Node ceilingNode(double key) {
for (; ; ) {
Node b = skipListMap.findGrandPredecessor(key, refCntCallback);
if (b == null) b = head;
if (b != head && key <= b.last()) {
return b;
}
assert b == head || b.last() < key;
Node n = safeNext(b);
release(b);
if (n == null) {
return null;
} else if (key <= n.last()) {
return n;
}
Node f = safeNext(n);
release(n);
if (f == null) {
return null;
} else {
if (isInconsistentNextNode(f, key)) {
release(f);
continue;
}
return f;
}
}
}
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);
}
}
int findBeginIndex(Node n, double key, boolean inclusive) {
boolean exclusive = !inclusive;
if (key <= n.first()) {
if (key == n.first() && exclusive) return 1;
return 0;
}
int pos = n.findKeyIndex(key);
if (pos < 0) pos = -(pos + 1);
else if (!inclusive) pos++;
return pos;
}
// 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;
}
}
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;
}
// 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;
}
}
}
private boolean isInconsistentNextNode(Node f, double key) {
/**
* With skipListMap.findGrandPredecessor, we expect the key of the target node (next of next
* node of returned node) to be greater than or equal to the given key. If not, there is
* inconsistency between skipListMap and this ordered list map.
*
* @see Node#putAtomicReally for the cause of this inconsistency
*/
return f.next != null && f.first() < key;
}
public void cancel(Node n) {
// It's possible (although very unlikely) that this release operation sets n.refcnt to 0,
// in which case n.refcnt could have been incremented from 0 by found(Node n) above.
// Hence, n.refcnt can be decremented to 0 two times; so even when n.refcnt is 0,
// we don't decrement n.next.refcnt immediately since it can double-decrement
// n.next.refcnt.
// We decrement n.next.refcnt in Node.alloc(), where we know that only a single thread is
// accessing the node.
Node.release(n);
}
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;
}
}
}
}
public void clear() {
for (Node n = head.next; n != null; n = n.next) {
Node.release(n);
assert n.getRefCnt() == 0;
n.clearEntry();
Node.free(n);
}
head.next = null;
}
int findEndIndex(Node n, double key, boolean inclusive) {
boolean exclusive = !inclusive;
if (key < n.first()) return -1;
if (key >= n.last()) {
if (key == n.last() && exclusive) return n.len() - 2;
return n.len() - 1;
}
int pos = n.findKeyIndex(key);
if (pos < 0) pos = -(pos + 1);
else if (!inclusive) pos--;
if (pos == n.len()) pos--;
return pos;
}
public void doSanityCheck() {
int count = 0;
double prevKey = Double.MIN_VALUE;
Node n = safeNext(head);
while (n != null) {
count++;
if (!skipListMap.containsKey(n.first())) {
System.out.println("Node n not in skiplistMap:" + n.first());
n._print();
}
if (n.first() < prevKey) {
System.out.println("Error in ordering, prevKey:" + prevKey + ", n:" + n);
}
prevKey = n.first();
Node next = safeNext(n);
release(n);
n = next;
}
if (skipListMap.size() != count) {
System.out.println("skipListMap.size:" + skipListMap.size() + ", count:" + count);
}
}
/*
* Methods for fetching next pointer of a node, preventing the node from being reclaimed by the pool.
* release() simply decrements the reference count of the node.
*/
Node safeNext(Node b) {
return Node.safeNext(b);
}
public void found(Node n) {
n.incRefCnt();
}
void release(Node b, Node n) {
Node.release(n);
Node.release(b);
}
// 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);
}
}
}
void release(Node b, Node n, Node f) {
Node.release(f);
Node.release(n);
Node.release(b);
}
public void _print() {
for (Node n = head; n != null; n = n.next) {
n._print();
}
}
// 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;
}
}
static void release(Node n) {
n.decRefCnt();
}
void release(Node n) {
Node.release(n);
}
V putAtomic(double key, V value, boolean onlyIfAbsent) {
if (value == null) throw new NullPointerException();
for (; ; ) {
Node b = skipListMap.findGrandPredecessor(key, refCntCallback);
if (b == null) b = head;
if (b != head && b.first() <= key && key <= b.last()) {
release(b);
continue;
}
assert b == head || b.last() < key;
Node n = safeNext(b);
if (n == null) {
if (b.appendNewAtomic(key, value, this)) {
release(b);
return null;
} else {
release(b);
continue;
}
} else if (n.first() <= key && key <= n.last()) {
Object val = n.putAtomic(key, value, b, onlyIfAbsent, this);
release(b, n);
if (val == Retry) continue;
return (V) val;
}
Node f = safeNext(n);
if (f == null) {
Object val = n.putAtomic(key, value, b, onlyIfAbsent, this);
release(b, n);
if (val == Retry) continue;
return (V) val;
} else {
if (f.first() == key) {
Object val = f.putAtomic(key, value, n, onlyIfAbsent, this);
release(b, n, f);
if (val == Retry) continue;
return (V) val;
} else {
if (key > f.first()) { // inconsistent read, retry
release(b, n, f);
continue;
}
Object val = n.putAtomic(key, value, b, onlyIfAbsent, this);
release(b, n, f);
if (val == Retry) continue;
return (V) val;
}
}
}
}
// no concurrent read/write is assumed
public V put(double key, V value) {
if (value == null) throw new NullPointerException();
// not incrementing b's refcnt, so need not release it.
Node b = skipListMap.findGrandPredecessor(key);
if (b == null) b = head;
Node n = b.next;
if (n == null) {
n = Node.alloc();
n.put(key, value, this);
n.next = null;
b.next = n;
return null;
}
Node f = n.next;
if (f == null) { // put (key,value) into node n
Object val = n.put(key, value, this);
return (V) val;
} else {
assert f.len() > 0 && f.first() >= key;
if (f.first() == key) {
Object val = f.put(key, value, this);
return (V) val;
} else {
Object val = n.put(key, value, this);
return (V) val;
}
}
}
V doReplace(double key, V old, V value) {
for (; ; ) {
Node b = skipListMap.findGrandPredecessor(key, refCntCallback);
if (b == null) b = head;
if (b != head && b.first() <= key && key <= b.last()) {
// can happen if there's inconsistency between skipListMap and orderedMap(this).
// The inconsistency can happen from Node.putAtomicReally(),
// where it adds to, and removes from skiplistMap.
Object val = b.replace(key, old, value);
release(b);
if (val == Retry) continue;
return (V) val;
}
assert b == head || b.last() < key;
Node n = safeNext(b);
release(b);
if (n == null) {
return null;
} else if (n.first() <= key && key <= n.last()) {
Object val = n.replace(key, old, value);
release(n);
if (val == Retry) continue;
return (V) val;
}
Node f = safeNext(n);
release(n);
if (f == null) {
return null;
} else {
if (isInconsistentNextNode(f, key)) {
release(f);
continue;
}
Object val = f.replace(key, old, value);
release(f);
if (val == Retry) continue;
return (V) val;
}
}
}
