src/main/java/com/googlesource/gerrit/plugins/verifystatus/VerifyStatusQueryShell.java - plugins/verify-status - Git at Google

 // Copyright (C) 2015 The Android Open Source Project
 //
 // 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.googlesource.gerrit.plugins.verifystatus;

 import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.gerrit.common.TimeUtil;
 import com.google.gerrit.common.Version;
 import com.google.gerrit.extensions.annotations.RequiresCapability;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonObject;
 import com.google.gwtorm.jdbc.JdbcSchema;
 import com.google.gwtorm.server.OrmException;
 import com.google.gwtorm.server.SchemaFactory;
 import com.google.inject.Inject;
 import com.google.inject.assistedinject.Assisted;
 import com.googlesource.gerrit.plugins.verifystatus.server.CiDb;
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.sql.Connection;
 import java.sql.DatabaseMetaData;
 import java.sql.ResultSet;
 import java.sql.ResultSetMetaData;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;

 /** Simple interactive SQL query tool. */
 @RequiresCapability(AccessCiDatabaseCapability.ID)
 public class VerifyStatusQueryShell {
   public interface Factory {
     VerifyStatusQueryShell create(@Assisted InputStream in, @Assisted OutputStream out);
   }

   public static enum OutputFormat {
     PRETTY,
     JSON,
     JSON_SINGLE
   }

   private final BufferedReader in;
   private final PrintWriter out;
   private final SchemaFactory<CiDb> dbFactory;
   private OutputFormat outputFormat = OutputFormat.PRETTY;

   private CiDb db;
   private Connection connection;
   private Statement statement;

   @Inject
   VerifyStatusQueryShell(
       SchemaFactory<CiDb> dbFactory, @Assisted InputStream in, @Assisted OutputStream out) {
     this.dbFactory = dbFactory;
     this.in = new BufferedReader(new InputStreamReader(in, UTF_8));
     this.out = new PrintWriter(new OutputStreamWriter(out, UTF_8));
   }

   public void setOutputFormat(OutputFormat fmt) {
     outputFormat = fmt;
   }

   public void run() {
     try {
       db = dbFactory.open();
       try {
         connection = ((JdbcSchema) db).getConnection();
         connection.setAutoCommit(true);

         statement = connection.createStatement();
         try {
           showBanner();
           readEvalPrintLoop();
         } finally {
           statement.close();
           statement = null;
         }
       } finally {
         db.close();
         db = null;
       }
     } catch (OrmException | SQLException err) {
       out.println("fatal: Cannot open connection: " + err.getMessage());
     } finally {
       out.flush();
     }
   }

   public void execute(String query) {
     try {
       db = dbFactory.open();
       try {
         connection = ((JdbcSchema) db).getConnection();
         connection.setAutoCommit(true);

         statement = connection.createStatement();
         try {
           executeStatement(query);
         } finally {
           statement.close();
           statement = null;
         }
       } finally {
         db.close();
         db = null;
       }
     } catch (OrmException | SQLException err) {
       out.println("fatal: Cannot open connection: " + err.getMessage());
     } finally {
       out.flush();
     }
   }

   private void readEvalPrintLoop() {
     final StringBuilder buffer = new StringBuilder();
     boolean executed = false;
     for (; ; ) {
       if (outputFormat == OutputFormat.PRETTY) {
         print(buffer.length() == 0 || executed ? "gerrit> " : "     -> ");
       }
       String line = readLine();
       if (line == null) {
         return;
       }

       if (line.startsWith("\\")) {
         // Shell command, check the various cases we recognize
         //
         line = line.substring(1);
         if (line.equals("h") || line.equals("?")) {
           showHelp();

         } else if (line.equals("q")) {
           if (outputFormat == OutputFormat.PRETTY) {
             println("Bye");
           }
           return;

         } else if (line.equals("r")) {
           buffer.setLength(0);
           executed = false;

         } else if (line.equals("p")) {
           println(buffer.toString());

         } else if (line.equals("g")) {
           if (buffer.length() > 0) {
             executeStatement(buffer.toString());
             executed = true;
           }

         } else if (line.equals("d")) {
           listTables();

         } else if (line.startsWith("d ")) {
           showTable(line.substring(2).trim());

         } else {
           final String msg = "'\\" + line + "' not supported";
           switch (outputFormat) {
             case JSON_SINGLE:
             case JSON:
               {
                 final JsonObject err = new JsonObject();
                 err.addProperty("type", "error");
                 err.addProperty("message", msg);
                 println(err.toString());
                 break;
               }
             case PRETTY:
             default:
               println("ERROR: " + msg);
               println("");
               showHelp();
               break;
           }
         }
         continue;
       }

       if (executed) {
         buffer.setLength(0);
         executed = false;
       }
       if (buffer.length() > 0) {
         buffer.append('\n');
       }
       buffer.append(line);

       if (buffer.length() > 0 && buffer.charAt(buffer.length() - 1) == ';') {
         executeStatement(buffer.toString());
         executed = true;
       }
     }
   }

