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root/jsr166/jsr166/src/jsr166y/ForkJoinPool.java

Comparing jsr166/src/jsr166y/ForkJoinPool.java (file contents):
Revision 1.26 by jsr166, Sun Jul 26 13:34:25 2009 UTC vs.
Revision 1.28 by jsr166, Mon Jul 27 20:57:44 2009 UTC

#	Line 311 | Line 311 | public class ForkJoinPool extends Abstra
311		}
312
313		/**
314	<	* Returns true if argument represents zero active count and
315	<	* nonzero runstate, which is the triggering condition for
314	>	* Returns {@code true} if argument represents zero active count
315	>	* and nonzero runstate, which is the triggering condition for
316		* terminating on shutdown.
317		*/
318		private static boolean canTerminateOnShutdown(int c) {
#	Line 720 | Line 720 | public class ForkJoinPool extends Abstra
720		* Returns the handler for internal worker threads that terminate
721		* due to unrecoverable errors encountered while executing tasks.
722		*
723	<	* @return the handler, or null if none
723	>	* @return the handler, or {@code null} if none
724		*/
725		public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler() {
726		Thread.UncaughtExceptionHandler h;
#	Line 741 | Line 741 | public class ForkJoinPool extends Abstra
741		* as handler.
742		*
743		* @param h the new handler
744	<	* @return the old handler, or null if none
744	>	* @return the old handler, or {@code null} if none
745		* @throws SecurityException if a security manager exists and
746		*         the caller is not permitted to modify threads
747		*         because it does not hold {@link
#	Line 851 | Line 851 | public class ForkJoinPool extends Abstra
851
852
853		/**
854	<	* Returns true if this pool dynamically maintains its target
855	<	* parallelism level. If false, new threads are added only to
856	<	* avoid possible starvation.
857	<	* This setting is by default true.
854	>	* Returns {@code true} if this pool dynamically maintains its
855	>	* target parallelism level. If false, new threads are added only
856	>	* to avoid possible starvation.  This setting is by default true.
857		*
858	<	* @return true if maintains parallelism
858	>	* @return {@code true} if maintains parallelism
859		*/
860		public boolean getMaintainsParallelism() {
861		return maintainsParallelism;
#	Line 867 | Line 866 | public class ForkJoinPool extends Abstra
866		* parallelism level. If false, new threads are added only to
867		* avoid possible starvation.
868		*
869	<	* @param enable true to maintains parallelism
869	>	* @param enable {@code true} to maintain parallelism
870		*/
871		public void setMaintainsParallelism(boolean enable) {
872		maintainsParallelism = enable;
#	Line 900 | Line 899 | public class ForkJoinPool extends Abstra
899		}
900
901		/**
902	<	* Returns true if this pool uses local first-in-first-out
902	>	* Returns {@code true} if this pool uses local first-in-first-out
903		* scheduling mode for forked tasks that are never joined.
904		*
905	<	* @return true if this pool uses async mode
905	>	* @return {@code true} if this pool uses async mode
906		*/
907		public boolean getAsyncMode() {
908		return locallyFifo;
#	Line 944 | Line 943 | public class ForkJoinPool extends Abstra
943		}
944
945		/**
946	<	* Returns true if all worker threads are currently idle. An idle
947	<	* worker is one that cannot obtain a task to execute because none
948	<	* are available to steal from other threads, and there are no
949	<	* pending submissions to the pool. This method is conservative;
950	<	* it might not return true immediately upon idleness of all
951	<	* threads, but will eventually become true if threads remain
952	<	* inactive.
946	>	* Returns {@code true} if all worker threads are currently idle.
947	>	* An idle worker is one that cannot obtain a task to execute
948	>	* because none are available to steal from other threads, and
949	>	* there are no pending submissions to the pool. This method is
950	>	* conservative; it might not return {@code true} immediately upon
951	>	* idleness of all threads, but will eventually become true if
952	>	* threads remain inactive.
953		*
954	<	* @return true if all threads are currently idle
954	>	* @return {@code true} if all threads are currently idle
955		*/
956		public boolean isQuiescent() {
957		return activeCountOf(runControl) == 0;
#	Line 1018 | Line 1017 | public class ForkJoinPool extends Abstra
1017		}
1018
1019		/**
1020	<	* Returns true if there are any tasks submitted to this pool
1021	<	* that have not yet begun executing.
1020	>	* Returns {@code true} if there are any tasks submitted to this
1021	>	* pool that have not yet begun executing.
1022		*
1023		* @return {@code true} if there are any queued submissions
1024		*/
#	Line 1032 | Line 1031 | public class ForkJoinPool extends Abstra
1031		* available.  This method may be useful in extensions to this
1032		* class that re-assign work in systems with multiple pools.
