implement ConnectionProvider

build.gradle.kts

@@ -17,19 +17,16 @@
 import net.ltgt.gradle.errorprone.errorprone
 
 plugins {
-    // Apply the java-library plugin for API and implementation separation.
     `java-library`
     alias(libs.plugins.spotless)
     alias(libs.plugins.errorprone)
 }
 
 repositories {
-    // Use Maven Central for resolving dependencies.
     mavenCentral()
 }
 
 dependencies {
-    // Use JUnit Jupiter for testing.
     testImplementation(libs.junit.jupiter)
 
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")
@@ -38,17 +35,18 @@ dependencies {
     api(libs.jspecify)
 
     errorprone(libs.google.errorprone.core)
+
+    implementation(libs.hibernate.core)
+    implementation(libs.mongo.java.driver.sync)
 }
 
-// Apply a specific Java toolchain to ease working on different environments.
 java {
     toolchain {
         languageVersion = JavaLanguageVersion.of(17)
     }
 }
 
 tasks.named<Test>("test") {
-    // Use JUnit Platform for unit tests.
     useJUnitPlatform()
 }
 

gradle/libs.versions.toml

@@ -9,12 +9,16 @@ errorprone = "4.0.1"
 google-errorprone-core = "2.9.0"
 nullaway = "0.10.26"
 jspecify = "0.3.0"
+hibernate-core = "6.6.1.Final"
+mongo-java-driver-sync = "5.2.0"
 
 [libraries]
 junit-jupiter = { module = "org.junit.jupiter:junit-jupiter", version.ref = "junit-jupiter" }
 nullaway = { module = "com.uber.nullaway:nullaway", version.ref = "nullaway" }
 jspecify = { module = "org.jspecify:jspecify", version.ref = "jspecify" }
 google-errorprone-core = { module = "com.google.errorprone:error_prone_core", version.ref = "google-errorprone-core" }
+hibernate-core = { module = "org.hibernate.orm:hibernate-core", version.ref = "hibernate-core" }
+mongo-java-driver-sync = { module = "org.mongodb:mongodb-driver-sync", version.ref = "mongo-java-driver-sync" }
 
 [plugins]
 spotless = { id = "com.diffplug.spotless", version.ref = "spotless" }

src/main/java/com/mongodb/hibernate/cfg/ConfigurationHelper.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2024-present MongoDB, Inc.
+ *
+ * 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
+ *
+ *   http://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 com.mongodb.hibernate.cfg;
+
+import static org.hibernate.internal.util.NullnessUtil.castNonNull;
+
+import com.mongodb.hibernate.exception.ConfigurationException;
+import java.util.Map;
+import org.jspecify.annotations.Nullable;
+
+/** Collection of helper methods for dealing with configuration settings. */
+public final class ConfigurationHelper {
+
+    private ConfigurationHelper() {}
+
+    public static String getRequiredConfiguration(Map<String, Object> configurationValues, String property) {
+        return castNonNull(doGetConfiguration(configurationValues, property, true));
+    }
+
+    public static @Nullable String getOptionalConfiguration(Map<String, Object> configurationValues, String property) {
+        return doGetConfiguration(configurationValues, property, false);
+    }
+
+    private static @Nullable String doGetConfiguration(
+            Map<String, Object> configurationValues, String property, boolean required) {
+        var configuration = configurationValues.get(property);
+        if (configuration == null && required) {
+            throw new ConfigurationException(property, "value required");
+        }
+        if (configuration != null && !(configuration instanceof String)) {
+            throw new ConfigurationException(property, "value is not of string type");
+        }
+        return (String) configuration;
+    }
+}

src/main/java/com/mongodb/hibernate/dialect/MongoDialect.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2024-present MongoDB, Inc.
+ *
+ * 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
+ *
+ *   http://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 com.mongodb.hibernate.dialect;
+
+import org.hibernate.dialect.DatabaseVersion;
+import org.hibernate.dialect.Dialect;
+import org.hibernate.engine.jdbc.dialect.spi.DialectResolutionInfo;
+
+public class MongoDialect extends Dialect {
+    public static final int MINIMUM_MONGODB_MAJOR_VERSION_SUPPORTED = 5;
+
+    private static final DatabaseVersion MINIMUM_VERSION =
+            DatabaseVersion.make(MINIMUM_MONGODB_MAJOR_VERSION_SUPPORTED);
+
+    public MongoDialect() {
+        this(MINIMUM_VERSION);
+    }
+
+    public MongoDialect(final DatabaseVersion version) {
+        super(version);
+    }
+
+    public MongoDialect(final DialectResolutionInfo dialectResolutionInfo) {
+        super(dialectResolutionInfo);
+    }
+}

src/main/java/com/mongodb/hibernate/exception/ConfigurationException.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2024-present MongoDB, Inc.
+ *
+ * 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
+ *
+ *   http://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 com.mongodb.hibernate.exception;
+
+public class ConfigurationException extends RuntimeException {
+
+    private final String property;
+
+    public ConfigurationException(String property, String message) {
+        super(message);
+        this.property = property;
+    }
+
+    public ConfigurationException(String property, String message, Throwable cause) {
+        super(message, cause);
+        this.property = property;
+    }
+
+    @Override
+    public String getMessage() {
+        return String.format("Invalid '%s' configuration: %s", property, super.getMessage());
+    }
+}

src/main/java/com/mongodb/hibernate/exception/NotYetImplementedException.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2024-present MongoDB, Inc.
+ *
+ * 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
+ *
+ *   http://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 com.mongodb.hibernate.exception;
+
+public class NotYetImplementedException extends RuntimeException {
+
+    public NotYetImplementedException() {}
+
+    public NotYetImplementedException(String message) {
+        super(message);
+    }
+}

