Add BlockHound to integration tests

Eagerly initialize Schedulers to avoid blocking calls in TzdbZoneRulesProvider.

[closes #276]

Author: mp911de

pom.xml

@@ -33,6 +33,7 @@
 
     <properties>
         <assertj.version>3.15.0</assertj.version>
+        <blockhound.version>1.0.3.RELEASE</blockhound.version>
         <hikari-cp.version>3.4.2</hikari-cp.version>
         <java.version>1.8</java.version>
         <jsr305.version>3.0.2</jsr305.version>
@@ -161,6 +162,18 @@
             <artifactId>reactor-test</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>io.projectreactor.tools</groupId>
+            <artifactId>blockhound</artifactId>
+            <version>${blockhound.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.projectreactor.tools</groupId>
+            <artifactId>blockhound-junit-platform</artifactId>
+            <version>${blockhound.version}</version>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>io.r2dbc</groupId>
             <artifactId>r2dbc-spi-test</artifactId>

src/main/java/io/r2dbc/postgresql/client/ReactorNettyClient.java

@@ -57,6 +57,7 @@
 import reactor.core.publisher.FluxSink;
 import reactor.core.publisher.Mono;
 import reactor.core.publisher.Operators;
+import reactor.core.scheduler.Schedulers;
 import reactor.netty.Connection;
 import reactor.netty.resources.ConnectionProvider;
 import reactor.netty.resources.LoopResources;
@@ -124,6 +125,12 @@ public final class ReactorNettyClient implements Client {
 
     private volatile Version version = new Version("", 0);
 
+    static {
+
+        // eagerly initialize the scheduler to avoid blocking calls due to TimeZoneDB retrieval
+        Schedulers.boundedElastic();
+    }
+
     /**
      * Creates a new frame processor connected to a given TCP connection.
      *
@@ -369,10 +376,19 @@ public static Mono<ReactorNettyClient> connect(ConnectionProvider connectionProv
 
     private static Mono<? extends Void> registerSslHandler(SSLConfig sslConfig, Connection it) {
 
-        if (sslConfig.getSslMode().startSsl()) {
-            SSLSessionHandlerAdapter sslSessionHandlerAdapter = new SSLSessionHandlerAdapter(it.outbound().alloc(), sslConfig);
-            it.addHandlerFirst(sslSessionHandlerAdapter);
-            return sslSessionHandlerAdapter.getHandshake();
+        try {
+            if (sslConfig.getSslMode().startSsl()) {
+
+                return Mono.defer(() -> {
+                    SSLSessionHandlerAdapter sslSessionHandlerAdapter = new SSLSessionHandlerAdapter(it.outbound().alloc(), sslConfig);
+                    it.addHandlerFirst(sslSessionHandlerAdapter);
+                    return sslSessionHandlerAdapter.getHandshake();
+
+                }).subscribeOn(Schedulers.boundedElastic());
+            }
+        } catch (Throwable e) {
+            e.printStackTrace();
+            throw new RuntimeException(e);
         }
 
         return Mono.empty();

src/test/java/io/r2dbc/postgresql/util/BlockhoundExceptions.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.r2dbc.postgresql.util;
+
+import reactor.blockhound.BlockHound;
+import reactor.blockhound.integration.BlockHoundIntegration;
+
+import java.security.SecureRandom;
+
+public class BlockhoundExceptions implements BlockHoundIntegration {
+
+    @Override
+    public void applyTo(BlockHound.Builder builder) {
+        builder.allowBlockingCallsInside(SecureRandom.class.getName(), "next");
+    }
+}

src/test/resources/META-INF/services/reactor.blockhound.integration.BlockHoundIntegration

@@ -0,0 +1 @@
+io.r2dbc.postgresql.util.BlockhoundExceptions