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dl |
1.2 |
/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain. Use, modify, and |
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* redistribute this code in any way without acknowledgement. |
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*/ |
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tim |
1.1 |
package java.util.concurrent; |
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dl |
1.10 |
import java.util.concurrent.locks.*; |
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1.1 |
import java.util.*; |
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import java.io.Serializable; |
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import java.io.IOException; |
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import java.io.ObjectInputStream; |
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import java.io.ObjectOutputStream; |
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/** |
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1.4 |
* A hash table supporting full concurrency of retrievals and |
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* adjustable expected concurrency for updates. This class obeys the |
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1.19 |
* same functional specification as <tt>java.util.Hashtable</tt>, and |
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* includes versions of methods corresponding to each method of |
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* <tt>Hashtable</tt> . However, even though all operations are |
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* thread-safe, retrieval operations do <em>not</em> entail locking, |
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* and there is <em>not</em> any support for locking the entire table |
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* in a way that prevents all access. This class is fully |
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* interoperable with <tt>Hashtable</tt> in programs that rely on its |
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1.4 |
* thread safety but not on its synchronization details. |
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1.11 |
* |
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1.4 |
* <p> Retrieval operations (including <tt>get</tt>) ordinarily |
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1.5 |
* overlap with update operations (including <tt>put</tt> and |
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1.4 |
* <tt>remove</tt>). Retrievals reflect the results of the most |
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* recently <em>completed</em> update operations holding upon their |
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* onset. For aggregate operations such as <tt>putAll</tt> and |
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* <tt>clear</tt>, concurrent retrievals may reflect insertion or |
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* removal of only some entries. Similarly, Iterators and |
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* Enumerations return elements reflecting the state of the hash table |
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* at some point at or since the creation of the iterator/enumeration. |
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* They do <em>not</em> throw ConcurrentModificationException. |
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* However, Iterators are designed to be used by only one thread at a |
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* time. |
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1.1 |
* |
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1.19 |
* <p> The allowed concurrency among update operations is guided by |
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* the optional <tt>concurrencyLevel</tt> constructor argument |
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* (default 16). The table is internally partitioned to permit the |
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* indicated number of concurrent updates without contention. Because |
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* placement in hash tables is essentially random, the actual |
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* concurrency will vary. Ideally, you should choose a value to |
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* accommodate as many threads as will ever concurrently access the |
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* table. Using a significantly higher value than you need can waste |
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* space and time, and a significantly lower value can lead to thread |
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* contention. But overestimates and underestimates within an order of |
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* magnitude do not usually have much noticeable impact. |
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1.1 |
* |
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1.4 |
* <p> Like Hashtable but unlike java.util.HashMap, this class does |
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* NOT allow <tt>null</tt> to be used as a key or value. |
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1.1 |
* |
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1.8 |
* @since 1.5 |
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* @author Doug Lea |
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*/ |
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1.1 |
public class ConcurrentHashMap<K, V> extends AbstractMap<K, V> |
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implements ConcurrentMap<K, V>, Cloneable, Serializable { |
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1.20 |
private static final long serialVersionUID = 7249069246763182397L; |
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1.1 |
|
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/* |
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1.4 |
* The basic strategy is to subdivide the table among Segments, |
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* each of which itself is a concurrently readable hash table. |
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*/ |
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1.1 |
|
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1.4 |
/* ---------------- Constants -------------- */ |
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1.11 |
|
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1.4 |
/** |
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1.19 |
* The default initial number of table slots for this table. |
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1.4 |
* Used when not otherwise specified in constructor. |
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*/ |
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1.11 |
private static int DEFAULT_INITIAL_CAPACITY = 16; |
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1.1 |
|
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/** |
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1.4 |
