/** compareAndSet in one thread enables another waiting for value to succeed */
public void testCompareAndSetInMultipleThreads() throws Exception {
x = one;
final AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a;
try {
a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
} catch (RuntimeException ok) {
return;
}
Thread t =
new Thread(
new CheckedRunnable() {
public void realRun() {
while (!a.compareAndSet(AtomicReferenceFieldUpdaterTest.this, two, three))
Thread.yield();
}
});
t.start();
assertTrue(a.compareAndSet(this, one, two));
t.join(LONG_DELAY_MS);
assertFalse(t.isAlive());
assertSame(a.get(this), three);
}
/** getAndSet returns previous value and sets to given value */
public void testGetAndSet() {
AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a;
try {
a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
} catch (RuntimeException ok) {
return;
}
x = one;
assertSame(one, a.getAndSet(this, zero));
assertSame(zero, a.getAndSet(this, m10));
assertSame(m10, a.getAndSet(this, 1));
}
boolean casNext(Node cmp, Node val) {
boolean success = nextUpdater.compareAndSet(this, cmp, val);
if (!success) {
System.err.println("setting next failed");
}
return success;
}
/** Constructor with non-volatile field throws exception */
public void testConstructor3() {
try {
AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "w");
shouldThrow();
} catch (RuntimeException success) {
}
}
/** compareAndSet succeeds in changing value if equal to expected else fails */
public void testCompareAndSet() {
AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a;
try {
a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
} catch (RuntimeException ok) {
return;
}
x = one;
assertTrue(a.compareAndSet(this, one, two));
assertTrue(a.compareAndSet(this, two, m4));
assertSame(m4, a.get(this));
assertFalse(a.compareAndSet(this, m5, seven));
assertFalse(seven == a.get(this));
assertTrue(a.compareAndSet(this, m4, seven));
assertSame(seven, a.get(this));
}
/** get returns the last value lazySet by same thread */
public void testGetLazySet() {
AtomicReferenceFieldUpdater<AtomicReferenceFieldUpdaterTest, Integer> a;
try {
a =
AtomicReferenceFieldUpdater.newUpdater(
AtomicReferenceFieldUpdaterTest.class, Integer.class, "x");
} catch (RuntimeException ok) {
return;
}
x = one;
assertSame(one, a.get(this));
a.lazySet(this, two);
assertSame(two, a.get(this));
a.lazySet(this, m3);
assertSame(m3, a.get(this));
}
static class Node {
static ConcurrentSoftQueue<Node> pool = new ConcurrentSoftQueue<Node>();
static Node alloc() {
final int threshold = 2;
int tryCnt = 0;
while (true) {
tryCnt++;
Node n = pool.poll();
if (n == null) {
return new Node();
} else {
if (n.getRefCnt() > 0) {
pool.add(n);
if (tryCnt <= threshold) continue;
else return new Node();
} else {
if (n.next != null) n.next.decRefCnt();
n.init();
return n;
}
}
}
}
static void free(Node n) {
pool.add(n);
}
private static void nodeCopy(
double[] srcKeys,
Object[] srcVals,
int srcBegin,
double[] targetKeys,
Object[] targetVals,
int targetBegin,
int copyLen) {
System.arraycopy(srcKeys, srcBegin, targetKeys, targetBegin, copyLen);
System.arraycopy(srcVals, srcBegin, targetVals, targetBegin, copyLen);
}
static Node safeNext(Node b) {
while (true) {
Node n = b.next;
if (n == null) return null;
n.incRefCnt();
if (n == b.next) return n;
else release(n);
}
}
static void release(Node n) {
n.decRefCnt();
}
volatile int refcnt;
volatile int length;
final double[] keys;
final Object[] vals;
volatile Node next;
Node() {
this(CHUNK_SIZE);
}
Node(int capacity) {
keys = new double[capacity];
vals = new Object[capacity];
refcnt = 1;
next = null;
}
void init() {
incRefCnt();
length = 0;
next = null;
clearEntry();
}
public void clearEntry() {
Arrays.fill(vals, null);
}
public String toString() {
String str =
"Node(refcnt:" + refcnt + ", isMarked:" + isMarked() + ", length:" + length + ")[";
for (int i = 0; i < len(); i++) {
