Struct chalk_integration::query::EnvironmentQuery

pub struct EnvironmentQuery;

Implementations

impl EnvironmentQuery

pub fn in_db(self, db: &dyn LoweringDatabase) -> QueryTable<'_, Self>

Get access to extra methods pertaining to this query. For example, you can use this to run the GC (sweep) across a single input. You can also use it to invoke this query, though it’s more common to use the trait method on the database itself.

impl EnvironmentQuery

pub fn in_db_mut(self, db: &mut dyn LoweringDatabase) -> QueryTableMut<'_, Self>

Like in_db, but gives access to methods for setting the value of an input. Not applicable to derived queries.

Threads, cancellation, and blocking

Mutating the value of a query cannot be done while there are still other queries executing. If you are using your database within a single thread, this is not a problem: you only have &self access to the database, but this method requires &mut self.

However, if you have used snapshot to create other threads, then attempts to set will block the current thread until those snapshots are dropped (usually when those threads complete). This also implies that if you create a snapshot but do not send it to another thread, then invoking set will deadlock.

Before blocking, the thread that is attempting to set will also set a cancellation flag. In the threads operating on snapshots, you can use the is_current_revision_canceled method to check for this flag and bring those operations to a close, thus allowing the set to succeed. Ignoring this flag may lead to “starvation”, meaning that the thread attempting to set has to wait a long, long time. =)

Trait Implementations

impl Debug for EnvironmentQuery

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

Formats the value using the given formatter.

impl Default for EnvironmentQuery

fn default() -> EnvironmentQuery

Returns the “default value” for a type.

impl Query for EnvironmentQuery

type Key = ()

Type that you you give as a parameter – for queries with zero or more than one input, this will be a tuple.

type Value = Result<Arc<ProgramEnvironment>, ChalkError>

What value does the query return?

type Storage = DerivedStorage<EnvironmentQuery, AlwaysMemoizeValue>

Internal struct storing the values for the query.

const QUERY_INDEX: u16 = 6u16

A unique index identifying this query within the group.

const QUERY_NAME: &'static str = "environment"

Name of the query method (e.g., foo)

fn query_storage<'a>( group_storage: &'a <Self as QueryDb<'_>>::GroupStorage, ) -> &'a Arc<Self::Storage>

Extact storage for this query from the storage for its group.

impl<'d> QueryDb<'d> for EnvironmentQuery

type DynDb = dyn LoweringDatabase + 'd

Dyn version of the associated trait for this query group.

type Group = Lowering

Associate query group struct.

type GroupStorage = LoweringDatabaseGroupStorage__

Generated struct that contains storage for all queries in a group.

impl QueryFunction for EnvironmentQuery

fn execute( db: &<Self as QueryDb<'_>>::DynDb, (): <Self as Query>::Key, ) -> <Self as Query>::Value

fn recover( db: &Self::DynDb, cycle: &[DatabaseKeyIndex], key: &Self::Key, ) -> Option<Self::Value>