Update to 2024.4.8

swervelib/parser/Cache.java

@@ -0,0 +1,105 @@
+package swervelib.parser;
+
+import edu.wpi.first.wpilibj.RobotController;
+import java.util.function.Supplier;
+
+/**
+ * Cache for frequently requested data.
+ */
+public class Cache<T>
+{
+
+  /**
+   * Cached value.
+   */
+  private T           value;
+  /**
+   * Supplier for cached value.
+   */
+  private Supplier<T> supplier;
+  /**
+   * Timestamp in microseconds.
+   */
+  private long        timestamp;
+  /**
+   * Validity period in microseconds.
+   */
+  private long        validityPeriod;
+
+  /**
+   * Cache for arbitrary values.
+   *
+   * @param val            Value to cache.
+   * @param validityPeriod Validity period in milliseconds.
+   */
+  public Cache(Supplier<T> val, long validityPeriod)
+  {
+    supplier = val;
+    value = supplier.get();
+    timestamp = RobotController.getFPGATime();
+    this.validityPeriod = validityPeriod * 1000L;
+  }
+
+  /**
+   * Return whether the cache is stale.
+   *
+   * @return The stale state of the cache.
+   */
+  public boolean isStale()
+  {
+    return (RobotController.getFPGATime() - timestamp) > validityPeriod;
+  }
+
+  /**
+   * Update the cache value and timestamp.
+   *
+   * @return {@link Cache} used.
+   */
+  public Cache<T> update()
+  {
+    this.value = supplier.get();
+    this.timestamp = RobotController.getFPGATime();
+    return this;
+  }
+
+  /**
+   * Update the supplier to a new source. Updates the value and timestamp as well.
+   *
+   * @param supplier new supplier source.
+   * @return {@link Cache} for chaining.
+   */
+  public Cache<T> updateSupplier(Supplier<T> supplier)
+  {
+    this.supplier = supplier;
+    update();
+    return this;
+  }
+
+  /**
+   * Update the validity period for the cached value, also updates the value.
+   *
+   * @param validityPeriod The new validity period in milliseconds.
+   * @return {@link Cache} for chaining.
+   */
+  public Cache<T> updateValidityPeriod(long validityPeriod)
+  {
+    this.validityPeriod = validityPeriod * 1000L;
+    update();
+    return this;
+  }
+
+  /**
+   * Get the most up to date cached value.
+   *
+   * @return {@link T} updated to the latest cached version.
+   */
+  public T getValue()
+  {
+    if (isStale())
+    {
+      update();
+    }
+    return value;
+  }
+
+}