   private void listTables() {
     final DatabaseMetaData meta;
     try {
       meta = connection.getMetaData();
     } catch (SQLException e) {
       error(e);
       return;
     }

     final String[] types = {"TABLE", "VIEW"};
     try (ResultSet rs = meta.getTables(null, null, null, types)) {
       if (outputFormat == OutputFormat.PRETTY) {
         println("                     List of relations");
       }
       showResultSet(
           rs,
           false,
           0,
           Identity.create(rs, "TABLE_SCHEM"),
           Identity.create(rs, "TABLE_NAME"),
           Identity.create(rs, "TABLE_TYPE"));
     } catch (SQLException e) {
       error(e);
     }

     println("");
   }

   private void showTable(String tableName) {
     final DatabaseMetaData meta;
     try {
       meta = connection.getMetaData();

       if (meta.storesUpperCaseIdentifiers()) {
         tableName = tableName.toUpperCase();
       } else if (meta.storesLowerCaseIdentifiers()) {
         tableName = tableName.toLowerCase();
       }
     } catch (SQLException e) {
       error(e);
       return;
     }

     try (ResultSet rs = meta.getColumns(null, null, tableName, null)) {
       if (!rs.next()) {
         throw new SQLException("Table " + tableName + " not found");
       }

       if (outputFormat == OutputFormat.PRETTY) {
         println("                     Table " + tableName);
       }
       showResultSet(
           rs,
           true,
           0,
           Identity.create(rs, "COLUMN_NAME"),
           new Function("TYPE") {
             @Override
             String apply(final ResultSet rs) throws SQLException {
               String type = rs.getString("TYPE_NAME");
               switch (rs.getInt("DATA_TYPE")) {
                 case java.sql.Types.CHAR:
                 case java.sql.Types.VARCHAR:
                   type += "(" + rs.getInt("COLUMN_SIZE") + ")";
                   break;
               }

               String def = rs.getString("COLUMN_DEF");
               if (def != null && !def.isEmpty()) {
                 type += " DEFAULT " + def;
               }

               int nullable = rs.getInt("NULLABLE");
               if (nullable == DatabaseMetaData.columnNoNulls) {
                 type += " NOT NULL";
               }
               return type;
             }
           });
     } catch (SQLException e) {
       error(e);
       return;
     }

     try (ResultSet rs = meta.getIndexInfo(null, null, tableName, false, true)) {
       Map<String, IndexInfo> indexes = new TreeMap<>();
       while (rs.next()) {
         final String indexName = rs.getString("INDEX_NAME");
         IndexInfo def = indexes.get(indexName);
         if (def == null) {
           def = new IndexInfo();
           def.name = indexName;
           indexes.put(indexName, def);
         }

         if (!rs.getBoolean("NON_UNIQUE")) {
           def.unique = true;
         }

         final int pos = rs.getInt("ORDINAL_POSITION");
         final String col = rs.getString("COLUMN_NAME");
         String desc = rs.getString("ASC_OR_DESC");
         if ("D".equals(desc)) {
           desc = " DESC";
         } else {
           desc = "";
         }
         def.addColumn(pos, col + desc);

         String filter = rs.getString("FILTER_CONDITION");
         if (filter != null && !filter.isEmpty()) {
           def.filter.append(filter);
         }
       }

       if (outputFormat == OutputFormat.PRETTY) {
         println("");
         println("Indexes on " + tableName + ":");
         for (IndexInfo def : indexes.values()) {
           println("  " + def);
         }
       }
     } catch (SQLException e) {
       error(e);
       return;
     }

     println("");
   }

   private void executeStatement(final String sql) {
     final long start = TimeUtil.nowMs();
     final boolean hasResultSet;
     try {
       hasResultSet = statement.execute(sql);
     } catch (SQLException e) {
       error(e);
       return;
     }

     try {
       if (hasResultSet) {
         try (ResultSet rs = statement.getResultSet()) {
           showResultSet(rs, false, start);
         }

       } else {
         final int updateCount = statement.getUpdateCount();
         final long ms = TimeUtil.nowMs() - start;
         switch (outputFormat) {
           case JSON_SINGLE:
           case JSON:
             {
               final JsonObject tail = new JsonObject();
               tail.addProperty("type", "update-stats");
               tail.addProperty("rowCount", updateCount);
               tail.addProperty("runTimeMilliseconds", ms);
               println(tail.toString());
               break;
             }

           case PRETTY:
           default:
             println("UPDATE " + updateCount + "; " + ms + " ms");
             break;
         }
       }
     } catch (SQLException e) {
       error(e);
     }
   }

