compose/ui/ui-text/src/commonMain/kotlin/androidx/compose/ui/text/caches/LruCache.kt - platform/frameworks/support - Git at Google

 /*
  * Copyright 2020 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 androidx.compose.ui.text.caches

 import androidx.compose.ui.text.platform.createSynchronizedObject
 import androidx.compose.ui.text.platform.synchronized
 import kotlin.jvm.JvmName

 /**
  * Copy from collection2 until that library can be added as a dependency
  */
 internal open class LruCache<K, V> {

     private val monitor = createSynchronizedObject()
     private val map: HashMap<K, V>
     private val keySet: LinkedHashSet<K>

     /** Size of this cache in units. Not necessarily the number of elements. */
     @get:JvmName("size")
     public var size: Int = 0
         /**
          * For caches that do not override [sizeOf], this returns the number
          * of entries in the cache. For all other caches, this returns the sum of
          * the sizes of the entries in this cache.
          */
         get() = synchronizedValue { return field }
         private set

     private var maxSize = 0

     private var putCount = 0
     private var createCount = 0
     private var evictionCount = 0
     private var hitCount = 0
     private var missCount = 0

     /**
      * @param maxSize for caches that do not override [sizeOf], this is
      *     the maximum number of entries in the cache. For all other caches,
      *     this is the maximum sum of the sizes of the entries in this cache.
      */
         constructor(maxSize: Int) {
         require(maxSize > 0) { "maxSize <= 0" }
         this.maxSize = maxSize
         map = HashMap<K, V>(0, 0.75f)
         keySet = LinkedHashSet<K>()
     }

     /**
      * Sets the size of the cache.
      *
      * @param maxSize The new maximum size.
      */
     open fun resize(maxSize: Int) {
         require(maxSize > 0) { "maxSize <= 0" }

         synchronized(monitor) {
             this.maxSize = maxSize
         }
         trimToSize(maxSize)
     }

     /**
      * Returns the value for [key] if it exists in the cache or can be
      * created by [create]. If a value was returned, it is moved to the
      * head of the queue. This returns `null` if a value is not cached and cannot
      * be created.
      */
         fun get(key: K): V? {
         var mapValue: V? = null

         synchronized(monitor) {
             mapValue = map.get(key)
             if (mapValue != null) {
                 // Push the key to the end of the keySet as the cached entry gets hit.
                 keySet.remove(key)
                 keySet.add(key)
                 hitCount++
                 return mapValue
             } else {
                 missCount++
             }
         }

         val createdValue: V? = create(key)
         if (createdValue == null) {
             return null
         }

         synchronized(monitor) {
             createCount++
             val previousValue: V? = map.put(key, createdValue)
             // Push the key to the end of the keySet as the cached entry gets hit.
             keySet.remove(key)
             keySet.add(key)
             if (previousValue != null) {
                 // There was a conflict so undo that last put
                 map.put(key, previousValue)
                 mapValue = previousValue
             } else {
                 size += safeSizeOf(key, createdValue)
             }
         }

         if (mapValue != null) {
             entryRemoved(false, key, createdValue, mapValue)
             return mapValue
         } else {
             trimToSize(maxSize)
             return createdValue
         }
     }

     /**
      * Caches [value] for [key]. The value is moved to the head of
      * the queue.
      *
      * @return the previous value mapped by [key].
      * @throws NullPointerException if [key] or [value] is null
      */
         fun put(key: K, value: V): V? {
         // Must throw NPE for JVM interop contract.
         if (key == null || value == null) {
             throw NullPointerException()
         }

         var previous: V? = null
         synchronized(monitor) {
             putCount++
             size += safeSizeOf(key, value)
             previous = map.put(key, value)
             if (previous != null) {
                 size -= safeSizeOf(key, previous!!)
             }
             if (keySet.contains(key)) {
                 keySet.remove(key)
             }
             keySet.add(key)
         }

         if (previous != null) {
             entryRemoved(false, key, previous!!, value)
         }

         trimToSize(maxSize)
         return previous
     }

     /**
      * Remove the eldest entries until the total of remaining entries is at or
      * below the requested size.
      *
      * @param maxSize the maximum size of the cache before returning. May be -1
      *            to evict even 0-sized elements.
      * @throws IllegalStateException
      */
     open fun trimToSize(maxSize: Int) {
         while (true) {
             var key: K? = null
             var value: V? = null

             synchronized(monitor) {
                 if (size < 0 ||
                     (map.isEmpty() && size != 0) ||
                     (map.isEmpty() != keySet.isEmpty())
                 ) {
                     throw IllegalStateException("map/keySet size inconsistency")
                 }

                 if (size > maxSize && !map.isEmpty()) {
                     key = keySet.first()
                     value = map.get(key) ?: throw IllegalStateException(
                         "inconsistent " +
                             "state"
                     )
                     map.remove(key)
                     keySet.remove(key)
                     size -= safeSizeOf(key!!, value!!)
                     evictionCount++
                 }
             }

             if (key == null && value == null) {
                 break
             } else {
                 entryRemoved(true, key!!, value!!, null)
             }
         }
     }