str += keys[i] + " ";
}
str += "]";
return str;
}
void _print() {
System.out.print("Node(refcnt:" + refcnt + "," + length + "/" + keys.length + ")[");
for (int i = 0; i < length; i++) {
// System.out.print(keys[i]+":"+vals[i]+" ");
System.out.print(keys[i] + " ");
}
System.out.println("]");
}
static final AtomicReferenceFieldUpdater<Node, Node> nextUpdater =
AtomicReferenceFieldUpdater.newUpdater(Node.class, Node.class, "next");
static final AtomicIntegerFieldUpdater<Node> lenUpdater =
AtomicIntegerFieldUpdater.newUpdater(Node.class, "length");
static final AtomicIntegerFieldUpdater<Node> refcntUpdater =
AtomicIntegerFieldUpdater.newUpdater(Node.class, "refcnt");
boolean casNext(Node cmp, Node val) {
boolean success = nextUpdater.compareAndSet(this, cmp, val);
if (!success) {
System.err.println("setting next failed");
}
return success;
}
boolean casLen(int cmp, int val) {
return lenUpdater.compareAndSet(this, cmp, val);
}
int incRefCnt() {
return refcntUpdater.incrementAndGet(this);
}
int decRefCnt() {
int refcnt = refcntUpdater.decrementAndGet(this);
if (refcnt < 0) {
throw new RuntimeException("refcnt:" + refcnt);
}
return refcnt;
}
int getRefCnt() {
return refcnt;
}
boolean isFull() {
return len() == keys.length;
}
int len() {
int len = length;
return (len >= 0) ? len : -len;
}
boolean mark() {
int len = length;
if (len < 0) return false;
return casLen(len, -len);
}
boolean isMarked() {
return length < 0;
}
double first() {
assert len() != 0;
return keys[0];
}
double last() {
assert len() != 0;
return keys[len() - 1];
}
boolean contains(double key) {
return Arrays.binarySearch(keys, 0, len(), key) >= 0;
}
int findKeyIndex(double key) {
return Arrays.binarySearch(keys, 0, len(), key);
}
Object get(double key) {
if (len() == 0) return null;
int pos;
if (key == keys[0]) pos = 0;
else pos = Arrays.binarySearch(keys, 0, len(), key);
if (pos < 0) return null;
return vals[pos];
}
Object replace(double key, Object expect, Object value) {
synchronized (this) {
if (isMarked()) return Retry;
int len = len();
int pos = Arrays.binarySearch(keys, 0, len, key);
if (pos < 0) return null;
Object old = vals[pos];
if (expect == null) {
vals[pos] = value;
return old;
} else if (expect.equals(old)) {
vals[pos] = value;
return old;
} else {
return null;
}
}
}
// no concurrent read/write access is assumed
Object put(double key, Object value, ConcurrentDoubleOrderedListMap orderedMap) {
int len = len();
int pos = Arrays.binarySearch(keys, 0, len, key);
if (pos >= 0) {
Object old = vals[pos];
vals[pos] = value;
return old;
} else {
pos = -(pos + 1);
putReally(pos, key, value, orderedMap);
return null;
}
}
private boolean emptySlotInNextTwo() {
if (next == null) return false;
if (!next.isFull()) return true;
if (next.next == null) return false;
if (!next.next.isFull()) return true;
return false;
}
// no concurrent read/write access is assumed
private void putReally(
int pos, double key, Object value, ConcurrentDoubleOrderedListMap orderedMap) {
int len = len();
if (len + 1 <= keys.length) { // inserted in the current node
nodeCopy(keys, vals, pos, keys, vals, pos + 1, len - pos);
keys[pos] = key;
vals[pos] = value;
length = len + 1;
if (pos == 0) {
orderedMap.skipListMap.put(keys[0], this);
if (len != 0) orderedMap.skipListMap.remove(keys[1], this);
}
} else if (emptySlotInNextTwo()) {
if (pos == len) {
next.put(key, value, orderedMap);
return;
}
next.put(keys[len - 1], vals[len - 1], orderedMap);
nodeCopy(keys, vals, pos, keys, vals, pos + 1, len - pos - 1);
keys[pos] = key;
vals[pos] = value;
if (pos == 0) {
orderedMap.skipListMap.remove(keys[1], this);
orderedMap.skipListMap.put(keys[0], this);
}
} else { // current node is full, so requires a new node
Node n = Node.alloc();
double[] nkeys = n.keys;
Object[] nvals = n.vals;
int l1 = len / 2, l2 = len - l1;
if (next == null && pos == len) { // this is the last node, simply add to the new node.
