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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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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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dl |
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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* same functional specification as |
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* <tt>java.util.Hashtable</tt>. However, even though all operations |
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* are thread-safe, retrieval operations do <em>not</em> entail |
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* locking, and there is <em>not</em> any support for locking the |
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* entire table in a way that prevents all access. This class is |
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* fully interoperable with Hashtable in programs that rely on its |
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* thread safety but not on its synchronization details. |
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* |
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* <p> Retrieval operations (including <tt>get</tt>) ordinarily |
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dl |
1.5 |
* overlap with update operations (including <tt>put</tt> and |
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dl |
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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tim |
1.1 |
* |
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dl |
1.4 |
* <p> The allowed concurrency among update operations is controlled |
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* by the optional <tt>segments</tt> constructor argument (default |
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brian |
1.7 |
* 16). The table is divided into this many independent parts, each of |
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dl |
1.4 |
* which can be updated concurrently. Because placement in hash tables |
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* is essentially random, the actual concurrency will vary. As a rough |
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* rule of thumb, you should choose at least as many segments as you |
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* expect concurrent threads. However, using more segments than you |
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* need can waste space and time. Using a value of 1 for |
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* <tt>segments</tt> results in a table that is concurrently readable |
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* but can only be updated by one thread at a time. |
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tim |
1.1 |
* |
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dl |
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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tim |
1.1 |
* |
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dl |
1.8 |
* @since 1.5 |
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* @author Doug Lea |
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*/ |
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tim |
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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/* |
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dl |
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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tim |
1.1 |
|
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dl |
1.4 |
/* ---------------- Constants -------------- */ |
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/** |
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* The default initial number of table slots for this table (32). |
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* Used when not otherwise specified in constructor. |
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*/ |
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dl |
1.8 |
private static int DEFAULT_INITIAL_CAPACITY = 16; |
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tim |
1.1 |
|
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/** |
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dl |
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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|
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tim |
1.1 |
/** |
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dl |
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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static final float DEFAULT_LOAD_FACTOR = 0.75f; |
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tim |
1.1 |
|
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/** |
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dl |
1.4 |
* The default number of concurrency control segments. |
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tim |
1.1 |
**/ |
88 |
dl |
1.4 |
private static final int DEFAULT_SEGMENTS = 16; |
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tim |
1.1 |
|
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dl |
1.4 |
/* ---------------- Fields -------------- */ |
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tim |
1.1 |
|
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/** |
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dl |
1.4 |
* Mask value for indexing into segments. The lower bits of a |
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* key's hash code are used to choose the segment, and the |
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* remaining bits are used as the placement hashcode used within |
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* the segment. |
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tim |
1.1 |
**/ |
98 |
dl |
1.4 |
private final int segmentMask; |
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tim |
1.1 |
|
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/** |
101 |
dl |
1.4 |
* Shift value for indexing within segments. |
102 |
tim |
1.1 |
**/ |
103 |
dl |
1.4 |
private final int segmentShift; |
104 |
tim |
1.1 |
|
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/** |
106 |
dl |
1.4 |
* The segments, each of which is a specialized hash table |
107 |
tim |
1.1 |
*/ |
108 |
dl |
1.4 |
private final Segment<K,V>[] segments; |
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110 |
dl |
1.6 |
private transient Set<K> keySet; |
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private transient Set/*<Map.Entry<K,V>>*/ entrySet; |
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private transient Collection<V> values; |