   /**
    * Outputs a result set to stdout.
    *
    * @param rs ResultSet to show.
    * @param alreadyOnRow true if rs is already on the first row. false otherwise.
    * @param start Timestamp in milliseconds when executing the statement started. This timestamp is
    *     used to compute statistics about the statement. If no statistics should be shown, set it to
    *     0.
    * @param show Functions to map columns
    * @throws SQLException
    */
   private void showResultSet(final ResultSet rs, boolean alreadyOnRow, long start, Function... show)
       throws SQLException {
     switch (outputFormat) {
       case JSON_SINGLE:
       case JSON:
         showResultSetJson(rs, alreadyOnRow, start, show);
         break;
       case PRETTY:
       default:
         showResultSetPretty(rs, alreadyOnRow, start, show);
         break;
     }
   }

   /**
    * Outputs a result set to stdout in Json format.
    *
    * @param rs ResultSet to show.
    * @param alreadyOnRow true if rs is already on the first row. false otherwise.
    * @param start Timestamp in milliseconds when executing the statement started. This timestamp is
    *     used to compute statistics about the statement. If no statistics should be shown, set it to
    *     0.
    * @param show Functions to map columns
    * @throws SQLException
    */
   private void showResultSetJson(
       final ResultSet rs, boolean alreadyOnRow, long start, Function... show) throws SQLException {
     JsonArray collector = new JsonArray();
     final ResultSetMetaData meta = rs.getMetaData();
     final Function[] columnMap;
     if (show != null && 0 < show.length) {
       columnMap = show;

     } else {
       final int colCnt = meta.getColumnCount();
       columnMap = new Function[colCnt];
       for (int colId = 0; colId < colCnt; colId++) {
         final int p = colId + 1;
         final String name = meta.getColumnLabel(p);
         columnMap[colId] = new Identity(p, name);
       }
     }

     int rowCnt = 0;
     while (alreadyOnRow || rs.next()) {
       final JsonObject row = new JsonObject();
       final JsonObject cols = new JsonObject();
       for (Function function : columnMap) {
         String v = function.apply(rs);
         if (v == null) {
           continue;
         }
         cols.addProperty(function.name.toLowerCase(), v);
       }
       row.addProperty("type", "row");
       row.add("columns", cols);
       switch (outputFormat) {
         case JSON:
           println(row.toString());
           break;
         case JSON_SINGLE:
           collector.add(row);
           break;
         default:
           final JsonObject obj = new JsonObject();
           obj.addProperty("type", "error");
           obj.addProperty("message", "Unsupported Json variant");
           println(obj.toString());
           return;
       }
       alreadyOnRow = false;
       rowCnt++;
     }

     JsonObject tail = null;
     if (start != 0) {
       tail = new JsonObject();
       tail.addProperty("type", "query-stats");
       tail.addProperty("rowCount", rowCnt);
       final long ms = TimeUtil.nowMs() - start;
       tail.addProperty("runTimeMilliseconds", ms);
     }

     switch (outputFormat) {
       case JSON:
         if (tail != null) {
           println(tail.toString());
         }
         break;
       case JSON_SINGLE:
         if (tail != null) {
           collector.add(tail);
         }
         println(collector.toString());
         break;
       default:
         final JsonObject obj = new JsonObject();
         obj.addProperty("type", "error");
         obj.addProperty("message", "Unsupported Json variant");
         println(obj.toString());
     }
   }

   /**
    * Outputs a result set to stdout in plain text format.
    *
    * @param rs ResultSet to show.
    * @param alreadyOnRow true if rs is already on the first row. false otherwise.
    * @param start Timestamp in milliseconds when executing the statement started. This timestamp is
    *     used to compute statistics about the statement. If no statistics should be shown, set it to
    *     0.
    * @param show Functions to map columns
    * @throws SQLException
    */
   private void showResultSetPretty(
       final ResultSet rs, boolean alreadyOnRow, long start, Function... show) throws SQLException {
     final ResultSetMetaData meta = rs.getMetaData();

     final Function[] columnMap;
     if (show != null && 0 < show.length) {
       columnMap = show;

     } else {
       final int colCnt = meta.getColumnCount();
       columnMap = new Function[colCnt];
       for (int colId = 0; colId < colCnt; colId++) {
         final int p = colId + 1;
         final String name = meta.getColumnLabel(p);
         columnMap[colId] = new Identity(p, name);
       }
     }

     final int colCnt = columnMap.length;
     final int[] widths = new int[colCnt];
     for (int c = 0; c < colCnt; c++) {
       widths[c] = columnMap[c].name.length();
     }

     final List<String[]> rows = new ArrayList<>();
     while (alreadyOnRow || rs.next()) {
       final String[] row = new String[columnMap.length];
       for (int c = 0; c < colCnt; c++) {
         row[c] = columnMap[c].apply(rs);
         if (row[c] == null) {
           row[c] = "NULL";
         }
         widths[c] = Math.max(widths[c], row[c].length());
       }
       rows.add(row);
       alreadyOnRow = false;
     }

     final StringBuilder b = new StringBuilder();
     for (int c = 0; c < colCnt; c++) {
       if (0 < c) {
         b.append(" | ");
       }

