feat: Add the in-commit timestamp field to CommitInfo

kernel/src/actions/mod.rs

@@ -331,8 +331,13 @@ where
 struct CommitInfo {
     /// The time this logical file was created, as milliseconds since the epoch.
     /// Read: optional, write: required (that is, kernel always writes).
-    /// If in-commit timestamps are enabled, this is always required.
     pub(crate) timestamp: Option<i64>,
+    /// The time this logical file was created, as milliseconds since the epoch. Unlike
+    /// `timestamp`, this field is guaranteed to be monotonically increase with each commit.
+    /// Note: If in-commit timestamps are enabled, both the following must be true:
+    /// - The `inCommitTimestamp` field must always be present in CommitInfo.
+    /// - The CommitInfo action must always be the first one in a commit.
+    pub(crate) in_commit_timestamp: Option<i64>,
     /// An arbitrary string that identifies the operation associated with this commit. This is
     /// specified by the engine. Read: optional, write: required (that is, kernel alwarys writes).
     pub(crate) operation: Option<String>,
@@ -694,6 +699,7 @@ mod tests {
             "commitInfo",
             StructType::new(vec![
                 StructField::new("timestamp", DataType::LONG, true),
+                StructField::new("inCommitTimestamp", DataType::LONG, true),
                 StructField::new("operation", DataType::STRING, true),
                 StructField::new(
                     "operationParameters",

kernel/src/transaction.rs

@@ -315,6 +315,12 @@ fn generate_commit_info(
         .get_mut("operationParameters")
         .ok_or_else(|| Error::missing_column("operationParameters"))?
         .data_type = hack_data_type;
+
+    // Since writing in-commit timestamps is not supported, we remove the field so it is not
+    // written to the log
+    commit_info_data_type
+        .fields
+        .shift_remove("inCommitTimestamp");
     commit_info_field.data_type = DataType::Struct(commit_info_data_type);
 
     let commit_info_evaluator = engine.get_expression_handler().get_evaluator(