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| org.apache.openjpa.lib.util.concurrent</FONT> |
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| Class ReentrantLock</H2> |
| <PRE> |
| <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">java.lang.Object</A> |
| <IMG SRC="../../../../../../resources/inherit.gif" ALT="extended by "><B>org.apache.openjpa.lib.util.concurrent.ReentrantLock</B> |
| </PRE> |
| <DL> |
| <DT><B>All Implemented Interfaces:</B> <DD><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/io/Serializable.html" title="class or interface in java.io">Serializable</A>, <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent">Lock</A></DD> |
| </DL> |
| <HR> |
| <DL> |
| <DT><PRE>public class <B>ReentrantLock</B><DT>extends <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A><DT>implements <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent">Lock</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/io/Serializable.html" title="class or interface in java.io">Serializable</A></DL> |
| </PRE> |
| |
| <P> |
| A reentrant mutual exclusion <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent"><CODE>Lock</CODE></A> with the same basic |
| behavior and semantics as the implicit monitor lock accessed using |
| <tt>synchronized</tt> methods and statements, but with extended capabilities. |
| A <tt>ReentrantLock</tt> is <em>owned</em> by the thread last |
| successfully locking, but not yet unlocking it. A thread invoking |
| <tt>lock</tt> will return, successfully acquiring the lock, when |
| the lock is not owned by another thread. The method will return |
| immediately if the current thread already owns the lock. This can |
| be checked using methods <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#isHeldByCurrentThread()"><CODE>isHeldByCurrentThread()</CODE></A>, and <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#getHoldCount()"><CODE>getHoldCount()</CODE></A>. The constructor for this class accepts an optional |
| <em>fairness</em> parameter. When set <tt>true</tt>, under |
| contention, locks favor granting access to the longest-waiting |
| thread. Otherwise this lock does not guarantee any particular |
| access order. Programs using fair locks accessed by many threads |
| may display lower overall throughput(i.e., are slower; often much |
| slower) than those using the default setting, but have smaller |
| variances in times to obtain locks and guarantee lack of |
| starvation. Note however, that fairness of locks does not guarantee |
| fairness of thread scheduling. Thus, one of many threads using a |
| fair lock may obtain it multiple times in succession while other |
| active threads are not progressing and not currently holding the lock. |
| Also note that the untimed <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#tryLock()"><CODE>tryLock</CODE></A> method does not |
| honor the fairness setting. It will succeed if the lock |
| is available even if other threads are waiting. |
| It is recommended practice to <em>always</em> immediately |
| follow a call to <tt>lock</tt> with a <tt>try</tt> block, most |
| typically in a before/after construction such as: |
| |
| <pre> class X { private final ReentrantLock lock = new ReentrantLock(); |
| // ... public void m() { lock.lock(); // block until condition holds try { |
| // ... method body } finally { lock.unlock() } } } |
| </pre> In addition to implementing the <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent"><CODE>Lock</CODE></A> interface, this |
| class defines methods <tt>isLocked</tt> and |
| <tt>getLockQueueLength</tt>, as well as some associated |
| <tt>protected</tt> access methods that may be useful for |
| instrumentation and monitoring. |
| Serialization of this class behaves in the same way as built-in |
| locks: a deserialized lock is in the unlocked state, regardless of |
| its state when serialized. |
| This lock supports a maximum of 2147483647 recursive locks by |
| the same thread. Attempts to exceed this limit result in |
| <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Error.html" title="class or interface in java.lang"><CODE>Error</CODE></A> throws from locking methods. |
| <P> |
| |
| <P> |
| <DL> |
| <DT><B>Since:</B></DT> |
| <DD>1.5</DD> |
| <DT><B>Author:</B></DT> |
| <DD>Doug Lea, Dawid Kurzyniec</DD> |
| <DT><B>See Also:</B><DD><A HREF="../../../../../../serialized-form.html#org.apache.openjpa.lib.util.concurrent.ReentrantLock">Serialized Form</A></DL> |
| <HR> |
| |
| <P> |
| |
| <!-- ======== CONSTRUCTOR SUMMARY ======== --> |
| |
| <A NAME="constructor_summary"><!-- --></A> |
| <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> |
| <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> |
| <TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"> |
| <B>Constructor Summary</B></FONT></TH> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#ReentrantLock()">ReentrantLock</A></B>()</CODE> |
| |
| <BR> |
| Creates an instance of <tt>ReentrantLock</tt>.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#ReentrantLock(boolean)">ReentrantLock</A></B>(boolean fair)</CODE> |