       String n = columnMap[c].name;
       if (widths[c] < n.length()) {
         n = n.substring(0, widths[c]);
       }
       b.append(n);

       if (c < colCnt - 1) {
         for (int pad = n.length(); pad < widths[c]; pad++) {
           b.append(' ');
         }
       }
     }
     println(" " + b.toString());

     b.setLength(0);
     for (int c = 0; c < colCnt; c++) {
       if (0 < c) {
         b.append("-+-");
       }
       for (int pad = 0; pad < widths[c]; pad++) {
         b.append('-');
       }
     }
     println(" " + b.toString());

     boolean dataTruncated = false;
     for (String[] row : rows) {
       b.setLength(0);
       b.append(' ');

       for (int c = 0; c < colCnt; c++) {
         final int max = widths[c];
         if (0 < c) {
           b.append(" | ");
         }

         String s = row[c];
         if (1 < colCnt && max < s.length()) {
           s = s.substring(0, max);
           dataTruncated = true;
         }
         b.append(s);

         if (c < colCnt - 1) {
           for (int pad = s.length(); pad < max; pad++) {
             b.append(' ');
           }
         }
       }
       println(b.toString());
     }

     if (dataTruncated) {
       warning("some column data was truncated");
     }

     if (start != 0) {
       final int rowCount = rows.size();
       final long ms = TimeUtil.nowMs() - start;
       println("(" + rowCount + (rowCount == 1 ? " row" : " rows") + "; " + ms + " ms)");
     }
   }

   private void warning(final String msg) {
     switch (outputFormat) {
       case JSON_SINGLE:
       case JSON:
         {
           final JsonObject obj = new JsonObject();
           obj.addProperty("type", "warning");
           obj.addProperty("message", msg);
           println(obj.toString());
           break;
         }

       case PRETTY:
       default:
         println("WARNING: " + msg);
         break;
     }
   }

   private void error(final SQLException err) {
     switch (outputFormat) {
       case JSON_SINGLE:
       case JSON:
         {
           final JsonObject obj = new JsonObject();
           obj.addProperty("type", "error");
           obj.addProperty("message", err.getMessage());
           println(obj.toString());
           break;
         }

       case PRETTY:
       default:
         println("ERROR: " + err.getMessage());
         break;
     }
   }

   private void print(String s) {
     out.print(s);
     out.flush();
   }

   private void println(String s) {
     out.print(s);
     out.print('\n');
     out.flush();
   }

   private String readLine() {
     try {
       return in.readLine();
     } catch (IOException e) {
       return null;
     }
   }

   private void showBanner() {
     if (outputFormat == OutputFormat.PRETTY) {
       println("Welcome to Gerrit Code Review " + Version.getVersion());
       try {
         print("(");
         print(connection.getMetaData().getDatabaseProductName());
         print(" ");
         print(connection.getMetaData().getDatabaseProductVersion());
         println(")");
       } catch (SQLException err) {
         error(err);
       }
       println("");
       println("Type '\\h' for help.  Type '\\r' to clear the buffer.");
       println("");
     }
   }

   private void showHelp() {
     final StringBuilder help = new StringBuilder();
     help.append("General\n");
     help.append("  \\q        quit\n");

     help.append("\n");
     help.append("Query Buffer\n");
     help.append("  \\g        execute the query buffer\n");
     help.append("  \\p        display the current buffer\n");
     help.append("  \\r        clear the query buffer\n");

     help.append("\n");
     help.append("Informational\n");
     help.append("  \\d        list all tables\n");
     help.append("  \\d NAME   describe table\n");

     help.append("\n");
     print(help.toString());
   }

   private abstract static class Function {
     final String name;

     Function(final String name) {
       this.name = name;
     }

     abstract String apply(ResultSet rs) throws SQLException;
   }

   private static class Identity extends Function {
     static Identity create(final ResultSet rs, final String name) throws SQLException {
       return new Identity(rs.findColumn(name), name);
     }

     final int colId;

     Identity(final int colId, final String name) {
       super(name);
       this.colId = colId;
     }

     @Override
     String apply(final ResultSet rs) throws SQLException {
       return rs.getString(colId);
     }
   }

   private static class IndexInfo {
     String name;
     boolean unique;
     final Map<Integer, String> columns = new TreeMap<>();
     final StringBuilder filter = new StringBuilder();

     void addColumn(int pos, String column) {
       columns.put(Integer.valueOf(pos), column);
     }

