Package ghidra.util.timer

Class GTimerCache<K,V>

java.lang.Object
ghidra.util.timer.GTimerCache<K,V>
Type Parameters:
K - the key
V - the value
public class GTimerCache<K,V> extends Object
Class for caching key,value entries for a limited time and cache size. Entries in this cache will be removed after the cache duration time has passed. If the cache ever exceeds its capacity, the least recently used entry will be removed.

This class uses a LinkedHashMap with it ordering mode set to "access order". This means that iterating through keys, values, or entries of the map will be presented oldest first. Inserting or accessing an entry in the map will move the entry to the back of the list, thus making it the youngest. This means that entries closest to or past expiration will be presented first.

This class is designed to be subclassed for two specific cases. The first case is for when additional processing is required when an entry is removed from the cache. This typically would be for cases where resources need to be released, such as closing a File or disposing the object. The second reason to subclass this cache is to get more control of expiring values. Overriding shouldRemoveFromCache(Object, Object), which gets called when an entry's time has expired, gives the client a chance to decide if the entry should be removed.

  • Constructor Summary

    Constructors
    Constructor
    Description
    GTimerCache(Duration lifetime, int capacity)
    Constructs new GTimerCache with a duration for cached entries and a maximum number of entries to cache.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    clear()
    Clears all the values in the cache.
    boolean
    containsKey(K key)
    Returns true if the cache contains a value for the given key.
    V
    get(K key)
    Returns the value for the given key.
    V
    put(K key, V value)
    Adds an key,value entry to the cache
    V
    remove(K key)
    Removes the cache entry with the given key.
    void
    setCapacity(int capacity)
    Sets the capacity for this cache.
    void
    setDuration(Duration duration)
    Sets the duration for keeping cached values.
    protected boolean
    shouldRemoveFromCache(K key, V value)
    Called when an item's cache time has expired to determine if the item should be removed from the cache.
    int
    size()
    Returns the number of entries in the cache.
    protected void
    valueAdded(K key, V value)
    Called when an value is being added to the cache.
    protected void
    valueRemoved(K key, V value)
    Called when an item is being removed from the cache.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • GTimerCache

      public GTimerCache(Duration lifetime, int capacity)
      Constructs new GTimerCache with a duration for cached entries and a maximum number of entries to cache.
      Parameters:
      lifetime - the duration that a key,value will remain in the cache without being accessed (accessing a cached entry resets its time)
      capacity - the maximum number of entries in the cache before least recently used entries are removed

  • Method Details

    • setCapacity

      public void setCapacity(int capacity)
      Sets the capacity for this cache. If this cache currently has more values than the new capacity, oldest values will be removed.
      Parameters:
      capacity - the new capacity for this cache

    • setDuration

      public void setDuration(Duration duration)
      Sets the duration for keeping cached values.
      Parameters:
      duration - the length of time to keep a cached value

    • put

      public V put(K key, V value)
      Adds an key,value entry to the cache
      Parameters:
      key - the key with which the value is associated
      value - the value being cached
      Returns:
      The previous value associated with the key or null if no previous value

    • remove

      public V remove(K key)
      Removes the cache entry with the given key.
      Parameters:
      key - the key of the entry to remove
      Returns:
      the value removed or null if the key wasn't in the cache

    • containsKey

      public boolean containsKey(K key)
      Returns true if the cache contains a value for the given key.
      Parameters:
      key - the key to check if it is in the cache
      Returns:
      true if the cache contains a value for the given key

    • size

      public int size()
      Returns the number of entries in the cache.
      Returns:
      the number of entries in the cache

    • get

      public V get(K key)
      Returns the value for the given key. Also, resets time the associated with this entry.
      Parameters:
      key - the key to retrieve a value
      Returns:
      the value for the given key

    • clear

      public void clear()
      Clears all the values in the cache. The expired callback will be called for each entry that was in the cache.

    • valueRemoved

      protected void valueRemoved(K key, V value)
      Called when an item is being removed from the cache. This method is for use by subclasses that need to do more processing on items as they are removed, such as releasing resources.

      Note: this method will always be called from within a synchronized block. Subclasses should be careful if they make any external calls from within this method.

      Parameters:
      key - The key of the value being removed
      value - the value that is being removed

    • valueAdded

      protected void valueAdded(K key, V value)
      Called when an value is being added to the cache. This method is for use by subclasses that need to do more processing on items when they are added to the cache.

      Note: this method will always be called from within a synchronized block. Subclasses should be careful if they make any external calls from within this method.

      Parameters:
      key - The key of the value being added
      value - the new value

    • shouldRemoveFromCache

      protected boolean shouldRemoveFromCache(K key, V value)
      Called when an item's cache time has expired to determine if the item should be removed from the cache. The default to to remove an item when its time has expired. Subclasses can override this method to have more control over expiring value removal.

      Note: this method will always be called from within a synchronized block. Subclasses should be careful if they make any external calls from within this method.

      Parameters:
      key - the key of the item whose time has expired
      value - the value of the item whose time has expired
      Returns:
      true if the item should be removed, false otherwise