src/main/java/com/mongodb/hibernate/jdbc/MongoConnectionProvider.java

@@ -0,0 +1,149 @@
+/*
+ * Copyright 2024-present MongoDB, Inc.
+ *
+ * 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
+ *
+ *   http://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 com.mongodb.hibernate.jdbc;
+
+import static org.bson.codecs.configuration.CodecRegistries.fromRegistries;
+import static org.hibernate.cfg.JdbcSettings.*;
+import static org.hibernate.internal.util.NullnessUtil.castNonNull;
+
+import com.mongodb.ConnectionString;
+import com.mongodb.MongoClientSettings;
+import com.mongodb.MongoCredential;
+import com.mongodb.client.MongoClient;
+import com.mongodb.client.MongoClients;
+import com.mongodb.hibernate.cfg.ConfigurationHelper;
+import com.mongodb.hibernate.exception.ConfigurationException;
+import com.mongodb.hibernate.exception.NotYetImplementedException;
+import java.sql.Connection;
+import java.util.Map;
+import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
+import org.hibernate.service.UnknownUnwrapTypeException;
+import org.hibernate.service.spi.Configurable;
+import org.hibernate.service.spi.Startable;
+import org.hibernate.service.spi.Stoppable;
+import org.jspecify.annotations.Nullable;
+
+/**
+ * MongoDB dialect's customized JDBC {@link ConnectionProvider} spi implementation, whose class name is supposed to be
+ * provided as the following Hibernate property to kick off MongoDB dialect's JDBC flow:
+ *
+ * <ul>
+ *   <li>hibernate.connection.provider_class
+ * </ul>
+ *
+ * <p>The following Hibernate JDBC properties will be relied upon by Hibernate's {@link Configurable} spi mechanism:
+ *
+ * <ul>
+ *   <li>jakarta.persistence.jdbc.url
+ *   <li>jakarta.persistence.jdbc.user
+ *   <li>jakarta.persistence.jdbc.password
+ * </ul>
+ *
+ * <p><code>jakarta.persistence.jdbc.url</code> property is mandatory and it maps to MongoDB's {@link ConnectionString},
+ * in which database name must be provided to align with JDBC URL's convention. The other two JDBC properties are
+ * optional.
+ *
+ * @see ConnectionProvider
+ * @see Configurable
+ */
+public class MongoConnectionProvider implements ConnectionProvider, Configurable, Startable, Stoppable {
+
+    // non-null after configure(Map<String, Object>) method is invoked successfully
+    private @Nullable ConnectionString connectionString;
+    private @Nullable String database;
+
+    // non-null after start() method is invoked successfully
+    private @Nullable MongoClient mongoClient;
+
+    private @Nullable String user;
+    private @Nullable String password;
+
+    @Override
+    public Connection getConnection() {
+        throw new NotYetImplementedException();
+    }
+
+    @Override
+    public void closeConnection(Connection connection) {
+        throw new NotYetImplementedException();
+    }
+
+    @Override
+    public boolean supportsAggressiveRelease() {
+        return false; // won't be used in container
+    }
+
+    @Override
+    public boolean isUnwrappableAs(Class<?> unwrapType) {
+        return ConnectionProvider.class.equals(unwrapType)
+                || MongoConnectionProvider.class.isAssignableFrom(unwrapType);
+    }
+
+    @Override
+    public <T> T unwrap(Class<T> unwrapType) {
+        if (isUnwrappableAs(unwrapType)) {
+            return unwrapType.cast(this);
+        } else {
+            throw new UnknownUnwrapTypeException(unwrapType);
+        }
+    }
+
+    @Override
+    public void configure(Map<String, Object> configurationValues) {
+        var jdbcUrl = ConfigurationHelper.getRequiredConfiguration(configurationValues, JAKARTA_JDBC_URL);
+        try {
+            this.connectionString = new ConnectionString(jdbcUrl);
+        } catch (IllegalArgumentException iae) {
+            throw new ConfigurationException(JAKARTA_JDBC_URL, "invalid MongoDB connection string", iae);
+        }
+        var database = this.connectionString.getDatabase();
+        if (database == null) {
+            throw new ConfigurationException(JAKARTA_JDBC_URL, "database must be provided");
+        }
+        this.database = database;
+        this.user = ConfigurationHelper.getOptionalConfiguration(configurationValues, JAKARTA_JDBC_USER);
+        this.password = ConfigurationHelper.getOptionalConfiguration(configurationValues, JAKARTA_JDBC_PASSWORD);
+    }
+
+    @Override
+    public void start() {
+        // connectionString and database are set as mandatory values in the above configure method
+        // if either is unset, exception would have been thrown and this method invocation would have be skipped
+        castNonNull(this.connectionString);
+        castNonNull(this.database);
+
+        var clientSettingsBuilder = MongoClientSettings.builder().applyConnectionString(connectionString);
+        if (this.user != null) {
+            var password = this.password == null ? null : this.password.toCharArray();
+            var credential = MongoCredential.createCredential(this.user, this.database, password);
+            clientSettingsBuilder.credential(credential);
+        }
+
+        var codecRegistry = fromRegistries(MongoClientSettings.getDefaultCodecRegistry());
+        clientSettingsBuilder.codecRegistry(codecRegistry);
+
+        var clientSettings = clientSettingsBuilder.build();
+        this.mongoClient = MongoClients.create(clientSettings);
+    }
+
+    @Override
+    public void stop() {
+        if (this.mongoClient != null) {
+            this.mongoClient.close();
+        }
+    }
+}

src/main/java/com/mongodb/hibernate/package-info.java

@@ -0,0 +1,4 @@
+@NullMarked
+package com.mongodb.hibernate;
+
+import org.jspecify.annotations.NullMarked;