merge: Add support for trace writing

This pull request extends the trace API to support writing new traces.

- Unify columns of different tables 
- Support column lookup via index
- Use index lookup in trace loader 
- Add property for describing partition keys
- Simplify TraceFormat SPI interface
- Add support for writing traces

**Breaking API Changes**

- `TraceFormat` SPI interface has been redesigned.

1 files changed, 101 insertions, 6 deletions

diff --git a/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/TableReader.kt b/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/TableReader.kt
index b5e7669f..8a796e6c 100644
--- a/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/TableReader.kt
+++ b/opendc-trace/opendc-trace-api/src/main/kotlin/org/opendc/trace/TableReader.kt
@@ -34,34 +34,129 @@ public interface TableReader : AutoCloseable {
     public fun nextRow(): Boolean
 
     /**
+     * Resolve the index of the specified [column] for this reader.
+     *
+     * @param column The column to lookup.
+     * @return The zero-based index of the column or a negative value if the column is not present in this table.
+     */
+    public fun resolve(column: TableColumn<*>): Int
+
+    /**
      * Determine whether the [TableReader] supports the specified [column].
      */
-    public fun hasColumn(column: TableColumn<*>): Boolean
+    public fun hasColumn(column: TableColumn<*>): Boolean = resolve(column) >= 0
+
+    /**
+     * Determine whether the specified [column] has a `null` value for the current row.
+     *
+     * @param index The zero-based index of the column to check for a null value.
+     * @throws IllegalArgumentException if the column index is not valid for this reader.
+     * @return `true` if the column value for the current value has a `null` value, `false` otherwise.
+     */
+    public fun isNull(index: Int): Boolean
+
+    /**
+     * Obtain the object value of the column with the specified [index].
+     *
+     * @param index The zero-based index of the column to obtain the value for.
+     * @throws IllegalArgumentException if the column index is not valid for this reader.
+     * @return The object value of the column.
+     */
+    public fun get(index: Int): Any?
+
+    /**
+     * Obtain the boolean value of the column with the specified [index].
+     *
+     * @param index The zero-based index of the column to obtain the value for.
+     * @throws IllegalArgumentException if the column index is not valid for this reader.
+     * @return The boolean value of the column or `false` if the column is `null`.
+     */
+    public fun getBoolean(index: Int): Boolean
+
+    /**
+     * Obtain the integer value of the column with the specified [index].
+     *
+     * @param index The zero-based index of the column to obtain the value for.
+     * @throws IllegalArgumentException if the column index is not valid for this reader.
+     * @return The integer value of the column or `0` if the column is `null`.
+     */
+    public fun getInt(index: Int): Int
+
+    /**
+     * Obtain the double value of the column with the specified [index].
+     *
+     * @param index The zero-based index of the column to obtain the value for.
+     * @throws IllegalArgumentException if the column index is not valid for this reader.
+     * @return The long value of the column or `0` if the column is `null`.
+     */
+    public fun getLong(index: Int): Long
+
+    /**
+     * Obtain the double value of the column with the specified [index].
+     *
+     * @param index The zero-based index of the column to obtain the value for.
+     * @throws IllegalArgumentException if the column index is not valid for this reader.
+     * @return The double value of the column or [Double.NaN] if the column is `null`.
+     */
+    public fun getDouble(index: Int): Double
+
+    /**
+     * Determine whether the specified [column] has a `null` value for the current row.
+     *
+     * @param column The column to lookup.
+     * @throws IllegalArgumentException if the column is not valid for this table.
+     * @return `true` if the column value for the current value has a `null` value, `false` otherwise.
+     */
+    public fun isNull(column: TableColumn<*>): Boolean = isNull(resolve(column))
 
     /**
      * Obtain the value of the current column with type [T].
+     *
+     * @param column The column to obtain the value for.
+     * @throws IllegalArgumentException if the column is not valid for this reader.
+     * @return The object value of the column.
      */
-    public fun <T> get(column: TableColumn<T>): T
+    public fun <T> get(column: TableColumn<T>): T {
+        // This cast should always succeed since the resolve the index of the typed column
+        @Suppress("UNCHECKED_CAST")
+        return get(resolve(column)) as T
+    }
 
     /**
      * Read the specified [column] as boolean.
+     *
+     * @param column The column to obtain the value for.
+     * @throws IllegalArgumentException if the column is not valid for this reader.
+     * @return The boolean value of the column or `false` if the column is `null`.
      */
-    public fun getBoolean(column: TableColumn<Boolean>): Boolean
+    public fun getBoolean(column: TableColumn<Boolean>): Boolean = getBoolean(resolve(column))
 
     /**
      * Read the specified [column] as integer.
+     *
+     * @param column The column to obtain the value for.
+     * @throws IllegalArgumentException if the column is not valid for this reader.
+     * @return The integer value of the column or `0` if the column is `null`.
      */
-    public fun getInt(column: TableColumn<Int>): Int
+    public fun getInt(column: TableColumn<Int>): Int = getInt(resolve(column))
 
     /**
      * Read the specified [column] as long.
+     *
+     * @param column The column to obtain the value for.
+     * @throws IllegalArgumentException if the column is not valid for this reader.
+     * @return The long value of the column or `0` if the column is `null`.
      */
-    public fun getLong(column: TableColumn<Long>): Long
+    public fun getLong(column: TableColumn<Long>): Long = getLong(resolve(column))
 
     /**
      * Read the specified [column] as double.
+     *
+     * @param column The column to obtain the value for.
+     * @throws IllegalArgumentException if the column is not valid for this reader.
+     * @return The double value of the column or [Double.NaN] if the column is `null`.
      */
-    public fun getDouble(column: TableColumn<Double>): Double
+    public fun getDouble(column: TableColumn<Double>): Double = getDouble(resolve(column))
 
     /**
      * Closes the reader so that no further iteration or data access can be made.