* The maximum capacity, used if a higher value is implicitly |
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* specified by either of the constructors with arguments. MUST |
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* be a power of two <= 1<<30. |
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*/ |
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static final int MAXIMUM_CAPACITY = 1 << 30; |
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1.11 |
|
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1.1 |
/** |
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1.4 |
* The default load factor for this table. Used when not |
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* otherwise specified in constructor. |
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*/ |
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1.11 |
static final float DEFAULT_LOAD_FACTOR = 0.75f; |
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1.1 |
|
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/** |
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1.4 |
* The default number of concurrency control segments. |
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1.1 |
**/ |
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1.4 |
private static final int DEFAULT_SEGMENTS = 16; |
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1.1 |
|
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1.4 |
/* ---------------- Fields -------------- */ |
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1.1 |
|
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/** |
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1.9 |
* Mask value for indexing into segments. The upper bits of a |
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* key's hash code are used to choose the segment. |
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1.1 |
**/ |
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1.4 |
private final int segmentMask; |
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1.1 |
|
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/** |
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1.4 |
* Shift value for indexing within segments. |
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1.1 |
**/ |
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1.4 |
private final int segmentShift; |
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1.1 |
|
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/** |
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1.4 |
* The segments, each of which is a specialized hash table |
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1.1 |
*/ |
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1.11 |
private final Segment[] segments; |
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1.4 |
|
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1.6 |
private transient Set<K> keySet; |
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1.12 |
private transient Set<Map.Entry<K,V>> entrySet; |
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1.6 |
private transient Collection<V> values; |
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1.4 |
|
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/* ---------------- Small Utilities -------------- */ |
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1.1 |
|
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/** |
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1.11 |
* Return a hash code for non-null Object x. |
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1.4 |
* Uses the same hash code spreader as most other j.u hash tables. |
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1.8 |
* @param x the object serving as a key |
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* @return the hash code |
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1.1 |
*/ |
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1.4 |
private static int hash(Object x) { |
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int h = x.hashCode(); |
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h += ~(h << 9); |
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h ^= (h >>> 14); |
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h += (h << 4); |
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h ^= (h >>> 10); |
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return h; |
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} |
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1.1 |
/** |
133 |
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1.4 |
* Return the segment that should be used for key with given hash |
134 |
tim |
1.1 |
*/ |
135 |
dl |
1.4 |
private Segment<K,V> segmentFor(int hash) { |
136 |
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1.12 |
return (Segment<K,V>) segments[(hash >>> segmentShift) & segmentMask]; |
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1.4 |
} |
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tim |
1.1 |
|
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dl |
1.4 |
/* ---------------- Inner Classes -------------- */ |
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1.1 |
|
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/** |
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1.6 |
* Segments are specialized versions of hash tables. This |
143 |
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1.4 |
* subclasses from ReentrantLock opportunistically, just to |
144 |
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* simplify some locking and avoid separate construction. |
145 |
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1.1 |
**/ |
146 |
dl |
1.8 |
private static final class Segment<K,V> extends ReentrantLock implements Serializable { |
147 |
dl |
1.4 |
/* |
148 |
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* Segments maintain a table of entry lists that are ALWAYS |
149 |
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* kept in a consistent state, so can be read without locking. |
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* Next fields of nodes are immutable (final). All list |
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* additions are performed at the front of each bin. This |
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* makes it easy to check changes, and also fast to traverse. |
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* When nodes would otherwise be changed, new nodes are |
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* created to replace them. This works well for hash tables |
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* since the bin lists tend to be short. (The average length |
156 |
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* is less than two for the default load factor threshold.) |
157 |
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* |
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* Read operations can thus proceed without locking, but rely |
159 |
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* on a memory barrier to ensure that completed write |
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* operations performed by other threads are |