1033		*
1034	<	* @return the next submission, or null if none
1034	>	* @return the next submission, or {@code null} if none
1035		*/
1036		protected ForkJoinTask<?> pollSubmission() {
1037		return submissionQueue.poll();
#	Line 1492 | Line 1491 | public class ForkJoinPool extends Abstra
1491		}
1492
1493		/**
1494	<	* Returns true if worker waiting on sync can proceed:
1494	>	* Returns {@code true} if worker waiting on sync can proceed:
1495		*  - on signal (thread == null)
1496		*  - on event count advance (winning race to notify vs signaller)
1497		*  - on interrupt
#	Line 1500 | Line 1499 | public class ForkJoinPool extends Abstra
1499		* If node was not signalled and event count not advanced on exit,
1500		* then we also help advance event count.
1501		*
1502	<	* @return true if node can be released
1502	>	* @return {@code true} if node can be released
1503		*/
1504		final boolean syncIsReleasable(WaitQueueNode node) {
1505		long prev = node.count;
#	Line 1519 | Line 1518 | public class ForkJoinPool extends Abstra
1518		}
1519
1520		/**
1521	<	* Returns true if a new sync event occurred since last call to
1522	<	* sync or this method, if so, updating caller's count.
1521	>	* Returns {@code true} if a new sync event occurred since last
1522	>	* call to sync or this method, if so, updating caller's count.
1523		*/
1524		final boolean hasNewSyncEvent(ForkJoinWorkerThread w) {
1525		long lc = w.lastEventCount;
#	Line 1604 | Line 1603 | public class ForkJoinPool extends Abstra
1603		}
1604
1605		/**
1606	<	* Returns true if a spare thread appears to be needed.  If
1607	<	* maintaining parallelism, returns true when the deficit in
1606	>	* Returns {@code true} if a spare thread appears to be needed.
1607	>	* If maintaining parallelism, returns true when the deficit in
1608		* running threads is more than the surplus of total threads, and
1609		* there is apparently some work to do.  This self-limiting rule
1610		* means that the more threads that have already been added, the
#	Line 1774 | Line 1773 | public class ForkJoinPool extends Abstra
1773		/**
1774		* Interface for extending managed parallelism for tasks running
1775		* in ForkJoinPools. A ManagedBlocker provides two methods.
1776	<	* Method {@code isReleasable} must return true if blocking is not
1777	<	* necessary. Method {@code block} blocks the current thread if
1778	<	* necessary (perhaps internally invoking {@code isReleasable}
1779	<	* before actually blocking.).
1776	>	* Method {@code isReleasable} must return {@code true} if
1777	>	* blocking is not necessary. Method {@code block} blocks the
1778	>	* current thread if necessary (perhaps internally invoking
1779	>	* {@code isReleasable} before actually blocking.).
1780		*
1781		* <p>For example, here is a ManagedBlocker based on a
1782		* ReentrantLock:
#	Line 1801 | Line 1800 | public class ForkJoinPool extends Abstra
1800		* Possibly blocks the current thread, for example waiting for
1801		* a lock or condition.
1802		*
1803	<	* @return true if no additional blocking is necessary (i.e.,
1804	<	* if isReleasable would return true)
1803	>	* @return {@code true} if no additional blocking is necessary
1804	>	* (i.e., if isReleasable would return true)
1805		* @throws InterruptedException if interrupted while waiting
1806		* (the method is not required to do so, but is allowed to)
1807		*/
1808		boolean block() throws InterruptedException;
1809
1810		/**
1811	<	* Returns true if blocking is unnecessary.
1811	>	* Returns {@code true} if blocking is unnecessary.
1812		*/
1813		boolean isReleasable();
1814		}
#	Line 1819 | Line 1818 | public class ForkJoinPool extends Abstra
1818		* is a ForkJoinWorkerThread, this method possibly arranges for a
1819		* spare thread to be activated if necessary to ensure parallelism
1820		* while the current thread is blocked.  If
1821	<	* {@code maintainParallelism} is true and the pool supports
1821	>	* {@code maintainParallelism} is {@code true} and the pool supports
1822		* it ({@link #getMaintainsParallelism}), this method attempts to
1823		* maintain the pool's nominal parallelism. Otherwise it activates
1824		* a thread only if necessary to avoid complete starvation. This
#	Line 1837 | Line 1836 | public class ForkJoinPool extends Abstra
1836		* be expanded to ensure parallelism, and later adjusted.
1837		*
1838		* @param blocker the blocker
1839	<	* @param maintainParallelism if true and supported by this pool,
1840	<	* attempt to maintain the pool's nominal parallelism; otherwise
1841	<	* activate a thread only if necessary to avoid complete
1842	<	* starvation.
1839	>	* @param maintainParallelism if {@code true} and supported by
1840	>	* this pool, attempt to maintain the pool's nominal parallelism;
1841	>	* otherwise activate a thread only if necessary to avoid
1842	>	* complete starvation.
