LinkRequest.java

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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file, and Oracle licenses the original version of this file under the BSD
 * license:
 */
/*
   Copyright 2009-2013 Attila Szegedi

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:
   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
   * Neither the name of the copyright holder nor the names of
     contributors may be used to endorse or promote products derived from
     this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
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   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

package jdk.dynalink.linker;

import jdk.dynalink.CallSiteDescriptor;
import jdk.dynalink.DynamicLinker;
import jdk.dynalink.DynamicLinkerFactory;

/**
 * Represents a request to link a particular invocation at a particular call
 * site. Instances of these requests will be constructed and passed to all
 * {@link GuardingDynamicLinker} objects managed by the {@link DynamicLinker}
 * that is trying to link the call site.
 */
public interface LinkRequest {
    /**
     * Returns the call site descriptor for the call site being linked.
     *
     * @return the call site descriptor for the call site being linked.
     */
    public CallSiteDescriptor getCallSiteDescriptor();

    /**
     * Returns the arguments for the invocation being linked. The returned array
     * must be a clone; modifications to it must not affect the arguments in
     * this request.
     *
     * @return the arguments for the invocation being linked.
     */
    public Object[] getArguments();

    /**
     * Returns the first argument for the invocation being linked; this is
     * typically the receiver object. This is a shorthand for
     * {@code getArguments()[0]} that also avoids the cloning of the arguments
     * array.
     *
     * @return the receiver object.
     */
    public Object getReceiver();

    /**
     * Returns true if the call site is considered unstable, that is, it has been relinked more times than was
     * specified in {@link DynamicLinkerFactory#setUnstableRelinkThreshold(int)}. Linkers should use this as a
     * hint to prefer producing linkage that is more stable (its guard fails less frequently), even if that assumption
     * causes a less effective version of an operation to be linked. This is just a hint, though, and linkers are
     * allowed to ignore this property.
     * @return true if the call site is considered unstable.
     */
    public boolean isCallSiteUnstable();

    /**
     * Returns a request identical to this one with call site descriptor and arguments replaced with the ones specified.
     *
     * @param callSiteDescriptor the new call site descriptor
     * @param arguments the new arguments
     * @return a new request identical to this one, except with the call site descriptor and arguments replaced with the
     * specified ones.
     */
    public LinkRequest replaceArguments(CallSiteDescriptor callSiteDescriptor, Object... arguments);
}