Retry obtaining DB connection

node/src/integration-test/kotlin/net/corda/node/services/MySQLNotaryServiceTests.kt

@@ -13,6 +13,7 @@ import net.corda.core.identity.Party
 import net.corda.core.transactions.TransactionBuilder
 import net.corda.core.utilities.getOrThrow
 import net.corda.node.internal.StartedNode
+import net.corda.node.services.config.MySQLConfiguration
 import net.corda.node.services.config.NotaryConfig
 import net.corda.nodeapi.internal.DevIdentityGenerator
 import net.corda.nodeapi.internal.network.NetworkParametersCopier
@@ -131,7 +132,7 @@ class MySQLNotaryServiceTests : IntegrationTest() {
                         legalName = notaryName,
                         entropyRoot = BigInteger.valueOf(60L),
                         configOverrides = {
-                            val notaryConfig = NotaryConfig(validating = false, mysql = dataStoreProperties)
+                            val notaryConfig = NotaryConfig(validating = false, mysql = MySQLConfiguration(dataStoreProperties))
                             doReturn(notaryConfig).whenever(it).notary
                         }
                 )

node/src/main/kotlin/net/corda/node/services/config/NodeConfiguration.kt

@@ -58,7 +58,7 @@ data class NotaryConfig(val validating: Boolean,
                         val raft: RaftConfig? = null,
                         val bftSMaRt: BFTSMaRtConfiguration? = null,
                         val custom: Boolean = false,
-                        val mysql: Properties? = null
+                        val mysql: MySQLConfiguration? = null
 ) {
     init {
         require(raft == null || bftSMaRt == null || !custom || mysql == null) {
@@ -68,6 +68,15 @@ data class NotaryConfig(val validating: Boolean,
     val isClusterConfig: Boolean get() = raft != null || bftSMaRt != null
 }
 
+data class MySQLConfiguration(
+        val dataSource: Properties,
+        val connectionRetries: Int = 0
+) {
+    init {
+        require(connectionRetries >= 0) { "connectionRetries cannot be negative" }
+    }
+}
+
 data class RaftConfig(val nodeAddress: NetworkHostAndPort, val clusterAddresses: List<NetworkHostAndPort>)
 
 /** @param exposeRaces for testing only, so its default is not in reference.conf but here. */

node/src/main/kotlin/net/corda/node/services/transactions/MySQLNotaryService.kt

@@ -5,6 +5,7 @@ import net.corda.core.flows.FlowSession
 import net.corda.core.node.services.TimeWindowChecker
 import net.corda.core.node.services.TrustedAuthorityNotaryService
 import net.corda.node.services.api.ServiceHubInternal
+import net.corda.node.services.config.MySQLConfiguration
 import java.security.PublicKey
 import java.util.*
 
@@ -12,14 +13,14 @@ import java.util.*
 abstract class MySQLNotaryService(
         final override val services: ServiceHubInternal,
         override val notaryIdentityKey: PublicKey,
-        dataSourceProperties: Properties,
+        configuration: MySQLConfiguration,
         /** Database table will be automatically created in dev mode */
         val devMode: Boolean) : TrustedAuthorityNotaryService() {
 
     override val timeWindowChecker = TimeWindowChecker(services.clock)
     override val uniquenessProvider = MySQLUniquenessProvider(
             services.monitoringService.metrics,
-            dataSourceProperties
+            configuration
     )
 
     override fun start() {
@@ -33,14 +34,14 @@ abstract class MySQLNotaryService(
 
 class MySQLNonValidatingNotaryService(services: ServiceHubInternal,
                                       notaryIdentityKey: PublicKey,
-                                      dataSourceProperties: Properties,
+                                      configuration: MySQLConfiguration,
-                                      devMode: Boolean = false) : MySQLNotaryService(services, notaryIdentityKey, dataSourceProperties, devMode) {
+                                      devMode: Boolean = false) : MySQLNotaryService(services, notaryIdentityKey, configuration, devMode) {
     override fun createServiceFlow(otherPartySession: FlowSession): FlowLogic<Void?> = NonValidatingNotaryFlow(otherPartySession, this)
 }
 
 class MySQLValidatingNotaryService(services: ServiceHubInternal,
                                       notaryIdentityKey: PublicKey,
-                                      dataSourceProperties: Properties,
+                                      configuration: MySQLConfiguration,
-                                      devMode: Boolean = false) : MySQLNotaryService(services, notaryIdentityKey, dataSourceProperties, devMode) {
+                                      devMode: Boolean = false) : MySQLNotaryService(services, notaryIdentityKey, configuration, devMode) {
     override fun createServiceFlow(otherPartySession: FlowSession): FlowLogic<Void?> = ValidatingNotaryFlow(otherPartySession, this)
 }

node/src/main/kotlin/net/corda/node/services/transactions/MySQLUniquenessProvider.kt

@@ -14,9 +14,11 @@ import net.corda.core.serialization.SingletonSerializeAsToken
 import net.corda.core.serialization.deserialize
 import net.corda.core.serialization.serialize
 import net.corda.core.utilities.loggerFor
+import net.corda.node.services.config.MySQLConfiguration
 import java.security.PublicKey
 import java.sql.BatchUpdateException
 import java.sql.Connection
+import java.sql.SQLTransientConnectionException
 import java.util.*
 
 /**
@@ -27,7 +29,7 @@ import java.util.*
  */
 class MySQLUniquenessProvider(
         metrics: MetricRegistry,
-        dataSourceProperties: Properties
+        configuration: MySQLConfiguration
 ) : UniquenessProvider, SingletonSerializeAsToken() {
     companion object {
         private val log = loggerFor<MySQLUniquenessProvider>()
@@ -57,13 +59,29 @@ class MySQLUniquenessProvider(
      * This is a useful heath metric.
      */
     private val rollbackCounter = metrics.counter("$metricPrefix.Rollback")
+    /** Incremented when we can not obtain a DB connection. */
+    private val connectionExceptionCounter = metrics.counter("$metricPrefix.ConnectionException")
     /** Track double spend attempts. Note that this will also include notarisation retries. */
     private val conflictCounter = metrics.counter("$metricPrefix.Conflicts")
 
-    val dataSource = HikariDataSource(HikariConfig(dataSourceProperties))
+    val dataSource = HikariDataSource(HikariConfig(configuration.dataSource))
+    private val connectionRetries = configuration.connectionRetries
 
     private val connection: Connection
-        get() = dataSource.connection
+        get() = getConnection()
+
+    private fun getConnection(nRetries: Int = 0): Connection =
+            try {
+                dataSource.connection
+            } catch (e: SQLTransientConnectionException) {
+                if (nRetries == connectionRetries) {
+                    log.warn("Couldn't obtain connection with {} retries, giving up, {}", nRetries, e)
+                    throw e
+                }
+                log.warn("Connection exception, retrying", nRetries+1)
+                connectionExceptionCounter.inc()
+                getConnection(nRetries + 1)
+            }
 
     fun createTable() {
         log.debug("Attempting to create DB table if it does not yet exist: $createTableStatement")