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SkewedLatestGenerator.java
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Created
Sat, Oct 19, 14:59
Size
3 KB
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text/x-c
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Mon, Oct 21, 14:59 (1 d, 21 h)
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21794096
Attached To
R7507 YCSB
SkewedLatestGenerator.java
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/**
* Copyright (c) 2010 Yahoo! Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you
* may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License. See accompanying
* LICENSE file.
*/
package
com.yahoo.ycsb.generator
;
/**
* Generate a popularity distribution of items, skewed to favor recent items significantly more than older items.
*/
public
class
SkewedLatestGenerator
extends
NumberGenerator
{
private
CounterGenerator
_basis
;
private
final
ZipfianGenerator
_zipfian
;
public
SkewedLatestGenerator
(
CounterGenerator
basis
)
{
_basis
=
basis
;
_zipfian
=
new
ZipfianGenerator
(
_basis
.
lastValue
());
nextValue
();
}
/**
* Generate the next string in the distribution, skewed Zipfian favoring the items most recently returned by the basis generator.
*/
@Override
public
Long
nextValue
()
{
long
max
=
_basis
.
lastValue
();
long
next
=
max
-
_zipfian
.
nextLong
(
max
);
setLastValue
(
next
);
return
next
;
}
public
static
void
main
(
String
[]
args
)
{
SkewedLatestGenerator
gen
=
new
SkewedLatestGenerator
(
new
CounterGenerator
(
1000
));
for
(
int
i
=
0
;
i
<
Integer
.
parseInt
(
args
[
0
]);
i
++)
{
System
.
out
.
println
(
gen
.
nextString
());
}
}
@Override
public
double
mean
()
{
throw
new
UnsupportedOperationException
(
"Can't compute mean of non-stationary distribution!"
);
}
}
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