ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/jsr166/jsr166/src/jsr166e/StripedAdder.java
(Generate patch)

Comparing jsr166/src/jsr166e/StripedAdder.java (file contents):
Revision 1.6 by dl, Tue Jul 26 17:16:36 2011 UTC vs.
Revision 1.7 by dl, Tue Jul 26 18:30:35 2011 UTC

# Line 140 | Line 140 | public class StripedAdder implements Ser
140      static final ThreadHashCode threadHashCode = new ThreadHashCode();
141  
142      /**
143 <     * Table of adders. Size is power of two, grows to be at most CAP.
143 >     * Common placeholder for empty arrays.
144 >     */
145 >    static final Adder[] EMPTY_ARRAY = new Adder[0];
146 >
147 >    /**
148 >     * Table of adders. Size is either zero or a power of two, grows
149 >     * to be at most CAP.
150       */
151      private transient volatile Adder[] adders;
152  
# Line 157 | Line 163 | public class StripedAdder implements Ser
163       * Creates a new adder with zero sum.
164       */
165      public StripedAdder() {
166 +        this.adders = EMPTY_ARRAY;
167          this.mutex = new AtomicInteger();
168          // remaining initialization on first call to add.
169      }
# Line 169 | Line 176 | public class StripedAdder implements Ser
176       * will concurrently update the sum.
177       */
178      public StripedAdder(int expectedContention) {
179 <        int cap = (expectedContention < CAP) ? expectedContention : CAP;
180 <        int size = 1;
181 <        while (size < cap)
182 <            size <<= 1;
183 <        Adder[] as = new Adder[size];
184 <        for (int i = 0; i < size; ++i)
185 <            as[i] = new Adder(0);
186 <        this.adders = as;
179 >        if (expectedContention > 0) {
180 >            int cap = (expectedContention < CAP) ? expectedContention : CAP;
181 >            int size = 1;
182 >            while (size < cap)
183 >                size <<= 1;
184 >            Adder[] as = new Adder[size];
185 >            for (int i = 0; i < size; ++i)
186 >                as[i] = new Adder(0);
187 >            this.adders = as;
188 >        }
189 >        else
190 >            this.adders = EMPTY_ARRAY;
191          this.mutex = new AtomicInteger();
192      }
193  
# Line 208 | Line 219 | public class StripedAdder implements Ser
219              Adder[] as; Adder a; long v; int k, n;
220              while ((as = adders) == null || (n = as.length) < 1) {
221                  synchronized(mutex) {                // Try to initialize
222 <                    if (adders == null) {
222 >                    if (adders == as) {
223                          Adder[] rs = new Adder[DEFAULT_INITIAL_SIZE];
224                          rs[h & (DEFAULT_INITIAL_SIZE - 1)] = new Adder(0);
225                          adders = rs;

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines