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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
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package org.graalvm.compiler.hotspot;

import org.graalvm.compiler.debug.GraalError;

import jdk.vm.ci.meta.JavaConstant;

A context for scoping the lifetime of foreign objects. The need for this mechanism is best explained with an example. When folding a GETFIELD bytecode denoting a final static non-primitive field, libgraal can create a JavaConstant wrapping a handle to the field's value in the HotSpot heap. This handle must be released before HotSpot can reclaim the object it references. Performing a compilation in the scope of a local context ensures the handle is released once the compilation completes, allowing the HotSpot GC to subsequently reclaim the HotSpot object. When libgraal creates data structures that outlive a single compilation and may contain foreign object references (e.g. snippet graphs), it must enter the global context. Foreign object handles created in the global context are only released once their JavaConstant wrappers are reclaimed by the libgraal GC. CompilationContexts have no impact on JavaConstants that do not encapsulate a foreign object reference. The object returned by HotSpotGraalServices.enterGlobalCompilationContext or HotSpotGraalServices.openLocalCompilationContext should be used in a try-with-resources statement. Failure to close a context will almost certainly result in foreign objects being leaked. /**
 * A context for scoping the lifetime of foreign objects.
 *
 * The need for this mechanism is best explained with an example. When folding a GETFIELD bytecode
 * denoting a {@code final static} non-primitive field, libgraal can create a {@link JavaConstant}
 * wrapping a handle to the field's value in the HotSpot heap. This handle must be released before
 * HotSpot can reclaim the object it references. Performing a compilation in the scope of a
 * {@linkplain HotSpotGraalServices#openLocalCompilationContext local} context ensures the handle is
 * released once the compilation completes, allowing the HotSpot GC to subsequently reclaim the
 * HotSpot object. When libgraal creates data structures that outlive a single compilation and may
 * contain foreign object references (e.g. snippet graphs), it must enter the
 * {@linkplain HotSpotGraalServices#enterGlobalCompilationContext global} context. Foreign object
 * handles created in the global context are only released once their {@link JavaConstant} wrappers
 * are reclaimed by the libgraal GC.
 *
 * {@link CompilationContext}s have no impact on {@link JavaConstant}s that do not encapsulate a
 * foreign object reference.
 *
 * The object returned by {@link HotSpotGraalServices#enterGlobalCompilationContext} or
 * {@link HotSpotGraalServices#openLocalCompilationContext} should be used in a try-with-resources
 * statement. Failure to close a context will almost certainly result in foreign objects being
 * leaked.
 */
public class CompilationContext implements AutoCloseable {
    private final AutoCloseable impl;

    CompilationContext(AutoCloseable impl) {
        this.impl = impl;
    }

    @Override
    public void close() {
        try {
            impl.close();
        } catch (Exception e) {
            GraalError.shouldNotReachHere(e);
        }
    }
}