Implement BlockHound integration properly

Now it relies on the ServiceLoader mechanism to load the
integration: if the user installs BlockHound and
`kotlinx-coroutines-debug` is in the classpath, then BlockHound
will know to detect blocking calls in scenarios that forbid it.

Author: dkhalanskyjb

kotlinx-coroutines-debug/api/kotlinx-coroutines-debug.api

@@ -8,6 +8,11 @@ public final class kotlinx/coroutines/debug/CoroutineInfo {
 	public fun toString ()Ljava/lang/String;
 }
 
+public final class kotlinx/coroutines/debug/CoroutinesBlockHoundIntegration : reactor/blockhound/integration/BlockHoundIntegration {
+	public fun <init> ()V
+	public fun applyTo (Lreactor/blockhound/BlockHound$Builder;)V
+}
+
 public final class kotlinx/coroutines/debug/DebugProbes {
 	public static final field INSTANCE Lkotlinx/coroutines/debug/DebugProbes;
 	public final fun dumpCoroutines (Ljava/io/PrintStream;)V

kotlinx-coroutines-debug/resources/META-INF/services/reactor.blockhound.integration.BlockHoundIntegration

@@ -0,0 +1 @@
+kotlinx.coroutines.debug.CoroutinesBlockHoundIntegration

kotlinx-coroutines-debug/src/CoroutinesBlockHoundIntegration.kt

@@ -0,0 +1,16 @@
+@file:Suppress("INVISIBLE_REFERENCE", "INVISIBLE_MEMBER")
+package kotlinx.coroutines.debug
+
+import reactor.blockhound.BlockHound
+import kotlinx.coroutines.scheduling.*
+import reactor.blockhound.integration.*
+
+@Suppress("UNUSED")
+public class CoroutinesBlockHoundIntegration: BlockHoundIntegration {
+
+    override fun applyTo(builder: BlockHound.Builder) {
+        builder.addDynamicThreadPredicate { isSchedulerWorker(it) }
+        builder.nonBlockingThreadPredicate { p -> p.or { mayNotBlock(it) } }
+    }
+
+}

kotlinx-coroutines-debug/src/internal/BlockHoundIntegration.kt

@@ -66,8 +66,6 @@ internal object DebugProbesImpl {
             .name(cl.name)
             .make()
             .load(cl.classLoader, ClassReloadingStrategy.fromInstalledAgent())
-
-        BlockHoundIntegration.install()
     }
 
     public fun uninstall(): Unit = coroutineStateLock.write {
@@ -84,8 +82,6 @@ internal object DebugProbesImpl {
             .name(cl.name)
             .make()
             .load(cl.classLoader, ClassReloadingStrategy.fromInstalledAgent())
-
-        BlockHoundIntegration.uninstall()
     }
 
     public fun hierarchyToString(job: Job): String = coroutineStateLock.write {

kotlinx-coroutines-debug/src/internal/DebugProbesImpl.kt

@@ -1,19 +1,13 @@
 package kotlinx.coroutines.debug
 import kotlinx.coroutines.*
-import kotlinx.coroutines.debug.internal.BlockHoundIntegration
 import org.junit.*
-import reactor.blockhound.BlockingOperationError
+import reactor.blockhound.*
 
 class BlockHoundTest : TestBase() {
 
     @Before
     fun init() {
-        BlockHoundIntegration.install()
-    }
-
-    @After
-    fun deinit() {
-        BlockHoundIntegration.uninstall()
+        BlockHound.install()
     }
 
     @Test(expected = BlockingOperationError::class)