1843		* @throws InterruptedException if blocker.block did so
1844		*/
1845		public static void managedBlock(ManagedBlocker blocker,
#	Line 1876 | Line 1875 | public class ForkJoinPool extends Abstra
1875		return new AdaptedCallable<T>(callable);
1876		}
1877
1878	<
1880	<	// Unsafe mechanics for jsr166y 3rd party package.
1881	<	private static sun.misc.Unsafe getUnsafe() {
1882	<	try {
1883	<	return sun.misc.Unsafe.getUnsafe();
1884	<	} catch (SecurityException se) {
1885	<	try {
1886	<	return java.security.AccessController.doPrivileged
1887	<	(new java.security.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1888	<	public sun.misc.Unsafe run() throws Exception {
1889	<	return getUnsafeByReflection();
1890	<	}});
1891	<	} catch (java.security.PrivilegedActionException e) {
1892	<	throw new RuntimeException("Could not initialize intrinsics",
1893	<	e.getCause());
1894	<	}
1895	<	}
1896	<	}
1897	<
1898	<	private static sun.misc.Unsafe getUnsafeByReflection()
1899	<	throws NoSuchFieldException, IllegalAccessException {
1900	<	java.lang.reflect.Field f =
1901	<	sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
1902	<	f.setAccessible(true);
1903	<	return (sun.misc.Unsafe) f.get(null);
1904	<	}
1905	<
1906	<	private static long fieldOffset(String fieldName, Class<?> klazz) {
1907	<	try {
1908	<	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(fieldName));
1909	<	} catch (NoSuchFieldException e) {
1910	<	// Convert Exception to Error
1911	<	NoSuchFieldError error = new NoSuchFieldError(fieldName);
1912	<	error.initCause(e);
1913	<	throw error;
1914	<	}
1915	<	}
1878	>	// Unsafe mechanics
1879
1880		private static final sun.misc.Unsafe UNSAFE = getUnsafe();
1881		private static final long eventCountOffset =
1882	<	fieldOffset("eventCount", ForkJoinPool.class);
1882	>	objectFieldOffset("eventCount", ForkJoinPool.class);
1883		private static final long workerCountsOffset =
1884	<	fieldOffset("workerCounts", ForkJoinPool.class);
1884	>	objectFieldOffset("workerCounts", ForkJoinPool.class);
1885		private static final long runControlOffset =
1886	<	fieldOffset("runControl", ForkJoinPool.class);
1886	>	objectFieldOffset("runControl", ForkJoinPool.class);
1887		private static final long syncStackOffset =
1888	<	fieldOffset("syncStack",ForkJoinPool.class);
1888	>	objectFieldOffset("syncStack",ForkJoinPool.class);
1889		private static final long spareStackOffset =
1890	<	fieldOffset("spareStack", ForkJoinPool.class);
1890	>	objectFieldOffset("spareStack", ForkJoinPool.class);
1891
1892		private boolean casEventCount(long cmp, long val) {
1893		return UNSAFE.compareAndSwapLong(this, eventCountOffset, cmp, val);
#	Line 1941 | Line 1904 | public class ForkJoinPool extends Abstra
1904		private boolean casBarrierStack(WaitQueueNode cmp, WaitQueueNode val) {
1905		return UNSAFE.compareAndSwapObject(this, syncStackOffset, cmp, val);
1906		}
1907	+
1908	+	private static long objectFieldOffset(String field, Class<?> klazz) {
1909	+	try {
1910	+	return UNSAFE.objectFieldOffset(klazz.getDeclaredField(field));
1911	+	} catch (NoSuchFieldException e) {
1912	+	// Convert Exception to corresponding Error
1913	+	NoSuchFieldError error = new NoSuchFieldError(field);
1914	+	error.initCause(e);
1915	+	throw error;
1916	+	}
1917	+	}
1918	+
1919	+	/**
1920	+	* Returns a sun.misc.Unsafe.  Suitable for use in a 3rd party package.
1921	+	* Replace with a simple call to Unsafe.getUnsafe when integrating
1922	+	* into a jdk.
1923	+	*
1924	+	* @return a sun.misc.Unsafe
1925	+	*/
1926	+	private static sun.misc.Unsafe getUnsafe() {
1927	+	try {
1928	+	return sun.misc.Unsafe.getUnsafe();
1929	+	} catch (SecurityException se) {
1930	+	try {
1931	+	return java.security.AccessController.doPrivileged
1932	+	(new java.security
1933	+	.PrivilegedExceptionAction<sun.misc.Unsafe>() {
1934	+	public sun.misc.Unsafe run() throws Exception {
1935	+	java.lang.reflect.Field f = sun.misc
1936	+	.Unsafe.class.getDeclaredField("theUnsafe");
1937	+	f.setAccessible(true);
1938	+	return (sun.misc.Unsafe) f.get(null);
1939	+	}});
1940	+	} catch (java.security.PrivilegedActionException e) {
1941	+	throw new RuntimeException("Could not initialize intrinsics",
1942	+	e.getCause());
1943	+	}
1944	+	}
1945	+	}
1946		}

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