| |
| <BR> |
| Creates an instance of <tt>ReentrantLock</tt> with the |
| given fairness policy.</TD> |
| </TR> |
| </TABLE> |
| |
| <!-- ========== METHOD SUMMARY =========== --> |
| |
| <A NAME="method_summary"><!-- --></A> |
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| <TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"> |
| <B>Method Summary</B></FONT></TH> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> int</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#getHoldCount()">getHoldCount</A></B>()</CODE> |
| |
| <BR> |
| Queries the number of holds on this lock by the current thread.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE>protected <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html" title="class or interface in java.lang">Thread</A></CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#getOwner()">getOwner</A></B>()</CODE> |
| |
| <BR> |
| <tt>null</tt> if not owned.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE>protected <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html" title="class or interface in java.util">Collection</A></CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#getQueuedThreads()">getQueuedThreads</A></B>()</CODE> |
| |
| <BR> |
| Returns a collection containing threads that may be waiting to |
| acquire this lock.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> int</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#getQueueLength()">getQueueLength</A></B>()</CODE> |
| |
| <BR> |
| Returns an estimate of the number of threads waiting to |
| acquire this lock.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE>protected <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html" title="class or interface in java.util">Collection</A></CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#getWaitingThreads(org.apache.openjpa.lib.util.concurrent.Condition)">getWaitingThreads</A></B>(<A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent">Condition</A> condition)</CODE> |
| |
| <BR> |
| Returns a collection containing those threads that may be |
| waiting on the given condition associated with this lock.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> int</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#getWaitQueueLength(org.apache.openjpa.lib.util.concurrent.Condition)">getWaitQueueLength</A></B>(<A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent">Condition</A> condition)</CODE> |
| |
| <BR> |
| Returns an estimate of the number of threads waiting on the |
| given condition associated with this lock.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> boolean</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#hasQueuedThread(java.lang.Thread)">hasQueuedThread</A></B>(<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html" title="class or interface in java.lang">Thread</A> thread)</CODE> |
| |
| <BR> |
| Queries whether the given thread is waiting to acquire this |
| lock.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> boolean</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#hasQueuedThreads()">hasQueuedThreads</A></B>()</CODE> |
| |
| <BR> |
| Queries whether any threads are waiting to acquire this lock.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> boolean</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#hasWaiters(org.apache.openjpa.lib.util.concurrent.Condition)">hasWaiters</A></B>(<A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent">Condition</A> condition)</CODE> |
| |
| <BR> |
| Queries whether any threads are waiting on the given condition |
| associated with this lock.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> boolean</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#isFair()">isFair</A></B>()</CODE> |
| |
| <BR> |
| Returns true if this lock has fairness set true.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> boolean</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#isHeldByCurrentThread()">isHeldByCurrentThread</A></B>()</CODE> |
| |
| <BR> |
| Queries if this lock is held by the current thread.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> boolean</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#isLocked()">isLocked</A></B>()</CODE> |
| |
| <BR> |
| Queries if this lock is held by any thread.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> void</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#lock()">lock</A></B>()</CODE> |
| |
| <BR> |
| Acquires the lock.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> void</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#lockInterruptibly()">lockInterruptibly</A></B>()</CODE> |
| |
| <BR> |
| Acquires the lock unless the current thread is |
| <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupted</CODE></A>.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent">Condition</A></CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#newCondition()">newCondition</A></B>()</CODE> |
| |
| <BR> |
| Returns a <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent"><CODE>Condition</CODE></A> instance for use with this |
| <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent"><CODE>Lock</CODE></A> instance.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A></CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#toString()">toString</A></B>()</CODE> |
| |
| <BR> |
| Returns a string identifying this lock, as well as its lock |
| state.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> boolean</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#tryLock()">tryLock</A></B>()</CODE> |
| |
| <BR> |
| Acquires the lock only if it is not held by another thread at the time |
| of invocation.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> boolean</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#tryLock(long, org.apache.openjpa.lib.util.concurrent.TimeUnit)">tryLock</A></B>(long timeout, |
| <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/TimeUnit.html" title="class in org.apache.openjpa.lib.util.concurrent">TimeUnit</A> unit)</CODE> |
| |
| <BR> |
| Acquires the lock if it is not held by another thread within the given |
| waiting time and the current thread has not been |
| <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupted</CODE></A>.</TD> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"> |
| <CODE> void</CODE></FONT></TD> |
| <TD><CODE><B><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#unlock()">unlock</A></B>()</CODE> |
| |
| <BR> |
| Attempts to release this lock.</TD> |
| </TR> |
| </TABLE> |
| <A NAME="methods_inherited_from_class_java.lang.Object"><!-- --></A> |
| <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> |
| <TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor"> |
| <TH ALIGN="left"><B>Methods inherited from class java.lang.<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A></B></TH> |
| </TR> |
| <TR BGCOLOR="white" CLASS="TableRowColor"> |
| <TD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#clone()" title="class or interface in java.lang">clone</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#equals(java.lang.Object)" title="class or interface in java.lang">equals</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#finalize()" title="class or interface in java.lang">finalize</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#getClass()" title="class or interface in java.lang">getClass</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#hashCode()" title="class or interface in java.lang">hashCode</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#notify()" title="class or interface in java.lang">notify</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#notifyAll()" title="class or interface in java.lang">notifyAll</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#wait()" title="class or interface in java.lang">wait</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#wait(long)" title="class or interface in java.lang">wait</A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#wait(long, int)" title="class or interface in java.lang">wait</A></CODE></TD> |
| </TR> |
| </TABLE> |
| |
| <P> |
| |
| <!-- ========= CONSTRUCTOR DETAIL ======== --> |
| |
| <A NAME="constructor_detail"><!-- --></A> |
| <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> |
| <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> |
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| <B>Constructor Detail</B></FONT></TH> |
| </TR> |
| </TABLE> |
| |
| <A NAME="ReentrantLock()"><!-- --></A><H3> |
| ReentrantLock</H3> |
| <PRE> |
| public <B>ReentrantLock</B>()</PRE> |
| <DL> |
| <DD>Creates an instance of <tt>ReentrantLock</tt>. |
| This is equivalent to using <tt>ReentrantLock(false)</tt>. |
| <P> |
| </DL> |
| <HR> |
| |
| <A NAME="ReentrantLock(boolean)"><!-- --></A><H3> |
| ReentrantLock</H3> |
| <PRE> |
| public <B>ReentrantLock</B>(boolean fair)</PRE> |
| <DL> |
| <DD>Creates an instance of <tt>ReentrantLock</tt> with the |
| given fairness policy. |
| <P> |
| <DL> |
| <DT><B>Parameters:</B><DD><CODE>fair</CODE> - true if this lock will be fair; else false</DL> |
| </DL> |
| |
| <!-- ============ METHOD DETAIL ========== --> |
| |
| <A NAME="method_detail"><!-- --></A> |
| <TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""> |
| <TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"> |
| <TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2"> |
| <B>Method Detail</B></FONT></TH> |
| </TR> |
| </TABLE> |
| |
| <A NAME="lock()"><!-- --></A><H3> |
| lock</H3> |
| <PRE> |
| public void <B>lock</B>()</PRE> |
| <DL> |
| <DD>Acquires the lock. |
| Acquires the lock if it is not held by another thread and returns |
| immediately, setting the lock hold count to one. If the current thread |
| already holds the lock then the hold count is incremented by one and |
| the method returns immediately. |
| If the lock is held by another thread then the |
| current thread becomes disabled for thread scheduling |
| purposes and lies dormant until the lock has been acquired, |
| at which time the lock hold count is set to one. |
| <P> |
| <DD><DL> |
| <DT><B>Specified by:</B><DD><CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html#lock()">lock</A></CODE> in interface <CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent">Lock</A></CODE></DL> |
| </DD> |
| <DD><DL> |
| </DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="lockInterruptibly()"><!-- --></A><H3> |
| lockInterruptibly</H3> |
| <PRE> |
| public void <B>lockInterruptibly</B>() |
| throws <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/InterruptedException.html" title="class or interface in java.lang">InterruptedException</A></PRE> |
| <DL> |
| <DD>Acquires the lock unless the current thread is |
| <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupted</CODE></A>. |
| Acquires the lock if it is not held by another thread and returns |
| immediately, setting the lock hold count to one. |
| If the current thread already holds this lock then the hold count |
| is incremented by one and the method returns immediately. |
| If the lock is held by another thread then the |
| current thread becomes disabled for thread scheduling |
| purposes and lies dormant until one of two things happens: |
| |
| <ul> |
| |
| <li>The lock is acquired by the current thread; or |
| |
| <li>Some other thread <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupts</CODE></A> the current |
| thread. |
| |
| </ul> If the lock is acquired by the current thread then the lock hold |
| count is set to one. If the current thread: |
| |
| <ul> |
| |
| <li>has its interrupted status set on entry to this method; or |
| |
| <li>is <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupted</CODE></A> while acquiring the lock, |
| |
| </ul> |
| then <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/InterruptedException.html" title="class or interface in java.lang"><CODE>InterruptedException</CODE></A> is thrown and the current thread's |
| interrupted status is cleared. |
| In this implementation, as this method is an explicit interruption |
| point, preference is |
| given to responding to the interrupt over normal or reentrant |
| acquisition of the lock. |
| <P> |
| <DD><DL> |
| <DT><B>Specified by:</B><DD><CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html#lockInterruptibly()">lockInterruptibly</A></CODE> in interface <CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent">Lock</A></CODE></DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Throws:</B> |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/InterruptedException.html" title="class or interface in java.lang">InterruptedException</A></CODE> - if the current thread is interrupted<DT><B>See Also:</B><DD><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>Thread.interrupt()</CODE></A></DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="tryLock()"><!-- --></A><H3> |
| tryLock</H3> |
| <PRE> |
| public boolean <B>tryLock</B>()</PRE> |
| <DL> |
| <DD>Acquires the lock only if it is not held by another thread at the time |
| of invocation. Acquires the lock if it is not held by another thread and |
| returns immediately with the value <tt>true</tt>, setting the |
| lock hold count to one. Even when this lock has been set to use a |
| fair ordering policy, a call to <tt>tryLock()</tt> <em>will</em> |
| immediately acquire the lock if it is available, whether or not |
| other threads are currently waiting for the lock. |
| This "barging" behavior can be useful in certain |
| circumstances, even though it breaks fairness. If you want to honor |
| the fairness setting for this lock, then use |
| <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#tryLock(long, org.apache.openjpa.lib.util.concurrent.TimeUnit)"><CODE>tryLock(0, TimeUnit.SECONDS) </CODE></A> |
| which is almost equivalent(it also detects interruption). |
| If the current thread |
| already holds this lock then the hold count is incremented by one and |
| the method returns <tt>true</tt>. |
| If the lock is held by another thread then this method will return |
| immediately with the value <tt>false</tt>. |
| <P> |
| <DD><DL> |
| <DT><B>Specified by:</B><DD><CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html#tryLock()">tryLock</A></CODE> in interface <CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent">Lock</A></CODE></DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD><tt>true</tt> if the lock was free and was acquired by the |
| current thread, or the lock was already held by the current thread; and |
| <tt>false</tt> otherwise.</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="tryLock(long, org.apache.openjpa.lib.util.concurrent.TimeUnit)"><!-- --></A><H3> |
| tryLock</H3> |
| <PRE> |
| public boolean <B>tryLock</B>(long timeout, |
| <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/TimeUnit.html" title="class in org.apache.openjpa.lib.util.concurrent">TimeUnit</A> unit) |
| throws <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/InterruptedException.html" title="class or interface in java.lang">InterruptedException</A></PRE> |
| <DL> |
| <DD>Acquires the lock if it is not held by another thread within the given |
| waiting time and the current thread has not been |
| <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupted</CODE></A>. |
| Acquires the lock if it is not held by another thread and returns |
| immediately with the value <tt>true</tt>, setting the lock hold count |
| to one. If this lock has been set to use a fair ordering policy then |
| an available lock <em>will not</em> be acquired if any other threads |
| are waiting for the lock. This is in contrast to the <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/ReentrantLock.html#tryLock()"><CODE>tryLock()</CODE></A> |
| method. If you want a timed <tt>tryLock</tt> that does permit barging on |
| a fair lock then combine the timed and un-timed forms together: |
| |
| <pre>if (lock.tryLock() || lock.tryLock(timeout, unit) ) { ... } |
| </pre> If the current thread |
| already holds this lock then the hold count is incremented by one and |
| the method returns <tt>true</tt>. |
| If the lock is held by another thread then the |
| current thread becomes disabled for thread scheduling |
| purposes and lies dormant until one of three things happens: |
| |
| <ul> |
| |
| <li>The lock is acquired by the current thread; or |
| |
| <li>Some other thread <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupts</CODE></A> the current |
| thread; or |
| |
| <li>The specified waiting time elapses |
| |
| </ul> |
| If the lock is acquired then the value <tt>true</tt> is returned and |
| the lock hold count is set to one. If the current thread: |
| |
| <ul> |
| |
| <li>has its interrupted status set on entry to this method; or |
| |
| <li>is <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupted</CODE></A> while acquiring the lock, |
| |
| </ul> |
| then <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/InterruptedException.html" title="class or interface in java.lang"><CODE>InterruptedException</CODE></A> is thrown and the current thread's |
| interrupted status is cleared. |
| If the specified waiting time elapses then the value <tt>false</tt> |
| is returned. If the time is |
| less than or equal to zero, the method will not wait at all. |
| In this implementation, as this method is an explicit interruption |
| point, preference is |
| given to responding to the interrupt over normal or reentrant |
| acquisition of the lock, and over reporting the elapse of the waiting |
| time. |
| <P> |
| <DD><DL> |
| <DT><B>Specified by:</B><DD><CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html#tryLock(long, org.apache.openjpa.lib.util.concurrent.TimeUnit)">tryLock</A></CODE> in interface <CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent">Lock</A></CODE></DL> |
| </DD> |
| <DD><DL> |
| <DT><B>Parameters:</B><DD><CODE>timeout</CODE> - the time to wait for the lock<DD><CODE>unit</CODE> - the time unit of the timeout argument |
| <DT><B>Returns:</B><DD><tt>true</tt> if the lock was free and was acquired by the |
| current thread, or the lock was already held by the current thread; and |
| <tt>false</tt> if the waiting time elapsed before the lock could be |
| acquired. |
| <DT><B>Throws:</B> |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/InterruptedException.html" title="class or interface in java.lang">InterruptedException</A></CODE> - if the current thread is interrupted |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if unit is null<DT><B>See Also:</B><DD><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>Thread.interrupt()</CODE></A></DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="unlock()"><!-- --></A><H3> |
| unlock</H3> |
| <PRE> |
| public void <B>unlock</B>()</PRE> |
| <DL> |
| <DD>Attempts to release this lock. If the current thread is the |
| holder of this lock then the hold count is decremented. If the |
| hold count is now zero then the lock is released. If the |
| current thread is not the holder of this lock then <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalMonitorStateException.html" title="class or interface in java.lang"><CODE>IllegalMonitorStateException</CODE></A> is thrown. |
| <P> |
| <DD><DL> |
| <DT><B>Specified by:</B><DD><CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html#unlock()">unlock</A></CODE> in interface <CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent">Lock</A></CODE></DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Throws:</B> |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalMonitorStateException.html" title="class or interface in java.lang">IllegalMonitorStateException</A></CODE> - if the current thread does not |
| hold this lock.</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="newCondition()"><!-- --></A><H3> |
| newCondition</H3> |
| <PRE> |
| public <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent">Condition</A> <B>newCondition</B>()</PRE> |
| <DL> |
| <DD>Returns a <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent"><CODE>Condition</CODE></A> instance for use with this |
| <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent"><CODE>Lock</CODE></A> instance. |