     /**
      * Removes the entry for [key] if it exists.
      *
      * @return the previous value mapped by [key].
      * @throws NullPointerException if [key] is null from a JVM caller.
      */
     fun remove(key: K): V? {
         // Must throw NPE for JVM interop contract.
         if (key == null) {
             throw NullPointerException()
         }

         var previous: V? = null
         synchronized(monitor) {
             previous = map.remove(key)
             keySet.remove(key)
             if (previous != null) {
                 size -= safeSizeOf(key, previous!!)
             }
         }

         if (previous != null) {
             entryRemoved(false, key, previous!!, null)
         }

         return previous
     }

     /**
      * Called for entries that have been evicted or removed. This method is
      * invoked when a value is evicted to make space, removed by a call to
      * [remove], or replaced by a call to [put]. The default
      * implementation does nothing.
      *
      * The method is called without synchronization: other threads may
      * access the cache while this method is executing.
      *
      * @param evicted `true` if the entry is being removed to make space, `false`
      *     if the removal was caused by a [put] or [remove].
      * @param key key of the entry that was evicted or removed.
      * @param oldValue the original value of the entry that was evicted removed.
      * @param newValue the new value for [key], if it exists. If non-null,
      *     this removal was caused by a [put]. Otherwise it was caused by
      *     an eviction or a [remove].
      */
     protected open fun entryRemoved(evicted: Boolean, key: K, oldValue: V, newValue: V?) {
     }

     /**
      * Called after a cache miss to compute a value for the corresponding key.
      * Returns the computed value or null if no value can be computed. The
      * default implementation returns null.
      *
      * The method is called without synchronization: other threads may
      * access the cache while this method is executing.
      *
      * If a value for [key] exists in the cache when this method
      * returns, the created value will be released with [entryRemoved]
      * and discarded. This can occur when multiple threads request the same key
      * at the same time (causing multiple values to be created), or when one
      * thread calls [put] while another is creating a value for the same
      * key.
      */
         protected open fun create(key: K): V? = null

     private fun safeSizeOf(key: K, value: V): Int {
         val result = sizeOf(key, value)
         check(result >= 0) { "Negative size: $key=$value" }
         return result
     }

     /**
      * Returns the size of the entry for [key] and [value] in
      * user-defined units.  The default implementation returns 1 so that size
      * is the number of entries and max size is the maximum number of entries.
      *
      * An entry's size must not change while it is in the cache.
      */
     protected open fun sizeOf(key: K, value: V) = 1

     /**
      * Clear the cache, calling [entryRemoved] on each removed entry.
      */
     fun evictAll() {
         trimToSize(-1) // -1 will evict 0-sized elements
     }

     /**
      * For caches that do not override [sizeOf], this returns the maximum
      * number of entries in the cache. For all other caches, this returns the
      * maximum sum of the sizes of the entries in this cache.
      */
     fun maxSize(): Int = synchronizedValue { maxSize }

     /**
      * Returns the number of times [get] returned a value that was
      * already present in the cache.
      */
     fun hitCount(): Int = synchronizedValue { hitCount }

     /**
      * Returns the number of times [get] returned null or required a new
      * value to be created.
      */
     fun missCount(): Int = synchronizedValue { missCount }

     /**
      * Returns the number of times [create] returned a value.
      */
     fun createCount(): Int = synchronizedValue { createCount }

     /**
      * Returns the number of times [put] was called.
      */
     fun putCount(): Int = synchronizedValue { putCount }

     /**
      * Returns the number of values that have been evicted.
      */
     fun evictionCount(): Int = synchronizedValue { evictionCount }

     /**
      * Returns a copy of the current contents of the cache, ordered from least
      * recently accessed to most recently accessed.
      */
     fun snapshot(): Map<K, V> {
         synchronized(monitor) {
             val linkedHashMap = LinkedHashMap<K, V>()
             for (key in keySet) {
                 linkedHashMap.put(key, map.get(key)!!)
             }
             return linkedHashMap
         }
     }

     override fun toString(): String {
         synchronized(monitor) {
             val accesses = hitCount + missCount
             val hitPercent = if (accesses != 0) 100 * hitCount / accesses else 0
             return "LruCache[maxSize=$maxSize,hits=$hitCount,misses=$missCount," +
                 "hitRate=$hitPercent%]"
         }
     }

     internal inline fun <R> synchronizedValue(block: () -> R): R {
         return synchronized(monitor, block)
     }
 }
	/*
	* Copyright 2020 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 androidx.compose.ui.text.caches

	import androidx.compose.ui.text.platform.createSynchronizedObject
	import androidx.compose.ui.text.platform.synchronized
	import kotlin.jvm.JvmName

