Shub/view interface (#3561)

# Description of Changes
Addresses -
#3487 (comment).
Can be reviewed commit wise.

1. Provide `ModuleSubscriptions` a interface to invoke
`ModuleHost::call_view`.
2. Handle `st_view_client table` insertion.
3. Make views available form sql.

Author: Shubham8287

Cargo.lock

@@ -72,65 +72,54 @@ impl Host {
         body: String,
     ) -> axum::response::Result<Vec<SqlStmtResult<ProductValue>>> {
         let module_host = self
-            .module()
+            .host_controller
+            .get_or_launch_module_host(database, self.replica_id)
             .await
             .map_err(|_| (StatusCode::NOT_FOUND, "module not found".to_string()))?;
 
-        let (tx_offset, durable_offset, json) = self
-            .host_controller
-            .using_database(
-                database,
-                self.replica_id,
-                move |db| -> axum::response::Result<_, (StatusCode, String)> {
-                    tracing::info!(sql = body);
-
-                    // We need a header for query results
-                    let mut header = vec![];
-
-                    let sql_start = std::time::Instant::now();
-                    let sql_span =
-                        tracing::trace_span!("execute_sql", total_duration = tracing::field::Empty,).entered();
-
-                    let result = sql::execute::run(
-                        // Returns an empty result set for mutations
-                        db,
-                        &body,
-                        auth,
-                        Some(&module_host.info().subscriptions),
-                        &mut header,
-                    )
-                    .map_err(|e| {
-                        log::warn!("{e}");
-                        if let Some(auth_err) = e.get_auth_error() {
-                            (StatusCode::UNAUTHORIZED, auth_err.to_string())
-                        } else {
-                            (StatusCode::BAD_REQUEST, e.to_string())
-                        }
-                    })?;
-
-                    let total_duration = sql_start.elapsed();
-                    sql_span.record("total_duration", tracing::field::debug(total_duration));
-
-                    // Turn the header into a `ProductType`
-                    let schema = header
-                        .into_iter()
-                        .map(|(col_name, col_type)| ProductTypeElement::new(col_type, Some(col_name)))
-                        .collect();
-
-                    Ok((
-                        result.tx_offset,
-                        db.durable_tx_offset(),
-                        vec![SqlStmtResult {
-                            schema,
-                            rows: result.rows,
-                            total_duration_micros: total_duration.as_micros() as u64,
-                            stats: SqlStmtStats::from_metrics(&result.metrics),
-                        }],
-                    ))
-                },
-            )
-            .await
-            .map_err(log_and_500)??;
+        tracing::info!(sql = body);
+        // We need a header for query results
+        let mut header = vec![];
+        let sql_start = std::time::Instant::now();
+        let sql_span = tracing::trace_span!("execute_sql", total_duration = tracing::field::Empty).entered();
+        let db = &module_host.module.replica_ctx().relational_db;
+
+        let result = sql::execute::run(
+            // Returns an empty result set for mutations
+            &db,
+            &body,
+            auth,
+            Some(&module_host),
+            auth.caller,
+            &mut header,
+        )
+        .await
+        .map_err(|e| {
+            log::warn!("{e}");
+            if let Some(auth_err) = e.get_auth_error() {
+                (StatusCode::UNAUTHORIZED, auth_err.to_string())
+            } else {
+                (StatusCode::BAD_REQUEST, e.to_string())
+            }
+        })?;
+
+        let total_duration = sql_start.elapsed();
+        sql_span.record("total_duration", tracing::field::debug(total_duration));
+
+        // Turn the header into a `ProductType`
+        let schema = header
+            .into_iter()
+            .map(|(col_name, col_type)| ProductTypeElement::new(col_type, Some(col_name)))
+            .collect();
+
+        let tx_offset = result.tx_offset;
+        let durable_offset = db.durable_tx_offset();
+        let json = vec![SqlStmtResult {
+            schema,
+            rows: result.rows,
+            total_duration_micros: total_duration.as_micros() as u64,
+            stats: SqlStmtStats::from_metrics(&result.metrics),
+        }];
 
         if confirmed_read {
             if let Some(mut durable_offset) = durable_offset {
@@ -141,7 +130,6 @@ impl Host {
 
