Optimize attaching the debug probes

I see a notable speed improvement even without any benchmarks,
simply by running `DebugProbes.withDebugProbes { }` in a loop.

Author: dkhalanskyjb

kotlinx-coroutines-debug/src/Attach.kt

@@ -16,23 +16,30 @@ internal class ByteBuddyDynamicAttach : Function1<Boolean, Unit> {
 
     private fun attach() {
         ByteBuddyAgent.install(ByteBuddyAgent.AttachmentProvider.ForEmulatedAttachment.INSTANCE)
-        val cl = Class.forName("kotlin.coroutines.jvm.internal.DebugProbesKt")
-        val cl2 = Class.forName("kotlinx.coroutines.debug.internal.DebugProbesKt")
-
-        ByteBuddy()
-            .redefine(cl2)
-            .name(cl.name)
-            .make()
-            .load(cl.classLoader, ClassReloadingStrategy.fromInstalledAgent())
+        dynamicTypeWithProbes
+            .load(Class.forName(classNameToOverride).classLoader, ClassReloadingStrategy.fromInstalledAgent())
     }
 
     private fun detach() {
-        val cl = Class.forName("kotlin.coroutines.jvm.internal.DebugProbesKt")
-        val cl2 = Class.forName("kotlinx.coroutines.debug.NoOpProbesKt")
-        ByteBuddy()
-            .redefine(cl2)
-            .name(cl.name)
-            .make()
-            .load(cl.classLoader, ClassReloadingStrategy.fromInstalledAgent())
+        dynamicTypeWithoutProbes
+            .load(Class.forName(classNameToOverride).classLoader, ClassReloadingStrategy.fromInstalledAgent())
     }
 }
+
+private const val classNameToOverride = "kotlin.coroutines.jvm.internal.DebugProbesKt"
+
+private val dynamicTypeWithProbes by lazy {
+    val classWithProbes = Class.forName("kotlinx.coroutines.debug.internal.DebugProbesKt")
+    ByteBuddy()
+        .redefine(classWithProbes)
+        .name(classNameToOverride)
+        .make()
+}
+
+private val dynamicTypeWithoutProbes by lazy {
+    val classWithoutProbes = Class.forName("kotlinx.coroutines.debug.NoOpProbesKt")
+    ByteBuddy()
+        .redefine(classWithoutProbes)
+        .name(classNameToOverride)
+        .make()
+}