	/**
	* Copy from collection2 until that library can be added as a dependency
	*/
	internal open class LruCache<K, V> {

	private val monitor = createSynchronizedObject()
	private val map: HashMap<K, V>
	private val keySet: LinkedHashSet<K>

	/** Size of this cache in units. Not necessarily the number of elements. */
	@get:JvmName("size")
	public var size: Int = 0
	/**
	* For caches that do not override [sizeOf], this returns the number
	* of entries in the cache. For all other caches, this returns the sum of
	* the sizes of the entries in this cache.
	*/
	get() = synchronizedValue { return field }
	private set

	private var maxSize = 0

	private var putCount = 0
	private var createCount = 0
	private var evictionCount = 0
	private var hitCount = 0
	private var missCount = 0

	/**
	* @param maxSize for caches that do not override [sizeOf], this is
	* the maximum number of entries in the cache. For all other caches,
	* this is the maximum sum of the sizes of the entries in this cache.
	*/
	constructor(maxSize: Int) {
	require(maxSize > 0) { "maxSize <= 0" }
	this.maxSize = maxSize
	map = HashMap<K, V>(0, 0.75f)
	keySet = LinkedHashSet<K>()
	}

	/**
	* Sets the size of the cache.
	*
	* @param maxSize The new maximum size.
	*/
	open fun resize(maxSize: Int) {
	require(maxSize > 0) { "maxSize <= 0" }

	synchronized(monitor) {
	this.maxSize = maxSize
	}
	trimToSize(maxSize)
	}

	/**
	* Returns the value for [key] if it exists in the cache or can be
	* created by [create]. If a value was returned, it is moved to the
	* head of the queue. This returns `null` if a value is not cached and cannot
	* be created.
	*/
	fun get(key: K): V? {
	var mapValue: V? = null

	synchronized(monitor) {
	mapValue = map.get(key)
	if (mapValue != null) {
	// Push the key to the end of the keySet as the cached entry gets hit.
	keySet.remove(key)
	keySet.add(key)
	hitCount++
	return mapValue
	} else {
	missCount++
	}
	}

	val createdValue: V? = create(key)
	if (createdValue == null) {
	return null
	}

	synchronized(monitor) {
	createCount++
	val previousValue: V? = map.put(key, createdValue)
	// Push the key to the end of the keySet as the cached entry gets hit.
	keySet.remove(key)
	keySet.add(key)
	if (previousValue != null) {
	// There was a conflict so undo that last put
	map.put(key, previousValue)
	mapValue = previousValue
	} else {
	size += safeSizeOf(key, createdValue)
	}
	}

	if (mapValue != null) {
	entryRemoved(false, key, createdValue, mapValue)
	return mapValue
	} else {
	trimToSize(maxSize)
	return createdValue
	}
	}

	/**
	* Caches [value] for [key]. The value is moved to the head of
	* the queue.
	*
	* @return the previous value mapped by [key].
	* @throws NullPointerException if [key] or [value] is null
	*/
	fun put(key: K, value: V): V? {
	// Must throw NPE for JVM interop contract.
	if (key == null \|\| value == null) {
	throw NullPointerException()
	}

	var previous: V? = null
	synchronized(monitor) {
	putCount++
	size += safeSizeOf(key, value)
	previous = map.put(key, value)
	if (previous != null) {
	size -= safeSizeOf(key, previous!!)
	}
	if (keySet.contains(key)) {
	keySet.remove(key)
	}
	keySet.add(key)
	}

	if (previous != null) {
	entryRemoved(false, key, previous!!, value)
	}

	trimToSize(maxSize)
	return previous
	}

	/**
	* Remove the eldest entries until the total of remaining entries is at or
	* below the requested size.
	*
	* @param maxSize the maximum size of the cache before returning. May be -1
	* to evict even 0-sized elements.
	* @throws IllegalStateException
	*/
	open fun trimToSize(maxSize: Int) {
	while (true) {
	var key: K? = null
	var value: V? = null

	synchronized(monitor) {
	if (size < 0 \|\|
	(map.isEmpty() && size != 0) \|\|
	(map.isEmpty() != keySet.isEmpty())
	) {
	throw IllegalStateException("map/keySet size inconsistency")
	}

	if (size > maxSize && !map.isEmpty()) {
	key = keySet.first()
	value = map.get(key) ?: throw IllegalStateException(
	"inconsistent " +
	"state"
	)
	map.remove(key)
	keySet.remove(key)
	size -= safeSizeOf(key!!, value!!)
	evictionCount++
	}
	}

	if (key == null && value == null) {
	break
	} else {
	entryRemoved(true, key!!, value!!, null)
	}
	}
	}

