/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
/**
* A {@code VolatileCallSite} is a {@link CallSite} whose target acts like a volatile variable.
* An {@code invokedynamic} instruction linked to a {@code VolatileCallSite} sees updates
* to its call site target immediately, even if the update occurs in another thread.
* There may be a performance penalty for such tight coupling between threads.
* <p>
* Unlike {@code MutableCallSite}, there is no
* {@linkplain MutableCallSite#syncAll syncAll operation} on volatile
* call sites, since every write to a volatile variable is implicitly
* synchronized with reader threads.
* <p>
* In other respects, a {@code VolatileCallSite} is interchangeable
* with {@code MutableCallSite}.
* @see MutableCallSite
* @author John Rose, JSR 292 EG
*/
/**
* Creates a call site with a volatile binding to its target.
* The initial target is set to a method handle
* of the given type which will throw an {@code IllegalStateException} if called.
* @param type the method type that this call site will have
* @throws NullPointerException if the proposed type is null
*/
super(type);
}
/**
* Creates a call site with a volatile binding to its target.
* The target is set to the given value.
* @param target the method handle that will be the initial target of the call site
* @throws NullPointerException if the proposed target is null
*/
super(target);
}
/**
* Returns the target method of the call site, which behaves
* like a {@code volatile} field of the {@code VolatileCallSite}.
* <p>
* The interactions of {@code getTarget} with memory are the same
* as of a read from a {@code volatile} field.
* <p>
* In particular, the current thread is required to issue a fresh
* read of the target from memory, and must not fail to see
* a recent update to the target by another thread.
*
* @return the linkage state of this call site, a method handle which can change over time
* @see #setTarget
*/
return getTargetVolatile();
}
/**
* Updates the target method of this call site, as a volatile variable.
* The type of the new target must agree with the type of the old target.
* <p>
* The interactions with memory are the same as of a write to a volatile field.
* In particular, any threads is guaranteed to see the updated target
* the next time it calls {@code getTarget}.
* @param newTarget the new target
* @throws NullPointerException if the proposed new target is null
* @throws WrongMethodTypeException if the proposed new target
* has a method type that differs from the previous target
* @see #getTarget
*/
}
/**
* {@inheritDoc}
*/
return makeDynamicInvoker();
}
}