Struct re_log_types::DataRow

pub struct DataRow {
    pub row_id: RowId,
    pub timepoint: TimePoint,
    pub entity_path: EntityPath,
    pub cells: DataCellRow,
}

A row’s worth of data, i.e. an event: a list of DataCells associated with an auto-generated RowId, a user-specified TimePoint and EntityPath, and an expected number of instances. This is the middle layer in our data model.

Behind the scenes, a DataRow is backed by a collection of independent DataCells which likely refer to unrelated/non-contiguous parts of the heap. Cloning a DataRow is not too costly but needs to be avoided on the happy path.

Field visibility

To facilitate destructuring (let DataRow { .. } = row), all the fields in DataRow are public.

Modifying any of these fields from outside this crate is considered undefined behavior. Use the appropriate getters and setters instead.

Layout

A row is a collection of cells where each cell can have an arbitrary number of instances: [[C1, C1, C1], [], [C3], [C4, C4, C4], …].

Consider this example:

let points: &[MyPoint] = &[[10.0, 10.0].into(), [20.0, 20.0].into()];
let colors: &[_] = &[MyColor::from_rgb(128, 128, 128)];
let labels: &[MyLabel] = &[];
let row = DataRow::from_cells3(row_id, timepoint, ent_path, (points, colors, labels));

A row has no arrow representation nor datatype of its own, as it is merely a collection of independent cells.

Visualized in the context of a larger table, it is simply a row of cells:

┌──────────────────────────────────┬─────────────────┬───────┐
│ Point2D                          ┆ Color           ┆ Text  │
╞══════════════════════════════════╪═════════════════╪═══════╡
│ [{x: 10, y: 10}, {x: 20, y: 20}] ┆ [2155905279]    ┆ []    │
└──────────────────────────────────┴─────────────────┴───────┘

Example

let points: &[MyPoint] = &[MyPoint { x: 10.0, y: 10.0}, MyPoint { x: 20.0, y: 20.0 }];
let colors: &[_] = &[MyColor(0xff7f7f7f)];
let labels: &[MyLabel] = &[];

let row = DataRow::from_cells3(
    row_id,
    "a/b/c",
    timepoint,
    (points, colors, labels),
).unwrap();
eprintln!("{row}");

Fields

row_id: RowId

Auto-generated TUID, uniquely identifying this event and keeping track of the client’s wall-clock.

timepoint: TimePoint

User-specified TimePoint for this event.

entity_path: EntityPath

User-specified EntityPath for this event.

cells: DataCellRow

The actual cells (== columns, == components).

Implementations

impl DataRow

pub fn from_archetype( row_id: RowId, timepoint: TimePoint, entity_path: EntityPath, as_components: &dyn AsComponents ) -> Result<Self>

Builds a new DataRow from anything implementing AsComponents.

pub fn from_component_batches<'a>( row_id: RowId, timepoint: TimePoint, entity_path: EntityPath, comp_batches: impl IntoIterator<Item = &'a dyn ComponentBatch> ) -> Result<Self>

Builds a new DataRow from anything implementing AsComponents.

pub fn from_cells( row_id: RowId, timepoint: impl Into<TimePoint>, entity_path: impl Into<EntityPath>, cells: impl IntoIterator<Item = DataCell> ) -> DataReadResult<Self>

Builds a new DataRow from an iterable of DataCells.

Fails if two or more cells share the same component type.

pub fn next(self) -> Self

Consumes the DataRow and returns a new one with an incremented RowId.

pub fn into_table(self) -> DataTable

Turns the DataRow into a single-row DataTable.

impl DataRow

pub fn row_id(&self) -> RowId

pub fn timepoint(&self) -> &TimePoint

pub fn entity_path(&self) -> &EntityPath

pub fn num_cells(&self) -> usize

pub fn component_names( &self ) -> impl ExactSizeIterator<Item = ComponentName> + '_

pub fn cells(&self) -> &DataCellRow

pub fn into_cells(self) -> DataCellRow

pub fn find_cell(&self, component: &ComponentName) -> Option<usize>

Returns the index of the cell with the given component type in the row, if it exists.

This is O(n).

pub fn compute_all_size_bytes(&mut self)

Compute and cache the total (heap) allocated size of each individual underlying DataCell. This does nothing for cells whose size has already been computed and cached before.

Beware: this is very costly!

impl DataRow

pub fn from_cells1_sized<C0>( row_id: RowId, entity_path: impl Into<EntityPath>, timepoint: impl Into<TimePoint>, into_cells: C0 ) -> DataReadResult<DataRow>

where C0: Into<DataCell>,

A helper that combines Self::from_cells1 followed by Self::compute_all_size_bytes.

See respective documentations for more information.

Beware: this is costly!

pub fn from_cells1<C0>( row_id: RowId, entity_path: impl Into<EntityPath>, timepoint: impl Into<TimePoint>, into_cells: C0 ) -> DataRowResult<DataRow>

where C0: TryInto<DataCell>, DataRowError: From<<C0 as TryInto<DataCell>>::Error>,

pub fn from_cells2_sized<C0, C1>( row_id: RowId, entity_path: impl Into<EntityPath>, timepoint: impl Into<TimePoint>, into_cells: (C0, C1) ) -> DataRowResult<DataRow>

where C0: Into<DataCell>, C1: Into<DataCell>,

A helper that combines Self::from_cells2 followed by Self::compute_all_size_bytes.

See respective documentations for more information.

Beware: this is costly!

pub fn from_cells2<C0, C1>( row_id: RowId, entity_path: impl Into<EntityPath>, timepoint: impl Into<TimePoint>, into_cells: (C0, C1) ) -> DataRowResult<DataRow>

where C0: TryInto<DataCell>, C1: TryInto<DataCell>, DataRowError: From<<C0 as TryInto<DataCell>>::Error> + From<<C1 as TryInto<DataCell>>::Error>,

pub fn from_cells3<C0, C1, C2>( row_id: RowId, entity_path: impl Into<EntityPath>, timepoint: impl Into<TimePoint>, into_cells: (C0, C1, C2) ) -> DataRowResult<DataRow>

where C0: TryInto<DataCell>, C1: TryInto<DataCell>, C2: TryInto<DataCell>, DataRowError: From<<C0 as TryInto<DataCell>>::Error> + From<<C1 as TryInto<DataCell>>::Error> + From<<C2 as TryInto<DataCell>>::Error>,

Trait Implementations

impl Clone for DataRow

fn clone(&self) -> DataRow

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DataRow

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

Formats the value using the given formatter.

impl Display for DataRow

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

Formats the value using the given formatter.

impl SizeBytes for DataRow

fn heap_size_bytes(&self) -> u64

Returns the total size of self on the heap, in bytes.

fn total_size_bytes(&self) -> u64

Returns the total size of self in bytes, accounting for both stack and heap space.

fn stack_size_bytes(&self) -> u64

Returns the total size of self on the stack, in bytes.

fn is_pod() -> bool

Is Self just plain old data?