1 files changed, 28 insertions, 0 deletions
diff --git a/src/main/kotlin/moe/nea/ledger/ExpiringValue.kt b/src/main/kotlin/moe/nea/ledger/ExpiringValue.kt
new file mode 100644
index 0000000..dac4751
--- /dev/null
+++ b/src/main/kotlin/moe/nea/ledger/ExpiringValue.kt
@@ -0,0 +1,28 @@
+package moe.nea.ledger
+
+import kotlin.time.Duration
+import kotlin.time.Duration.Companion.nanoseconds
+
+class ExpiringValue<T>(private val value: T) {
+	val lastSeenAt: Long = System.nanoTime()
+	val age get() = (System.nanoTime() - lastSeenAt).nanoseconds
+	var taken = false
+	fun get(expiry: Duration): T? {
+		return if (!taken && expiry > age) value
+		else null
+	}
+
+	companion object {
+		fun <T> empty(): ExpiringValue<T> {
+			val value = ExpiringValue(Unit)
+			value.take()
+			@Suppress("UNCHECKED_CAST")
+			return value as ExpiringValue<T>
+		}
+	}
+
+	fun consume(expiry: Duration): T? = get(expiry).also { take() }
+	fun take() {
+		taken = true
+	}
+}
+\ No newline at end of file