     @Override
     public String toString() {
       final StringBuilder r = new StringBuilder();
       r.append(name);
       if (unique) {
         r.append(" UNIQUE");
       }
       r.append(" (");
       boolean first = true;
       for (String c : columns.values()) {
         if (!first) {
           r.append(", ");
         }
         r.append(c);
         first = false;
       }
       r.append(")");
       if (filter.length() > 0) {
         r.append(" WHERE ");
         r.append(filter);
       }
       return r.toString();
     }
   }
 }
	// Copyright (C) 2015 The Android Open Source Project
	//
	// 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.googlesource.gerrit.plugins.verifystatus;

	import static java.nio.charset.StandardCharsets.UTF_8;

	import com.google.gerrit.common.TimeUtil;
	import com.google.gerrit.common.Version;
	import com.google.gerrit.extensions.annotations.RequiresCapability;
	import com.google.gson.JsonArray;
	import com.google.gson.JsonObject;
	import com.google.gwtorm.jdbc.JdbcSchema;
	import com.google.gwtorm.server.OrmException;
	import com.google.gwtorm.server.SchemaFactory;
	import com.google.inject.Inject;
	import com.google.inject.assistedinject.Assisted;
	import com.googlesource.gerrit.plugins.verifystatus.server.CiDb;
	import java.io.BufferedReader;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.io.OutputStream;
	import java.io.OutputStreamWriter;
	import java.io.PrintWriter;
	import java.sql.Connection;
	import java.sql.DatabaseMetaData;
	import java.sql.ResultSet;
	import java.sql.ResultSetMetaData;
	import java.sql.SQLException;
	import java.sql.Statement;
	import java.util.ArrayList;
	import java.util.List;
	import java.util.Map;
	import java.util.TreeMap;

	/** Simple interactive SQL query tool. */
	@RequiresCapability(AccessCiDatabaseCapability.ID)
	public class VerifyStatusQueryShell {
	public interface Factory {
	VerifyStatusQueryShell create(@Assisted InputStream in, @Assisted OutputStream out);
	}

	public static enum OutputFormat {
	PRETTY,
	JSON,
	JSON_SINGLE
	}

	private final BufferedReader in;
	private final PrintWriter out;
	private final SchemaFactory<CiDb> dbFactory;
	private OutputFormat outputFormat = OutputFormat.PRETTY;

	private CiDb db;
	private Connection connection;
	private Statement statement;

	@Inject
	VerifyStatusQueryShell(
	SchemaFactory<CiDb> dbFactory, @Assisted InputStream in, @Assisted OutputStream out) {
	this.dbFactory = dbFactory;
	this.in = new BufferedReader(new InputStreamReader(in, UTF_8));
	this.out = new PrintWriter(new OutputStreamWriter(out, UTF_8));
	}

	public void setOutputFormat(OutputFormat fmt) {
	outputFormat = fmt;
	}

	public void run() {
	try {
	db = dbFactory.open();
	try {
	connection = ((JdbcSchema) db).getConnection();
	connection.setAutoCommit(true);

	statement = connection.createStatement();
	try {
	showBanner();
	readEvalPrintLoop();
	} finally {
	statement.close();
	statement = null;
	}
	} finally {
	db.close();
	db = null;
	}
	} catch (OrmException \| SQLException err) {
	out.println("fatal: Cannot open connection: " + err.getMessage());
	} finally {
	out.flush();
	}
	}

	public void execute(String query) {
	try {
	db = dbFactory.open();
	try {
	connection = ((JdbcSchema) db).getConnection();
	connection.setAutoCommit(true);

	statement = connection.createStatement();
	try {
	executeStatement(query);
	} finally {
	statement.close();
	statement = null;
	}
	} finally {
	db.close();
	db = null;
	}
	} catch (OrmException \| SQLException err) {
	out.println("fatal: Cannot open connection: " + err.getMessage());
	} finally {
	out.flush();
	}
	}

	private void readEvalPrintLoop() {
	final StringBuilder buffer = new StringBuilder();
	boolean executed = false;
	for (; ; ) {
	if (outputFormat == OutputFormat.PRETTY) {
	print(buffer.length() == 0 \|\| executed ? "gerrit> " : " -> ");
	}
	String line = readLine();
	if (line == null) {
	return;
	}

	if (line.startsWith("\\")) {
	// Shell command, check the various cases we recognize
	//
	line = line.substring(1);
	if (line.equals("h") \|\| line.equals("?")) {
	showHelp();

	} else if (line.equals("q")) {
	if (outputFormat == OutputFormat.PRETTY) {
	println("Bye");
	}
	return;

	} else if (line.equals("r")) {
	buffer.setLength(0);
	executed = false;

	} else if (line.equals("p")) {
	println(buffer.toString());

	} else if (line.equals("g")) {
	if (buffer.length() > 0) {
	executeStatement(buffer.toString());
	executed = true;
	}

	} else if (line.equals("d")) {
	listTables();

	} else if (line.startsWith("d ")) {
	showTable(line.substring(2).trim());