113 |
dl |
1.4 |
|
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/* ---------------- Small Utilities -------------- */ |
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tim |
1.1 |
|
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/** |
117 |
dl |
1.4 |
* Return a hash code for non-null Object x. |
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* Uses the same hash code spreader as most other j.u hash tables. |
119 |
dl |
1.8 |
* @param x the object serving as a key |
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* @return the hash code |
121 |
tim |
1.1 |
*/ |
122 |
dl |
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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/** |
132 |
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* Check for equality of non-null references x and y. |
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**/ |
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private static boolean eq(Object x, Object y) { |
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return x == y || x.equals(y); |
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} |
137 |
tim |
1.1 |
|
138 |
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/** |
139 |
dl |
1.4 |
* Return index for hash code h in table of given length. |
140 |
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*/ |
141 |
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private static int indexFor(int h, int length) { |
142 |
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return h & (length-1); |
143 |
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} |
144 |
tim |
1.1 |
|
145 |
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/** |
146 |
dl |
1.4 |
* Return the segment that should be used for key with given hash |
147 |
tim |
1.1 |
*/ |
148 |
dl |
1.4 |
private Segment<K,V> segmentFor(int hash) { |
149 |
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return segments[hash & segmentMask]; |
150 |
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} |
151 |
tim |
1.1 |
|
152 |
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/** |
153 |
dl |
1.4 |
* Strip the segment index from hash code to use as a per-segment hash. |
154 |
tim |
1.1 |
*/ |
155 |
dl |
1.4 |
private int segmentHashFor(int hash) { |
156 |
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return hash >>> segmentShift; |
157 |
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} |
158 |
tim |
1.1 |
|
159 |
dl |
1.4 |
/* ---------------- Inner Classes -------------- */ |
160 |
tim |
1.1 |
|
161 |
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/** |
162 |
dl |
1.6 |
* Segments are specialized versions of hash tables. This |
163 |
dl |
1.4 |
* subclasses from ReentrantLock opportunistically, just to |
164 |
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* simplify some locking and avoid separate construction. |
165 |
tim |
1.1 |
**/ |
166 |
dl |
1.8 |
private static final class Segment<K,V> extends ReentrantLock implements Serializable { |
167 |
dl |
1.4 |
/* |
168 |
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* Segments maintain a table of entry lists that are ALWAYS |
169 |
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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 |
174 |
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* created to replace them. This works well for hash tables |
175 |
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* since the bin lists tend to be short. (The average length |
176 |
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* is less than two for the default load factor threshold.) |
177 |
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* |
178 |
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* Read operations can thus proceed without locking, but rely |
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* on a memory barrier to ensure that completed write |
180 |
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* operations performed by other threads are |
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* noticed. Conveniently, the "count" field, tracking the |
182 |
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* number of elements, can also serve as the volatile variable |
183 |
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* providing proper read/write barriers. This is convenient |
184 |
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* because this field needs to be read in many read operations |
185 |
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* anyway. The use of volatiles for this purpose is only |
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* guaranteed to work in accord with reuirements in |
187 |
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* multithreaded environments when run on JVMs conforming to |
188 |
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* the clarified JSR133 memory model specification. This true |
189 |
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* for hotspot as of release 1.4. |
190 |
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* |
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* Implementors note. The basic rules for all this are: |
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* |
193 |
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* - All unsynchronized read operations must first read the |
194 |
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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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* |
197 |
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* - All synchronized write operations should write to |
198 |
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* the "count" field after updating. The operations must not |
199 |
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* take any action that could even momentarily cause |
200 |
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* a concurrent read operation to see inconsistent |
201 |
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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 |
208 |
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* in code comments. |
209 |
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*/ |
210 |
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211 |
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/** |
212 |
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* The number of elements in this segment's region. |
213 |
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**/ |
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transient volatile int count; |
215 |
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216 |
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/** |
