edu.mit.streamjit.impl.compiler2.DoubleArrayConcreteStorage.java Source code

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Here is the source code for edu.mit.streamjit.impl.compiler2.DoubleArrayConcreteStorage.java

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/*
 * Copyright (c) 2013-2015 Massachusetts Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package edu.mit.streamjit.impl.compiler2;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import edu.mit.streamjit.util.bytecode.methodhandles.Combinators;
import static edu.mit.streamjit.util.bytecode.methodhandles.LookupUtils.findGetter;
import static edu.mit.streamjit.util.bytecode.methodhandles.LookupUtils.findVirtual;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.util.Map;

/**
 * A ConcreteStorage backed by double-buffered storage.
 * @author Jeffrey Bosboom <jbosboom@csail.mit.edu>
 * @since 10/10/2013
 */
public class DoubleArrayConcreteStorage implements ConcreteStorage {
    private static final Lookup LOOKUP = MethodHandles.lookup();
    private static final MethodHandle ADJUST = findVirtual(LOOKUP, "adjust");
    private static final MethodHandle STATE_GETTER = findGetter(LOOKUP, "state");
    private final Arrayish readArray, writeArray;
    /**
     * If true, read from readArray, else writeArray, and resp. for writes.
     */
    private boolean state = true;
    private final int capacity, throughput, readOffset;
    private final MethodHandle readHandle, writeHandle, adjustHandle;

    public DoubleArrayConcreteStorage(Arrayish.Factory arrayFactory, Storage s) {
        this.capacity = s.steadyStateCapacity();
        assert capacity > 0 : s + " has capacity " + capacity;
        this.throughput = s.throughput();
        assert capacity == 2 * throughput : "can't double buffer " + s;
        this.readArray = arrayFactory.make(s.type(), throughput);
        this.writeArray = arrayFactory.make(s.type(), throughput);

        ImmutableSet<ActorGroup> relevantGroups = ImmutableSet.<ActorGroup>builder().addAll(s.upstreamGroups())
                .addAll(s.downstreamGroups()).build();
        Map<ActorGroup, Integer> oneMap = Maps.asMap(relevantGroups, x -> 1);
        this.readOffset = s.readIndices(oneMap).first();
        int writeOffset = s.writeIndices(oneMap).first();

        MethodHandle stateGetter = STATE_GETTER.bindTo(this);
        this.readHandle = MethodHandles.filterArguments(
                MethodHandles.guardWithTest(stateGetter, readArray.get(), writeArray.get()), 0,
                Combinators.adder(-readOffset));
        this.writeHandle = MethodHandles.filterArguments(
                MethodHandles.guardWithTest(stateGetter, writeArray.set(), readArray.set()), 0,
                Combinators.adder(-writeOffset));
        this.adjustHandle = ADJUST.bindTo(this);
    }

    @Override
    public Class<?> type() {
        return readArray.type();
    }

    @Override
    public void write(int index, Object data) {
        try {
            //Pretend the read and write arrays are contiguous.
            index -= readOffset;
            if (index < throughput)
                (state ? readArray : writeArray).set().invoke(index, data);
            else
                (state ? writeArray : readArray).set().invoke(index - throughput, data);
        } catch (Throwable ex) {
            throw new AssertionError(String.format("%s.write(%d, %s)", this, index, data), ex);
        }
    }

    @Override
    public void adjust() {
        //state != state doesn't work, heh.
        state = !state;
    }

    @Override
    public void sync() {
    }

    @Override
    public MethodHandle readHandle() {
        return readHandle;
    }

    @Override
    public MethodHandle writeHandle() {
        return writeHandle;
    }

    @Override
    public MethodHandle adjustHandle() {
        return adjustHandle;
    }

    public static StorageFactory factory() {
        return storage -> storage.steadyStateCapacity() == 0 ? new EmptyConcreteStorage(storage)
                : new DoubleArrayConcreteStorage(Arrayish.ArrayArrayish.factory(), storage);
    }
}