1 files changed, 140 insertions, 0 deletions
diff --git a/src/com/android/bitmap/UnrefedBitmapCache.java b/src/com/android/bitmap/UnrefedBitmapCache.java
new file mode 100644
index 0000000..6c9db73
--- /dev/null
+++ b/src/com/android/bitmap/UnrefedBitmapCache.java
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.bitmap;
+
+import android.util.Log;
+import android.util.LruCache;
+
+import com.android.bitmap.DecodeTask.Request;
+import com.android.bitmap.ReusableBitmap.NullReusableBitmap;
+import com.android.bitmap.util.Trace;
+
+/**
+ * This subclass provides custom pool behavior. The pool can be set to block on {@link #poll()} if
+ * nothing can be returned. This is useful if you know you will incur high costs upon receiving
+ * nothing from the pool, and you do not want to incur those costs at the critical moment when the
+ * UI is animating.
+ *
+ * This subclass provides custom cache behavior. Null values can be cached. Later,
+ * when the same key is used to retrieve the value, a {@link NullReusableBitmap} singleton will
+ * be returned.
+ */
+public class UnrefedBitmapCache extends UnrefedPooledCache<Request, ReusableBitmap>
+        implements BitmapCache {
+    private boolean mBlocking = false;
+    private final Object mLock = new Object();
+
+    private LruCache<Request, NullReusableBitmap> mNullRequests;
+
+    private final static boolean DEBUG = false;
+    private final static String TAG = UnrefedBitmapCache.class.getSimpleName();
+
+    public UnrefedBitmapCache(final int targetSizeBytes, final float nonPooledFraction,
+            final int nullCapacity) {
+        super(targetSizeBytes, nonPooledFraction);
+
+        if (nullCapacity > 0) {
+            mNullRequests = new LruCache<Request, NullReusableBitmap>(nullCapacity);
+        }
+    }
+
+    /**
+     * Declare that {@link #poll()} should now block until it can return something.
+     */
+    @Override
+    public void setBlocking(final boolean blocking) {
+        synchronized (mLock) {
+            if (DEBUG) {
+                Log.d(TAG, String.format("AltBitmapCache: block %b", blocking));
+            }
+            mBlocking = blocking;
+            if (!mBlocking) {
+                // no longer blocking. Notify every thread.
+                mLock.notifyAll();
+            }
+        }
+    }
+
+    @Override
+    protected int sizeOf(final ReusableBitmap value) {
+        return value.getByteCount();
+    }
+
+    /**
+     * If {@link #setBlocking(boolean)} has been called with true, this method will block until a
+     * resource is available.
+     * @return an available resource, or null if none are available. Null will never be returned
+     * until blocking is set to false.
+     */
+    @Override
+    public ReusableBitmap poll() {
+        ReusableBitmap bitmap;
+        synchronized (mLock) {
+            while ((bitmap = super.poll()) == null && mBlocking) {
+                if (DEBUG) {
+                    Log.d(TAG, String.format(
+                            "AltBitmapCache: %s waiting", Thread.currentThread().getName()));
+                }
+                Trace.beginSection("sleep");
+                try {
+                    // block
+                    mLock.wait();
+                    if (DEBUG) {
+                        Log.d(TAG, String.format("AltBitmapCache: %s notified",
+                                Thread.currentThread().getName()));
+                    }
+                } catch (InterruptedException ignored) {
+                }
+                Trace.endSection();
+            }
+        }
+        return bitmap;
+    }
+
+    @Override
+    public void offer(final ReusableBitmap value) {
+        synchronized (mLock) {
+            super.offer(value);
+            if (DEBUG) {
+                Log.d(TAG, "AltBitmapCache: offer +1");
+            }
+            // new resource gained. Notify one thread.
+            mLock.notify();
+        }
+    }
+
+    @Override
+    public ReusableBitmap get(final Request key, final boolean incrementRefCount) {
+        if (mNullRequests != null && mNullRequests.get(key) != null) {
+            return NullReusableBitmap.getInstance();
+        }
+        return super.get(key, incrementRefCount);
+    }
+
+    /**
+     * Note: The cache only supports same-sized bitmaps.
+     */
+    @Override
+    public ReusableBitmap put(final Request key, final ReusableBitmap value) {
+        if (mNullRequests != null && (value == null || value == NullReusableBitmap.getInstance())) {
+            mNullRequests.put(key, NullReusableBitmap.getInstance());
+            return null;
+        }
+
+        return super.put(key, value);
+    }
+}