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8321594: NativeThreadSet should use placeholder for virtual threads

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Reviewed-by: bpb
This commit is contained in:
Alan Bateman 2023-12-12 07:55:56 +00:00
parent 973bcdab81
commit b8c0b2fd8c
3 changed files with 52 additions and 56 deletions
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88
src/java.base/share/classes/sun/nio/ch/NativeThreadSet.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2002, 2022, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2002, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -27,77 +27,89 @@ package sun.nio.ch;
// Special-purpose data structure for sets of native threads
class NativeThreadSet {
private static final int OTHER_THREAD_INDEX = -99;
private long[] elts;
private int used = 0;
private final int initialCapacity;
private long[] threads; // array of thread handles, created lazily
private int used; // number of thread handles in threads array
private int otherThreads; // count of threads without a native thread handle
private boolean waitingToEmpty;
NativeThreadSet(int n) {
elts = new long[n];
initialCapacity = n;
}
/**
* Adds the current native thread to this set, returning its index so that
* Adds the current thread handle to this set, returning an index so that
* it can efficiently be removed later.
*/
int add() {
long th = NativeThread.currentNativeThread();
// 0 and -1 are treated as placeholders, not real thread handles
if (th == 0)
th = -1;
long th = NativeThread.current();
synchronized (this) {
if (!NativeThread.isNativeThread(th)) {
otherThreads++;
return OTHER_THREAD_INDEX;
}
// add native thread handle to array, creating or growing array if needed
int start = 0;
if (used >= elts.length) {
int on = elts.length;
if (threads == null) {
threads = new long[initialCapacity];
} else if (used >= threads.length) {
int on = threads.length;
int nn = on * 2;
long[] nelts = new long[nn];
System.arraycopy(elts, 0, nelts, 0, on);
elts = nelts;
long[] nthreads = new long[nn];
System.arraycopy(threads, 0, nthreads, 0, on);
threads = nthreads;
start = on;
}
for (int i = start; i < elts.length; i++) {
if (elts[i] == 0) {
elts[i] = th;
for (int i = start; i < threads.length; i++) {
if (threads[i] == 0) {
threads[i] = th;
used++;
return i;
}
}
assert false;
return -1;
throw new InternalError();
}
}
/**
* Removes the thread at the give index.
* Removes the thread at the given index. A no-op if index is -1.
*/
void remove(int i) {
synchronized (this) {
assert (elts[i] == NativeThread.currentNativeThread()) || (elts[i] == -1);
elts[i] = 0;
used--;
if (used == 0 && waitingToEmpty)
if (i >= 0) {
assert threads[i] == NativeThread.current();
threads[i] = 0;
used--;
} else if (i == OTHER_THREAD_INDEX) {
otherThreads--;
} else {
assert i == -1;
return;
}
if (used == 0 && otherThreads == 0 && waitingToEmpty) {
notifyAll();
}
}
}
// Signals all threads in this set.
//
/**
* Signals all native threads in the thread set and wait for the thread set to empty.
*/
synchronized void signalAndWait() {
boolean interrupted = false;
while (used > 0) {
int u = used;
int n = elts.length;
for (int i = 0; i < n; i++) {
long th = elts[i];
if (th == 0)
continue;
if (th != -1)
while (used > 0 || otherThreads > 0) {
int u = used, i = 0;
while (u > 0 && i < threads.length) {
long th = threads[i];
if (th != 0) {
NativeThread.signal(th);
if (--u == 0)
break;
u--;
}
i++;
}
waitingToEmpty = true;
try {

10
src/java.base/unix/classes/sun/nio/ch/NativeThread.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2002, 2022, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2002, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -52,14 +52,6 @@ public class NativeThread {
}
}
/**
* Returns the id of the current native thread if the platform can signal
* native threads, 0 if the platform can not signal native threads.
*/
static long currentNativeThread() {
return current0();
}
/**
* Signals the given native thread.
*

10
src/java.base/windows/classes/sun/nio/ch/NativeThread.java
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2002, 2022, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2002, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -45,14 +45,6 @@ public class NativeThread {
}
}
/**
* Returns the id of the current native thread if the platform can signal
* native threads, 0 if the platform can not signal native threads.
*/
static long currentNativeThread() {
return 0;
}
/**
* Signals the given native thread.
*