Add TextLayout Cache

- use GenerationCache for caching
- move GenerationCache.h from libs/hwui/utils to include/utils
- add #define for cache activation / deactivation

Change-Id: Ifaf519f0b5e33b087a453e4aa6430162d8438f20

1 files changed, 255 insertions, 0 deletions

diff --git a/include/utils/GenerationCache.h b/include/utils/GenerationCache.h
new file mode 100644
index 0000000..bb9ddd6
--- /dev/null
+++ b/include/utils/GenerationCache.h
@@ -0,0 +1,255 @@
+/*
+ * Copyright (C) 2010 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.
+ */
+
+#ifndef ANDROID_UTILS_GENERATION_CACHE_H
+#define ANDROID_UTILS_GENERATION_CACHE_H
+
+#include <utils/KeyedVector.h>
+#include <utils/RefBase.h>
+
+namespace android {
+
+/**
+ * GenerationCache callback used when an item is removed
+ */
+template<typename EntryKey, typename EntryValue>
+class OnEntryRemoved {
+public:
+    virtual ~OnEntryRemoved() { };
+    virtual void operator()(EntryKey& key, EntryValue& value) = 0;
+}; // class OnEntryRemoved
+
+template<typename EntryKey, typename EntryValue>
+struct Entry: public LightRefBase<Entry<EntryKey, EntryValue> > {
+    Entry() { }
+    Entry(const Entry<EntryKey, EntryValue>& e):
+            key(e.key), value(e.value), parent(e.parent), child(e.child) { }
+    Entry(sp<Entry<EntryKey, EntryValue> > e):
+            key(e->key), value(e->value), parent(e->parent), child(e->child) { }
+
+    EntryKey key;
+    EntryValue value;
+
+    sp<Entry<EntryKey, EntryValue> > parent;
+    sp<Entry<EntryKey, EntryValue> > child;
+}; // struct Entry
+
+/**
+ * A LRU type cache
+ */
+template<typename K, typename V>
+class GenerationCache {
+public:
+    GenerationCache(uint32_t maxCapacity);
+    virtual ~GenerationCache();
+
+    enum Capacity {
+        kUnlimitedCapacity,
+    };
+
+    void setOnEntryRemovedListener(OnEntryRemoved<K, V>* listener);
+
+    void clear();
+
+    bool contains(K key) const;
+    V get(K key);
+    K getKeyAt(uint32_t index) const;
+    bool put(K key, V value);
+    V remove(K key);
+    V removeOldest();
+    V getValueAt(uint32_t index) const;
+
+    uint32_t size() const;
+
+    void addToCache(sp<Entry<K, V> > entry, K key, V value);
+    void attachToCache(sp<Entry<K, V> > entry);
+    void detachFromCache(sp<Entry<K, V> > entry);
+
+    V removeAt(ssize_t index);
+
+private:
+    KeyedVector<K, sp<Entry<K, V> > > mCache;
+    uint32_t mMaxCapacity;
+
+    OnEntryRemoved<K, V>* mListener;
+
+    sp<Entry<K, V> > mOldest;
+    sp<Entry<K, V> > mYoungest;
+}; // class GenerationCache
+
+template<typename K, typename V>
+GenerationCache<K, V>::GenerationCache(uint32_t maxCapacity): mMaxCapacity(maxCapacity),
+    mListener(NULL) {
+};
+
+template<typename K, typename V>
+GenerationCache<K, V>::~GenerationCache() {
+    clear();
+};
+
+template<typename K, typename V>
+uint32_t GenerationCache<K, V>::size() const {
+    return mCache.size();
+}
+
+/**
+ * Should be set by the user of the Cache so that the callback is called whenever an item is
+ * removed from the cache
+ */
+template<typename K, typename V>
+void GenerationCache<K, V>::setOnEntryRemovedListener(OnEntryRemoved<K, V>* listener) {
+    mListener = listener;
+}
+
+template<typename K, typename V>
+void GenerationCache<K, V>::clear() {
+    if (mListener) {
+        for (uint32_t i = 0; i < mCache.size(); i++) {