nkeys[0] = key;
nvals[0] = value;
n.length = 1;
orderedMap.skipListMap.put(nkeys[0], n);
} else if (pos < l1) { // key,value is stored in the current node
length = l1 + 1;
n.length = l2;
nodeCopy(keys, vals, l1, nkeys, nvals, 0, l2);
nodeCopy(keys, vals, pos, keys, vals, pos + 1, l1 - pos);
keys[pos] = key;
vals[pos] = value;
if (pos == 0) {
orderedMap.skipListMap.remove(keys[1]);
orderedMap.skipListMap.put(keys[0], this);
}
orderedMap.skipListMap.put(nkeys[0], n);
} else { // key,value is stored in the new node
length = l1;
n.length = l2 + 1;
int newpos = pos - l1;
nodeCopy(keys, vals, l1, nkeys, nvals, 0, newpos);
nkeys[newpos] = key;
nvals[newpos] = value;
nodeCopy(keys, vals, pos, nkeys, nvals, newpos + 1, l2 - newpos);
orderedMap.skipListMap.put(nkeys[0], n);
}
n.next = this.next;
this.next = n;
}
}
// concurrent read/write access is allowed
boolean appendNewAtomic(double key, Object value, ConcurrentDoubleOrderedListMap orderedMap) {
synchronized (this) {
if (isMarked()) return false;
if (next != null) return false;
Node n = Node.alloc();
n.put(key, value, orderedMap);
// assert n.len()==1;
n.next = null;
boolean success = casNext(null, n);
assert success;
return true;
}
}
// concurrent read/write access is allowed
Object putAtomic(
double key,
Object value,
Node b,
boolean onlyIfAbsent,
ConcurrentDoubleOrderedListMap orderedMap) {
synchronized (b) {
if (b.isMarked()) return Retry;
synchronized (this) {
if (isMarked()) return Retry;
int len = len();
int pos = Arrays.binarySearch(keys, 0, len, key);
if (pos >= 0) {
Object old = vals[pos];
if (onlyIfAbsent) {
if (old == null) {
vals[pos] = value;
return null;
} else {
return old;
}
}
vals[pos] = value;
return old;
}
pos = -(pos + 1);
putAtomicReally(b, pos, key, value, orderedMap);
return null;
}
}
}
// only used by putAtomic and PutAtomicIfAbsent. Inside synchronized(b) and synchronized(this).
private void putAtomicReally(
Node b, int pos, double key, Object value, ConcurrentDoubleOrderedListMap orderedMap) {
int len = len();
if (len + 1 <= keys.length) {
if (pos == len) { // in-place append in the current node
keys[pos] = key;
vals[pos] = value;
length = len + 1;
if (pos == 0) {
orderedMap.skipListMap.put(keys[0], this);
}
} else { // copied to a new node, replacing the current node
mark();
Node n = Node.alloc();
n.next = this.next;
if (next != null) next.incRefCnt();
double[] nkeys = n.keys;
Object[] nvals = n.vals;
n.length = len + 1;
nodeCopy(keys, vals, 0, nkeys, nvals, 0, pos);
nkeys[pos] = key;
nvals[pos] = value;
nodeCopy(keys, vals, pos, nkeys, nvals, pos + 1, len - pos);
orderedMap.skipListMap.put(nkeys[0], n);
b.casNext(this, n); // should always succeed.
if (pos == 0) {
orderedMap.skipListMap.remove(keys[0], this);
}
release(this);
free(this);
}
} else { // requires 2 new nodes, to replace the current node
mark();
Node n1 = Node.alloc();
double[] n1keys = n1.keys;
Object[] n1vals = n1.vals;
Node n2 = Node.alloc();
double[] n2keys = n2.keys;
Object[] n2vals = n2.vals;
int l1 = len / 2, l2 = len - l1;
if (pos < l1) { // key, value stored in n1
n1.length = l1 + 1;
n2.length = l2;
nodeCopy(keys, vals, 0, n1keys, n1vals, 0, pos);
n1keys[pos] = key;
n1vals[pos] = value;
nodeCopy(keys, vals, pos, n1keys, n1vals, pos + 1, l1 - pos);
nodeCopy(keys, vals, l1, n2keys, n2vals, 0, l2);
n1.next = n2;
n2.next = this.next;
if (next != null) next.incRefCnt();
orderedMap.skipListMap.put(n1keys[0], n1);
orderedMap.skipListMap.put(n2keys[0], n2);
b.casNext(this, n1); // should always succeed.
if (pos == 0) {
orderedMap.skipListMap.remove(keys[0], this);
}
release(this);
free(this);
} else { // key,value is stored in n2
n1.length = l1;
n2.length = l2 + 1;
int newpos = pos - l1;
nodeCopy(keys, vals, 0, n1keys, n1vals, 0, l1);
nodeCopy(keys, vals, l1, n2keys, n2vals, 0, newpos);
n2keys[newpos] = key;
n2vals[newpos] = value;
nodeCopy(keys, vals, pos, n2keys, n2vals, newpos + 1, l2 - newpos);
n1.next = n2;
n2.next = this.next;
if (next != null) next.incRefCnt();
orderedMap.skipListMap.put(n1keys[0], n1);
orderedMap.skipListMap.put(n2keys[0], n2);
b.casNext(this, n1); // should always succeed.
release(this);
free(this);
}
}
}
}
