[AURON-1307] Add docs comments to the method in filter_exec.rs and ff…

native-engine/datafusion-ext-plans/src/ffi_reader_exec.rs

@@ -141,6 +141,44 @@ impl ExecutionPlan for FFIReaderExec {
     }
 }
 
+/// Reads Arrow data from a Java-side exporter via FFI (Foreign Function
+/// Interface).
+///
+/// This function establishes a bridge between Java and Rust to read Arrow data
+/// efficiently using the Arrow C Data Interface. It continuously fetches record
+/// batches from the Java exporter, converts them from FFI format to native Rust
+/// Arrow format, and streams them back to the execution engine.
+///
+/// # Arguments
+///
+/// * `schema` - The Arrow schema reference defining the structure of the data
+/// * `exporter` - A JNI global reference to the Java-side Arrow FFI exporter
+///   object
+/// * `exec_ctx` - The execution context for metrics collection and stream
+///   management
+///
+/// # Returns
+///
+/// Returns a `Result<SendableRecordBatchStream>` containing a stream of record
+/// batches on success, or an error if the FFI operation fails.
+///
+/// # Behavior
+///
+/// - Continuously polls the Java exporter for new batches until no more data is
+///   available
+/// - Converts FFI Arrow arrays to native Rust Arrow data structures
+/// - Tracks memory usage and output row counts via metrics
+/// - Automatically closes the Java exporter resource when the stream ends or
+///   fails
+/// - Processes batches asynchronously using tokio's blocking task spawning
+///
+/// # FFI Safety
+///
+/// This function uses unsafe operations to convert FFI Arrow data. The safety
+/// is ensured by:
+/// - Proper FFI Arrow array initialization and cleanup
+/// - Correct data type matching between Java and Rust sides
+/// - Automatic resource management through RAII patterns
 fn read_ffi(
     schema: SchemaRef,
     exporter: GlobalRef,

native-engine/datafusion-ext-plans/src/filter_exec.rs

@@ -171,6 +171,32 @@ impl ExecuteWithColumnPruning for FilterExec {
     }
 }
 
+/// Executes filtering operation on the input record batch stream.
+///
+/// This function applies the provided predicates to filter records from the
+/// input stream. It uses a cached expression evaluator for efficient predicate
+/// evaluation and returns a filtered stream containing only records that
+/// satisfy all predicates.
+///
+/// # Arguments
+///
+/// * `input` - The input record batch stream to be filtered
+/// * `predicates` - A vector of physical expressions representing filter
+///   predicates
+/// * `exec_ctx` - The execution context containing metrics and runtime
+///   information
+///
+/// # Returns
+///
+/// Returns a `Result<SendableRecordBatchStream>` containing the filtered record
+/// batch stream on success, or an error if the filtering operation fails.
+///
+/// # Behavior
+///
+/// - Evaluates all predicates against each record batch in the input stream
+/// - Records metrics for computation time and output record counts
+/// - Processes batches asynchronously while maintaining order
+/// - Only includes records that satisfy all provided predicates
 fn execute_filter(
     mut input: SendableRecordBatchStream,
     predicates: Vec<PhysicalExprRef>,