Struct MeteredJsonHandler 

pub struct MeteredJsonHandler { /* private fields */ }

Decorator over an engine-provided Arc<dyn JsonHandler> that emits a JsonReadCompleted span on every read_json_files call. parse_json and write_json_file are pass-through and emit nothing.

Implementations

impl MeteredJsonHandler

pub fn new(inner: Arc<dyn JsonHandler>) -> Self

Wrap inner. Debug-asserts that inner is not already a MeteredJsonHandler so spans are emitted exactly once.

Trait Implementations

impl Debug for MeteredJsonHandler

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl JsonHandler for MeteredJsonHandler

fn parse_json( &self, json_strings: Box<dyn EngineData>, output_schema: SchemaRef, ) -> DeltaResult<Box<dyn EngineData>>

Parse the given json strings and return the fields requested by output schema as columns in EngineData. json_strings MUST be a single column batch of engine data, and the column type must be string

fn read_json_files( &self, files: &[FileMeta], physical_schema: SchemaRef, predicate: Option<PredicateRef>, ) -> DeltaResult<FileDataReadResultIterator>

Read and parse the JSON format file at given locations and return the data as EngineData with the columns requested by physical schema. Note: The FileDataReadResultIterator must emit data from files in the order that files is given. For example if files [“a”, “b”] is provided, then the engine data iterator must first return all the engine data from file “a”, then all the engine data from file “b”. Moreover, for a given file, all of its EngineData and constituent rows must be in order that they occur in the file. Consider a file with rows (1, 2, 3). The following are legal iterator batches: iter: [EngineData(1, 2), EngineData(3)] iter: [EngineData(1), EngineData(2, 3)] iter: [EngineData(1, 2, 3)] The following are illegal batches: iter: [EngineData(3), EngineData(1, 2)] iter: [EngineData(1), EngineData(3, 2)] iter: [EngineData(2, 1, 3)]

fn read_json_files_with_cancellation( &self, files: &[FileMeta], physical_schema: SchemaRef, predicate: Option<PredicateRef>, cancellation_token: Option<CancellationTokenRef>, ) -> DeltaResult<FileDataReadResultIterator>

Cancellation-aware variant of read_json_files.

fn write_json_file( &self, path: &Url, data: DeltaResultIterator<'_, FilteredEngineData>, overwrite: bool, ) -> DeltaResult<()>

Atomically (!) write a single JSON file. Each selected row of the input data must be written as a new JSON object appended to the file; rows not selected by a batch’s selection vector (see FilteredEngineData) must not be written. FilteredEngineData::apply_selection_vector produces the selected-rows view for implementations that do not filter during serialization. This write must: (1) serialize the selected rows to newline-delimited json (each row is a json object literal) (2) write the data to storage atomically (i.e. if the file already exists, fail unless the overwrite flag is set)