| The returned <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent"><CODE>Condition</CODE></A> instance supports the same |
| usages as do the <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang"><CODE>Object</CODE></A> monitor methods(<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#wait()" title="class or interface in java.lang"><CODE>wait</CODE></A>, <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#notify()" title="class or interface in java.lang"><CODE>notify</CODE></A>, and <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#notifyAll()" title="class or interface in java.lang"><CODE>notifyAll</CODE></A>) when used with the built-in monitor lock. |
| |
| <ul> |
| |
| <li>If this lock is not held when any of the <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent"><CODE>Condition</CODE></A> |
| <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html#await()"><CODE>waiting</CODE></A> or <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html#signal()"><CODE>signalling</CODE></A> methods are called, then an <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalMonitorStateException.html" title="class or interface in java.lang"><CODE>IllegalMonitorStateException</CODE></A> is thrown. |
| |
| <li>When the condition <A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html#await()"><CODE>waiting</CODE></A> |
| methods are called the lock is released and, before they |
| return, the lock is reacquired and the lock hold count restored |
| to what it was when the method was called. |
| |
| <li>If a thread is <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#interrupt()" title="class or interface in java.lang"><CODE>interrupted</CODE></A> while |
| waiting then the wait will terminate, an <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/InterruptedException.html" title="class or interface in java.lang"><CODE>InterruptedException</CODE></A> will be thrown, and the thread's |
| interrupted status will be cleared. |
| |
| <li> Waiting threads are signalled in FIFO order |
| |
| <li>The ordering of lock reacquisition for threads returning |
| from waiting methods is the same as for threads initially |
| acquiring the lock, which is in the default case not specified, |
| but for <em>fair</em> locks favors those threads that have been |
| waiting the longest. |
| |
| </ul> |
| <P> |
| <DD><DL> |
| <DT><B>Specified by:</B><DD><CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html#newCondition()">newCondition</A></CODE> in interface <CODE><A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Lock.html" title="interface in org.apache.openjpa.lib.util.concurrent">Lock</A></CODE></DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD>the Condition object</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="getHoldCount()"><!-- --></A><H3> |
| getHoldCount</H3> |
| <PRE> |
| public int <B>getHoldCount</B>()</PRE> |
| <DL> |
| <DD>Queries the number of holds on this lock by the current thread. |
| A thread has a hold on a lock for each lock action that is not |
| matched by an unlock action. |
| The hold count information is typically only used for testing and |
| debugging purposes. For example, if a certain section of code should |
| not be entered with the lock already held then we can assert that fact: |
| |
| <pre> class X { ReentrantLock lock = new ReentrantLock(); // ... |
| public void m() { assert lock.getHoldCount() == 0; lock.lock(); try { |
| // ... method body } finally { lock.unlock(); } } } |
| </pre> |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD>the number of holds on this lock by the current thread, |
| or zero if this lock is not held by the current thread.</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="isHeldByCurrentThread()"><!-- --></A><H3> |
| isHeldByCurrentThread</H3> |
| <PRE> |
| public boolean <B>isHeldByCurrentThread</B>()</PRE> |
| <DL> |
| <DD>Queries if this lock is held by the current thread. |
| Analogous to the <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#holdsLock(java.lang.Object)" title="class or interface in java.lang"><CODE>Thread.holdsLock(java.lang.Object)</CODE></A> method for built-in |
| monitor locks, this method is typically used for debugging and |
| testing. For example, a method that should only be called while |
| a lock is held can assert that this is the case: |
| |
| <pre> class X { ReentrantLock lock = new ReentrantLock(); // ... |
| public void m() { assert lock.isHeldByCurrentThread(); |
| // ... method body } } |
| </pre> It can also be used to ensure that a reentrant lock is used |
| in a non-reentrant manner, for example: |
| |
| <pre> class X { ReentrantLock lock = new ReentrantLock(); // ... |
| public void m() { assert !lock.isHeldByCurrentThread(); lock.lock(); |
| try { // ... method body } finally { lock.unlock(); } } } |
| </pre> |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD><tt>true</tt> if current thread holds this lock and |
| <tt>false</tt> otherwise.</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="isLocked()"><!-- --></A><H3> |
| isLocked</H3> |
| <PRE> |