217 |
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* The table is rehashed when its size exceeds this threshold. |
218 |
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* (The value of this field is always (int)(capacity * |
219 |
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* loadFactor).) |
220 |
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*/ |
221 |
dl |
1.8 |
private transient int threshold; |
222 |
dl |
1.4 |
|
223 |
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/** |
224 |
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* The per-segment table |
225 |
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*/ |
226 |
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transient HashEntry<K,V>[] table; |
227 |
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228 |
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/** |
229 |
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* The load factor for the hash table. Even though this value |
230 |
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* is same for all segments, it is replicated to avoid needing |
231 |
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* links to outer object. |
232 |
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* @serial |
233 |
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*/ |
234 |
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private final float loadFactor; |
235 |
tim |
1.1 |
|
236 |
dl |
1.4 |
Segment(int initialCapacity, float lf) { |
237 |
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loadFactor = lf; |
238 |
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setTable(new HashEntry<K,V>[initialCapacity]); |
239 |
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} |
240 |
tim |
1.1 |
|
241 |
dl |
1.4 |
/** |
242 |
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* Set table to new HashEntry array. |
243 |
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* Call only while holding lock or in constructor. |
244 |
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**/ |
245 |
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private void setTable(HashEntry<K,V>[] newTable) { |
246 |
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table = newTable; |
247 |
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threshold = (int)(newTable.length * loadFactor); |
248 |
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count = count; // write-volatile |
249 |
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} |
250 |
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251 |
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/* Specialized implementations of map methods */ |
252 |
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253 |
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V get(K key, int hash) { |
254 |
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if (count != 0) { // read-volatile |
255 |
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HashEntry<K,V>[] tab = table; |
256 |
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int index = indexFor(hash, tab.length); |
257 |
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HashEntry<K,V> e = tab[index]; |
258 |
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while (e != null) { |
259 |
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if (e.hash == hash && eq(key, e.key)) |
260 |
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return e.value; |
261 |
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e = e.next; |
262 |
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} |
263 |
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} |
264 |
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return null; |
265 |
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} |
266 |
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267 |
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boolean containsKey(Object key, int hash) { |
268 |
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if (count != 0) { // read-volatile |
269 |
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HashEntry<K,V>[] tab = table; |
270 |
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int index = indexFor(hash, tab.length); |
271 |
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HashEntry<K,V> e = tab[index]; |
272 |
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while (e != null) { |
273 |
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if (e.hash == hash && eq(key, e.key)) |
274 |
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return true; |
275 |
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e = e.next; |
276 |
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} |
277 |
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} |
278 |
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return false; |
279 |
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} |
280 |
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281 |
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boolean containsValue(Object value) { |
282 |
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if (count != 0) { // read-volatile |
283 |
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HashEntry<K,V> tab[] = table; |
284 |
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int len = tab.length; |
285 |
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for (int i = 0 ; i < len; i++) |
286 |
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for (HashEntry<K,V> e = tab[i] ; e != null ; e = e.next) |
287 |
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if (value.equals(e.value)) |
288 |
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return true; |
289 |
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} |
290 |
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return false; |
291 |
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} |
292 |
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293 |
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V put(K key, int hash, V value, boolean onlyIfAbsent) { |
294 |
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lock(); |
295 |
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try { |
296 |
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HashEntry<K,V>[] tab = table; |
297 |
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int index = indexFor(hash, tab.length); |
298 |
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HashEntry<K,V> first = tab[index]; |
299 |
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300 |
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for (HashEntry<K,V> e = first; e != null; e = e.next) { |
301 |
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if (e.hash == hash && eq(key, e.key)) { |
