Compare MySQL server and client time method.

embulk-output-mysql/src/main/java/org/embulk/output/MySQLOutputPlugin.java

@@ -8,9 +8,12 @@
 import org.embulk.config.ConfigDefault;
 import org.embulk.output.jdbc.AbstractJdbcOutputPlugin;
 import org.embulk.output.jdbc.BatchInsert;
+import org.embulk.output.jdbc.JdbcOutputConnection;
 import org.embulk.output.jdbc.MergeConfig;
+import org.embulk.output.mysql.MySQLOutputConnection;
 import org.embulk.output.mysql.MySQLOutputConnector;
 import org.embulk.output.mysql.MySQLBatchInsert;
+import org.embulk.spi.Schema;
 
 public class MySQLOutputPlugin
         extends AbstractJdbcOutputPlugin
@@ -122,4 +125,13 @@ protected boolean isRetryableException(String sqlState, int errorCode)
                 return false;
         }
     }
+
+    @Override
+    protected void doBegin(JdbcOutputConnection con,
+                           PluginTask task, final Schema schema, int taskCount) throws SQLException
+    {
+        MySQLOutputConnection mySQLCon = (MySQLOutputConnection)con;
+        mySQLCon.compareTimeZone();
+        super.doBegin(con,task,schema,taskCount);
+    }
 }

embulk-output-mysql/src/main/java/org/embulk/output/MySQLTimeZoneComparison.java

@@ -0,0 +1,107 @@
+package org.embulk.output;
+
+import org.embulk.spi.Exec;
+import org.slf4j.Logger;
+
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.Date;
+import java.util.Locale;
+import java.util.TimeZone;
+
+public class MySQLTimeZoneComparison {
+
+    private static final int ONE_HOUR_SEC = 3600;
+    private static final int ONE_MIN_SEC = 60;
+
+    private Connection connection;
+
+    private final Logger logger = Exec.getLogger(getClass());
+
+    public MySQLTimeZoneComparison(Connection connection)
+    {
+        this.connection = connection;
+    }
+
+    public void compareTimeZone()
+            throws SQLException
+    {
+        TimeZone serverTimeZone = null;
+        try {
+            serverTimeZone = getServerTimeZone();
+        }
+        catch (SQLException ex) {
+            logger.warn("Can't get server TimeZone.");
+            logger.warn(String.format(Locale.ENGLISH, "SQLException raised %s", ex.toString()));
+        }
+
+        TimeZone clientTimeZone = TimeZone.getDefault();
+        Date today = new Date();
+        int clientOffset = clientTimeZone.getRawOffset();
+
+        if (clientTimeZone.inDaylightTime(today)) {
+            clientOffset += clientTimeZone.getDSTSavings();
+        }
+
+        //
+        // Compare offset only. Although I expect to return true, the following code return false,
+        //
+        // TimeZone tz_jst   = TimeZone.getTimeZone("JST");
+        // TimeZone tz_gmt9  = TimeZone.getTimeZone("GMT+9");
+        // tz_jst.hasSameRules(tz_gmt9) // return false.
+        //
+        if (clientOffset != serverTimeZone.getRawOffset()) {
+            logger.warn(String.format(Locale.ENGLISH,
+                    "The client timezone(%s) is different from the server timezone(%s). The plugin will store wrong datetime values.",
+                    clientTimeZone.getID(), serverTimeZone.getID()));
+            logger.warn(String.format(Locale.ENGLISH,
+                    "You may need to set options `useLegacyDatetimeCode` and `serverTimezone`"));
+            logger.warn(String.format(Locale.ENGLISH,
+                    "Example. `options: { useLegacyDatetimeCode: false, serverTimezone: UTC }`"));
+        }
+        logger.warn(String.format(Locale.ENGLISH, "The plugin will set `useLegacyDatetimeCode=false` by default in future."));
+    }
+
+    private TimeZone getServerTimeZone()
+            throws SQLException
+    {
+        //
+        // First, I used `@@system_time_zone`. but It return non Time Zone Abbreviations name on a specific platform.
+        // So, This method calculate GMT offset with query.
+        //
+        String query = "select TIME_TO_SEC(timediff(now(),utc_timestamp()));";
+        Statement stmt = connection.createStatement();
+
+        try {
+            ResultSet rs = stmt.executeQuery(query);
+            if (rs.next()) {
+                int offsetSeconds = rs.getInt(1);
+                return fromGMTOffsetSeconds(offsetSeconds);
+            }
+            throw new SQLException(String.format(Locale.ENGLISH,
+                    "The timezone comparison query(%s) doesn't return the result.",query));
+        }
+        finally {
+            stmt.close();
+        }
+    }
+
+    private TimeZone fromGMTOffsetSeconds(int offsetSeconds)
+    {
+        if (offsetSeconds == 0) {
+            return TimeZone.getTimeZone("UTC");
+        }
+
+        String sign = offsetSeconds > 0 ? "+" : "-";
+        int absOffsetSec = Math.abs(offsetSeconds);
+        int tzHour = absOffsetSec / ONE_HOUR_SEC;
+        int tzMin = absOffsetSec % ONE_HOUR_SEC / ONE_MIN_SEC;
+        String tzName = String.format(Locale.ENGLISH, "GMT%s%02d:%02d", sign, tzHour, tzMin);
+        return TimeZone.getTimeZone(tzName);
+    }
+
+
+}

embulk-output-mysql/src/main/java/org/embulk/output/mysql/MySQLOutputConnection.java

@@ -4,6 +4,7 @@
 import java.sql.Connection;
 import java.sql.SQLException;
 
+import org.embulk.output.MySQLTimeZoneComparison;
 import org.embulk.output.jdbc.JdbcColumn;
 import org.embulk.output.jdbc.JdbcSchema;
 import org.embulk.output.jdbc.JdbcOutputConnection;
@@ -110,4 +111,11 @@ protected String buildColumnTypeName(JdbcColumn c)
             return super.buildColumnTypeName(c);
         }
     }
+
+    public void compareTimeZone() throws SQLException
+    {
+        MySQLTimeZoneComparison timeZoneComparison = new MySQLTimeZoneComparison(connection);
+        timeZoneComparison.compareTimeZone();
+    }
+
 }