Add support for refresh/refresh all (#39)

* Add support for refresh/refresh all

* docs

* tests

Author: sksamuel

aedile-core/src/main/kotlin/com/sksamuel/aedile/core/LoadingCache.kt

@@ -175,6 +175,26 @@ class LoadingCache<K, V>(
       cache.synchronous().invalidateAll()
    }
 
+   /**
+    * Loads a new value for the key, asynchronously. While the new value is loading the
+    * previous value (if any) will continue to be returned by get(key) unless it is evicted.
+    *
+    * See full docs at [com.github.benmanes.caffeine.cache.LoadingCache.refresh].
+    */
+   fun refresh(key: K) {
+      cache.synchronous().refresh(key)
+   }
+
+   /**
+    * Loads a new value for each key, asynchronously. While the new value is loading the
+    * previous value (if any) will continue to be returned by get(key) unless it is evicted.
+    *
+    * See full docs at [com.github.benmanes.caffeine.cache.LoadingCache.refreshAll].
+    */
+   fun refreshAll(keys: Collection<K>) {
+      cache.synchronous().refreshAll(keys)
+   }
+
    private suspend fun scope(): CoroutineScope {
       return if (useCallingContext) CoroutineScope(coroutineContext) else defaultScope
    }

aedile-core/src/test/kotlin/com/sksamuel/aedile/core/AsLoadingCacheTest.kt

@@ -2,6 +2,7 @@ package com.sksamuel.aedile.core
 
 import com.github.benmanes.caffeine.cache.Caffeine
 import com.github.benmanes.caffeine.cache.Expiry
+import io.kotest.assertions.nondeterministic.eventually
 import io.kotest.assertions.throwables.shouldNotThrowAny
 import io.kotest.assertions.throwables.shouldThrow
 import io.kotest.core.spec.style.FunSpec
@@ -13,6 +14,7 @@ import kotlinx.coroutines.yield
 import org.checkerframework.checker.index.qual.NonNegative
 import java.util.concurrent.atomic.AtomicInteger
 import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.seconds
 
 class AsLoadingCacheTest : FunSpec() {
    init {
@@ -319,6 +321,34 @@ class AsLoadingCacheTest : FunSpec() {
          cache.contains("bubble") shouldBe false
       }
 
+      test("support refresh") {
+         var counter = 0
+         val cache = Caffeine.newBuilder().asLoadingCache<String, Int> {
+            counter++
+            counter
+         }
+         cache.get("foo") shouldBe 1
+         cache.refresh("foo")
+         eventually(5.seconds) {
+            cache.get("foo") shouldBe 2
+         }
+      }
+
+      test("support refresh all") {
+         var counter = 0
+         val cache = Caffeine.newBuilder().asLoadingCache<String, Int> {
+            counter++
+            counter
+         }
+         cache.get("foo") shouldBe 1
+         cache.get("bar") shouldBe 2
+         cache.refreshAll(setOf("foo", "bar"))
+         eventually(5.seconds) {
+            cache.get("foo") shouldBe 3
+            cache.get("bar") shouldBe 4
+         }
+      }
+
       test("check invariants on expire after") {
          val loggerExpiry = object : Expiry<Int, String> {
             override fun expireAfterRead(