302 |
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V oldValue = e.value; |
303 |
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if (!onlyIfAbsent) |
304 |
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e.value = value; |
305 |
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count = count; // write-volatile |
306 |
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return oldValue; |
307 |
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} |
308 |
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} |
309 |
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310 |
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tab[index] = new HashEntry<K,V>(hash, key, value, first); |
311 |
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if (++count > threshold) // write-volatile |
312 |
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rehash(); |
313 |
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return null; |
314 |
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} |
315 |
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finally { |
316 |
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unlock(); |
317 |
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} |
318 |
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} |
319 |
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320 |
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private void rehash() { |
321 |
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HashEntry<K,V>[] oldTable = table; |
322 |
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int oldCapacity = oldTable.length; |
323 |
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if (oldCapacity >= MAXIMUM_CAPACITY) |
324 |
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return; |
325 |
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|
326 |
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/* |
327 |
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* Reclassify nodes in each list to new Map. Because we are |
328 |
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* using power-of-two expansion, the elements from each bin |
329 |
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* must either stay at same index, or move with a power of two |
330 |
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* offset. We eliminate unnecessary node creation by catching |
331 |
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* cases where old nodes can be reused because their next |
332 |
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* fields won't change. Statistically, at the default |
333 |
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* threshhold, only about one-sixth of them need cloning when |
334 |
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* a table doubles. The nodes they replace will be garbage |
335 |
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* collectable as soon as they are no longer referenced by any |
336 |
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* reader thread that may be in the midst of traversing table |
337 |
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* right now. |
338 |
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*/ |
339 |
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|
340 |
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HashEntry<K,V>[] newTable = new HashEntry<K,V>[oldCapacity << 1]; |
341 |
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int sizeMask = newTable.length - 1; |
342 |
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for (int i = 0; i < oldCapacity ; i++) { |
343 |
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// We need to guarantee that any existing reads of old Map can |
344 |
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// proceed. So we cannot yet null out each bin. |
345 |
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HashEntry<K,V> e = oldTable[i]; |
346 |
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347 |
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if (e != null) { |
348 |
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HashEntry<K,V> next = e.next; |
349 |
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int idx = e.hash & sizeMask; |
350 |
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|
351 |
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// Single node on list |
352 |
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if (next == null) |
353 |
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newTable[idx] = e; |
354 |
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355 |
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else { |
356 |
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// Reuse trailing consecutive sequence at same slot |
357 |
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HashEntry<K,V> lastRun = e; |
358 |
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int lastIdx = idx; |
359 |
|
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for (HashEntry<K,V> last = next; |
360 |
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last != null; |
361 |
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last = last.next) { |
362 |
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int k = last.hash & sizeMask; |
363 |
|
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if (k != lastIdx) { |
364 |
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lastIdx = k; |
365 |
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lastRun = last; |
366 |
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} |
367 |
|
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} |
368 |
|
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newTable[lastIdx] = lastRun; |
369 |
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|
370 |
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// Clone all remaining nodes |
371 |
|
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for (HashEntry<K,V> p = e; p != lastRun; p = p.next) { |
372 |
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int k = p.hash & sizeMask; |
373 |
dl |
1.8 |
newTable[k] = new HashEntry<K,V>(p.hash, |
374 |
|
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p.key, |
375 |
|
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p.value, |
376 |
|
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newTable[k]); |
377 |
dl |
1.4 |
} |
378 |
|
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} |
379 |
|
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} |
380 |
|
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} |
381 |
|
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setTable(newTable); |
382 |
|
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} |
