the counter contained in this tree.
* @param txn storage transaction
* @return Sum of all the counter contained in this tree
*/
{
}
/**
* Removes the counter associated to the given key, but does not update the total count.
* @param txn storage transaction
* @param entryID The entryID identifying the counter
* @return Value of the counter before it's deletion.
*/
long counterValue = 0;
// Iterate over and remove all the thread local shards
}
}
}
return counterValue;
}
}