/**
* Copyright 2013, Landz and its 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.
*/
package z.util.concurrent;
import java.util.function.Supplier;
import static z.util.Unsafes.currentThreadId;
/**
*/
public class ThreadLocalValueHolder<T> implements AutoCloseable {
private static final int MAX_SUPPORTED_THREAD_ID = 1024;//FIXME
//TODO: false sharing
private final T[] tlValues = (T[])new Object[MAX_SUPPORTED_THREAD_ID];
private final Supplier<T> supplier;//return supplier.get();
public ThreadLocalValueHolder(Supplier<T> supplier) {
this.supplier = supplier;
}
public T get() {
int tid = (int)currentThreadId();
//FIXME as contract
if (tid==MAX_SUPPORTED_THREAD_ID)
throw new IllegalStateException(
"the supported threadId should be less than "
+MAX_SUPPORTED_THREAD_ID);
T rt = tlValues[tid];
if (rt==null) {
rt = supplier.get();
tlValues[tid] = rt;
}
return rt;
}
@Override
public void close() throws Exception {
for (int i = 0; i < tlValues.length; i++) {
T tlValue = tlValues[i];
if (tlValue instanceof AutoCloseable)
((AutoCloseable)tlValue).close();
tlValues[i] = null;
}
}
}