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* noticed. Conveniently, the "count" field, tracking the |
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* number of elements, can also serve as the volatile variable |
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* providing proper read/write barriers. This is convenient |
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* because this field needs to be read in many read operations |
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dl |
1.19 |
* anyway. |
166 |
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1.4 |
* |
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* Implementors note. The basic rules for all this are: |
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* |
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* - All unsynchronized read operations must first read the |
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* "count" field, and should not look at table entries if |
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* it is 0. |
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tim |
1.11 |
* |
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1.4 |
* - All synchronized write operations should write to |
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* the "count" field after updating. The operations must not |
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* take any action that could even momentarily cause |
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* a concurrent read operation to see inconsistent |
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* data. This is made easier by the nature of the read |
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* operations in Map. For example, no operation |
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* can reveal that the table has grown but the threshold |
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* has not yet been updated, so there are no atomicity |
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* requirements for this with respect to reads. |
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* |
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* As a guide, all critical volatile reads and writes are marked |
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* in code comments. |
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*/ |
186 |
tim |
1.11 |
|
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dl |
1.4 |
/** |
188 |
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* The number of elements in this segment's region. |
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**/ |
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transient volatile int count; |
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/** |
193 |
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* The table is rehashed when its size exceeds this threshold. |
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* (The value of this field is always (int)(capacity * |
195 |
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* loadFactor).) |
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*/ |
197 |
dl |
1.8 |
private transient int threshold; |
198 |
dl |
1.4 |
|
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/** |
200 |
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* The per-segment table |
201 |
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*/ |
202 |
tim |
1.11 |
transient HashEntry[] table; |
203 |
dl |
1.4 |
|
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/** |
205 |
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* The load factor for the hash table. Even though this value |
206 |
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* is same for all segments, it is replicated to avoid needing |
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* links to outer object. |
208 |
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* @serial |
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*/ |
210 |
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private final float loadFactor; |
211 |
tim |
1.1 |
|
212 |
dl |
1.4 |
Segment(int initialCapacity, float lf) { |
213 |
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loadFactor = lf; |
214 |
tim |
1.11 |
setTable(new HashEntry[initialCapacity]); |
215 |
dl |
1.4 |
} |
216 |
tim |
1.1 |
|
217 |
dl |
1.4 |
/** |
218 |
tim |
1.11 |
* Set table to new HashEntry array. |
219 |
dl |
1.4 |
* Call only while holding lock or in constructor. |
220 |
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**/ |
221 |
tim |
1.11 |
private void setTable(HashEntry[] newTable) { |
222 |
dl |
1.4 |
table = newTable; |
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threshold = (int)(newTable.length * loadFactor); |
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count = count; // write-volatile |
225 |
tim |
1.11 |
} |
226 |
dl |
1.4 |
|
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/* Specialized implementations of map methods */ |
228 |
tim |
1.11 |
|
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V get(K key, int hash) { |
230 |
dl |
1.4 |
if (count != 0) { // read-volatile |
231 |
tim |
1.11 |
HashEntry[] tab = table; |
232 |
dl |
1.9 |
int index = hash & (tab.length - 1); |
233 |
tim |
1.11 |
HashEntry<K,V> e = (HashEntry<K,V>) tab[index]; |
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dl |
1.4 |
while (e != null) { |
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tim |
1.11 |
if (e.hash == hash && key.equals(e.key)) |
236 |
dl |
1.4 |
return e.value; |
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e = e.next; |
238 |
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} |
239 |
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} |
240 |
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return null; |
241 |
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} |
242 |
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boolean containsKey(Object key, int hash) { |
244 |
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if (count != 0) { // read-volatile |
245 |
tim |
1.11 |
HashEntry[] tab = table; |
246 |
dl |
1.9 |
int index = hash & (tab.length - 1); |
247 |
tim |
1.11 |
HashEntry<K,V> e = (HashEntry<K,V>) tab[index]; |
248 |
dl |
1.4 |
while (e != null) { |
249 |
tim |
1.11 |
if (e.hash == hash && key.equals(e.key)) |
250 |
dl |
1.4 |
return true; |
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e = e.next; |
252 |
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} |
253 |
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} |
254 |
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return false; |
255 |
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} |
256 |
tim |
1.11 |
|
257 |
dl |
1.4 |
boolean containsValue(Object value) { |
258 |
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if (count != 0) { // read-volatile |
259 |
tim |
1.11 |
HashEntry[] tab = table; |
260 |
dl |
1.4 |
int len = tab.length; |
261 |
tim |
1.11 |
for (int i = 0 ; i < len; i++) |
262 |
tim |
1.12 |
for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i] ; e != null ; e = e.next) |
263 |
dl |
1.4 |
if (value.equals(e.value)) |
