This project contains a R2DBC connection pool using reactor-pool
for reactive connection pooling.
This project is governed by the R2DBC Code of Conduct. By participating, you are expected to uphold this code of conduct. Please report unacceptable behavior to info@r2dbc.io.
Configuration of the ConnectionPool
can be accomplished in several ways:
URL Connection Factory Discovery
// Creates a ConnectionPool wrapping an underlying ConnectionFactory
ConnectionFactory pooledConnectionFactory = ConnectionFactories.get("r2dbc:pool:<my-driver>://<host>:<port>/<database>[?maxIdleTime=PT60S[&…]");
// Make sure to close the connection after usage.
Publisher<? extends Connection> connectionPublisher = pooledConnectionFactory.create();
Programmatic Connection Factory Discovery
// Creates a ConnectionPool wrapping an underlying ConnectionFactory
ConnectionFactory pooledConnectionFactory = ConnectionFactories.get(ConnectionFactoryOptions.builder()
.option(DRIVER,"pool")
.option(PROTOCOL,"postgresql") // driver identifier, PROTOCOL is delegated as DRIVER by the pool.
.option(HOST,"…")
.option(PORT,"…")
.option(USER,"…")
.option(PASSWORD,"…")
.option(DATABASE,"…")
.build());
The delegated DRIVER
(via PROTOCOL
) above refers to the r2dbc-driver, such as h2
, postgresql
, mssql
, mysql
, spanner
.
// Make sure to close the connection after usage.
Publisher<? extends Connection> connectionPublisher = pooledConnectionFactory.create();
// Creating a Mono using Project Reactor. Using `usingWhen` for resource management and disposal.
Mono<Object> resultMono = Mono.usingWhen(pooledConnectionFactory.create(),
connection -> …,
Connection::close);
Supported ConnectionFactory Discovery Options
Option | Description |
---|---|
driver |
Must be pool |
protocol |
Driver identifier. The value is propagated by the pool to the driver property. |
acquireRetry |
Number of retries if the first connection acquisition attempt fails. Defaults to 1 . |
backgroundEvictionInterval |
Interval for background eviction enabling background eviction. Disabled by default. Setting the value to Duration.ZERO disables background eviction even if maxIdleTime is configured. |
initialSize |
Initial pool size. Defaults to 10 . |
minIdle |
Minimum idle connection count. Defaults to 0 . |
maxSize |
Maximum pool size. Defaults to 10 . |
maxLifeTime |
Maximum lifetime of the connection in the pool. Negative values indicate no timeout. Defaults to no timeout. |
maxIdleTime |
Maximum idle time of the connection in the pool. Negative values indicate no timeout. Defaults to 30 minutes.This value is used as an interval for background eviction of idle connections unless configuring backgroundEvictionInterval . |
maxAcquireTime |
Maximum time to acquire connection from pool. Negative values indicate no timeout. Defaults to no timeout. |
maxCreateConnectionTime |
Maximum time to create a new connection. Negative values indicate no timeout. Defaults to no timeout. |
maxValidationTime |
Maximum time to validate connection from pool. Negative values indicate no timeout. Defaults to no timeout. |
poolName |
Name of the Connection Pool. |
postAllocate |
Lifecycle function to prepare a connection after allocating it. |
preRelease |
Lifecycle function to prepare/cleanup a connection before releasing it. |
registerJmx |
Whether to register the pool to JMX. |
validationDepth |
Validation depth used to validate an R2DBC connection. Defaults to LOCAL . |
validationQuery |
Query that will be executed just before a connection is given to you from the pool to validate that the connection to the database is still alive. |
All other properties are driver-specific.
Programmatic Configuration
// Creates a ConnectionFactory for the specified DRIVER
ConnectionFactory connectionFactory = ConnectionFactories.get(ConnectionFactoryOptions.builder()
.option(DRIVER,"postgresql")
.option(HOST,"…")
.option(PORT,"…")
.option(USER,"…")
.option(PASSWORD,"…")
.option(DATABASE,"…")
.build());
// Create a ConnectionPool for connectionFactory
ConnectionPoolConfiguration configuration = ConnectionPoolConfiguration.builder(connectionFactory)
.maxIdleTime(Duration.ofMillis(1000))
.maxSize(20)
.build();
ConnectionPool pool = new ConnectionPool(configuration);
Using `usingWhen` for resource management and disposal.
Mono<Object> resultMono = Mono.usingWhen(pooledConnectionFactory.create(), // allocates a connection from the pool
connection -> …, // you get hold of the connection to run queries, manage transactions, …
Connection::close); // releases the connection back to the pool
// application shutdown
pool.dispose();
Lifecycle
supportThe R2DBC specification defines as of version 0.9 lifecycle support for connections (Lifecycle.postAllocate
, Lifecycle.preRelease
). R2DBC Pool integrates with connections that implement lifecycle methods by inspecting the actual connection. postAllocate
is called after allocating a connection and before returning it to the caller. preRelease
is called upon Connection.close()
, right before returning the connection into the pool. Any error signals in postAllocate
are propagated to the allocation subscriber. Error signals of preRelease
are logged and suppressed. In both cases, error signals lead to immediate invalidation of the connection.
Additionally, the pool accepts custom postAllocate
and preRelease
functions through the builder to prepare the connection or to cleanup the connection before returning it into the pool. Custom lifecycle methods are called within the Lifecycle
closure to ensure the connection-side lifecycle.
ConnectionPoolConfiguration configuration = ConnectionPoolConfiguration.builder(connectionFactory)
.postAllocate(connection -> Flux.from(connection.createStatement("SET schema = …").execute()).flatMap(Result::getRowsUpdated).then())
.preRelease(Connection::rollbackTransaction)
.build();
ConnectionPool pool = new ConnectionPool(configuration);
Artifacts can be found on Maven Central:
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-pool</artifactId>
<version>${version}</version>
</dependency>
If you'd rather like the latest snapshots of the upcoming major version, use our Maven snapshot repository and declare the appropriate dependency version.
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-pool</artifactId>
<version>${version}.BUILD-SNAPSHOT</version>
</dependency>
<repository>
<id>sonatype-nexus-snapshots</id>
<name>Sonatype OSS Snapshot Repository</name>
<url>https://oss.sonatype.org/content/repositories/snapshots</url>
</repository>
Having trouble with R2DBC? We'd love to help!
r2dbc
.
You can also chat with the community on Gitter.R2DBC uses GitHub as issue tracking system to record bugs and feature requests. If you want to raise an issue, please follow the recommendations below:
You don't need to build from source to use R2DBC Pool (binaries in Maven Central), but if you want to try out the latest and greatest, R2DBC Pool can be easily built with the maven wrapper. You also need JDK 1.8.
$ ./mvnw clean install
If you want to build with the regular mvn
command, you will need Maven v3.5.0 or above.
Also see CONTRIBUTING.adoc if you wish to submit pull requests. Commits require Signed-off-by
(git commit -s
) to ensure Developer Certificate of Origin.
To stage a release to Maven Central, you need to create a release tag (release version) that contains the desired state and version numbers (mvn versions:set versions:commit -q -o -DgenerateBackupPoms=false -DnewVersion=x.y.z.(RELEASE|Mnnn|RCnnn
) and force-push it to the release-0.x
branch. This push will trigger a Maven staging build (see build-and-deploy-to-maven-central.sh
).
This project is released under version 2.0 of the Apache License.