383 |
dl |
1.6 |
|
384 |
|
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/** |
385 |
|
|
* Remove; match on key only if value null, else match both. |
386 |
|
|
*/ |
387 |
dl |
1.4 |
V remove(Object key, int hash, Object value) { |
388 |
|
|
lock(); |
389 |
|
|
try { |
390 |
|
|
HashEntry[] tab = table; |
391 |
|
|
int index = indexFor(hash, tab.length); |
392 |
|
|
HashEntry<K,V> first = tab[index]; |
393 |
|
|
|
394 |
|
|
HashEntry<K,V> e = first; |
395 |
|
|
while (true) { |
396 |
|
|
if (e == null) |
397 |
|
|
return null; |
398 |
|
|
if (e.hash == hash && eq(key, e.key)) |
399 |
|
|
break; |
400 |
|
|
e = e.next; |
401 |
|
|
} |
402 |
|
|
|
403 |
|
|
V oldValue = e.value; |
404 |
|
|
if (value != null && !value.equals(oldValue)) |
405 |
|
|
return null; |
406 |
|
|
|
407 |
|
|
// All entries following removed node can stay in list, but |
408 |
|
|
// all preceeding ones need to be cloned. |
409 |
|
|
HashEntry<K,V> newFirst = e.next; |
410 |
|
|
for (HashEntry<K,V> p = first; p != e; p = p.next) |
411 |
dl |
1.8 |
newFirst = new HashEntry<K,V>(p.hash, p.key, |
412 |
|
|
p.value, newFirst); |
413 |
dl |
1.4 |
tab[index] = newFirst; |
414 |
|
|
|
415 |
|
|
count--; // write-volatile |
416 |
|
|
return e.value; |
417 |
|
|
} |
418 |
|
|
finally { |
419 |
|
|
unlock(); |
420 |
|
|
} |
421 |
|
|
} |
422 |
|
|
|
423 |
|
|
void clear() { |
424 |
|
|
lock(); |
425 |
|
|
try { |
426 |
|
|
HashEntry<K,V> tab[] = table; |
427 |
|
|
for (int i = 0; i < tab.length ; i++) |
428 |
|
|
tab[i] = null; |
429 |
|
|
count = 0; // write-volatile |
430 |
|
|
} |
431 |
|
|
finally { |
432 |
|
|
unlock(); |
433 |
|
|
} |
434 |
|
|
} |
435 |
tim |
1.1 |
} |
436 |
|
|
|
437 |
|
|
/** |
438 |
dl |
1.4 |
* ConcurrentReaderHashMap list entry. |
439 |
tim |
1.1 |
*/ |
440 |
dl |
1.4 |
private static class HashEntry<K,V> implements Entry<K,V> { |
441 |
|
|
private final K key; |
442 |
|
|
private V value; |
443 |
|
|
private final int hash; |
444 |
|
|
private final HashEntry<K,V> next; |
445 |
|
|
|
446 |
|
|
HashEntry(int hash, K key, V value, HashEntry<K,V> next) { |
447 |
|
|
this.value = value; |
448 |
|
|
this.hash = hash; |
449 |
|
|
this.key = key; |
450 |
|
|
this.next = next; |
451 |
|
|
} |
452 |
|
|
|
453 |
|
|
public K getKey() { |
454 |
|
|
return key; |
455 |
|
|
} |
456 |
tim |
1.1 |
|
457 |
dl |
1.4 |
public V getValue() { |
458 |
|
|
return value; |
459 |
tim |
1.1 |
} |
460 |
|
|
|
461 |
dl |
1.4 |
public V setValue(V newValue) { |
462 |
|
|
// We aren't required to, and don't provide any |
463 |
|
|
// visibility barriers for setting value. |
464 |
|
|
if (newValue == null) |
465 |
|
|
throw new NullPointerException(); |
466 |
|
|
V oldValue = this.value; |
467 |
|
|
this.value = newValue; |
468 |
|
|
return oldValue; |
469 |
|
|
} |
470 |
tim |
1.1 |
|
471 |
dl |
1.4 |
public boolean equals(Object o) { |
472 |
|
|
if (!(o instanceof Entry)) |
473 |
|
|
return false; |
474 |
|
|
Entry<K,V> e = (Entry)o; |
475 |
|
|
return (key.equals(e.getKey()) && value.equals(e.getValue())); |
476 |
|
|
} |
477 |
|
|
|
478 |
|
|
public int hashCode() { |
479 |
|
|
return key.hashCode() ^ value.hashCode(); |
480 |
|
|
} |
481 |
tim |
1.1 |
|
482 |
dl |
1.4 |
public String toString() { |
483 |
|
|
return key + "=" + value; |
484 |
|
|
} |
485 |
tim |
1.1 |
} |
486 |
|
|
|
487 |
dl |
1.4 |
|
488 |
|
|
/* ---------------- Public operations -------------- */ |
489 |
tim |
1.1 |
|
490 |
|
|
/** |
491 |
|
|
* Constructs a new, empty map with the specified initial |
492 |
|
|
* capacity and the specified load factor. |
493 |
|
|
* |
494 |
dl |
1.4 |
* @param initialCapacity the initial capacity. The actual |
495 |
|
|
* initial capacity is rounded up to the nearest power of two. |
496 |
tim |
1.1 |
* @param loadFactor the load factor threshold, used to control resizing. |
497 |
dl |
1.4 |
* @param segments the number of concurrently accessible segments. the |
498 |
|
|
* actual number of segments is rounded to the next power of two. |
499 |
|
|
* @throws IllegalArgumentException if the initial capacity is |
500 |
|
|
* negative or the load factor or number of segments are |
501 |
|
|
* nonpositive. |
502 |
|
|
*/ |
503 |
dl |
1.8 |
public ConcurrentHashMap(int initialCapacity, |
504 |
|
|
float loadFactor, int segments) { |
505 |
dl |
1.4 |
if (!(loadFactor > 0) || initialCapacity < 0 || segments <= 0) |
506 |
|
|
throw new IllegalArgumentException(); |
507 |
|
|
|
508 |
|
|
// Find power-of-two sizes best matching arguments |
509 |
|
|
int sshift = 0; |
510 |
|
|
int ssize = 1; |
511 |
|
|
while (ssize < segments) { |
512 |
|
|
++sshift; |
513 |
|
|
ssize <<= 1; |
514 |
|
|
} |
515 |
|
|
segmentShift = sshift; |
516 |
dl |
1.8 |
segmentMask = ssize - 1; |
517 |
dl |
1.4 |
this.segments = new Segment<K,V>[ssize]; |
518 |
|
|
|
519 |
|
|
if (initialCapacity > MAXIMUM_CAPACITY) |
520 |
|
|
initialCapacity = MAXIMUM_CAPACITY; |
521 |
|
|
int c = initialCapacity / ssize; |
522 |
|
|
if (c * ssize < initialCapacity) |
523 |
|
|
++c; |
524 |
|
|
int cap = 1; |
525 |
|
|
while (cap < c) |
526 |
|
|
cap <<= 1; |
527 |
|
|
|
528 |
|
|
for (int i = 0; i < this.segments.length; ++i) |
529 |
|
|
this.segments[i] = new Segment<K,V>(cap, loadFactor); |
530 |
tim |
1.1 |
} |
531 |
|
|
|
532 |
|
|
/** |
533 |
|
|
* Constructs a new, empty map with the specified initial |
534 |
dl |
1.4 |
* capacity, and with default load factor and segments. |
535 |
tim |
1.1 |
* |
536 |
dl |
1.4 |
* @param initialCapacity the initial capacity of the |
537 |
|
|
* ConcurrentHashMap. |
538 |
|
|
* @throws IllegalArgumentException if the initial capacity of |
539 |
|
|
* elements is negative. |
540 |
tim |
1.1 |
*/ |
541 |
|
|
public ConcurrentHashMap(int initialCapacity) { |
542 |
dl |
1.4 |
this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS); |
543 |
tim |
1.1 |
} |
544 |
|
|
|
545 |
|
|
/** |
546 |
dl |
1.4 |
* Constructs a new, empty map with a default initial capacity, |
547 |
|
|
* load factor, and number of segments |
548 |
tim |
1.1 |
*/ |
549 |
|
|
public ConcurrentHashMap() { |
550 |
dl |
1.4 |
this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS); |
551 |
tim |
1.1 |
} |
552 |
|
|
|
553 |
|
|
/** |
554 |
|
|
* Constructs a new map with the same mappings as the given map. The |
555 |
|
|
* map is created with a capacity of twice the number of mappings in |
556 |
dl |
1.4 |
* the given map or 11 (whichever is greater), and a default load factor. |
557 |
tim |
1.1 |
*/ |
558 |
|
|
public <A extends K, B extends V> ConcurrentHashMap(Map<A,B> t) { |
559 |
|
|
this(Math.max((int) (t.size() / DEFAULT_LOAD_FACTOR) + 1, |
560 |
dl |
1.4 |
11), |
561 |
|
|
DEFAULT_LOAD_FACTOR, DEFAULT_SEGMENTS); |
562 |
|
|
putAll(t); |
563 |
tim |
1.1 |
} |
564 |
|
|
|
565 |
dl |
1.4 |
// inherit Map javadoc |
566 |
tim |
1.1 |
public int size() { |