264 |
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return true; |
265 |
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} |
266 |
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return false; |
267 |
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} |
268 |
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269 |
tim |
1.11 |
V put(K key, int hash, V value, boolean onlyIfAbsent) { |
270 |
dl |
1.4 |
lock(); |
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try { |
272 |
dl |
1.9 |
int c = count; |
273 |
tim |
1.11 |
HashEntry[] tab = table; |
274 |
dl |
1.9 |
int index = hash & (tab.length - 1); |
275 |
tim |
1.11 |
HashEntry<K,V> first = (HashEntry<K,V>) tab[index]; |
276 |
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277 |
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for (HashEntry<K,V> e = first; e != null; e = (HashEntry<K,V>) e.next) { |
278 |
dl |
1.9 |
if (e.hash == hash && key.equals(e.key)) { |
279 |
tim |
1.11 |
V oldValue = e.value; |
280 |
dl |
1.4 |
if (!onlyIfAbsent) |
281 |
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e.value = value; |
282 |
dl |
1.9 |
count = c; // write-volatile |
283 |
dl |
1.4 |
return oldValue; |
284 |
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} |
285 |
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} |
286 |
tim |
1.11 |
|
287 |
dl |
1.4 |
tab[index] = new HashEntry<K,V>(hash, key, value, first); |
288 |
dl |
1.9 |
++c; |
289 |
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count = c; // write-volatile |
290 |
tim |
1.11 |
if (c > threshold) |
291 |
dl |
1.9 |
setTable(rehash(tab)); |
292 |
dl |
1.4 |
return null; |
293 |
tim |
1.16 |
} finally { |
294 |
dl |
1.4 |
unlock(); |
295 |
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} |
296 |
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} |
297 |
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|
298 |
tim |
1.11 |
private HashEntry[] rehash(HashEntry[] oldTable) { |
299 |
dl |
1.4 |
int oldCapacity = oldTable.length; |
300 |
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if (oldCapacity >= MAXIMUM_CAPACITY) |
301 |
dl |
1.9 |
return oldTable; |
302 |
dl |
1.4 |
|
303 |
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/* |
304 |
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* Reclassify nodes in each list to new Map. Because we are |
305 |
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* using power-of-two expansion, the elements from each bin |
306 |
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* must either stay at same index, or move with a power of two |
307 |
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* offset. We eliminate unnecessary node creation by catching |
308 |
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* cases where old nodes can be reused because their next |
309 |
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* fields won't change. Statistically, at the default |
310 |
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* threshhold, only about one-sixth of them need cloning when |
311 |
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* a table doubles. The nodes they replace will be garbage |
312 |
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* collectable as soon as they are no longer referenced by any |
313 |
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* reader thread that may be in the midst of traversing table |
314 |
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* right now. |
315 |
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*/ |
316 |
tim |
1.11 |
|
317 |
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HashEntry[] newTable = new HashEntry[oldCapacity << 1]; |
318 |
dl |
1.4 |
int sizeMask = newTable.length - 1; |
319 |
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for (int i = 0; i < oldCapacity ; i++) { |
320 |
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// We need to guarantee that any existing reads of old Map can |
321 |
tim |
1.11 |
// proceed. So we cannot yet null out each bin. |
322 |
tim |
1.12 |
HashEntry<K,V> e = (HashEntry<K,V>)oldTable[i]; |
323 |
tim |
1.11 |
|
324 |
dl |
1.4 |
if (e != null) { |
325 |
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HashEntry<K,V> next = e.next; |
326 |
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int idx = e.hash & sizeMask; |
327 |
tim |
1.11 |
|
328 |
dl |
1.4 |
// Single node on list |
329 |
tim |
1.11 |
if (next == null) |
330 |
dl |
1.4 |
newTable[idx] = e; |
331 |
tim |
1.11 |
|
332 |
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else { |
333 |
dl |
1.4 |
// Reuse trailing consecutive sequence at same slot |
334 |
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HashEntry<K,V> lastRun = e; |
335 |
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int lastIdx = idx; |
336 |
tim |
1.11 |
for (HashEntry<K,V> last = next; |
337 |
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last != null; |
338 |
dl |
1.4 |
last = last.next) { |
339 |
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int k = last.hash & sizeMask; |
340 |
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if (k != lastIdx) { |
341 |
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lastIdx = k; |
342 |
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lastRun = last; |
343 |
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} |
344 |
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} |
345 |
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newTable[lastIdx] = lastRun; |
346 |
tim |
1.11 |
|
347 |
dl |
1.4 |
// Clone all remaining nodes |
348 |
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for (HashEntry<K,V> p = e; p != lastRun; p = p.next) { |
349 |
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int k = p.hash & sizeMask; |
350 |
tim |
1.11 |
newTable[k] = new HashEntry<K,V>(p.hash, |
351 |
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p.key, |
352 |
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p.value, |
353 |
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(HashEntry<K,V>) newTable[k]); |
354 |
dl |
1.4 |
} |
355 |
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} |
356 |
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} |
357 |
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} |
358 |
dl |
1.9 |
return newTable; |
359 |
dl |
1.4 |
} |
360 |
dl |
1.6 |
|
361 |
|
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/** |
362 |
|
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* Remove; match on key only if value null, else match both. |
363 |
|
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*/ |
364 |
dl |
1.4 |
V remove(Object key, int hash, Object value) { |
365 |
tim |
1.11 |
lock(); |
366 |
dl |
1.4 |
try { |
367 |
dl |
1.9 |
int c = count; |
368 |
dl |
1.4 |
HashEntry[] tab = table; |
369 |
dl |
1.9 |
int index = hash & (tab.length - 1); |
370 |
tim |
1.12 |
HashEntry<K,V> first = (HashEntry<K,V>)tab[index]; |
371 |
tim |
1.11 |
|
372 |
dl |
1.4 |
HashEntry<K,V> e = first; |
373 |
dl |
1.9 |
for (;;) { |
374 |
dl |
1.4 |
if (e == null) |
375 |
|
|
return null; |
376 |
dl |
1.9 |
if (e.hash == hash && key.equals(e.key)) |
377 |
dl |
1.4 |
break; |
378 |
|
|
e = e.next; |
379 |
|
|
} |
