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kai-niemikai-niemi
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Update plain jdbc example
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11 files changed

+357
-283
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11 files changed

+357
-283
lines changed

‎roach-data-jdbc-plain/src/main/java/io/roach/data/jdbc/plain/Account.java‎

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package io.roach.data.jdbc.plain;
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import java.math.BigDecimal;
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public class Account {
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String name;
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BigDecimal amount;
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Account(String name, BigDecimal amount) {
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this.name = name;
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this.amount = amount;
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}
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}

‎roach-data-jdbc-plain/src/main/java/io/roach/data/jdbc/plain/ConnectionCallback.java‎

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package io.roach.data.jdbc.plain;
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import java.sql.Connection;
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import java.sql.SQLException;
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interface ConnectionCallback<T> {
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T doInConnection(Connection conn) throws SQLException;
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}

‎roach-data-jdbc-plain/src/main/java/io/roach/data/jdbc/plain/ConnectionTemplate.java‎

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package io.roach.data.jdbc.plain;
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import java.lang.reflect.UndeclaredThrowableException;
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import java.sql.Connection;
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import java.sql.SQLException;
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import javax.sql.DataSource;
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public abstract class ConnectionTemplate {
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public static <T> T execute(DataSource ds,
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ConnectionCallback<T> action) {
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try (Connection conn = ds.getConnection()) {
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T result;
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try {
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result = action.doInConnection(conn);
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} catch (RuntimeException | Error ex) {
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throw ex;
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} catch (Throwable ex) {
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throw new UndeclaredThrowableException(ex,
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"TransactionCallback threw undeclared checked exception");
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}
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return result;
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} catch (SQLException e) {
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throw new DataAccessException(e);
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}
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}
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}

‎roach-data-jdbc-plain/src/main/java/io/roach/data/jdbc/plain/DataAccessException.java‎

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package io.roach.data.jdbc.plain;
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public class DataAccessException extends RuntimeException {
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public DataAccessException(String message) {
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super(message);
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}
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public DataAccessException(Throwable cause) {
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super(cause);
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}
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}

‎roach-data-jdbc-plain/src/main/java/io/roach/data/jdbc/plain/PlainJdbcApplication.java‎