567 |
|
|
int c = 0; |
568 |
|
|
for (int i = 0; i < segments.length; ++i) |
569 |
dl |
1.4 |
c += segments[i].count; |
570 |
tim |
1.1 |
return c; |
571 |
|
|
} |
572 |
|
|
|
573 |
dl |
1.4 |
// inherit Map javadoc |
574 |
tim |
1.1 |
public boolean isEmpty() { |
575 |
|
|
for (int i = 0; i < segments.length; ++i) |
576 |
dl |
1.4 |
if (segments[i].count != 0) |
577 |
tim |
1.1 |
return false; |
578 |
|
|
return true; |
579 |
|
|
} |
580 |
|
|
|
581 |
|
|
/** |
582 |
|
|
* Returns the value to which the specified key is mapped in this table. |
583 |
|
|
* |
584 |
|
|
* @param key a key in the table. |
585 |
|
|
* @return the value to which the key is mapped in this table; |
586 |
|
|
* <code>null</code> if the key is not mapped to any value in |
587 |
|
|
* this table. |
588 |
dl |
1.8 |
* @throws NullPointerException if the key is |
589 |
tim |
1.1 |
* <code>null</code>. |
590 |
|
|
* @see #put(Object, Object) |
591 |
|
|
*/ |
592 |
dl |
1.4 |
public V get(K key) { |
593 |
|
|
int hash = hash(key); // throws NullPointerException if key null |
594 |
|
|
return segmentFor(hash).get(key, segmentHashFor(hash)); |
595 |
tim |
1.1 |
} |
596 |
|
|
|
597 |
|
|
/** |
598 |
|
|
* Tests if the specified object is a key in this table. |
599 |
dl |
1.4 |
* |
600 |
tim |
1.1 |
* @param key possible key. |
601 |
dl |
1.4 |
* @return <code>true</code> if and only if the specified object |
602 |
|
|
* is a key in this table, as determined by the |
603 |
tim |
1.1 |
* <tt>equals</tt> method; <code>false</code> otherwise. |
604 |
dl |
1.8 |
* @throws NullPointerException if the key is |
605 |
tim |
1.1 |
* <code>null</code>. |
606 |
|
|
* @see #contains(Object) |
607 |
|
|
*/ |
608 |
|
|
public boolean containsKey(Object key) { |
609 |
dl |
1.4 |
int hash = hash(key); // throws NullPointerException if key null |
610 |
|
|
return segmentFor(hash).containsKey(key, segmentHashFor(hash)); |
611 |
tim |
1.1 |
} |
612 |
|
|
|
613 |
|
|
/** |
614 |
|
|
* Returns <tt>true</tt> if this map maps one or more keys to the |
615 |
|
|
* specified value. Note: This method requires a full internal |
616 |
|
|
* traversal of the hash table, and so is much slower than |
617 |
|
|
* method <tt>containsKey</tt>. |
618 |
|
|
* |
619 |
|
|
* @param value value whose presence in this map is to be tested. |
620 |
|
|
* @return <tt>true</tt> if this map maps one or more keys to the |
621 |
dl |
1.4 |
* specified value. |
622 |
dl |
1.8 |
* @throws NullPointerException if the value is <code>null</code>. |
623 |
tim |
1.1 |
*/ |
624 |
|
|
public boolean containsValue(Object value) { |
625 |
dl |
1.4 |
if (value == null) |
626 |
|
|
throw new NullPointerException(); |
627 |
tim |
1.1 |
|
628 |
dl |
1.4 |
for (int i = 0; i < segments.length; ++i) { |
629 |
|
|
if (segments[i].containsValue(value)) |
630 |
|
|
return true; |
631 |
tim |
1.1 |
} |
632 |
|
|
return false; |
633 |
|
|
} |
634 |
|
|
/** |
635 |
|
|
* Tests if some key maps into the specified value in this table. |
636 |
|
|
* This operation is more expensive than the <code>containsKey</code> |
637 |
|
|
* method.<p> |
638 |
|
|
* |
639 |
|
|
* Note that this method is identical in functionality to containsValue, |
640 |
|
|
* (which is part of the Map interface in the collections framework). |
641 |
dl |
1.4 |
* |
642 |
tim |
1.1 |
* @param value a value to search for. |
643 |
|
|
* @return <code>true</code> if and only if some key maps to the |
644 |
dl |
1.4 |
* <code>value</code> argument in this table as |
645 |
tim |
1.1 |
* determined by the <tt>equals</tt> method; |
646 |
|
|
* <code>false</code> otherwise. |
647 |
dl |
1.8 |
* @throws NullPointerException if the value is <code>null</code>. |
648 |
tim |
1.1 |
* @see #containsKey(Object) |
649 |
|
|
* @see #containsValue(Object) |
650 |
dl |
1.8 |
* @see Map |
651 |
tim |
1.1 |
*/ |
652 |
dl |
1.4 |
public boolean contains(Object value) { |
653 |
tim |
1.1 |
return containsValue(value); |
654 |
|
|
} |
655 |
|
|
|
656 |
|
|
/** |
657 |
dl |
1.4 |
* Maps the specified <code>key</code> to the specified |
658 |
|
|
* <code>value</code> in this table. Neither the key nor the |
659 |
|
|
* value can be <code>null</code>. <p> |
660 |
|
|
* |
661 |
|
|
* The value can be retrieved by calling the <code>get</code> method |
662 |
|
|
* with a key that is equal to the original key. |
663 |
|
|
* |
664 |
|
|
* @param key the table key. |
665 |
|
|
* @param value the value. |
666 |
|
|
* @return the previous value of the specified key in this table, |
667 |
|
|
* or <code>null</code> if it did not have one. |
668 |
dl |
1.8 |
* @throws NullPointerException if the key or value is |
669 |
dl |
1.4 |
* <code>null</code>. |
670 |
|
|
* @see Object#equals(Object) |
671 |
|
|
* @see #get(Object) |
672 |
|
|
*/ |
673 |
|
|
public V put(K key, V value) { |
674 |
|
|
if (value == null) |
675 |
|
|
throw new NullPointerException(); |
676 |
|
|
int hash = hash(key); |
677 |
|
|
return segmentFor(hash).put(key, segmentHashFor(hash), value, false); |
678 |
|
|
} |
679 |
|
|
|
680 |
|
|
/** |
681 |
|
|
* If the specified key is not already associated |
682 |
|
|
* with a value, associate it with the given value. |
683 |
|
|
* This is equivalent to |
684 |
|
|
* <pre> |
685 |
|
|
* if (!map.containsKey(key)) map.put(key, value); |
686 |
|
|
* return get(key); |
687 |
|
|
* </pre> |
688 |
|
|
* Except that the action is performed atomically. |
689 |
|
|
* @param key key with which the specified value is to be associated. |
690 |
|
|
* @param value value to be associated with the specified key. |
691 |
|
|
* @return previous value associated with specified key, or <tt>null</tt> |
692 |
|
|
* if there was no mapping for key. A <tt>null</tt> return can |
693 |
|
|
* also indicate that the map previously associated <tt>null</tt> |
694 |
|
|
* with the specified key, if the implementation supports |
695 |
|
|
* <tt>null</tt> values. |
696 |
|
|
* |
697 |
|
|
* @throws NullPointerException this map does not permit <tt>null</tt> |
698 |
|
|
* keys or values, and the specified key or value is |
699 |
|
|
* <tt>null</tt>. |
700 |
|
|
* |
701 |
|
|
**/ |
702 |
|
|
public V putIfAbsent(K key, V value) { |
703 |
|
|
if (value == null) |
704 |
|
|
throw new NullPointerException(); |
705 |
|
|
int hash = hash(key); |
706 |
|
|
return segmentFor(hash).put(key, segmentHashFor(hash), value, true); |
707 |
|
|
} |
708 |
|
|
|
709 |
|
|
|
710 |
|
|
/** |
711 |
tim |
1.1 |
* Copies all of the mappings from the specified map to this one. |
712 |
|
|
* |
713 |
|
|
* These mappings replace any mappings that this map had for any of the |
714 |
|
|
* keys currently in the specified Map. |
715 |
|
|
* |
716 |
|
|
* @param t Mappings to be stored in this map. |
717 |
|
|
*/ |
718 |
dl |
1.4 |
public <K1 extends K, V1 extends V> void putAll(Map<K1,V1> t) { |
719 |
dl |
1.8 |
