/**
* Returns <tt>true</tt> if this map maps one or more keys to the specified value. Note: This
* method requires a full internal traversal of the hash table, and so is much slower than method
* <tt>containsKey</tt>.
*
* @param value value whose presence in this map is to be tested
* @return <tt>true</tt> if this map maps one or more keys to the specified value
* @throws NullPointerException if the specified value is null
*/
public boolean containsValue(Object value) {
if (value == null) throw new NullPointerException();
// See explanation of modCount use above
final Segment<V>[] segments = this.segments;
int[] mc = new int[segments.length];
// Try a few times without locking
for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
// int sum = 0;
int mcsum = 0;
for (int i = 0; i < segments.length; ++i) {
// int c = segments[i].count;
mcsum += mc[i] = segments[i].modCount;
if (segments[i].containsValue(value)) return true;
}
boolean cleanSweep = true;
if (mcsum != 0) {
for (int i = 0; i < segments.length; ++i) {
// int c = segments[i].count;
if (mc[i] != segments[i].modCount) {
cleanSweep = false;
break;
}
}
}
if (cleanSweep) return false;
}
// Resort to locking all segments
for (Segment<V> segment : segments) segment.lock();
boolean found = false;
try {
for (Segment<V> segment : segments) {
if (segment.containsValue(value)) {
found = true;
break;
}
}
} finally {
for (Segment<V> segment : segments) segment.unlock();
}
return found;
}
/**
* Save the state of the <tt>ConcurrentHashMap</tt> instance to a stream (i.e., serialize it).
*
* @param s the stream
* @serialData the key (Object) and value (Object) for each key-value mapping, followed by a null
* pair. The key-value mappings are emitted in no particular order.
*/
private void writeObject(java.io.ObjectOutputStream s) throws IOException {
s.defaultWriteObject();
for (int k = 0; k < segments.length; ++k) {
Segment<K, V> seg = (Segment<K, V>) segments[k];
seg.lock();
try {
HashEntry[] tab = seg.table;
for (int i = 0; i < tab.length; ++i) {
for (HashEntry<K, V> e = (HashEntry<K, V>) tab[i]; e != null; e = e.next) {
s.writeObject(e.key);
s.writeObject(e.value);
}
}
} finally {
seg.unlock();
}
}
s.writeObject(null);
s.writeObject(null);
}
/**
* Returns the number of key-value mappings in this map. If the map contains more than
* <tt>Integer.MAX_VALUE</tt> elements, returns <tt>Integer.MAX_VALUE</tt>.
*
* @return the number of key-value mappings in this map
*/
@Override
public int size() {
final Segment<V>[] segments = this.segments;
long sum = 0;
long check = 0;
int[] mc = new int[segments.length];
// Try a few times to get accurate count. On failure due to
// continuous async changes in table, resort to locking.
for (int k = 0; k < RETRIES_BEFORE_LOCK; ++k) {
check = 0;
sum = 0;
int mcsum = 0;
for (int i = 0; i < segments.length; ++i) {
sum += segments[i].count;
mcsum += mc[i] = segments[i].modCount;
}
if (mcsum != 0) {
for (int i = 0; i < segments.length; ++i) {
check += segments[i].count;
if (mc[i] != segments[i].modCount) {
check = -1; // force retry
break;
}
}
}
if (check == sum) break;
}
if (check != sum) { // Resort to locking all segments
sum = 0;
for (Segment<V> segment : segments) segment.lock();
for (Segment<V> segment : segments) sum += segment.count;
for (Segment<V> segment : segments) segment.unlock();
}
if (sum > Integer.MAX_VALUE) return Integer.MAX_VALUE;
else return (int) sum;
}