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package io.roach.data.jdbc.plain;
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import java.math.BigDecimal;
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import java.sql.Connection;
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import java.sql.PreparedStatement;
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import java.sql.ResultSet;
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import java.sql.SQLException;
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import java.util.ArrayDeque;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Deque;
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import java.util.List;
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import java.util.concurrent.ExecutionException;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import java.util.concurrent.Future;
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import java.util.concurrent.ThreadLocalRandom;
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import java.util.stream.IntStream;
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import javax.sql.DataSource;
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import com.zaxxer.hikari.HikariDataSource;
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import net.ttddyy.dsproxy.support.ProxyDataSourceBuilder;
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public class PlainJdbcApplication {
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private static class BusinessException extends RuntimeException {
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public BusinessException(String message) {
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super(message);
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}
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}
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private static TransactionCallback<BigDecimal> transfer(List<Account> legs) {
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return conn -> {
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BigDecimal total = BigDecimal.ZERO;
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BigDecimal checksum = BigDecimal.ZERO;
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for (Account leg : legs) {
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BigDecimal balance = readBalance(conn, leg.name);
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updateBalance(conn, leg.name, balance.add(leg.amount));
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checksum = checksum.add(leg.amount);
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total = total.add(leg.amount.abs());
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}
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if (checksum.compareTo(BigDecimal.ZERO) != 0) {
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throw new BusinessException(
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"Sum of account legs must equal 0 (got " + checksum.toPlainString() + ")"
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);
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}
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return total;
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};
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}
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private static List<String> readAccountNames(Connection conn) throws SQLException {
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List<String> names = new ArrayList<>();
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try (PreparedStatement ps = conn.prepareStatement("SELECT name FROM account")) {
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try (ResultSet res = ps.executeQuery()) {
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while (res.next()) {
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names.add(res.getString(1));
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}
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}
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}
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return names;
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}
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private static BigDecimal readBalance(Connection conn, String name) throws SQLException {
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try (PreparedStatement ps = conn.prepareStatement("SELECT balance FROM account WHERE name = ?")) {
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ps.setString(1, name);
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try (ResultSet res = ps.executeQuery()) {
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if (!res.next()) {
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throw new BusinessException("Account not found: " + name);
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}
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return res.getBigDecimal("balance");
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}
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}
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}
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private static void updateBalance(Connection conn, String name, BigDecimal balance) throws SQLException {
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try (PreparedStatement ps = conn
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.prepareStatement(
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"UPDATE account SET balance = ?, updated=clock_timestamp() where name = ?")) {
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ps.setBigDecimal(1, balance);
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ps.setString(2, name);
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if (ps.executeUpdate() != 1) {
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throw new DataAccessException("Rows affected != 1 for " + name);
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}
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}
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}
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private static BigDecimal readTotalBalance(Connection conn) throws SQLException {
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try (PreparedStatement ps = conn.prepareStatement(
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"select sum(balance) balance from account")) {
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try (ResultSet res = ps.executeQuery()) {
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if (!res.next()) {
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throw new SQLException("Empty result");
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}
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return res.getBigDecimal("balance");
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}
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}
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}
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public static void main(String[] args) throws Exception {
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int workers = Runtime.getRuntime().availableProcessors();
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final HikariDataSource hikariDS = new HikariDataSource();
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hikariDS.setJdbcUrl("jdbc:postgresql://localhost:26257/roach_data?sslmode=disable");
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hikariDS.setUsername("root");
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hikariDS.setAutoCommit(true);
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hikariDS.setMaximumPoolSize(workers);
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hikariDS.setMinimumIdle(workers);
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boolean enableProxy = Arrays.asList(args).contains("--enable-proxy");
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DataSource ds = enableProxy ?
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ProxyDataSourceBuilder
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.create(hikariDS)
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.asJson()
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.logQueryBySlf4j()
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.build() : hikariDS;
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SchemaSupport.setupSchema(ds);
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ConnectionTemplate.execute(ds, PlainJdbcApplication::readAccountNames).forEach(name -> {
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System.out.printf("Balance before for %s: %s\n", name,
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ConnectionTemplate.execute(ds, c -> readBalance(c, name)));
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});
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final BigDecimal initialBalance = ConnectionTemplate.execute(ds, PlainJdbcApplication::readTotalBalance);
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System.out.printf("Total balance before: %s\n", initialBalance);
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// Run concurrently for more exiting effects
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final ExecutorService executorService = Executors.newFixedThreadPool(workers);
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final Deque<Future<BigDecimal>> futures = new ArrayDeque<>();
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final int iterations = 200;
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final ThreadLocalRandom random = ThreadLocalRandom.current();
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IntStream.rangeClosed(1, iterations).forEach(
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value -> futures.add(executorService.submit(() -> {
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List<Account> legs = new ArrayList<>();
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IntStream.rangeClosed(1, 4).forEach(leg -> {
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String from = "customer:" + random.nextInt(1, 100);
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String to = "customer:" + random.nextInt(1, 100);
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if (!from.equals(to)) {
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BigDecimal amt = new BigDecimal("0.15");
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legs.add(new Account(from, amt));
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legs.add(new Account(to, amt.negate()));
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}
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});
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System.out.printf("\r%,8d/%d", value, iterations);
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return TransactionTemplate.execute(ds, transfer(legs));
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}
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)));
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int success = 0;
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int fail = 0;
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BigDecimal total = BigDecimal.ZERO;
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while (!futures.isEmpty()) {
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System.out.printf("Awaiting completion (%d futures)\n", futures.size());
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try {
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BigDecimal tot = futures.pop().get();
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total = total.add(tot);
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success++;
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} catch (InterruptedException e) {
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Thread.currentThread().interrupt();
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break;
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} catch (ExecutionException e) {
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e.getCause().printStackTrace();
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fail++;
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}
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}
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executorService.shutdownNow();
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ConnectionTemplate.execute(ds, PlainJdbcApplication::readAccountNames).forEach(name -> {
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System.out.printf("Balance after for %s: %s\n", name,
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ConnectionTemplate.execute(ds, c -> readBalance(c, name)));
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});
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final BigDecimal finalBalance = ConnectionTemplate.execute(ds, PlainJdbcApplication::readTotalBalance);
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System.out.printf("Transaction success: %d\n", success);
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System.out.printf("Transaction fail: %d\n", fail);
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System.out.printf("Total turnover: %s\n", total);
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System.out.printf("Total balance before: %s\n", initialBalance);
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System.out.printf("Total balance after: %s\n", finalBalance);
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if (!finalBalance.equals(initialBalance)) {
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System.out.println("Balance invariant violation! (╯°□°)╯︵ ┻━┻");
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System.out.printf("Lost funds: %s\n", initialBalance.subtract(finalBalance));
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}
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}
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}

‎roach-data-jdbc-plain/src/main/java/io/roach/data/jdbc/plain/SchemaSupport.java‎

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package io.roach.data.jdbc.plain;
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import java.net.URL;
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import java.nio.file.Files;
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import java.nio.file.Paths;
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import java.sql.Statement;
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import javax.sql.DataSource;
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public abstract class SchemaSupport {
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private SchemaSupport() {
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}
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public static void setupSchema(DataSource ds) throws Exception {
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URL sql = PlainJdbcApplication.class.getResource("/db/create.sql");
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StringBuilder buffer = new StringBuilder();
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Files.readAllLines(Paths.get(sql.toURI())).forEach(line -> {
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if (!line.startsWith("--") && !line.isEmpty()) {
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buffer.append(line);
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}
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if (line.endsWith(";") && buffer.length() > 0) {
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ConnectionTemplate.execute(ds, conn -> {
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try (Statement statement = conn.createStatement()) {
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statement.execute(buffer.toString());
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}
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buffer.setLength(0);
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return null;
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});
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}
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});
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}
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}

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