Add enum, constants for data loader

data-loader/core/src/main/java/com/scalar/db/dataloader/core/Constants.java

@@ -0,0 +1,27 @@
+package com.scalar.db.dataloader.core;
+
+/** The constants that are used in the com.scalar.dataloader.core package */
+public class Constants {
+
+  public static final String IMPORT_LOG_ENTRY_STATUS_FIELD = "data_loader_import_status";
+  public static final String TABLE_LOOKUP_KEY_FORMAT = "%s.%s";
+
+  public static final String LOG_UPDATE_SUCCESS = "Row %s has been updated in table %s.%s";
+  public static final String LOG_INSERT_SUCCESS = "Row %s has been inserted into table %s.%s";
+  public static final String LOG_IMPORT_VALIDATION = "Validating data for line %s ...";
+  public static final String LOG_IMPORT_GET_DATA =
+      "Retrieving existing data record from database ...";
+  public static final String LOG_IMPORT_LINE_SUCCESS = "Row %s import is completed";
+  public static final String LOG_IMPORT_LINE_FAILED = "Row %s import has failed: %s";
+  public static final String LOG_IMPORT_COMPLETED =
+      "The import process has been completed. Please check the success and failed output files for a detailed report";
+
+  public static final String LOG_SCANNING_START = "Retrieving data from %s.%s table ...";
+  public static final String LOG_CONVERTING = "Converting %s.%s data to %s ...";
+  public static final String MISSING_CSV_HEADERS =
+      "Valid headers are not present or missing in the provided CSV file";
+  public static final String ERROR_MISSING_SOURCE_FIELD =
+      "the data mapping source field '%s' for table '%s' is missing in the json data record";
+  public static final String ABORT_TRANSACTION_STATUS =
+      "Transaction aborted as part of batch transaction aborted";
+}

data-loader/core/src/main/java/com/scalar/db/dataloader/core/DatabaseKeyType.java

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+package com.scalar.db.dataloader.core;
+
+/** Type of key in database */
+public enum DatabaseKeyType {
+  PARTITION,
+  CLUSTERING
+}

data-loader/core/src/main/java/com/scalar/db/dataloader/core/ScalarDBMode.java

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+package com.scalar.db.dataloader.core;
+
+/** The available modes a ScalarDB instance can run in */
+public enum ScalarDBMode {
+  STORAGE,
+  TRANSACTION
+}

data-loader/core/src/main/java/com/scalar/db/dataloader/core/ScanRange.java

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+package com.scalar.db.dataloader.core;
+
+import com.scalar.db.io.Key;
+import lombok.Value;
+
+/** * The scan range which is used in data export scan filtering */
+@Value
+public class ScanRange {
+  /** The key for scan start filter */
+  Key scanStartKey;
+  /** The key for scan end filter */
+  Key scanEndKey;
+  /** To include the scan start key value in the export data scan */
+  boolean isStartInclusive;
+  /** To include the scan end key value in the export data scan */
+  boolean isEndInclusive;
+}