380 |
|
|
|
381 |
|
|
V oldValue = e.value; |
382 |
|
|
if (value != null && !value.equals(oldValue)) |
383 |
|
|
return null; |
384 |
dl |
1.9 |
|
385 |
dl |
1.4 |
// All entries following removed node can stay in list, but |
386 |
tim |
1.11 |
// all preceeding ones need to be cloned. |
387 |
dl |
1.4 |
HashEntry<K,V> newFirst = e.next; |
388 |
tim |
1.11 |
for (HashEntry<K,V> p = first; p != e; p = p.next) |
389 |
|
|
newFirst = new HashEntry<K,V>(p.hash, p.key, |
390 |
dl |
1.8 |
p.value, newFirst); |
391 |
dl |
1.4 |
tab[index] = newFirst; |
392 |
dl |
1.9 |
count = c-1; // write-volatile |
393 |
|
|
return oldValue; |
394 |
tim |
1.16 |
} finally { |
395 |
dl |
1.4 |
unlock(); |
396 |
|
|
} |
397 |
|
|
} |
398 |
|
|
|
399 |
|
|
void clear() { |
400 |
|
|
lock(); |
401 |
|
|
try { |
402 |
tim |
1.11 |
HashEntry[] tab = table; |
403 |
|
|
for (int i = 0; i < tab.length ; i++) |
404 |
dl |
1.4 |
tab[i] = null; |
405 |
|
|
count = 0; // write-volatile |
406 |
tim |
1.16 |
} finally { |
407 |
dl |
1.4 |
unlock(); |
408 |
|
|
} |
409 |
|
|
} |
410 |
tim |
1.1 |
} |
411 |
|
|
|
412 |
|
|
/** |
413 |
dl |
1.4 |
* ConcurrentReaderHashMap list entry. |
414 |
tim |
1.1 |
*/ |
415 |
dl |
1.4 |
private static class HashEntry<K,V> implements Entry<K,V> { |
416 |
|
|
private final K key; |
417 |
|
|
private V value; |
418 |
|
|
private final int hash; |
419 |
|
|
private final HashEntry<K,V> next; |
420 |
|
|
|
421 |
|
|
HashEntry(int hash, K key, V value, HashEntry<K,V> next) { |
422 |
|
|
this.value = value; |
423 |
|
|
this.hash = hash; |
424 |
|
|
this.key = key; |
425 |
|
|
this.next = next; |
426 |
|
|
} |
427 |
|
|
|
428 |
|
|
public K getKey() { |
429 |
|
|
return key; |
430 |
|
|
} |
431 |
tim |
1.1 |
|
432 |
dl |
1.4 |
public V getValue() { |
433 |
tim |
1.11 |
return value; |
434 |
tim |
1.1 |
} |
435 |
|
|
|
436 |
dl |
1.4 |
public V setValue(V newValue) { |
437 |
|
|
// We aren't required to, and don't provide any |
438 |
|
|
// visibility barriers for setting value. |
439 |
|
|
if (newValue == null) |
440 |
|
|
throw new NullPointerException(); |
441 |
|
|
V oldValue = this.value; |
442 |
|
|
this.value = newValue; |
443 |
|
|
return oldValue; |
444 |
|
|
} |
445 |
tim |
1.1 |
|
446 |
dl |
1.4 |
public boolean equals(Object o) { |
447 |
|
|
if (!(o instanceof Entry)) |
448 |
|
|
return false; |
449 |
tim |
1.12 |
Entry<K,V> e = (Entry<K,V>)o; |
450 |
dl |
1.4 |
return (key.equals(e.getKey()) && value.equals(e.getValue())); |
451 |
|
|
} |
452 |
tim |
1.11 |
|
453 |
dl |
1.4 |
public int hashCode() { |
454 |
|
|
return key.hashCode() ^ value.hashCode(); |
455 |
|
|
} |
456 |
tim |
1.1 |
|
457 |
dl |
1.4 |
public String toString() { |
458 |
|
|
return key + "=" + value; |
459 |
|
|
} |
460 |
tim |
1.1 |
} |
461 |
|
|
|
462 |
tim |
1.11 |
|
463 |
dl |
1.4 |
/* ---------------- Public operations -------------- */ |
464 |
tim |
1.1 |
|
465 |
|
|
/** |
466 |
|
|
* Constructs a new, empty map with the specified initial |
467 |
|
|
* capacity and the specified load factor. |
468 |
|
|
* |
469 |
dl |
1.19 |
* @param initialCapacity the initial capacity. The implementation |
470 |
|
|
* performs internal sizing to accommodate this many elements. |
471 |
tim |
1.1 |
* @param loadFactor the load factor threshold, used to control resizing. |
472 |
dl |
1.19 |
* @param concurrencyLevel the estimated number of concurrently |
473 |
|
|
* updating threads. The implementation performs internal sizing |
474 |
|
|
* to accommodate this many threads. |
475 |
dl |
1.4 |
* @throws IllegalArgumentException if the initial capacity is |
476 |
dl |
1.19 |
* negative or the load factor or concurrencyLevel are |
477 |
dl |
1.4 |
* nonpositive. |
478 |
|
|
*/ |
479 |
tim |
1.11 |
public ConcurrentHashMap(int initialCapacity, |
480 |
dl |
1.19 |
float loadFactor, int concurrencyLevel) { |
481 |
|
|
if (!(loadFactor > 0) || initialCapacity < 0 || concurrencyLevel <= 0) |
482 |
dl |
1.4 |
throw new IllegalArgumentException(); |
483 |
|
|
|
484 |
|
|
// Find power-of-two sizes best matching arguments |
485 |
|
|
int sshift = 0; |
486 |
|
|
int ssize = 1; |
487 |
dl |
1.19 |
while (ssize < concurrencyLevel) { |
488 |
dl |
1.4 |
++sshift; |
489 |
|
|
ssize <<= 1; |
490 |
|
|
} |
491 |
dl |
1.9 |
segmentShift = 32 - sshift; |
492 |
dl |
1.8 |
segmentMask = ssize - 1; |
493 |
tim |
1.11 |
this.segments = new Segment[ssize]; |
494 |
dl |
1.4 |
|
495 |
|
|
if (initialCapacity > MAXIMUM_CAPACITY) |
496 |
|
|
initialCapacity = MAXIMUM_CAPACITY; |
497 |
|
|
int c = initialCapacity / ssize; |
498 |
tim |
1.11 |
if (c * ssize < initialCapacity) |
499 |
dl |
1.4 |
++c; |
500 |
|
|
int cap = 1; |
501 |
|
|
while (cap < c) |
502 |
|
|
cap <<= 1; |
503 |
|
|
|
504 |
|
|
for (int i = 0; i < this.segments.length; ++i) |
505 |
|
|
this.segments[i] = new Segment<K,V>(cap, loadFactor); |
506 |
tim |
1.1 |
} |
507 |
|
|
|
508 |
|
|
/** |
509 |
|
|
* Constructs a new, empty map with the specified initial |
510 |
dl |
1.19 |
* capacity, and with default load factor and concurrencyLevel. |
511 |
tim |
1.1 |
* |
512 |
dl |
1.19 |
* @param initialCapacity The implementation performs internal |
513 |
|
|
* sizing to accommodate this many elements. |
514 |
dl |
1.4 |
* @throws IllegalArgumentException if the initial capacity of |
515 |
|
|
* elements is negative. |
516 |
tim |
1.1 |
*/ |
517 |
|
|
public ConcurrentHashMap(int initialCapacity) { |
518 |
dl |
1.4 |
this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS); |
519 |
tim |
1.1 |
} |
520 |
|
|
|
521 |
|
|
/** |
522 |
dl |
1.4 |
* Constructs a new, empty map with a default initial capacity, |
523 |
dl |
1.19 |
* load factor, and number of concurrencyLevel. |
524 |
tim |
1.1 |
*/ |
525 |
|
|
public ConcurrentHashMap() { |
526 |
dl |
1.4 |
this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS); |
527 |
tim |
1.1 |
} |
528 |
|
|
|
529 |
|
|
/** |
530 |
|
|
* Constructs a new map with the same mappings as the given map. The |
531 |
|
|
* map is created with a capacity of twice the number of mappings in |
532 |
dl |
1.4 |
* the given map or 11 (whichever is greater), and a default load factor. |
533 |
tim |
1.1 |
*/ |
534 |
|
|
public <A extends K, B extends V> ConcurrentHashMap(Map<A,B> t) { |
535 |
|
|
this(Math.max((int) (t.size() / DEFAULT_LOAD_FACTOR) + 1, |
536 |
dl |
1.4 |
11), |
537 |
|
|
DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS); |
538 |
|
|
putAll(t); |
539 |
tim |
1.1 |
} |
540 |
|
|
|
541 |
dl |
1.4 |
// inherit Map javadoc |
542 |
tim |
1.1 |
public int size() { |
543 |
|
|
int c = 0; |
544 |
|
|
for (int i = 0; i < segments.length; ++i) |
545 |
dl |
1.4 |
c += segments[i].count; |
546 |
tim |
1.1 |
return c; |
547 |
|
|
} |
548 |
|
|
|
549 |
dl |
1.4 |
// inherit Map javadoc |
550 |
tim |
1.1 |
public boolean isEmpty() { |
551 |
|
|
for (int i = 0; i < segments.length; ++i) |
552 |
dl |
1.4 |
if (segments[i].count != 0) |
553 |
tim |
1.1 |
return false; |
554 |
|
|
return true; |
555 |
|
|
} |
556 |
|
|
|
557 |
|
|
/** |
558 |
|
|
* Returns the value to which the specified key is mapped in this table. |
559 |
|
|
* |
560 |
|
|
* @param key a key in the table. |
561 |
|
|
* @return the value to which the key is mapped in this table; |
562 |
dl |
1.19 |
* <tt>null</tt> if the key is not mapped to any value in |
