com.bumptech.glide.provider.LoadPathCache Maven / Gradle / Ivy

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A fast and efficient image loading library for Android focused on smooth scrolling.

There is a newer version: 5.0.0-rc01

package com.bumptech.glide.provider;

import androidx.annotation.Nullable;
import androidx.collection.ArrayMap;
import com.bumptech.glide.load.ResourceDecoder;
import com.bumptech.glide.load.engine.DecodePath;
import com.bumptech.glide.load.engine.LoadPath;
import com.bumptech.glide.load.resource.transcode.UnitTranscoder;
import com.bumptech.glide.util.MultiClassKey;
import java.util.Collections;
import java.util.concurrent.atomic.AtomicReference;

/**
 * Maintains a cache of data, resource, and transcode classes to available {@link
 * com.bumptech.glide.load.engine.LoadPath}s capable of decoding with the requested types.
 */
public class LoadPathCache {
  private static final LoadPath NO_PATHS_SIGNAL =
      new LoadPath<>(
          Object.class,
          Object.class,
          Object.class,
          Collections.singletonList(
              new DecodePath<>(
                  Object.class,
                  Object.class,
                  Object.class,
                  Collections.>emptyList(),
                  new UnitTranscoder<>(),
                  /*listPool=*/ null)),
          /*listPool=*/ null);

  private final ArrayMap> cache = new ArrayMap<>();
  private final AtomicReference keyRef = new AtomicReference<>();

  /**
   * Returns {@code} true if the given {@link LoadPath} is the signal object returned from {@link
   * #get(Class, Class, Class)} that indicates that we've previously found that there are no
   * available paths to load the requested resources and {@code false} otherwise.
   */
  public boolean isEmptyLoadPath(@Nullable LoadPath path) {
    return NO_PATHS_SIGNAL.equals(path);
  }

  /**
   * May return {@link #NO_PATHS_SIGNAL} to indicate that we've previously found that there are 0
   * available load paths for the requested types. Callers must check using {@link
   * #isEmptyLoadPath(LoadPath)} before using any load path returned by this method.
   */
  @SuppressWarnings("unchecked")
  @Nullable
  public  LoadPath get(
      Class dataClass, Class resourceClass, Class transcodeClass) {
    MultiClassKey key = getKey(dataClass, resourceClass, transcodeClass);
    LoadPath result;
    synchronized (cache) {
      result = cache.get(key);
    }
    keyRef.set(key);

    return (LoadPath) result;
  }

  public void put(
      Class dataClass,
      Class resourceClass,
      Class transcodeClass,
      @Nullable LoadPath loadPath) {
    synchronized (cache) {
      cache.put(
          new MultiClassKey(dataClass, resourceClass, transcodeClass),
          loadPath != null ? loadPath : NO_PATHS_SIGNAL);
    }
  }

  private MultiClassKey getKey(
      Class dataClass, Class resourceClass, Class transcodeClass) {
    MultiClassKey key = keyRef.getAndSet(null);
    if (key == null) {
      key = new MultiClassKey();
    }
    key.set(dataClass, resourceClass, transcodeClass);
    return key;
  }
}