	} else {
	final String msg = "'\\" + line + "' not supported";
	switch (outputFormat) {
	case JSON_SINGLE:
	case JSON:
	{
	final JsonObject err = new JsonObject();
	err.addProperty("type", "error");
	err.addProperty("message", msg);
	println(err.toString());
	break;
	}
	case PRETTY:
	default:
	println("ERROR: " + msg);
	println("");
	showHelp();
	break;
	}
	}
	continue;
	}

	if (executed) {
	buffer.setLength(0);
	executed = false;
	}
	if (buffer.length() > 0) {
	buffer.append('\n');
	}
	buffer.append(line);

	if (buffer.length() > 0 && buffer.charAt(buffer.length() - 1) == ';') {
	executeStatement(buffer.toString());
	executed = true;
	}
	}
	}

	private void listTables() {
	final DatabaseMetaData meta;
	try {
	meta = connection.getMetaData();
	} catch (SQLException e) {
	error(e);
	return;
	}

	final String[] types = {"TABLE", "VIEW"};
	try (ResultSet rs = meta.getTables(null, null, null, types)) {
	if (outputFormat == OutputFormat.PRETTY) {
	println(" List of relations");
	}
	showResultSet(
	rs,
	false,
	0,
	Identity.create(rs, "TABLE_SCHEM"),
	Identity.create(rs, "TABLE_NAME"),
	Identity.create(rs, "TABLE_TYPE"));
	} catch (SQLException e) {
	error(e);
	}

	println("");
	}

	private void showTable(String tableName) {
	final DatabaseMetaData meta;
	try {
	meta = connection.getMetaData();

	if (meta.storesUpperCaseIdentifiers()) {
	tableName = tableName.toUpperCase();
	} else if (meta.storesLowerCaseIdentifiers()) {
	tableName = tableName.toLowerCase();
	}
	} catch (SQLException e) {
	error(e);
	return;
	}

	try (ResultSet rs = meta.getColumns(null, null, tableName, null)) {
	if (!rs.next()) {
	throw new SQLException("Table " + tableName + " not found");
	}

	if (outputFormat == OutputFormat.PRETTY) {
	println(" Table " + tableName);
	}
	showResultSet(
	rs,
	true,
	0,
	Identity.create(rs, "COLUMN_NAME"),
	new Function("TYPE") {
	@Override
	String apply(final ResultSet rs) throws SQLException {
	String type = rs.getString("TYPE_NAME");
	switch (rs.getInt("DATA_TYPE")) {
	case java.sql.Types.CHAR:
	case java.sql.Types.VARCHAR:
	type += "(" + rs.getInt("COLUMN_SIZE") + ")";
	break;
	}

	String def = rs.getString("COLUMN_DEF");
	if (def != null && !def.isEmpty()) {
	type += " DEFAULT " + def;
	}

	int nullable = rs.getInt("NULLABLE");
	if (nullable == DatabaseMetaData.columnNoNulls) {
	type += " NOT NULL";
	}
	return type;
	}
	});
	} catch (SQLException e) {
	error(e);
	return;
	}

	try (ResultSet rs = meta.getIndexInfo(null, null, tableName, false, true)) {
	Map<String, IndexInfo> indexes = new TreeMap<>();
	while (rs.next()) {
	final String indexName = rs.getString("INDEX_NAME");
	IndexInfo def = indexes.get(indexName);
	if (def == null) {
	def = new IndexInfo();
	def.name = indexName;
	indexes.put(indexName, def);
	}

	if (!rs.getBoolean("NON_UNIQUE")) {
	def.unique = true;
	}

	final int pos = rs.getInt("ORDINAL_POSITION");
	final String col = rs.getString("COLUMN_NAME");
	String desc = rs.getString("ASC_OR_DESC");
	if ("D".equals(desc)) {
	desc = " DESC";
	} else {
	desc = "";
	}
	def.addColumn(pos, col + desc);

	String filter = rs.getString("FILTER_CONDITION");
	if (filter != null && !filter.isEmpty()) {
	def.filter.append(filter);
	}
	}

	if (outputFormat == OutputFormat.PRETTY) {
	println("");
	println("Indexes on " + tableName + ":");
	for (IndexInfo def : indexes.values()) {
	println(" " + def);
	}
	}
	} catch (SQLException e) {
	error(e);
	return;
	}

	println("");
	}

	private void executeStatement(final String sql) {
	final long start = TimeUtil.nowMs();
	final boolean hasResultSet;
	try {
	hasResultSet = statement.execute(sql);
	} catch (SQLException e) {
	error(e);
	return;
	}

	try {
	if (hasResultSet) {
	try (ResultSet rs = statement.getResultSet()) {
	showResultSet(rs, false, start);
	}

	} else {
	final int updateCount = statement.getUpdateCount();
	final long ms = TimeUtil.nowMs() - start;
	switch (outputFormat) {
	case JSON_SINGLE:
	case JSON:
	{
	final JsonObject tail = new JsonObject();
	tail.addProperty("type", "update-stats");
	tail.addProperty("rowCount", updateCount);
	tail.addProperty("runTimeMilliseconds", ms);
	println(tail.toString());
	break;
	}

	case PRETTY:
	default:
	println("UPDATE " + updateCount + "; " + ms + " ms");
	break;
	}
	}
	} catch (SQLException e) {
	error(e);
	}
	}