563 |
tim |
1.1 |
* this table. |
564 |
dl |
1.8 |
* @throws NullPointerException if the key is |
565 |
dl |
1.19 |
* <tt>null</tt>. |
566 |
tim |
1.1 |
* @see #put(Object, Object) |
567 |
|
|
*/ |
568 |
tim |
1.11 |
public V get(Object key) { |
569 |
dl |
1.4 |
int hash = hash(key); // throws NullPointerException if key null |
570 |
tim |
1.11 |
return segmentFor(hash).get((K) key, hash); |
571 |
tim |
1.1 |
} |
572 |
|
|
|
573 |
|
|
/** |
574 |
|
|
* Tests if the specified object is a key in this table. |
575 |
tim |
1.11 |
* |
576 |
tim |
1.1 |
* @param key possible key. |
577 |
dl |
1.19 |
* @return <tt>true</tt> if and only if the specified object |
578 |
tim |
1.11 |
* is a key in this table, as determined by the |
579 |
dl |
1.19 |
* <tt>equals</tt> method; <tt>false</tt> otherwise. |
580 |
dl |
1.8 |
* @throws NullPointerException if the key is |
581 |
dl |
1.19 |
* <tt>null</tt>. |
582 |
tim |
1.1 |
* @see #contains(Object) |
583 |
|
|
*/ |
584 |
|
|
public boolean containsKey(Object key) { |
585 |
dl |
1.4 |
int hash = hash(key); // throws NullPointerException if key null |
586 |
dl |
1.9 |
return segmentFor(hash).containsKey(key, hash); |
587 |
tim |
1.1 |
} |
588 |
|
|
|
589 |
|
|
/** |
590 |
|
|
* Returns <tt>true</tt> if this map maps one or more keys to the |
591 |
|
|
* specified value. Note: This method requires a full internal |
592 |
|
|
* traversal of the hash table, and so is much slower than |
593 |
|
|
* method <tt>containsKey</tt>. |
594 |
|
|
* |
595 |
|
|
* @param value value whose presence in this map is to be tested. |
596 |
|
|
* @return <tt>true</tt> if this map maps one or more keys to the |
597 |
tim |
1.11 |
* specified value. |
598 |
dl |
1.19 |
* @throws NullPointerException if the value is <tt>null</tt>. |
599 |
tim |
1.1 |
*/ |
600 |
|
|
public boolean containsValue(Object value) { |
601 |
tim |
1.11 |
if (value == null) |
602 |
dl |
1.4 |
throw new NullPointerException(); |
603 |
tim |
1.1 |
|
604 |
dl |
1.4 |
for (int i = 0; i < segments.length; ++i) { |
605 |
|
|
if (segments[i].containsValue(value)) |
606 |
|
|
return true; |
607 |
tim |
1.1 |
} |
608 |
|
|
return false; |
609 |
|
|
} |
610 |
dl |
1.19 |
|
611 |
tim |
1.1 |
/** |
612 |
dl |
1.18 |
* Legacy method testing if some key maps into the specified value |
613 |
|
|
* in this table. This operation is more expensive than the |
614 |
dl |
1.19 |
* <tt>containsKey</tt> method. |
615 |
dl |
1.17 |
* |
616 |
|
|
* <p> Note that this method is identical in functionality to |
617 |
dl |
1.18 |
* <tt>containsValue</tt>, This method esists solely to ensure |
618 |
dl |
1.19 |
* full compatibility with class {@link java.util.Hashtable}, |
619 |
dl |
1.18 |
* which supported this method prior to introduction of the |
620 |
|
|
* collections framework. |
621 |
dl |
1.17 |
|
622 |
tim |
1.1 |
* @param value a value to search for. |
623 |
dl |
1.19 |
* @return <tt>true</tt> if and only if some key maps to the |
624 |
|
|
* <tt>value</tt> argument in this table as |
625 |
tim |
1.1 |
* determined by the <tt>equals</tt> method; |
626 |
dl |
1.19 |
* <tt>false</tt> otherwise. |
627 |
|
|
* @throws NullPointerException if the value is <tt>null</tt>. |
628 |
tim |
1.1 |
* @see #containsKey(Object) |
629 |
|
|
* @see #containsValue(Object) |
630 |
dl |
1.8 |
* @see Map |
631 |
tim |
1.1 |
*/ |
632 |
dl |
1.4 |
public boolean contains(Object value) { |
633 |
tim |
1.1 |
return containsValue(value); |
634 |
|
|
} |
635 |
|
|
|
636 |
|
|
/** |
637 |
dl |
1.19 |
* Maps the specified <tt>key</tt> to the specified |
638 |
|
|
* <tt>value</tt> in this table. Neither the key nor the |
639 |
|
|
* value can be <tt>null</tt>. <p> |
640 |
dl |
1.4 |
* |
641 |
dl |
1.19 |
* The value can be retrieved by calling the <tt>get</tt> method |
642 |
tim |
1.11 |
* with a key that is equal to the original key. |
643 |
dl |
1.4 |
* |
644 |
|
|
* @param key the table key. |
645 |
|
|
* @param value the value. |
646 |
|
|
* @return the previous value of the specified key in this table, |
647 |
dl |
1.19 |
* or <tt>null</tt> if it did not have one. |
648 |
dl |
1.8 |
* @throws NullPointerException if the key or value is |
649 |
dl |
1.19 |
* <tt>null</tt>. |
650 |
dl |
1.4 |
* @see Object#equals(Object) |
651 |
|
|
* @see #get(Object) |
652 |
|
|
*/ |
653 |
tim |
1.11 |
public V put(K key, V value) { |
654 |
|
|
if (value == null) |
655 |
dl |
1.4 |
throw new NullPointerException(); |
656 |
tim |
1.11 |
int hash = hash(key); |
657 |
dl |
1.9 |
return segmentFor(hash).put(key, hash, value, false); |
658 |
dl |
1.4 |
} |
659 |
|
|
|
660 |
|
|
/** |
661 |
|
|
* If the specified key is not already associated |
662 |
|
|
* with a value, associate it with the given value. |
663 |
|
|
* This is equivalent to |
664 |
|
|
* <pre> |
665 |
dl |
1.17 |
* if (!map.containsKey(key)) |
666 |
|
|
* return map.put(key, value); |
667 |
|
|
* else |
668 |
|
|
* return map.get(key); |
669 |
dl |
1.4 |
* </pre> |
670 |
|
|
* Except that the action is performed atomically. |
671 |
|
|
* @param key key with which the specified value is to be associated. |
672 |
|
|
* @param value value to be associated with the specified key. |
673 |
|
|
* @return previous value associated with specified key, or <tt>null</tt> |
674 |
|
|
* if there was no mapping for key. A <tt>null</tt> return can |
675 |
|
|
* also indicate that the map previously associated <tt>null</tt> |
676 |
|
|
* with the specified key, if the implementation supports |
677 |
|
|
* <tt>null</tt> values. |
678 |
|
|
* |
679 |
dl |
1.17 |
* @throws UnsupportedOperationException if the <tt>put</tt> operation is |
680 |
|
|
* not supported by this map. |
681 |
|
|
* @throws ClassCastException if the class of the specified key or value |
682 |
|
|
* prevents it from being stored in this map. |
683 |
|
|
* @throws NullPointerException if the specified key or value is |
684 |
dl |
1.4 |
* <tt>null</tt>. |
685 |
|
|
* |
686 |
|
|
**/ |
687 |
tim |
1.11 |
public V putIfAbsent(K key, V value) { |
688 |
|
|
if (value == null) |
689 |
dl |
1.4 |
throw new NullPointerException(); |
690 |
tim |
1.11 |
int hash = hash(key); |
691 |
dl |
1.9 |
return segmentFor(hash).put(key, hash, value, true); |
692 |
dl |
1.4 |
} |
693 |
|
|
|
694 |
|
|
|
695 |
|
|
/** |
696 |
tim |
1.1 |
* Copies all of the mappings from the specified map to this one. |
697 |
|
|
* |
698 |
|
|
* These mappings replace any mappings that this map had for any of the |
699 |
|
|
* keys currently in the specified Map. |
700 |
|
|
* |
701 |
|
|
* @param t Mappings to be stored in this map. |
702 |
|
|
*/ |
703 |
tim |
1.11 |
public void putAll(Map<? extends K, ? extends V> t) { |
704 |
tim |
1.12 |
Iterator<Map.Entry<? extends K, ? extends V>> it = t.entrySet().iterator(); |
705 |
dl |
1.8 |
while (it.hasNext()) { |
706 |
tim |
1.12 |
Entry<? extends K, ? extends V> e = it.next(); |
707 |
dl |
1.4 |
put(e.getKey(), e.getValue()); |
708 |
tim |
1.1 |
} |
709 |
dl |
1.4 |
} |
710 |
|
|
|
711 |
|
|
/** |
712 |
tim |
1.11 |
* Removes the key (and its corresponding value) from this |
713 |
dl |
1.4 |
* table. This method does nothing if the key is not in the table. |
714 |
|
|
* |
715 |
|
|
* @param key the key that needs to be removed. |
716 |
|
|
* @return the value to which the key had been mapped in this table, |
