Convert Dialect to interface, fix race condition in migration code

transactionoutbox-core/src/main/java/com/gruelbox/transactionoutbox/DefaultDialect.java

@@ -0,0 +1,160 @@
+package com.gruelbox.transactionoutbox;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.Collection;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.function.Function;
+import java.util.stream.Stream;
+import lombok.AccessLevel;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.Setter;
+import lombok.experimental.Accessors;
+
+@AllArgsConstructor(access = AccessLevel.PRIVATE)
+class DefaultDialect implements Dialect {
+
+  static Builder builder(String name) {
+    return new Builder(name);
+  }
+
+  @Getter private final String name;
+  @Getter private final boolean supportsSkipLock;
+  @Getter private final String deleteExpired;
+  @Getter private final String limitCriteria;
+  @Getter private final String checkSql;
+  private final Collection<Migration> migrations;
+
+  @Override
+  public String booleanValue(boolean criteriaValue) {
+    return criteriaValue ? Boolean.TRUE.toString() : Boolean.FALSE.toString();
+  }
+
+  @Override
+  public void createVersionTableIfNotExists(Connection connection) throws SQLException {
+    try (Statement s = connection.createStatement()) {
+      s.execute(
+          "CREATE TABLE IF NOT EXISTS TXNO_VERSION (id INT DEFAULT 0, version INT, PRIMARY KEY (id))");
+    }
+  }
+
+  @Override
+  public String toString() {
+    return name;
+  }
+
+  @Override
+  public Stream<Migration> getMigrations() {
+    return migrations.stream();
+  }
+
+  @Setter
+  @Accessors(fluent = true)
+  static final class Builder {
+    private final String name;
+    private boolean supportsSkipLock = false;
+    private String deleteExpired =
+        "DELETE FROM {{table}} WHERE nextAttemptTime < ? AND processed = true AND blocked = false LIMIT ?";
+    private String limitCriteria = " LIMIT ?";
+    private String checkSql = "SELECT 1";
+    private Map<Integer, Migration> migrations;
+    private Function<Boolean, String> booleanValueFrom;
+    private SQLAction createVersionTableBy;
+
+    Builder(String name) {
+      this.name = name;
+      this.migrations = new TreeMap<>();
+      migrations.put(
+          1,
+          new Migration(
+              1,
+              "Create outbox table",
+              "CREATE TABLE TXNO_OUTBOX (\n"
+                  + "    id VARCHAR(36) PRIMARY KEY,\n"
+                  + "    invocation TEXT,\n"
+                  + "    nextAttemptTime TIMESTAMP(6),\n"
+                  + "    attempts INT,\n"
+                  + "    blacklisted BOOLEAN,\n"
+                  + "    version INT\n"
+                  + ")"));
+      migrations.put(
+          2,
+          new Migration(
+              2,
+              "Add unique request id",
+              "ALTER TABLE TXNO_OUTBOX ADD COLUMN uniqueRequestId VARCHAR(100) NULL UNIQUE"));
+      migrations.put(
+          3,
+          new Migration(
+              3, "Add processed flag", "ALTER TABLE TXNO_OUTBOX ADD COLUMN processed BOOLEAN"));
+      migrations.put(
+          4,
+          new Migration(
+              4,
+              "Add flush index",
+              "CREATE INDEX IX_TXNO_OUTBOX_1 ON TXNO_OUTBOX (processed, blacklisted, nextAttemptTime)"));
+      migrations.put(
+          5,
+          new Migration(
+              5,
+              "Increase size of uniqueRequestId",
+              "ALTER TABLE TXNO_OUTBOX MODIFY COLUMN uniqueRequestId VARCHAR(250)"));
+      migrations.put(
+          6,
+          new Migration(
+              6,
+              "Rename column blacklisted to blocked",
+              "ALTER TABLE TXNO_OUTBOX CHANGE COLUMN blacklisted blocked VARCHAR(250)"));
+      migrations.put(
+          7,
+          new Migration(
+              7,
+              "Add lastAttemptTime column to outbox",
+              "ALTER TABLE TXNO_OUTBOX ADD COLUMN lastAttemptTime TIMESTAMP(6) NULL AFTER invocation"));
+      migrations.put(
+          8,
+          new Migration(
+              8,
+              "Update length of invocation column on outbox for MySQL dialects only.",
+              "ALTER TABLE TXNO_OUTBOX MODIFY COLUMN invocation MEDIUMTEXT"));
+    }
+
+    Builder setMigration(Migration migration) {
+      this.migrations.put(migration.getVersion(), migration);
+      return this;
+    }
+
+    Builder changeMigration(int version, String sql) {
+      return setMigration(this.migrations.get(version).withSql(sql));
+    }
+
+    Builder disableMigration(@SuppressWarnings("SameParameterValue") int version) {
+      return setMigration(this.migrations.get(version).withSql(null));
+    }
+
+    Dialect build() {
+      return new DefaultDialect(
+          name, supportsSkipLock, deleteExpired, limitCriteria, checkSql, migrations.values()) {
+        @Override
+        public String booleanValue(boolean criteriaValue) {
+          if (booleanValueFrom != null) {
+            return booleanValueFrom.apply(criteriaValue);
+          }
+          return super.booleanValue(criteriaValue);
+        }
+
+        @Override
+        public void createVersionTableIfNotExists(Connection connection) throws SQLException {
+          if (createVersionTableBy != null) {
+            createVersionTableBy.doAction(connection);
+          } else {
+            super.createVersionTableIfNotExists(connection);
+          }
+        }
+      };
+    }
+  }
+}