	/**
	* Outputs a result set to stdout.
	*
	* @param rs ResultSet to show.
	* @param alreadyOnRow true if rs is already on the first row. false otherwise.
	* @param start Timestamp in milliseconds when executing the statement started. This timestamp is
	* used to compute statistics about the statement. If no statistics should be shown, set it to
	* 0.
	* @param show Functions to map columns
	* @throws SQLException
	*/
	private void showResultSet(final ResultSet rs, boolean alreadyOnRow, long start, Function... show)
	throws SQLException {
	switch (outputFormat) {
	case JSON_SINGLE:
	case JSON:
	showResultSetJson(rs, alreadyOnRow, start, show);
	break;
	case PRETTY:
	default:
	showResultSetPretty(rs, alreadyOnRow, start, show);
	break;
	}
	}

	/**
	* Outputs a result set to stdout in Json format.
	*
	* @param rs ResultSet to show.
	* @param alreadyOnRow true if rs is already on the first row. false otherwise.
	* @param start Timestamp in milliseconds when executing the statement started. This timestamp is
	* used to compute statistics about the statement. If no statistics should be shown, set it to
	* 0.
	* @param show Functions to map columns
	* @throws SQLException
	*/
	private void showResultSetJson(
	final ResultSet rs, boolean alreadyOnRow, long start, Function... show) throws SQLException {
	JsonArray collector = new JsonArray();
	final ResultSetMetaData meta = rs.getMetaData();
	final Function[] columnMap;
	if (show != null && 0 < show.length) {
	columnMap = show;

	} else {
	final int colCnt = meta.getColumnCount();
	columnMap = new Function[colCnt];
	for (int colId = 0; colId < colCnt; colId++) {
	final int p = colId + 1;
	final String name = meta.getColumnLabel(p);
	columnMap[colId] = new Identity(p, name);
	}
	}

	int rowCnt = 0;
	while (alreadyOnRow \|\| rs.next()) {
	final JsonObject row = new JsonObject();
	final JsonObject cols = new JsonObject();
	for (Function function : columnMap) {
	String v = function.apply(rs);
	if (v == null) {
	continue;
	}
	cols.addProperty(function.name.toLowerCase(), v);
	}
	row.addProperty("type", "row");
	row.add("columns", cols);
	switch (outputFormat) {
	case JSON:
	println(row.toString());
	break;
	case JSON_SINGLE:
	collector.add(row);
	break;
	default:
	final JsonObject obj = new JsonObject();
	obj.addProperty("type", "error");
	obj.addProperty("message", "Unsupported Json variant");
	println(obj.toString());
	return;
	}
	alreadyOnRow = false;
	rowCnt++;
	}

	JsonObject tail = null;
	if (start != 0) {
	tail = new JsonObject();
	tail.addProperty("type", "query-stats");
	tail.addProperty("rowCount", rowCnt);
	final long ms = TimeUtil.nowMs() - start;
	tail.addProperty("runTimeMilliseconds", ms);
	}

	switch (outputFormat) {
	case JSON:
	if (tail != null) {
	println(tail.toString());
	}
	break;
	case JSON_SINGLE:
	if (tail != null) {
	collector.add(tail);
	}
	println(collector.toString());
	break;
	default:
	final JsonObject obj = new JsonObject();
	obj.addProperty("type", "error");
	obj.addProperty("message", "Unsupported Json variant");
	println(obj.toString());
	}
	}

	/**
	* Outputs a result set to stdout in plain text format.
	*
	* @param rs ResultSet to show.
	* @param alreadyOnRow true if rs is already on the first row. false otherwise.
	* @param start Timestamp in milliseconds when executing the statement started. This timestamp is
	* used to compute statistics about the statement. If no statistics should be shown, set it to
	* 0.
	* @param show Functions to map columns
	* @throws SQLException
	*/
	private void showResultSetPretty(
	final ResultSet rs, boolean alreadyOnRow, long start, Function... show) throws SQLException {
	final ResultSetMetaData meta = rs.getMetaData();

	final Function[] columnMap;
	if (show != null && 0 < show.length) {
	columnMap = show;

	} else {
	final int colCnt = meta.getColumnCount();
	columnMap = new Function[colCnt];
	for (int colId = 0; colId < colCnt; colId++) {
	final int p = colId + 1;
	final String name = meta.getColumnLabel(p);
	columnMap[colId] = new Identity(p, name);
	}
	}

	final int colCnt = columnMap.length;
	final int[] widths = new int[colCnt];
	for (int c = 0; c < colCnt; c++) {
	widths[c] = columnMap[c].name.length();
	}

	final List<String[]> rows = new ArrayList<>();
	while (alreadyOnRow \|\| rs.next()) {
	final String[] row = new String[columnMap.length];
	for (int c = 0; c < colCnt; c++) {
	row[c] = columnMap[c].apply(rs);
	if (row[c] == null) {
	row[c] = "NULL";
	}
	widths[c] = Math.max(widths[c], row[c].length());
	}
	rows.add(row);
	alreadyOnRow = false;
	}

	final StringBuilder b = new StringBuilder();
	for (int c = 0; c < colCnt; c++) {
	if (0 < c) {
	b.append(" \| ");
	}

