116 * if (Thread.interrupted())
117 * wasInterrupted = true;
118 * }
119 *
120 * waiters.remove();
121 * // ensure correct interrupt status on return
122 * if (wasInterrupted)
123 * Thread.currentThread().interrupt();
124 * }
125 *
126 * public void unlock() {
127 * locked.set(false);
128 * LockSupport.unpark(waiters.peek());
129 * }
130 *
131 * static {
132 * // Reduce the risk of "lost unpark" due to classloading
133 * Class<?> ensureLoaded = LockSupport.class;
134 * }
135 * }}</pre>
136 */
137 public class LockSupport {
138 private LockSupport() {} // Cannot be instantiated.
139
140 private static void setBlocker(Thread t, Object arg) {
141 // Even though volatile, hotspot doesn't need a write barrier here.
142 U.putObject(t, PARKBLOCKER, arg);
143 }
144
145 /**
146 * Makes available the permit for the given thread, if it
147 * was not already available. If the thread was blocked on
148 * {@code park} then it will unblock. Otherwise, its next call
149 * to {@code park} is guaranteed not to block. This operation
150 * is not guaranteed to have any effect at all if the given
151 * thread has not been started.
152 *
153 * @param thread the thread to unpark, or {@code null}, in which case
154 * this operation has no effect
155 */
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116 * if (Thread.interrupted())
117 * wasInterrupted = true;
118 * }
119 *
120 * waiters.remove();
121 * // ensure correct interrupt status on return
122 * if (wasInterrupted)
123 * Thread.currentThread().interrupt();
124 * }
125 *
126 * public void unlock() {
127 * locked.set(false);
128 * LockSupport.unpark(waiters.peek());
129 * }
130 *
131 * static {
132 * // Reduce the risk of "lost unpark" due to classloading
133 * Class<?> ensureLoaded = LockSupport.class;
134 * }
135 * }}</pre>
136 *
137 * @since 1.5
138 */
139 public class LockSupport {
140 private LockSupport() {} // Cannot be instantiated.
141
142 private static void setBlocker(Thread t, Object arg) {
143 // Even though volatile, hotspot doesn't need a write barrier here.
144 U.putObject(t, PARKBLOCKER, arg);
145 }
146
147 /**
148 * Makes available the permit for the given thread, if it
149 * was not already available. If the thread was blocked on
150 * {@code park} then it will unblock. Otherwise, its next call
151 * to {@code park} is guaranteed not to block. This operation
152 * is not guaranteed to have any effect at all if the given
153 * thread has not been started.
154 *
155 * @param thread the thread to unpark, or {@code null}, in which case
156 * this operation has no effect
157 */
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