/*
 * Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
 * and the EPL 1.0 (https://h2database.com/html/license.html).
 * Initial Developer: H2 Group
 */
package org.h2.test.db;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Random;
import java.util.concurrent.TimeUnit;

import org.h2.api.ErrorCode;
import org.h2.test.TestBase;
import org.h2.test.TestDb;
import org.h2.util.Utils;

/**
 * Tests the memory usage of the cache.
 */
public class TestMemoryUsage extends TestDb {

    private Connection conn;

    /**
     * Run just this test.
     *
     * @param a ignored
     */
    public static void main(String... a) throws Exception {
        TestBase.createCaller().init().testFromMain();
    }

    @Override
    public void test() throws SQLException {
        testOpenCloseConnections();
        if (getBaseDir().indexOf(':') >= 0) {
            // can't test in-memory databases
            return;
        }
        // comment this out for now, not reliable when running on my 64-bit
        // Java1.8 VM
        // testCreateDropLoop();
        testCreateIndex();
        testClob();
        testReconnectOften();

        deleteDb("memoryUsage");
        reconnect();
        insertUpdateSelectDelete();
        reconnect();
        insertUpdateSelectDelete();
        conn.close();

        deleteDb("memoryUsage");
    }

    private void testOpenCloseConnections() throws SQLException {
        if (!config.big) {
            return;
        }
        deleteDb("memoryUsage");
        // to eliminate background thread interference
        conn = getConnection("memoryUsage;WRITE_DELAY=0");
        try {
            eatMemory(4000);
            for (int i = 0; i < 4000; i++) {
                Connection c2 = getConnection("memoryUsage");
                c2.createStatement();
                c2.close();
            }
        } finally {
            freeMemory();
            closeConnection(conn);
        }
    }

    private void testCreateDropLoop() throws SQLException {
        deleteDb("memoryUsageCreateDropLoop");
        conn = getConnection("memoryUsageCreateDropLoop");
        Statement stat = conn.createStatement();
        for (int i = 0; i < 100; i++) {
            stat.execute("CREATE TABLE TEST(ID INT)");
            stat.execute("DROP TABLE TEST");
        }
        stat.execute("checkpoint");
        long used = Utils.getMemoryUsed();
        for (int i = 0; i < 1000; i++) {
            stat.execute("CREATE TABLE TEST(ID INT PRIMARY KEY)");
            stat.execute("DROP TABLE TEST");
        }
        stat.execute("checkpoint");
        long usedNow = Utils.getMemoryUsed();
        if (usedNow > used * 1.3) {
            // try to lower memory usage (because it might be wrong)
            // by forcing OOME
            for (int i = 1024; i < (1 >> 31); i *= 2) {
                try {
                    byte[] oome = new byte[1024 * 1024 * 256];
                    oome[0] = (byte) i;
                } catch (OutOfMemoryError e) {
                    break;
                }
            }
            usedNow = Utils.getMemoryUsed();
            if (usedNow > used * 1.3) {
                assertEquals(used, usedNow);
            }
        }
        conn.close();
    }


    private void reconnect() throws SQLException {
        if (conn != null) {
            conn.close();
        }
        // Class.forName("org.hsqldb.jdbcDriver");
        // conn = DriverManager.getConnection("jdbc:hsqldb:test", "sa", "");
        conn = getConnection("memoryUsage");
    }

    private void testClob() throws SQLException {
        if (config.memory || !config.big) {
            return;
        }
        deleteDb("memoryUsageClob");
        conn = getConnection("memoryUsageClob;WRITE_DELAY=0");
        Statement stat = conn.createStatement();
        stat.execute("SET MAX_LENGTH_INPLACE_LOB 8192");
        stat.execute("SET CACHE_SIZE 8000");
        stat.execute("CREATE TABLE TEST(ID IDENTITY, DATA CLOB)");
        try {
            long base = Utils.getMemoryUsed();
            for (int i = 0; i < 4; i++) {
                stat.execute("INSERT INTO TEST(DATA) " +
                        "SELECT SPACE(8000) FROM SYSTEM_RANGE(1, 800)");
                long used = Utils.getMemoryUsed();
                if ((used - base) > 3 * 8192) {
                    fail("Used: " + (used - base) + " i: " + i);
                }
            }
        } finally {
            freeMemory();
            closeConnection(conn);
        }
    }