	/**
	* Removes the entry for [key] if it exists.
	*
	* @return the previous value mapped by [key].
	* @throws NullPointerException if [key] is null from a JVM caller.
	*/
	fun remove(key: K): V? {
	// Must throw NPE for JVM interop contract.
	if (key == null) {
	throw NullPointerException()
	}

	var previous: V? = null
	synchronized(monitor) {
	previous = map.remove(key)
	keySet.remove(key)
	if (previous != null) {
	size -= safeSizeOf(key, previous!!)
	}
	}

	if (previous != null) {
	entryRemoved(false, key, previous!!, null)
	}

	return previous
	}

	/**
	* Called for entries that have been evicted or removed. This method is
	* invoked when a value is evicted to make space, removed by a call to
	* [remove], or replaced by a call to [put]. The default
	* implementation does nothing.
	*
	* The method is called without synchronization: other threads may
	* access the cache while this method is executing.
	*
	* @param evicted `true` if the entry is being removed to make space, `false`
	* if the removal was caused by a [put] or [remove].
	* @param key key of the entry that was evicted or removed.
	* @param oldValue the original value of the entry that was evicted removed.
	* @param newValue the new value for [key], if it exists. If non-null,
	* this removal was caused by a [put]. Otherwise it was caused by
	* an eviction or a [remove].
	*/
	protected open fun entryRemoved(evicted: Boolean, key: K, oldValue: V, newValue: V?) {
	}

	/**
	* Called after a cache miss to compute a value for the corresponding key.
	* Returns the computed value or null if no value can be computed. The
	* default implementation returns null.
	*
	* The method is called without synchronization: other threads may
	* access the cache while this method is executing.
	*
	* If a value for [key] exists in the cache when this method
	* returns, the created value will be released with [entryRemoved]
	* and discarded. This can occur when multiple threads request the same key
	* at the same time (causing multiple values to be created), or when one
	* thread calls [put] while another is creating a value for the same
	* key.
	*/
	protected open fun create(key: K): V? = null

	private fun safeSizeOf(key: K, value: V): Int {
	val result = sizeOf(key, value)
	check(result >= 0) { "Negative size: $key=$value" }
	return result
	}

	/**
	* Returns the size of the entry for [key] and [value] in
	* user-defined units. The default implementation returns 1 so that size
	* is the number of entries and max size is the maximum number of entries.
	*
	* An entry's size must not change while it is in the cache.
	*/
	protected open fun sizeOf(key: K, value: V) = 1

	/**
	* Clear the cache, calling [entryRemoved] on each removed entry.
	*/
	fun evictAll() {
	trimToSize(-1) // -1 will evict 0-sized elements
	}

	/**
	* For caches that do not override [sizeOf], this returns the maximum
	* number of entries in the cache. For all other caches, this returns the
	* maximum sum of the sizes of the entries in this cache.
	*/
	fun maxSize(): Int = synchronizedValue { maxSize }

	/**
	* Returns the number of times [get] returned a value that was
	* already present in the cache.
	*/
	fun hitCount(): Int = synchronizedValue { hitCount }

	/**
	* Returns the number of times [get] returned null or required a new
	* value to be created.
	*/
	fun missCount(): Int = synchronizedValue { missCount }

	/**
	* Returns the number of times [create] returned a value.
	*/
	fun createCount(): Int = synchronizedValue { createCount }

	/**
	* Returns the number of times [put] was called.
	*/
	fun putCount(): Int = synchronizedValue { putCount }

	/**
	* Returns the number of values that have been evicted.
	*/
	fun evictionCount(): Int = synchronizedValue { evictionCount }

	/**
	* Returns a copy of the current contents of the cache, ordered from least
	* recently accessed to most recently accessed.
	*/
	fun snapshot(): Map<K, V> {
	synchronized(monitor) {
	val linkedHashMap = LinkedHashMap<K, V>()
	for (key in keySet) {
	linkedHashMap.put(key, map.get(key)!!)
	}
	return linkedHashMap
	}
	}

	override fun toString(): String {
	synchronized(monitor) {
	val accesses = hitCount + missCount
	val hitPercent = if (accesses != 0) 100 * hitCount / accesses else 0
	return "LruCache[maxSize=$maxSize,hits=$hitCount,misses=$missCount," +
	"hitRate=$hitPercent%]"
	}
	}

	internal inline fun <R> synchronizedValue(block: () -> R): R {
	return synchronized(monitor, block)
	}
	}