Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F76029216
AcknowledgedCounterGenerator.java
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Mon, Aug 5, 20:00
Size
2 KB
Mime Type
text/x-java
Expires
Wed, Aug 7, 20:00 (2 d)
Engine
blob
Format
Raw Data
Handle
19630854
Attached To
R7507 YCSB
AcknowledgedCounterGenerator.java
View Options
/**
* Copyright (c) 2015 YCSB contributors. 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
;
import
java.util.concurrent.locks.ReentrantLock
;
/**
* A CounterGenerator that reports generated integers via lastInt()
* only after they have been acknowledged.
*/
public
class
AcknowledgedCounterGenerator
extends
CounterGenerator
{
/** The size of the window of pending id ack's. 2^20 = {@value} */
static
final
int
WINDOW_SIZE
=
Integer
.
rotateLeft
(
1
,
20
);
/** The mask to use to turn an id into a slot in {@link #window}. */
private
static
final
int
WINDOW_MASK
=
WINDOW_SIZE
-
1
;
private
final
ReentrantLock
lock
;
private
final
boolean
[]
window
;
private
volatile
int
limit
;
/**
* Create a counter that starts at countstart.
*/
public
AcknowledgedCounterGenerator
(
int
countstart
)
{
super
(
countstart
);
lock
=
new
ReentrantLock
();
window
=
new
boolean
[
WINDOW_SIZE
];
limit
=
countstart
-
1
;
}
/**
* In this generator, the highest acknowledged counter value
* (as opposed to the highest generated counter value).
*/
@Override
public
int
lastInt
()
{
return
limit
;
}
/**
* Make a generated counter value available via lastInt().
*/
public
void
acknowledge
(
int
value
)
{
final
int
currentSlot
=
(
value
&
WINDOW_MASK
);
if
(
window
[
currentSlot
]
==
true
)
{
throw
new
RuntimeException
(
"Too many unacknowledged insertion keys."
);
}
window
[
currentSlot
]
=
true
;
if
(
lock
.
tryLock
())
{
// move a contiguous sequence from the window
// over to the "limit" variable
try
{
// Only loop through the entire window at most once.
int
beforeFirstSlot
=
(
limit
&
WINDOW_MASK
);
int
index
;
for
(
index
=
limit
+
1
;
index
!=
beforeFirstSlot
;
++
index
)
{
int
slot
=
(
index
&
WINDOW_MASK
);
if
(!
window
[
slot
])
{
break
;
}
window
[
slot
]
=
false
;
}
limit
=
index
-
1
;
}
finally
{
lock
.
unlock
();
}
}
}
}
Event Timeline
Log In to Comment