Iterator<Map.Entry<K1,V1>> it = t.entrySet().iterator(); |
720 |
|
|
while (it.hasNext()) { |
721 |
|
|
Entry<K,V> e = (Entry) it.next(); |
722 |
dl |
1.4 |
put(e.getKey(), e.getValue()); |
723 |
tim |
1.1 |
} |
724 |
dl |
1.4 |
} |
725 |
|
|
|
726 |
|
|
/** |
727 |
|
|
* Removes the key (and its corresponding value) from this |
728 |
|
|
* table. This method does nothing if the key is not in the table. |
729 |
|
|
* |
730 |
|
|
* @param key the key that needs to be removed. |
731 |
|
|
* @return the value to which the key had been mapped in this table, |
732 |
|
|
* or <code>null</code> if the key did not have a mapping. |
733 |
dl |
1.8 |
* @throws NullPointerException if the key is |
734 |
dl |
1.4 |
* <code>null</code>. |
735 |
|
|
*/ |
736 |
|
|
public V remove(Object key) { |
737 |
|
|
int hash = hash(key); |
738 |
|
|
return segmentFor(hash).remove(key, segmentHashFor(hash), null); |
739 |
|
|
} |
740 |
tim |
1.1 |
|
741 |
dl |
1.4 |
/** |
742 |
|
|
* Removes the (key, value) pair from this |
743 |
|
|
* table. This method does nothing if the key is not in the table, |
744 |
dl |
1.6 |
* or if the key is associated with a different value. |
745 |
dl |
1.4 |
* |
746 |
|
|
* @param key the key that needs to be removed. |
747 |
|
|
* @param value the associated value. If the value is null, |
748 |
|
|
* it means "any value". |
749 |
|
|
* @return the value to which the key had been mapped in this table, |
750 |
|
|
* or <code>null</code> if the key did not have a mapping. |
751 |
dl |
1.8 |
* @throws NullPointerException if the key is |
752 |
dl |
1.4 |
* <code>null</code>. |
753 |
|
|
*/ |
754 |
|
|
public V remove(Object key, Object value) { |
755 |
|
|
int hash = hash(key); |
756 |
|
|
return segmentFor(hash).remove(key, segmentHashFor(hash), value); |
757 |
tim |
1.1 |
} |
758 |
|
|
|
759 |
|
|
/** |
760 |
|
|
* Removes all mappings from this map. |
761 |
|
|
*/ |
762 |
|
|
public void clear() { |
763 |
dl |
1.4 |
for (int i = 0; i < segments.length; ++i) |
764 |
|
|
segments[i].clear(); |
765 |
tim |
1.1 |
} |
766 |
|
|
|
767 |
dl |
1.4 |
|
768 |
tim |
1.1 |
/** |
769 |
|
|
* Returns a shallow copy of this |
770 |
|
|
* <tt>ConcurrentHashMap</tt> instance: the keys and |
771 |
|
|
* values themselves are not cloned. |
772 |
|
|
* |
773 |
|
|
* @return a shallow copy of this map. |
774 |
|
|
*/ |
775 |
|
|
public Object clone() { |
776 |
dl |
1.4 |
// We cannot call super.clone, since it would share final |
777 |
|
|
// segments array, and there's no way to reassign finals. |
778 |
|
|
|
779 |
|
|
float lf = segments[0].loadFactor; |
780 |
|
|
int segs = segments.length; |
781 |
|
|
int cap = (int)(size() / lf); |
782 |
|
|
if (cap < segs) cap = segs; |
783 |
|
|
ConcurrentHashMap t = new ConcurrentHashMap(cap, lf, segs); |
784 |
|
|
t.putAll(this); |
785 |
|
|
return t; |
786 |
tim |
1.1 |
} |
787 |
|
|
|
788 |
|
|
/** |
789 |
|
|
* Returns a set view of the keys contained in this map. The set is |
790 |
|
|
* backed by the map, so changes to the map are reflected in the set, and |
791 |
|
|
* vice-versa. The set supports element removal, which removes the |
792 |
|
|
* corresponding mapping from this map, via the <tt>Iterator.remove</tt>, |
793 |
|
|
* <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt>, and |
794 |
|
|
* <tt>clear</tt> operations. It does not support the <tt>add</tt> or |
795 |
|
|
* <tt>addAll</tt> operations. |
796 |
|
|
* |
797 |
|
|
* @return a set view of the keys contained in this map. |
798 |
|
|
*/ |
799 |
|
|
public Set<K> keySet() { |
800 |
|
|
Set<K> ks = keySet; |
801 |
dl |
1.8 |
return (ks != null) ? ks : (keySet = new KeySet()); |
802 |
tim |
1.1 |
} |
803 |
|
|
|
804 |
|
|
|
805 |
|
|
/** |
806 |
|
|
* Returns a collection view of the values contained in this map. The |
807 |
|
|
* collection is backed by the map, so changes to the map are reflected in |
808 |
|
|
* the collection, and vice-versa. The collection supports element |
809 |
|
|
* removal, which removes the corresponding mapping from this map, via the |
810 |
|
|
* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>, |
811 |
|
|
* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations. |
812 |
|
|
* It does not support the <tt>add</tt> or <tt>addAll</tt> operations. |
813 |
|
|
* |
814 |
|
|
* @return a collection view of the values contained in this map. |
815 |
|
|
*/ |
816 |
|
|
public Collection<V> values() { |
817 |
|
|
Collection<V> vs = values; |
818 |
dl |
1.8 |
return (vs != null) ? vs : (values = new Values()); |
819 |
tim |
1.1 |
} |
820 |
|
|
|
821 |
|
|
|
822 |
|
|
/** |
823 |
|
|
* Returns a collection view of the mappings contained in this map. Each |
824 |
|
|
* element in the returned collection is a <tt>Map.Entry</tt>. The |
825 |
|
|
* collection is backed by the map, so changes to the map are reflected in |
826 |
|
|
* the collection, and vice-versa. The collection supports element |
827 |
|
|
* removal, which removes the corresponding mapping from the map, via the |
828 |
|
|
* <tt>Iterator.remove</tt>, <tt>Collection.remove</tt>, |
829 |
|
|
* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt> operations. |
830 |
|
|
* It does not support the <tt>add</tt> or <tt>addAll</tt> operations. |
831 |
|
|
* |
832 |
|
|
* @return a collection view of the mappings contained in this map. |
833 |
|
|
*/ |
834 |
|
|
public Set<Map.Entry<K,V>> entrySet() { |
835 |
|
|
Set<Map.Entry<K,V>> es = entrySet; |
836 |
|
|
return (es != null) ? es : (entrySet = new EntrySet()); |
837 |
|
|
} |
838 |
|
|
|
839 |
|
|
|
840 |
|
|
/** |
841 |
|
|
* Returns an enumeration of the keys in this table. |
842 |
|
|
* |
843 |
|
|
* @return an enumeration of the keys in this table. |
844 |
|
|
* @see Enumeration |
845 |
|
|
* @see #elements() |
846 |
|
|
* @see #keySet() |
847 |
|
|
* @see Map |
848 |
|
|
*/ |
849 |
dl |
1.4 |
public Enumeration<K> keys() { |
850 |
tim |
1.1 |
return new KeyIterator(); |
851 |
|
|
} |
852 |
|
|
|
853 |
|
|
/** |
854 |
|
|
* Returns an enumeration of the values in this table. |
855 |
|
|
* Use the Enumeration methods on the returned object to fetch the elements |
856 |
|
|
* sequentially. |
857 |
|
|
* |
858 |
|
|
* @return an enumeration of the values in this table. |
859 |
|
|
* @see java.util.Enumeration |
860 |
|
|
* @see #keys() |
861 |
|
|
* @see #values() |
862 |
|
|
* @see Map |
863 |
|
|
*/ |
864 |
dl |
1.4 |
public Enumeration<V> elements() { |
865 |
tim |
1.1 |
return new ValueIterator(); |
866 |
|
|
} |
867 |
|
|
|
868 |
dl |
1.4 |
/* ---------------- Iterator Support -------------- */ |
869 |
|
|
|
870 |
|
|
private abstract class HashIterator { |
871 |
|
|
private int nextSegmentIndex; |
872 |
|
|
private int nextTableIndex; |
873 |
|
|
private HashEntry<K, V>[] currentTable; |
874 |
|
|
private HashEntry<K, V> nextEntry; |
875 |
|
|
private HashEntry<K, V> lastReturned; |
