ENT-2414 Named caches (#3848)

* Add named caches and apply to NonInvalidingUnboundCache and all usages.

* Add named caches and apply to NonInvalidingCache and all usages.

* Add named caches and apply to NonInvalidingWeightBasedCache and all usages.

* Move NamedCache to core/internal

* Remove type `NamedCache` and `NamedLoadingCache`

* Suppressed 'name not used' warning, added comment, and fixed generic parameters on the buildNamed functions.

* Use `buildNamed` in all caffeine instances in production code. Not using it for caches that are created in test code.

* Add checks for the cache name

* Formatting

* Minor code review revisions

core/src/main/kotlin/net/corda/core/internal/NamedCache.kt

@@ -0,0 +1,41 @@
+package net.corda.core.internal
+
+import com.github.benmanes.caffeine.cache.Cache
+import com.github.benmanes.caffeine.cache.CacheLoader
+import com.github.benmanes.caffeine.cache.Caffeine
+import com.github.benmanes.caffeine.cache.LoadingCache
+
+/**
+ * Restrict the allowed characters of a cache name - this ensures that each cache has a name, and that
+ * the name can be used to create a file name or a metric name.
+ */
+internal fun checkCacheName(name: String) {
+    require(!name.isBlank())
+    require(allowedChars.matches(name))
+}
+
+private val allowedChars = Regex("^[0-9A-Za-z_.]*\$")
+
+/* buildNamed is the central helper method to build caffeine caches in Corda.
+ * This allows to easily add tweaks to all caches built in Corda, and also forces
+ * cache users to give their cache a (meaningful) name that can be used e.g. for
+ * capturing cache traces etc.
+ *
+ * Currently it is not used in this version of CORDA, but there are plans to do so.
+ */
+
+fun <K, V> Caffeine<in K, in V>.buildNamed(name: String): Cache<K, V> {
+    checkCacheName(name)
+    return this.build<K, V>()
+}
+
+fun <K, V> Caffeine<in K, in V>.buildNamed(name: String, loadFunc: (K) -> V): LoadingCache<K, V> {
+    checkCacheName(name)
+    return this.build<K, V>(loadFunc)
+}
+
+
+fun <K, V> Caffeine<in K, in V>.buildNamed(name: String, loader: CacheLoader<K, V>): LoadingCache<K, V> {
+    checkCacheName(name)
+    return this.build<K, V>(loader)
+}

core/src/test/kotlin/net/corda/core/internal/NamedCacheTest.kt

@@ -0,0 +1,24 @@
+package net.corda.core.internal
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class NamedCacheTest {
+    fun checkNameHelper(name: String, throws: Boolean) {
+        var exceptionThrown = false
+        try {
+            checkCacheName(name)
+        } catch (e: Exception) {
+            exceptionThrown = true
+        }
+        assertEquals(throws, exceptionThrown)
+    }
+
+    @Test
+    fun TestCheckCacheName() {
+        checkNameHelper("abc_123.234", false)
+        checkNameHelper("", true)
+        checkNameHelper("abc 123", true)
+        checkNameHelper("abc/323", true)
+    }
+}