+            sp<Entry<K, V> > entry = mCache.valueAt(i);
+            if (mListener) {
+                (*mListener)(entry->key, entry->value);
+            }
+        }
+    }
+    mCache.clear();
+    mYoungest.clear();
+    mOldest.clear();
+}
+
+template<typename K, typename V>
+bool GenerationCache<K, V>::contains(K key) const {
+    return mCache.indexOfKey(key) >= 0;
+}
+
+template<typename K, typename V>
+K GenerationCache<K, V>::getKeyAt(uint32_t index) const {
+    return mCache.keyAt(index);
+}
+
+template<typename K, typename V>
+V GenerationCache<K, V>::getValueAt(uint32_t index) const {
+    return mCache.valueAt(index)->value;
+}
+
+template<typename K, typename V>
+V GenerationCache<K, V>::get(K key) {
+    ssize_t index = mCache.indexOfKey(key);
+    if (index >= 0) {
+        sp<Entry<K, V> > entry = mCache.valueAt(index);
+        if (entry.get()) {
+            detachFromCache(entry);
+            attachToCache(entry);
+            return entry->value;
+        }
+    }
+
+    return NULL;
+}
+
+template<typename K, typename V>
+bool GenerationCache<K, V>::put(K key, V value) {
+    if (mMaxCapacity != kUnlimitedCapacity && mCache.size() >= mMaxCapacity) {
+        removeOldest();
+    }
+
+    ssize_t index = mCache.indexOfKey(key);
+    if (index < 0) {
+        sp<Entry<K, V> > entry = new Entry<K, V>;
+        addToCache(entry, key, value);
+        return true;
+    }
+
+    return false;
+}
+
+template<typename K, typename V>
+void GenerationCache<K, V>::addToCache(sp<Entry<K, V> > entry, K key, V value) {
+    entry->key = key;
+    entry->value = value;
+    mCache.add(key, entry);
+    attachToCache(entry);
+}
+
+template<typename K, typename V>
+V GenerationCache<K, V>::remove(K key) {
+    ssize_t index = mCache.indexOfKey(key);
+    if (index >= 0) {
+        return removeAt(index);
+    }
+
+    return NULL;
+}
+
+template<typename K, typename V>
+V GenerationCache<K, V>::removeAt(ssize_t index) {
+    sp<Entry<K, V> > entry = mCache.valueAt(index);
+    if (mListener) {
+        (*mListener)(entry->key, entry->value);
+    }
+    mCache.removeItemsAt(index, 1);
+    detachFromCache(entry);
+
+    return entry->value;
+}
+
+template<typename K, typename V>
+V GenerationCache<K, V>::removeOldest() {
+    if (mOldest.get()) {
+        ssize_t index = mCache.indexOfKey(mOldest->key);
+        if (index >= 0) {
+            return removeAt(index);
+        }
+    }
+
+    return NULL;
+}
+
+template<typename K, typename V>
+void GenerationCache<K, V>::attachToCache(sp<Entry<K, V> > entry) {
+    if (!mYoungest.get()) {
+        mYoungest = mOldest = entry;
+    } else {
+        entry->parent = mYoungest;
+        mYoungest->child = entry;
+        mYoungest = entry;
+    }
+}
+
+template<typename K, typename V>
+void GenerationCache<K, V>::detachFromCache(sp<Entry<K, V> > entry) {
+    if (entry->parent.get()) {
+        entry->parent->child = entry->child;
+    }
+
+    if (entry->child.get()) {
+        entry->child->parent = entry->parent;
+    }
+
+    if (mOldest == entry) {
+        mOldest = entry->child;
+    }
+
+    if (mYoungest == entry) {
+        mYoungest = entry->parent;
+    }
+
+    entry->parent.clear();
+    entry->child.clear();
+}
+
+}; // namespace android
+
+#endif // ANDROID_UTILS_GENERATION_CACHE_H