876 |
tim |
1.1 |
|
877 |
|
|
private HashIterator() { |
878 |
dl |
1.8 |
nextSegmentIndex = segments.length - 1; |
879 |
dl |
1.4 |
nextTableIndex = -1; |
880 |
|
|
advance(); |
881 |
tim |
1.1 |
} |
882 |
|
|
|
883 |
|
|
public boolean hasMoreElements() { return hasNext(); } |
884 |
|
|
|
885 |
dl |
1.4 |
private void advance() { |
886 |
|
|
if (nextEntry != null && (nextEntry = nextEntry.next) != null) |
887 |
|
|
return; |
888 |
|
|
|
889 |
|
|
while (nextTableIndex >= 0) { |
890 |
|
|
if ( (nextEntry = currentTable[nextTableIndex--]) != null) |
891 |
|
|
return; |
892 |
|
|
} |
893 |
|
|
|
894 |
|
|
while (nextSegmentIndex >= 0) { |
895 |
|
|
Segment<K,V> seg = segments[nextSegmentIndex--]; |
896 |
|
|
if (seg.count != 0) { |
897 |
|
|
currentTable = seg.table; |
898 |
dl |
1.8 |
for (int j = currentTable.length - 1; j >= 0; --j) { |
899 |
dl |
1.4 |
if ( (nextEntry = currentTable[j]) != null) { |
900 |
dl |
1.8 |
nextTableIndex = j - 1; |
901 |
dl |
1.4 |
return; |
902 |
|
|
} |
903 |
tim |
1.1 |
} |
904 |
|
|
} |
905 |
|
|
} |
906 |
|
|
} |
907 |
|
|
|
908 |
dl |
1.4 |
public boolean hasNext() { return nextEntry != null; } |
909 |
tim |
1.1 |
|
910 |
dl |
1.4 |
HashEntry<K,V> nextEntry() { |
911 |
|
|
if (nextEntry == null) |
912 |
tim |
1.1 |
throw new NoSuchElementException(); |
913 |
dl |
1.4 |
lastReturned = nextEntry; |
914 |
|
|
advance(); |
915 |
|
|
return lastReturned; |
916 |
tim |
1.1 |
} |
917 |
|
|
|
918 |
|
|
public void remove() { |
919 |
|
|
if (lastReturned == null) |
920 |
|
|
throw new IllegalStateException(); |
921 |
|
|
ConcurrentHashMap.this.remove(lastReturned.key); |
922 |
|
|
lastReturned = null; |
923 |
|
|
} |
924 |
dl |
1.4 |
} |
925 |
|
|
|
926 |
|
|
private class KeyIterator extends HashIterator implements Iterator<K>, Enumeration<K> { |
927 |
|
|
public K next() { return super.nextEntry().key; } |
928 |
|
|
public K nextElement() { return super.nextEntry().key; } |
929 |
|
|
} |
930 |
|
|
|
931 |
|
|
private class ValueIterator extends HashIterator implements Iterator<V>, Enumeration<V> { |
932 |
|
|
public V next() { return super.nextEntry().value; } |
933 |
|
|
public V nextElement() { return super.nextEntry().value; } |
934 |
|
|
} |
935 |
tim |
1.1 |
|
936 |
dl |
1.4 |
private class EntryIterator extends HashIterator implements Iterator<Entry<K,V>> { |
937 |
|
|
public Map.Entry<K,V> next() { return super.nextEntry(); } |
938 |
tim |
1.1 |
} |
939 |
|
|
|
940 |
dl |
1.4 |
private class KeySet extends AbstractSet<K> { |
941 |
|
|
public Iterator<K> iterator() { |
942 |
|
|
return new KeyIterator(); |
943 |
|
|
} |
944 |
|
|
public int size() { |
945 |
|
|
return ConcurrentHashMap.this.size(); |
946 |
|
|
} |
947 |
|
|
public boolean contains(Object o) { |
948 |
|
|
return ConcurrentHashMap.this.containsKey(o); |
949 |
|
|
} |
950 |
|
|
public boolean remove(Object o) { |
951 |
|
|
return ConcurrentHashMap.this.remove(o) != null; |
952 |
|
|
} |
953 |
|
|
public void clear() { |
954 |
|
|
ConcurrentHashMap.this.clear(); |
955 |
|
|
} |
956 |
tim |
1.1 |
} |
957 |
|
|
|
958 |
dl |
1.4 |
private class Values extends AbstractCollection<V> { |
959 |
|
|
public Iterator<V> iterator() { |
960 |
|
|
return new ValueIterator(); |
961 |
|
|
} |
962 |
|
|
public int size() { |
963 |
|
|
return ConcurrentHashMap.this.size(); |
964 |
|
|
} |
965 |
|
|
public boolean contains(Object o) { |
966 |
|
|
return ConcurrentHashMap.this.containsValue(o); |
967 |
|
|
} |
968 |
|
|
public void clear() { |
969 |
|
|
ConcurrentHashMap.this.clear(); |
970 |
|
|
} |
971 |
tim |
1.1 |
} |
972 |
|
|
|
973 |
dl |
1.4 |
private class EntrySet extends AbstractSet { |
974 |
|
|
public Iterator<Map.Entry<K,V>> iterator() { |
975 |
|
|
return new EntryIterator(); |
976 |
|
|
} |
977 |
|
|
public boolean contains(Object o) { |
978 |
|
|
if (!(o instanceof Map.Entry)) |
979 |
|
|
return false; |
980 |
|
|
Map.Entry<K,V> e = (Map.Entry<K,V>)o; |
981 |
|
|
V v = ConcurrentHashMap.this.get(e.getKey()); |
982 |
|
|
return v != null && v.equals(e.getValue()); |
983 |
|
|
} |
984 |
|
|
public boolean remove(Object o) { |
985 |
|
|
if (!(o instanceof Map.Entry)) |
986 |
|
|
return false; |
987 |
|
|
Map.Entry<K,V> e = (Map.Entry<K,V>)o; |
988 |
|
|
return ConcurrentHashMap.this.remove(e.getKey(), e.getValue()) != null; |
989 |
|
|
} |
990 |
|
|
public int size() { |
991 |
|
|
return ConcurrentHashMap.this.size(); |
992 |
|
|
} |
993 |
|
|
public void clear() { |
994 |
|
|
ConcurrentHashMap.this.clear(); |
995 |
|
|
} |
996 |
tim |
1.1 |
} |
997 |
|
|
|
998 |
dl |
1.4 |
/* ---------------- Serialization Support -------------- */ |
999 |
|
|
|
1000 |
tim |
1.1 |
/** |
1001 |
|
|
* Save the state of the <tt>ConcurrentHashMap</tt> |
1002 |
|
|
* instance to a stream (i.e., |
1003 |
|
|
* serialize it). |
1004 |
dl |
1.8 |
* @param s the stream |
1005 |
tim |
1.1 |
* @serialData |
1006 |
|
|
* the key (Object) and value (Object) |
1007 |
|
|
* for each key-value mapping, followed by a null pair. |
1008 |
|
|
* The key-value mappings are emitted in no particular order. |
1009 |
|
|
*/ |
1010 |
|
|
private void writeObject(java.io.ObjectOutputStream s) throws IOException { |
1011 |
|
|
s.defaultWriteObject(); |
1012 |
|
|
|
1013 |
|
|
for (int k = 0; k < segments.length; ++k) { |
1014 |
dl |
1.4 |
Segment<K,V> seg = segments[k]; |
1015 |
dl |
1.2 |
seg.lock(); |
1016 |
|
|
try { |
1017 |
dl |
1.4 |
HashEntry<K,V>[] tab = seg.table; |
1018 |
|
|
for (int i = 0; i < tab.length; ++i) { |
1019 |
|
|
for (HashEntry<K,V> e = tab[i]; e != null; e = e.next) { |
1020 |
|
|
s.writeObject(e.key); |
1021 |
|
|
s.writeObject(e.value); |
1022 |
|
|
} |
1023 |
|
|
} |
1024 |
dl |
1.2 |
} |
1025 |
|
|
finally { |
1026 |
|
|
seg.unlock(); |
1027 |
|
|
} |
1028 |
tim |
1.1 |
} |
1029 |
|
|
s.writeObject(null); |
1030 |
|
|
s.writeObject(null); |
1031 |
|
|
} |
1032 |
|
|
|
1033 |
|
|
/** |
1034 |
|
|
* Reconstitute the <tt>ConcurrentHashMap</tt> |
1035 |
|
|
* instance from a stream (i.e., |
1036 |
|
|
* deserialize it). |
1037 |
dl |
1.8 |
* @param s the stream |
1038 |
tim |
1.1 |
*/ |
1039 |
|
|
private void readObject(java.io.ObjectInputStream s) |
1040 |
|
|
throws IOException, ClassNotFoundException { |
1041 |
|
|
s.defaultReadObject(); |
1042 |
|
|
|
1043 |
dl |
1.4 |
// Initialize each segment to be minimally sized, and let grow. |
1044 |
|
|
for (int i = 0; i < segments.length; ++i) { |
1045 |
|
|
segments[i].setTable(new HashEntry<K,V>[1]); |
1046 |
|
|
} |
1047 |
tim |
1.1 |
|
1048 |
|
|
// Read the keys and values, and put the mappings in the table |
1049 |
|
|
while (true) { |
1050 |
|
|
K key = (K) s.readObject(); |
1051 |
|
|
V value = (V) s.readObject(); |
1052 |
|
|
if (key == null) |
1053 |
|
|
break; |
1054 |
|
|
put(key, value); |
1055 |
|
|
} |
1056 |
|
|
} |
1057 |
|
|
} |
1058 |
dl |
1.4 |
|