| public boolean <B>isLocked</B>()</PRE> |
| <DL> |
| <DD>Queries if this lock is held by any thread. This method is |
| designed for use in monitoring of the system state, |
| not for synchronization control. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD><tt>true</tt> if any thread holds this lock and |
| <tt>false</tt> otherwise.</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="isFair()"><!-- --></A><H3> |
| isFair</H3> |
| <PRE> |
| public final boolean <B>isFair</B>()</PRE> |
| <DL> |
| <DD>Returns true if this lock has fairness set true. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD>true if this lock has fairness set true.</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="getOwner()"><!-- --></A><H3> |
| getOwner</H3> |
| <PRE> |
| protected <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html" title="class or interface in java.lang">Thread</A> <B>getOwner</B>()</PRE> |
| <DL> |
| <DD><tt>null</tt> if not owned. When this method is called by a |
| thread that is not the owner, the return value reflects a |
| best-effort approximation of current lock status. For example, |
| the owner may be momentarily <tt>null</tt> even if there are |
| threads trying to acquire the lock but have not yet done so. |
| This method is designed to facilitate construction of |
| subclasses that provide more extensive lock monitoring facilities. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD>the owner, or <tt>null</tt> if not owned</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="hasQueuedThreads()"><!-- --></A><H3> |
| hasQueuedThreads</H3> |
| <PRE> |
| public final boolean <B>hasQueuedThreads</B>()</PRE> |
| <DL> |
| <DD>Queries whether any threads are waiting to acquire this lock. Note that |
| because cancellations may occur at any time, a <tt>true</tt> |
| return does not guarantee that any other thread will ever |
| acquire this lock. This method is designed primarily for use in |
| monitoring of the system state. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD>true if there may be other threads waiting to acquire the lock.</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="hasQueuedThread(java.lang.Thread)"><!-- --></A><H3> |
| hasQueuedThread</H3> |
| <PRE> |
| public final boolean <B>hasQueuedThread</B>(<A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html" title="class or interface in java.lang">Thread</A> thread)</PRE> |
| <DL> |
| <DD>Queries whether the given thread is waiting to acquire this |
| lock. Note that because cancellations may occur at any time, a |
| <tt>true</tt> return does not guarantee that this thread |
| will ever acquire this lock. This method is designed primarily for use |
| in monitoring of the system state. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| <DT><B>Parameters:</B><DD><CODE>thread</CODE> - the thread |
| <DT><B>Returns:</B><DD>true if the given thread is queued waiting for this lock. |
| <DT><B>Throws:</B> |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if thread is null</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="getQueueLength()"><!-- --></A><H3> |
| getQueueLength</H3> |
| <PRE> |
| public final int <B>getQueueLength</B>()</PRE> |
| <DL> |
| <DD>Returns an estimate of the number of threads waiting to |
| acquire this lock. The value is only an estimate because the number of |
| threads may change dynamically while this method traverses |
| internal data structures. This method is designed for use in |
| monitoring of the system state, not for synchronization control. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD>the estimated number of threads waiting for this lock</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="getQueuedThreads()"><!-- --></A><H3> |
| getQueuedThreads</H3> |
| <PRE> |
| protected <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html" title="class or interface in java.util">Collection</A> <B>getQueuedThreads</B>()</PRE> |
| <DL> |
| <DD>Returns a collection containing threads that may be waiting to |
| acquire this lock. Because the actual set of threads may change |
| dynamically while constructing this result, the returned |
| collection is only a best-effort estimate. The elements of the |
| returned collection are in no particular order. This method is |
| designed to facilitate construction of subclasses that provide |
| more extensive monitoring facilities. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD>the collection of threads</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="hasWaiters(org.apache.openjpa.lib.util.concurrent.Condition)"><!-- --></A><H3> |
| hasWaiters</H3> |
| <PRE> |
| public boolean <B>hasWaiters</B>(<A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent">Condition</A> condition)</PRE> |
| <DL> |
| <DD>Queries whether any threads are waiting on the given condition |
| associated with this lock. Note that because timeouts and |
| interrupts may occur at any time, a <tt>true</tt> return does |
| not guarantee that a future <tt>signal</tt> will awaken any |
| threads. This method is designed primarily for use in |
