Fixed #18 Allow specifying a default transaction isolation level.

core/src/main/java/com/zaxxer/hikari/HikariConfig.java

@@ -19,6 +19,8 @@ package com.zaxxer.hikari;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
+import java.lang.reflect.Field;
+import java.sql.Connection;
 import java.util.Properties;
 import java.util.concurrent.TimeUnit;
 
@@ -50,6 +52,7 @@ public final class HikariConfig implements HikariConfigMBean
 
     // Properties NOT changeable at runtime
     //
+    private int transactionIsolation;
     private String poolName;
     private String connectionTestQuery;
     private String dataSourceClassName;
@@ -79,6 +82,7 @@ public final class HikariConfig implements HikariConfigMBean
         maxPoolSize = 60;
         maxLifetime = MAX_LIFETIME;
         poolName = "HikariPool-" + poolNumber++;
+        transactionIsolation = -1;
     }
 
     /**
@@ -89,7 +93,7 @@ public final class HikariConfig implements HikariConfigMBean
     public HikariConfig(Properties properties)
     {
         this();
-	PropertyBeanSetter.setTargetFromProperties(this, properties);
+        PropertyBeanSetter.setTargetFromProperties(this, properties);
     }
 
 
@@ -376,6 +380,32 @@ public final class HikariConfig implements HikariConfigMBean
         this.shadedCodexMapping = mapping;
     }
 
+    public int getTransactionIsolation()
+    {
+        return transactionIsolation;
+    }
+
+    /**
+     * Set the default transaction isolation level.  The specified value is the
+     * constant name from the <code>Connection</code> class, eg. 
+     * <code>TRANSACTION_REPEATABLE_READ</code>.
+     *
+     * @param isolationLevel the name of the isolation level
+     */
+    public void setTransactionIsolation(String isolationLevel)
+    {
+        try
+        {
+            Field field = Connection.class.getField(isolationLevel);
+            int level = field.getInt(null);
+            this.transactionIsolation = level;
+        }
+        catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e)
+        {
+            throw new IllegalArgumentException("Invalid transaction isolation value: " + isolationLevel);
+        }
+    }
+
     public void validate()
     {
         Logger logger = LoggerFactory.getLogger(getClass());

core/src/main/java/com/zaxxer/hikari/HikariPool.java

@@ -58,6 +58,7 @@ public final class HikariPool implements HikariPoolMBean
     private final boolean jdbc4ConnectionTest;
     private final boolean isAutoCommit;
     private final boolean delegationProxies;
+    private int transactionIsolation;
 
     private final Timer houseKeepingTimer;
 
@@ -79,6 +80,7 @@ public final class HikariPool implements HikariPoolMBean
         this.jdbc4ConnectionTest = configuration.isJdbc4ConnectionTest();
         this.leakDetectionThreshold = configuration.getLeakDetectionThreshold();
         this.isAutoCommit = configuration.isAutoCommit();
+        this.transactionIsolation = configuration.getTransactionIsolation();
 
         String dsClassName = configuration.getDataSourceClassName();
         try
@@ -162,6 +164,7 @@ public final class HikariPool implements HikariPoolMBean
                 }
 
                 connection.setAutoCommit(isAutoCommit);
+                connection.setTransactionIsolation(transactionIsolation);
                 connection.clearWarnings();
 
                 return connection;
@@ -345,6 +348,11 @@ public final class HikariPool implements HikariPoolMBean
                     throw new RuntimeException("Connection not alive, retry.");
                 }
 
+                if (transactionIsolation < 0)
+                {
+                    transactionIsolation = connection.getTransactionIsolation();
+                }
+
                 String initSql = configuration.getConnectionInitSql();
                 if (initSql != null && initSql.length() > 0)
                 {

core/src/test/java/com/zaxxer/hikari/CreationTest.java

@@ -193,4 +193,14 @@ public class CreationTest
         Assert.assertSame("Totals connections not as expected", 2, ds.pool.getTotalConnections());
         Assert.assertSame("Idle connections not as expected", 2, ds.pool.getIdleConnections());
     }
+
+    @Test
+    public void testIsolation() throws Exception
+    {
+        HikariConfig config = new HikariConfig();
+        config.setTransactionIsolation("TRANSACTION_REPEATABLE_READ");
+        int transactionIsolation = config.getTransactionIsolation();
+
+        Assert.assertSame(Connection.TRANSACTION_REPEATABLE_READ, transactionIsolation);
+    }
 }