-
Notifications
You must be signed in to change notification settings - Fork 26
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
impl: Factor Thread Storage into pluggable provider
- Loading branch information
1 parent
8e74dfa
commit 6e5673b
Showing
4 changed files
with
455 additions
and
64 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,32 @@ | ||
/* | ||
* Copyright 2022 Carl Mastrangelo | ||
* | ||
* 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 io.perfmark.impl; | ||
|
||
public abstract class LocalMarkHolder { | ||
|
||
/** | ||
* Removes the local markholder storage. | ||
*/ | ||
public abstract void clear(); | ||
|
||
public abstract MarkHolder acquire(); | ||
|
||
/** | ||
* This method is meant to be overridden and should not be called from subclasses. | ||
*/ | ||
public void release(MarkHolder markHolder) {} | ||
} |
155 changes: 155 additions & 0 deletions
155
impl/src/main/java/io/perfmark/impl/MostlyThreadLocal.java
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,155 @@ | ||
/* | ||
* Copyright 2022 Carl Mastrangelo | ||
* | ||
* 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 io.perfmark.impl; | ||
|
||
import java.util.concurrent.CopyOnWriteArrayList; | ||
import java.util.concurrent.atomic.AtomicReferenceArray; | ||
|
||
/** | ||
* This class tries to access the mark holder in a thread local. If the class is unable to store the created | ||
* MarkHolder in the thread local, a concurrent map of Thread to MarkHolders is used for lookup. In Java 19 | ||
* Thread Locals can be disabled due to use of Virtual threads. | ||
* | ||
* <p> | ||
* Note that this class avoids using {@link #initialValue()} because it may be called multiple times, in the | ||
* case that ThreadLocals are unsettable. | ||
*/ | ||
final class MostlyThreadLocal extends ThreadLocal<MarkHolder> { | ||
private static final int BITS = 11; | ||
private static final int SIZE = 1 << BITS; | ||
private static final int MASK = SIZE - 1; | ||
private static final AtomicReferenceArray<CopyOnWriteArrayList<Storage.MarkHolderHandle>> threadToHandles = | ||
new AtomicReferenceArray<CopyOnWriteArrayList<Storage.MarkHolderHandle>>(SIZE); | ||
|
||
MostlyThreadLocal() {} | ||
|
||
@Override | ||
public MarkHolder get() { | ||
MarkHolder markHolder = super.get(); | ||
if (markHolder != null) { | ||
return markHolder; | ||
} | ||
return getAndSetSlow(); | ||
} | ||
|
||
private MarkHolder getAndSetSlow() { | ||
assert super.get() == null; | ||
Thread thread = Thread.currentThread(); | ||
CopyOnWriteArrayList<Storage.MarkHolderHandle> handles = getHandles(thread); | ||
Storage.MarkHolderHandle markHolderHandle; | ||
MarkHolder markHolder; | ||
Storage.MarkHolderAndHandle markHolderAndHandle; | ||
if (handles == null) { | ||
markHolderAndHandle = Storage.allocateMarkHolder(); | ||
markHolder = markHolderAndHandle.markHolder(); | ||
assert markHolder != null; | ||
markHolderHandle = markHolderAndHandle.handle(); | ||
try { | ||
set(markHolder); | ||
return markHolder; | ||
} catch (UnsupportedOperationException e) { | ||
// ignore. | ||
} | ||
handles = getOrCreateHandles(thread); | ||
} else { | ||
if ((markHolderHandle = getConcurrent(handles)) != null) { | ||
if ((markHolder = markHolderHandle.markHolder()) != null) { | ||
return markHolder; | ||
} | ||
} | ||
markHolderAndHandle = Storage.allocateMarkHolder(); | ||
markHolder = markHolderAndHandle.markHolder(); | ||
assert markHolder != null; | ||
markHolderHandle = markHolderAndHandle.handle(); | ||
} | ||
handles.add(markHolderHandle); | ||
return markHolder; | ||
} | ||
|
||
@Override | ||
public void remove() { | ||
Thread thread = Thread.currentThread(); | ||
CopyOnWriteArrayList<Storage.MarkHolderHandle> handles = getHandles(thread); | ||
if (handles == null) { | ||
super.remove(); | ||
} else { | ||
assert super.get() == null; | ||
for (Storage.MarkHolderHandle handle : handles) { | ||
Thread t = handle.threadRef().get(); | ||
if (t == null || t == thread) { | ||
handles.remove(handle); | ||
} | ||
} | ||
} | ||
} | ||
|
||
/** | ||
* Returns the handles for the given thread index bucket, or {@code null}. | ||
*/ | ||
private static CopyOnWriteArrayList<Storage.MarkHolderHandle> getHandles(Thread thread) { | ||
int hashCode = System.identityHashCode(thread); | ||
int index = hashCode & MASK; | ||
return threadToHandles.get(index); | ||
} | ||
|
||
private static CopyOnWriteArrayList<Storage.MarkHolderHandle> getOrCreateHandles(Thread thread) { | ||
int hashCode = System.identityHashCode(thread); | ||
int index = hashCode & MASK; | ||
CopyOnWriteArrayList<Storage.MarkHolderHandle> handles; | ||
do { | ||
if ((handles = threadToHandles.get(index)) != null) { | ||
break; | ||
} | ||
} while ( | ||
!threadToHandles.compareAndSet(index, null, (handles = new CopyOnWriteArrayList<Storage.MarkHolderHandle>()))); | ||
return handles; | ||
} | ||
|
||
/** | ||
* May return {@code null} if not found. | ||
*/ | ||
private static Storage.MarkHolderHandle getConcurrent(CopyOnWriteArrayList<Storage.MarkHolderHandle> handles) { | ||
if (!handles.isEmpty()) { | ||
Storage.MarkHolderHandle handle; | ||
try { | ||
handle = handles.get(0); | ||
} catch (IndexOutOfBoundsException e) { | ||
return null; | ||
} | ||
if (handle.threadRef().get() == Thread.currentThread()) { | ||
return handle; | ||
} | ||
return slowGetConcurrent(handles); | ||
} | ||
return null; | ||
} | ||
|
||
/** | ||
* May return {@code null} if not found. | ||
*/ | ||
private static Storage.MarkHolderHandle slowGetConcurrent(CopyOnWriteArrayList<Storage.MarkHolderHandle> handles) { | ||
for (Storage.MarkHolderHandle handle : handles) { | ||
Thread thread = handle.threadRef().get(); | ||
if (thread == null) { | ||
handles.remove(handle); | ||
} else if (thread == Thread.currentThread()) { | ||
return handle; | ||
} | ||
} | ||
return null; | ||
} | ||
} |
37 changes: 37 additions & 0 deletions
37
impl/src/main/java/io/perfmark/impl/MostlyThreadLocalMarkHolder.java
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,37 @@ | ||
/* | ||
* Copyright 2022 Carl Mastrangelo | ||
* | ||
* 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 io.perfmark.impl; | ||
|
||
final class MostlyThreadLocalMarkHolder extends LocalMarkHolder { | ||
|
||
private static final MostlyThreadLocal localMarkHolder = new MostlyThreadLocal(); | ||
|
||
MostlyThreadLocalMarkHolder() {} | ||
|
||
@Override | ||
public MarkHolder acquire() { | ||
return localMarkHolder.get(); | ||
} | ||
|
||
@Override | ||
public void release(MarkHolder markHolder) {} | ||
|
||
@Override | ||
public void clear() { | ||
localMarkHolder.remove(); | ||
} | ||
} |
Oops, something went wrong.