    /**
     * Closes the specified connection. It silently consumes OUT_OF_MEMORY that
     * may happen in background thread during the tests.
     *
     * @param conn connection to close
     * @throws SQLException on other SQL exception
     */
    private static void closeConnection(Connection conn) throws SQLException {
        try {
            conn.close();
        } catch (SQLException e) {
            if (e.getErrorCode() != ErrorCode.OUT_OF_MEMORY) {
                throw e;
            }
        }
    }

    private void testCreateIndex() throws SQLException {
        if (config.memory) {
            return;
        }
        deleteDb("memoryUsage");
        conn = getConnection("memoryUsage");
        Statement stat = conn.createStatement();
        stat.execute("create table test(id int, name varchar(255))");
        PreparedStatement prep = conn.prepareStatement(
                "insert into test values(?, space(200))");
        int len = getSize(10000, 100000);
        for (int i = 0; i < len; i++) {
            if (i % 1000 == 0) {
                // trace("[" + i + "/" + len + "] KB: " +
                //         MemoryUtils.getMemoryUsed());
            }
            prep.setInt(1, i);
            prep.executeUpdate();
        }
        long base = Utils.getMemoryUsed();
        stat.execute("create index idx_test_id on test(id)");
        for (int i = 0;; i++) {
            System.gc();
            long used = Utils.getMemoryUsed() - base;
            if (used <= getSize(7500, 12000)) {
                break;
            }
            if (i < 16) {
                continue;
            }
            fail("Used: " + used);
        }
        stat.execute("drop table test");
        conn.close();
    }

    private void testReconnectOften() throws SQLException {
        deleteDb("memoryUsage");
        Connection conn1 = getConnection("memoryUsage");
        int len = getSize(1, 2000);
        printTimeMemory("start", 0);
        long time = System.nanoTime();
        for (int i = 0; i < len; i++) {
            Connection conn2 = getConnection("memoryUsage");
            conn2.close();
            if (i % 10000 == 0) {
                printTimeMemory("connect",
                        TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - time));
            }
        }
        printTimeMemory("connect",
                TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - time));
        conn1.close();
    }

    private void insertUpdateSelectDelete() throws SQLException {
        Statement stat = conn.createStatement();
        long time;
        int len = getSize(1, 2000);

        // insert
        time = System.nanoTime();
        stat.execute("DROP TABLE IF EXISTS TEST");
        trace("drop=" + TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - time));
        stat.execute("CREATE CACHED TABLE TEST(ID INT PRIMARY KEY, NAME VARCHAR(255))");
        PreparedStatement prep = conn.prepareStatement(
                "INSERT INTO TEST VALUES(?, 'Hello World')");
        printTimeMemory("start", 0);
        time = System.nanoTime();
        for (int i = 0; i < len; i++) {
            prep.setInt(1, i);
            prep.execute();
            if (i % 50000 == 0) {
                trace("  " + (100 * i / len) + "%");
            }
        }
        printTimeMemory("insert", TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - time));

        // update
        time = System.nanoTime();
        prep = conn.prepareStatement(
                "UPDATE TEST SET NAME='Hallo Welt' || ID WHERE ID = ?");
        for (int i = 0; i < len; i++) {
            prep.setInt(1, i);
            prep.execute();
            if (i % 50000 == 0) {
                trace("  " + (100 * i / len) + "%");
            }
        }
        printTimeMemory("update", TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - time));

        // select
        time = System.nanoTime();
        prep = conn.prepareStatement("SELECT * FROM TEST WHERE ID = ?");
        for (int i = 0; i < len; i++) {
            prep.setInt(1, i);
            ResultSet rs = prep.executeQuery();
            rs.next();
            assertFalse(rs.next());
            if (i % 50000 == 0) {
                trace("  " + (100 * i / len) + "%");
            }
        }
        printTimeMemory("select",
                TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - time));

        // select randomized
        Random random = new Random(1);
        time = System.nanoTime();
        prep = conn.prepareStatement("SELECT * FROM TEST WHERE ID = ?");
        for (int i = 0; i < len; i++) {
            prep.setInt(1, random.nextInt(len));
            ResultSet rs = prep.executeQuery();
            rs.next();
            assertFalse(rs.next());
            if (i % 50000 == 0) {
                trace("  " + (100 * i / len) + "%");
            }
        }
        printTimeMemory("select randomized",
                TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - time));

        // delete
        time = System.nanoTime();
        prep = conn.prepareStatement("DELETE FROM TEST WHERE ID = ?");
        for (int i = 0; i < len; i++) {
            prep.setInt(1, random.nextInt(len));
            prep.executeUpdate();
            if (i % 50000 == 0) {
                trace("  " + (100 * i / len) + "%");
            }
        }
        printTimeMemory("delete",
                TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - time));
    }

}