717 |
dl |
1.19 |
* or <tt>null</tt> if the key did not have a mapping. |
718 |
dl |
1.8 |
* @throws NullPointerException if the key is |
719 |
dl |
1.19 |
* <tt>null</tt>. |
720 |
dl |
1.4 |
*/ |
721 |
|
|
public V remove(Object key) { |
722 |
|
|
int hash = hash(key); |
723 |
dl |
1.9 |
return segmentFor(hash).remove(key, hash, null); |
724 |
dl |
1.4 |
} |
725 |
tim |
1.1 |
|
726 |
dl |
1.4 |
/** |
727 |
dl |
1.17 |
* Remove entry for key only if currently mapped to given value. |
728 |
|
|
* Acts as |
729 |
|
|
* <pre> |
730 |
|
|
* if (map.get(key).equals(value)) { |
731 |
|
|
* map.remove(key); |
732 |
|
|
* return true; |
733 |
|
|
* } else return false; |
734 |
|
|
* </pre> |
735 |
|
|
* except that the action is performed atomically. |
736 |
|
|
* @param key key with which the specified value is associated. |
737 |
|
|
* @param value value associated with the specified key. |
738 |
|
|
* @return true if the value was removed |
739 |
|
|
* @throws NullPointerException if the specified key is |
740 |
|
|
* <tt>null</tt>. |
741 |
dl |
1.4 |
*/ |
742 |
dl |
1.13 |
public boolean remove(Object key, Object value) { |
743 |
dl |
1.4 |
int hash = hash(key); |
744 |
dl |
1.13 |
return segmentFor(hash).remove(key, hash, value) != null; |
745 |
tim |
1.1 |
} |
746 |
|
|
|
747 |
|
|
/** |
748 |
|
|
* Removes all mappings from this map. |
749 |
|
|
*/ |
750 |
|
|
public void clear() { |
751 |
tim |
1.11 |
for (int i = 0; i < segments.length; ++i) |
752 |
dl |
1.4 |
segments[i].clear(); |
753 |
tim |
1.1 |
} |
754 |
|
|
|
755 |
dl |
1.4 |
|
756 |
tim |
1.1 |
/** |
757 |
|
|
* Returns a shallow copy of this |
758 |
|
|
* <tt>ConcurrentHashMap</tt> instance: the keys and |
759 |
|
|
* values themselves are not cloned. |
760 |
|
|
* |
761 |
|
|
* @return a shallow copy of this map. |
762 |
|
|
*/ |
763 |
|
|
public Object clone() { |
764 |
dl |
1.4 |
// We cannot call super.clone, since it would share final |
765 |
|
|
// segments array, and there's no way to reassign finals. |
766 |
|
|
|
767 |
|
|
float lf = segments[0].loadFactor; |
768 |
|
|
int segs = segments.length; |
769 |
|
|
int cap = (int)(size() / lf); |
770 |
|
|
if (cap < segs) cap = segs; |
771 |
tim |
1.12 |
ConcurrentHashMap<K,V> t = new ConcurrentHashMap<K,V>(cap, lf, segs); |
772 |
dl |
1.4 |
t.putAll(this); |
773 |
|
|
return t; |
774 |
tim |
1.1 |
} |
775 |
|
|
|
776 |
|
|
/** |
777 |
|
|
* Returns a set view of the keys contained in this map. The set is |
778 |
|
|
* backed by the map, so changes to the map are reflected in the set, and |
779 |
|
|
* vice-versa. The set supports element removal, which removes the |
780 |
|
|
* corresponding mapping from this map, via the <tt>Iterator.remove</tt>, |
781 |
|
|
* <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt>, and |
782 |
|
|
* <tt>clear</tt> operations. It does not support the <tt>add</tt> or |
783 |
|
|
* <tt>addAll</tt> operations. |
784 |
dl |
1.14 |
* The returned <tt>iterator</tt> is a "weakly consistent" iterator that |
785 |
|
|
* will never throw {@link java.util.ConcurrentModificationException}, |
786 |
|
|
* and guarantees to traverse elements as they existed upon |
787 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
788 |
|
|
* reflect any modifications subsequent to construction. |
789 |
tim |
1.1 |
* |
790 |
|
|
* @return a set view of the keys contained in this map. |
791 |
|
|
*/ |
792 |
|
|
public Set<K> keySet() { |
793 |
|
|
Set<K> ks = keySet; |
794 |
dl |
1.8 |
return (ks != null) ? ks : (keySet = new KeySet()); |
795 |
tim |
1.1 |
} |
796 |
|
|
|
797 |
|
|
|
798 |
|
|
/** |
799 |
|
|
* Returns a collection view of the values contained in this map. The |
800 |
|
|
* collection is backed by the map, so changes to the map are reflected in |
801 |
|
|
* the collection, and vice-versa. The collection supports element |
802 |
|
|
* removal, which removes the corresponding mapping from this map, via the |
803 |
|
|
* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>, |
804 |
|
|
* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations. |
805 |
|
|
* It does not support the <tt>add</tt> or <tt>addAll</tt> operations. |
806 |
dl |
1.14 |
* The returned <tt>iterator</tt> is a "weakly consistent" iterator that |
807 |
|
|
* will never throw {@link java.util.ConcurrentModificationException}, |
808 |
|
|
* and guarantees to traverse elements as they existed upon |
809 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
810 |
|
|
* reflect any modifications subsequent to construction. |
811 |
tim |
1.1 |
* |
812 |
|
|
* @return a collection view of the values contained in this map. |
813 |
|
|
*/ |
814 |
|
|
public Collection<V> values() { |
815 |
|
|
Collection<V> vs = values; |
816 |
dl |
1.8 |
return (vs != null) ? vs : (values = new Values()); |
817 |
tim |
1.1 |
} |
818 |
|
|
|
819 |
|
|
|
820 |
|
|
/** |
821 |
|
|
* Returns a collection view of the mappings contained in this map. Each |
822 |
|
|
* element in the returned collection is a <tt>Map.Entry</tt>. The |
823 |
|
|
* collection is backed by the map, so changes to the map are reflected in |
824 |
|
|
* the collection, and vice-versa. The collection supports element |
825 |
|
|
* removal, which removes the corresponding mapping from the map, via the |
826 |
|
|
* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>, |
827 |
|
|
* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations. |
828 |
|
|
* It does not support the <tt>add</tt> or <tt>addAll</tt> operations. |
829 |
dl |
1.14 |
* The returned <tt>iterator</tt> is a "weakly consistent" iterator that |
830 |
|
|
* will never throw {@link java.util.ConcurrentModificationException}, |
831 |
|
|
* and guarantees to traverse elements as they existed upon |
832 |
|
|
* construction of the iterator, and may (but is not guaranteed to) |
833 |
|
|
* reflect any modifications subsequent to construction. |
834 |
tim |
1.1 |
* |
835 |
|
|
* @return a collection view of the mappings contained in this map. |
836 |
|
|
*/ |
837 |
|
|
public Set<Map.Entry<K,V>> entrySet() { |
838 |
|
|
Set<Map.Entry<K,V>> es = entrySet; |
839 |
|
|
return (es != null) ? es : (entrySet = new EntrySet()); |
840 |
|
|
} |
841 |
|
|
|
842 |
|
|
|
843 |
|
|
/** |
844 |
|
|
* Returns an enumeration of the keys in this table. |
845 |
|
|
* |
846 |
|
|
* @return an enumeration of the keys in this table. |
847 |
|
|
* @see Enumeration |
848 |
|
|
* @see #elements() |
849 |
|
|
* @see #keySet() |
850 |
|
|
* @see Map |
851 |
|
|
*/ |
852 |
dl |
1.4 |
public Enumeration<K> keys() { |
853 |
tim |
1.1 |
return new KeyIterator(); |
854 |
|
|
} |
855 |
|
|
|
856 |
|
|
/** |
857 |
|
|
* Returns an enumeration of the values in this table. |
858 |
|
|
* Use the Enumeration methods on the returned object to fetch the elements |
859 |
|
|
* sequentially. |
860 |
|
|
* |
861 |
|
|
* @return an enumeration of the values in this table. |
862 |
|
|
* @see java.util.Enumeration |
863 |
|
|
* @see #keys() |
864 |
|
|
* @see #values() |
865 |
|
|
* @see Map |
866 |
|
|
*/ |
867 |
dl |
1.4 |
public Enumeration<V> elements() { |
868 |
tim |
1.1 |
return new ValueIterator(); |
869 |
|
|
} |
870 |
|
|
|
871 |
dl |
1.4 |
/* ---------------- Iterator Support -------------- */ |
872 |
tim |
1.11 |
|
873 |
dl |
1.4 |