	String n = columnMap[c].name;
	if (widths[c] < n.length()) {
	n = n.substring(0, widths[c]);
	}
	b.append(n);

	if (c < colCnt - 1) {
	for (int pad = n.length(); pad < widths[c]; pad++) {
	b.append(' ');
	}
	}
	}
	println(" " + b.toString());

	b.setLength(0);
	for (int c = 0; c < colCnt; c++) {
	if (0 < c) {
	b.append("-+-");
	}
	for (int pad = 0; pad < widths[c]; pad++) {
	b.append('-');
	}
	}
	println(" " + b.toString());

	boolean dataTruncated = false;
	for (String[] row : rows) {
	b.setLength(0);
	b.append(' ');

	for (int c = 0; c < colCnt; c++) {
	final int max = widths[c];
	if (0 < c) {
	b.append(" \| ");
	}

	String s = row[c];
	if (1 < colCnt && max < s.length()) {
	s = s.substring(0, max);
	dataTruncated = true;
	}
	b.append(s);

	if (c < colCnt - 1) {
	for (int pad = s.length(); pad < max; pad++) {
	b.append(' ');
	}
	}
	}
	println(b.toString());
	}

	if (dataTruncated) {
	warning("some column data was truncated");
	}

	if (start != 0) {
	final int rowCount = rows.size();
	final long ms = TimeUtil.nowMs() - start;
	println("(" + rowCount + (rowCount == 1 ? " row" : " rows") + "; " + ms + " ms)");
	}
	}

	private void warning(final String msg) {
	switch (outputFormat) {
	case JSON_SINGLE:
	case JSON:
	{
	final JsonObject obj = new JsonObject();
	obj.addProperty("type", "warning");
	obj.addProperty("message", msg);
	println(obj.toString());
	break;
	}

	case PRETTY:
	default:
	println("WARNING: " + msg);
	break;
	}
	}

	private void error(final SQLException err) {
	switch (outputFormat) {
	case JSON_SINGLE:
	case JSON:
	{
	final JsonObject obj = new JsonObject();
	obj.addProperty("type", "error");
	obj.addProperty("message", err.getMessage());
	println(obj.toString());
	break;
	}

	case PRETTY:
	default:
	println("ERROR: " + err.getMessage());
	break;
	}
	}

	private void print(String s) {
	out.print(s);
	out.flush();
	}

	private void println(String s) {
	out.print(s);
	out.print('\n');
	out.flush();
	}

	private String readLine() {
	try {
	return in.readLine();
	} catch (IOException e) {
	return null;
	}
	}

	private void showBanner() {
	if (outputFormat == OutputFormat.PRETTY) {
	println("Welcome to Gerrit Code Review " + Version.getVersion());
	try {
	print("(");
	print(connection.getMetaData().getDatabaseProductName());
	print(" ");
	print(connection.getMetaData().getDatabaseProductVersion());
	println(")");
	} catch (SQLException err) {
	error(err);
	}
	println("");
	println("Type '\\h' for help. Type '\\r' to clear the buffer.");
	println("");
	}
	}

	private void showHelp() {
	final StringBuilder help = new StringBuilder();
	help.append("General\n");
	help.append(" \\q quit\n");

	help.append("\n");
	help.append("Query Buffer\n");
	help.append(" \\g execute the query buffer\n");
	help.append(" \\p display the current buffer\n");
	help.append(" \\r clear the query buffer\n");

	help.append("\n");
	help.append("Informational\n");
	help.append(" \\d list all tables\n");
	help.append(" \\d NAME describe table\n");

	help.append("\n");
	print(help.toString());
	}

	private abstract static class Function {
	final String name;

	Function(final String name) {
	this.name = name;
	}

	abstract String apply(ResultSet rs) throws SQLException;
	}

	private static class Identity extends Function {
	static Identity create(final ResultSet rs, final String name) throws SQLException {
	return new Identity(rs.findColumn(name), name);
	}

	final int colId;

	Identity(final int colId, final String name) {
	super(name);
	this.colId = colId;
	}

	@Override
	String apply(final ResultSet rs) throws SQLException {
	return rs.getString(colId);
	}
	}

	private static class IndexInfo {
	String name;
	boolean unique;
	final Map<Integer, String> columns = new TreeMap<>();
	final StringBuilder filter = new StringBuilder();

	void addColumn(int pos, String column) {
	columns.put(Integer.valueOf(pos), column);
	}

	@Override
	public String toString() {
	final StringBuilder r = new StringBuilder();
	r.append(name);
	if (unique) {
	r.append(" UNIQUE");
	}
	r.append(" (");
	boolean first = true;
	for (String c : columns.values()) {
	if (!first) {
	r.append(", ");
	}
	r.append(c);
	first = false;
	}
	r.append(")");
	if (filter.length() > 0) {
	r.append(" WHERE ");
	r.append(filter);
	}
	return r.toString();
	}
	}
	}