| monitoring of the system state. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| <DT><B>Parameters:</B><DD><CODE>condition</CODE> - the condition |
| <DT><B>Returns:</B><DD><tt>true</tt> if there are any waiting threads. |
| <DT><B>Throws:</B> |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalMonitorStateException.html" title="class or interface in java.lang">IllegalMonitorStateException</A></CODE> - if this lock is not held |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalArgumentException.html" title="class or interface in java.lang">IllegalArgumentException</A></CODE> - if the given condition is |
| not associated with this lock |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if condition null</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="getWaitQueueLength(org.apache.openjpa.lib.util.concurrent.Condition)"><!-- --></A><H3> |
| getWaitQueueLength</H3> |
| <PRE> |
| public int <B>getWaitQueueLength</B>(<A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent">Condition</A> condition)</PRE> |
| <DL> |
| <DD>Returns an estimate of the number of threads waiting on the |
| given condition associated with this lock. Note that because |
| timeouts and interrupts may occur at any time, the estimate |
| serves only as an upper bound on the actual number of waiters. |
| This method is designed for use in monitoring of the system |
| state, not for synchronization control. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| <DT><B>Parameters:</B><DD><CODE>condition</CODE> - the condition |
| <DT><B>Returns:</B><DD>the estimated number of waiting threads. |
| <DT><B>Throws:</B> |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalMonitorStateException.html" title="class or interface in java.lang">IllegalMonitorStateException</A></CODE> - if this lock is not held |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalArgumentException.html" title="class or interface in java.lang">IllegalArgumentException</A></CODE> - if the given condition is |
| not associated with this lock |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if condition null</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="getWaitingThreads(org.apache.openjpa.lib.util.concurrent.Condition)"><!-- --></A><H3> |
| getWaitingThreads</H3> |
| <PRE> |
| protected <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html" title="class or interface in java.util">Collection</A> <B>getWaitingThreads</B>(<A HREF="../../../../../../org/apache/openjpa/lib/util/concurrent/Condition.html" title="interface in org.apache.openjpa.lib.util.concurrent">Condition</A> condition)</PRE> |
| <DL> |
| <DD>Returns a collection containing those threads that may be |
| waiting on the given condition associated with this lock. |
| Because the actual set of threads may change dynamically while |
| constructing this result, the returned collection is only a |
| best-effort estimate. The elements of the returned collection |
| are in no particular order. This method is designed to |
| facilitate construction of subclasses that provide more |
| extensive condition monitoring facilities. |
| <P> |
| <DD><DL> |
| </DL> |
| </DD> |
| <DD><DL> |
| <DT><B>Parameters:</B><DD><CODE>condition</CODE> - the condition |
| <DT><B>Returns:</B><DD>the collection of threads |
| <DT><B>Throws:</B> |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalMonitorStateException.html" title="class or interface in java.lang">IllegalMonitorStateException</A></CODE> - if this lock is not held |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/IllegalArgumentException.html" title="class or interface in java.lang">IllegalArgumentException</A></CODE> - if the given condition is |
| not associated with this lock |
| <DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/NullPointerException.html" title="class or interface in java.lang">NullPointerException</A></CODE> - if condition null</DL> |
| </DD> |
| </DL> |
| <HR> |
| |
| <A NAME="toString()"><!-- --></A><H3> |
| toString</H3> |
| <PRE> |
| public <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/String.html" title="class or interface in java.lang">String</A> <B>toString</B>()</PRE> |
| <DL> |
| <DD>Returns a string identifying this lock, as well as its lock |
| state. The state, in brackets, includes either the String |
| "Unlocked" or the String "Locked by" |
| followed by the <A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#getName()" title="class or interface in java.lang"><CODE>Thread.getName()</CODE></A> of the owning thread. |
| <P> |
| <DD><DL> |
| <DT><B>Overrides:</B><DD><CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html#toString()" title="class or interface in java.lang">toString</A></CODE> in class <CODE><A HREF="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Object.html" title="class or interface in java.lang">Object</A></CODE></DL> |
| </DD> |
| <DD><DL> |
| |
| <DT><B>Returns:</B><DD>a string identifying this lock, as well as its lock state.</DL> |
| </DD> |
| </DL> |
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