private abstract class HashIterator { |
874 |
|
|
private int nextSegmentIndex; |
875 |
|
|
private int nextTableIndex; |
876 |
tim |
1.11 |
private HashEntry[] currentTable; |
877 |
dl |
1.4 |
private HashEntry<K, V> nextEntry; |
878 |
|
|
private HashEntry<K, V> lastReturned; |
879 |
tim |
1.1 |
|
880 |
|
|
private HashIterator() { |
881 |
dl |
1.8 |
nextSegmentIndex = segments.length - 1; |
882 |
dl |
1.4 |
nextTableIndex = -1; |
883 |
|
|
advance(); |
884 |
tim |
1.1 |
} |
885 |
|
|
|
886 |
|
|
public boolean hasMoreElements() { return hasNext(); } |
887 |
|
|
|
888 |
dl |
1.4 |
private void advance() { |
889 |
|
|
if (nextEntry != null && (nextEntry = nextEntry.next) != null) |
890 |
|
|
return; |
891 |
tim |
1.11 |
|
892 |
dl |
1.4 |
while (nextTableIndex >= 0) { |
893 |
tim |
1.12 |
if ( (nextEntry = (HashEntry<K,V>)currentTable[nextTableIndex--]) != null) |
894 |
dl |
1.4 |
return; |
895 |
|
|
} |
896 |
tim |
1.11 |
|
897 |
dl |
1.4 |
while (nextSegmentIndex >= 0) { |
898 |
tim |
1.12 |
Segment<K,V> seg = (Segment<K,V>)segments[nextSegmentIndex--]; |
899 |
dl |
1.4 |
if (seg.count != 0) { |
900 |
|
|
currentTable = seg.table; |
901 |
dl |
1.8 |
for (int j = currentTable.length - 1; j >= 0; --j) { |
902 |
tim |
1.12 |
if ( (nextEntry = (HashEntry<K,V>)currentTable[j]) != null) { |
903 |
dl |
1.8 |
nextTableIndex = j - 1; |
904 |
dl |
1.4 |
return; |
905 |
|
|
} |
906 |
tim |
1.1 |
} |
907 |
|
|
} |
908 |
|
|
} |
909 |
|
|
} |
910 |
|
|
|
911 |
dl |
1.4 |
public boolean hasNext() { return nextEntry != null; } |
912 |
tim |
1.1 |
|
913 |
dl |
1.4 |
HashEntry<K,V> nextEntry() { |
914 |
|
|
if (nextEntry == null) |
915 |
tim |
1.1 |
throw new NoSuchElementException(); |
916 |
dl |
1.4 |
lastReturned = nextEntry; |
917 |
|
|
advance(); |
918 |
|
|
return lastReturned; |
919 |
tim |
1.1 |
} |
920 |
|
|
|
921 |
|
|
public void remove() { |
922 |
|
|
if (lastReturned == null) |
923 |
|
|
throw new IllegalStateException(); |
924 |
|
|
ConcurrentHashMap.this.remove(lastReturned.key); |
925 |
|
|
lastReturned = null; |
926 |
|
|
} |
927 |
dl |
1.4 |
} |
928 |
|
|
|
929 |
|
|
private class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> { |
930 |
|
|
public K next() { return super.nextEntry().key; } |
931 |
|
|
public K nextElement() { return super.nextEntry().key; } |
932 |
|
|
} |
933 |
|
|
|
934 |
|
|
private class ValueIterator extends HashIterator implements Iterator<V>, Enumeration<V> { |
935 |
|
|
public V next() { return super.nextEntry().value; } |
936 |
|
|
public V nextElement() { return super.nextEntry().value; } |
937 |
|
|
} |
938 |
tim |
1.1 |
|
939 |
dl |
1.4 |
private class EntryIterator extends HashIterator implements Iterator<Entry<K,V>> { |
940 |
|
|
public Map.Entry<K,V> next() { return super.nextEntry(); } |
941 |
tim |
1.1 |
} |
942 |
|
|
|
943 |
dl |
1.4 |
private class KeySet extends AbstractSet<K> { |
944 |
|
|
public Iterator<K> iterator() { |
945 |
|
|
return new KeyIterator(); |
946 |
|
|
} |
947 |
|
|
public int size() { |
948 |
|
|
return ConcurrentHashMap.this.size(); |
949 |
|
|
} |
950 |
|
|
public boolean contains(Object o) { |
951 |
|
|
return ConcurrentHashMap.this.containsKey(o); |
952 |
|
|
} |
953 |
|
|
public boolean remove(Object o) { |
954 |
|
|
return ConcurrentHashMap.this.remove(o) != null; |
955 |
|
|
} |
956 |
|
|
public void clear() { |
957 |
|
|
ConcurrentHashMap.this.clear(); |
958 |
|
|
} |
959 |
tim |
1.1 |
} |
960 |
|
|
|
961 |
dl |
1.4 |
private class Values extends AbstractCollection<V> { |
962 |
|
|
public Iterator<V> iterator() { |
963 |
|
|
return new ValueIterator(); |
964 |
|
|
} |
965 |
|
|
public int size() { |
966 |
|
|
return ConcurrentHashMap.this.size(); |
967 |
|
|
} |
968 |
|
|
public boolean contains(Object o) { |
969 |
|
|
return ConcurrentHashMap.this.containsValue(o); |
970 |
|
|
} |
971 |
|
|
public void clear() { |
972 |
|
|
ConcurrentHashMap.this.clear(); |
973 |
|
|
} |
974 |
tim |
1.1 |
} |
975 |
|
|
|
976 |
tim |
1.12 |
private class EntrySet extends AbstractSet<Map.Entry<K,V>> { |
977 |
dl |
1.4 |
public Iterator<Map.Entry<K,V>> iterator() { |
978 |
|
|
return new EntryIterator(); |
979 |
|
|
} |
980 |
|
|
public boolean contains(Object o) { |
981 |
|
|
if (!(o instanceof Map.Entry)) |
982 |
|
|
return false; |
983 |
|
|
Map.Entry<K,V> e = (Map.Entry<K,V>)o; |
984 |
|
|
V v = ConcurrentHashMap.this.get(e.getKey()); |
985 |
|
|
return v != null && v.equals(e.getValue()); |
986 |
|
|
} |
987 |
|
|
public boolean remove(Object o) { |
988 |
|
|
if (!(o instanceof Map.Entry)) |
989 |
|
|
return false; |
990 |
|
|
Map.Entry<K,V> e = (Map.Entry<K,V>)o; |
991 |
dl |
1.13 |
return ConcurrentHashMap.this.remove(e.getKey(), e.getValue()); |
992 |
dl |
1.4 |
} |
993 |
|
|
public int size() { |
994 |
|
|
return ConcurrentHashMap.this.size(); |
995 |
|
|
} |
996 |
|
|
public void clear() { |
997 |
|
|
ConcurrentHashMap.this.clear(); |
998 |
|
|
} |
999 |
tim |
1.1 |
} |
1000 |
|
|
|
1001 |
dl |
1.4 |
/* ---------------- Serialization Support -------------- */ |
1002 |
|
|
|
1003 |
tim |
1.1 |
/** |
1004 |
|
|
* Save the state of the <tt>ConcurrentHashMap</tt> |
1005 |
|
|
* instance to a stream (i.e., |
1006 |
|
|
* serialize it). |
1007 |
dl |
1.8 |
* @param s the stream |
1008 |
tim |
1.1 |
* @serialData |
1009 |
|
|
* the key (Object) and value (Object) |
1010 |
|
|
* for each key-value mapping, followed by a null pair. |
1011 |
|
|
* The key-value mappings are emitted in no particular order. |
1012 |
|
|
*/ |
1013 |
|
|
private void writeObject(java.io.ObjectOutputStream s) throws IOException { |
1014 |
|
|
s.defaultWriteObject(); |
1015 |
|
|
|
1016 |
|
|
for (int k = 0; k < segments.length; ++k) { |
1017 |
tim |
1.12 |
Segment<K,V> seg = (Segment<K,V>)segments[k]; |
1018 |
dl |
1.2 |
seg.lock(); |
1019 |
|
|
try { |
1020 |
tim |
1.11 |
HashEntry[] tab = seg.table; |
1021 |
dl |
1.4 |
for (int i = 0; i < tab.length; ++i) { |
1022 |
tim |
1.12 |
for (HashEntry<K,V> e = (HashEntry<K,V>)tab[i]; e != null; e = e.next) { |
1023 |
dl |
1.4 |
s.writeObject(e.key); |
1024 |
|
|
s.writeObject(e.value); |
1025 |
|
|
} |
1026 |
|
|
} |
1027 |
tim |
1.16 |
} finally { |
1028 |
dl |
1.2 |
seg.unlock(); |
1029 |
|
|
} |
1030 |
tim |
1.1 |
} |
1031 |
|
|
s.writeObject(null); |
1032 |
|
|
s.writeObject(null); |
1033 |
|
|
} |
1034 |
|
|
|
1035 |
|
|
/** |
1036 |
|
|
* Reconstitute the <tt>ConcurrentHashMap</tt> |
1037 |
|
|
* instance from a stream (i.e., |
1038 |
|
|
* deserialize it). |
1039 |
dl |
1.8 |
* @param s the stream |
1040 |
tim |
1.1 |
*/ |
1041 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1042 |
|
|
throws IOException, ClassNotFoundException { |
1043 |
|
|
s.defaultReadObject(); |
1044 |
|
|
|
1045 |
dl |
1.4 |
// Initialize each segment to be minimally sized, and let grow. |
1046 |
|
|
for (int i = 0; i < segments.length; ++i) { |
1047 |
tim |
1.11 |
segments[i].setTable(new HashEntry[1]); |
1048 |
dl |
1.4 |
} |
1049 |
tim |
1.1 |
|
1050 |
|
|
// Read the keys and values, and put the mappings in the table |
1051 |
dl |
1.9 |
for (;;) { |
1052 |
tim |
1.1 |
K key = (K) s.readObject(); |
1053 |
|
|
V value = (V) s.readObject(); |
1054 |
|
|
if (key == null) |
1055 |
|
|
break; |
1056 |
|
|
put(key, value); |
1057 |
|
|
} |
1058 |
|
|
} |
1059 |
|
|
} |
1060 |
tim |
1.11 |
|