         Ok(json)
     }
-
     pub async fn update(
         &self,
         database: Database,

crates/client-api/src/lib.rs

@@ -1,5 +1,5 @@
 use crate::db::MetricsRecorderQueue;
-use crate::error::{DBError, DatabaseError, RestoreSnapshotError, ViewError};
+use crate::error::{DBError, DatabaseError, RestoreSnapshotError};
 use crate::host::ArgsTuple;
 use crate::messages::control_db::HostType;
 use crate::subscription::ExecutionCounters;
@@ -14,16 +14,16 @@ use spacetimedb_commitlog as commitlog;
 use spacetimedb_commitlog::repo::OnNewSegmentFn;
 use spacetimedb_data_structures::map::IntSet;
 use spacetimedb_datastore::db_metrics::DB_METRICS;
-use spacetimedb_datastore::error::{DatastoreError, TableError};
+use spacetimedb_datastore::error::{DatastoreError, TableError, ViewError};
 use spacetimedb_datastore::execution_context::{ReducerContext, Workload, WorkloadType};
 use spacetimedb_datastore::locking_tx_datastore::datastore::TxMetrics;
 use spacetimedb_datastore::locking_tx_datastore::state_view::{
     IterByColEqMutTx, IterByColRangeMutTx, IterMutTx, IterTx, StateView,
 };
 use spacetimedb_datastore::locking_tx_datastore::{MutTxId, TxId};
-use spacetimedb_datastore::system_tables::{system_tables, StModuleRow, StViewArgFields, StViewRow, ST_VIEW_ID};
+use spacetimedb_datastore::system_tables::ST_VIEW_ID;
+use spacetimedb_datastore::system_tables::{system_tables, StModuleRow, StViewRow};
 use spacetimedb_datastore::system_tables::{StFields, StVarFields, StVarName, StVarRow, ST_MODULE_ID, ST_VAR_ID};
-use spacetimedb_datastore::system_tables::{StViewArgRow, ST_VIEW_ARG_ID};
 use spacetimedb_datastore::traits::{
     InsertFlags, IsolationLevel, Metadata, MutTx as _, MutTxDatastore, Program, RowTypeForTable, Tx as _, TxDatastore,
     UpdateFlags,
@@ -1519,27 +1519,6 @@ impl RelationalDB {
         })
     }
 
-    /// Get or insert view argument into `ST_VIEW_ARG_ID`.
-    pub fn get_or_insert_st_view_arg(&self, tx: &mut MutTxId, args: &Bytes) -> Result<u64, DBError> {
-        let bytes_av = AlgebraicValue::Bytes(args.to_vec().into());
-        let mut rows = self.iter_by_col_eq_mut(tx, ST_VIEW_ARG_ID, [StViewArgFields::Bytes], &bytes_av)?;
-
-        // Extract the first matching `arg_id`, if any.
-        if let Some(res) = rows.next() {
-            let row = StViewArgRow::try_from(res).expect("valid StViewArgRow");
-            return Ok(row.id);
-        }
-
-        let view_arg_bytes = product![0u64, bytes_av]
-            .to_bsatn_vec()
-            .map_err(|_| ViewError::SerializeArgs)?;
-
-        let (_, view_arg_row, _) = self.insert(tx, ST_VIEW_ARG_ID, &view_arg_bytes)?;
-        let StViewArgRow { id: arg_id, .. } = view_arg_row.try_into().expect("valid StViewArgRow");
-
-        Ok(arg_id)
-    }
-
     /// Evaluate and update View.
     /// This involves:
     /// 1. Serializing the view arguments into `ST_VIEW_ARG_ID`
@@ -1569,12 +1548,11 @@ impl RelationalDB {
         let (table_id, is_anonymous) = (
             st_view_row
                 .table_id
-                .ok_or_else(|| ViewError::ViewNotFound(view.to_string()))?,
+                .expect("Tables are always created for views upon view creation"),
             st_view_row.is_anonymous,
         );
 
-        // Insert the view arguments into ST_VIEW_ARG_ID
-        let arg_id = self.get_or_insert_st_view_arg(tx, &args.get_bsatn())?;
+        let arg_id = tx.get_or_insert_st_view_arg(&args.get_bsatn())?;
 
         let input_rows = product![
             if is_anonymous {
@@ -1598,7 +1576,7 @@ impl RelationalDB {
         let seed = spacetimedb_sats::WithTypespace::new(typespace, &return_type);
         let return_val = seed
             .deserialize(bsatn::Deserializer::new(&mut &bytes[..]))
-            .map_err(|e| ViewError::DeserializeReturn(e.to_string()))?;
+            .map_err(|e| DatastoreError::from(ViewError::DeserializeReturn(e.to_string())))?;
 
         let products: Vec<ProductValue> = if return_type.is_array() {
             let arr = return_val.into_array().expect("return type is array");
@@ -1607,7 +1585,7 @@ impl RelationalDB {
             let opt = return_val.into_option().expect("return type is option");
             Ok(opt.into_iter().map(|v| v.into_product().unwrap()).collect())
         } else {
-            Err(ViewError::InvalidReturnType(return_type.clone()))
+            Err(DatastoreError::from(ViewError::InvalidReturnType(return_type.clone())))
         }?;
 
         // Insert all rows from the return value into the view table
@@ -1621,7 +1599,9 @@ impl RelationalDB {
                     elements: elements.into_boxed_slice(),
                 }
             };
-            let row_bytes = row.to_bsatn_vec().map_err(|_| ViewError::SerializeRow)?;
+            let row_bytes = row
+                .to_bsatn_vec()
+                .map_err(|_| DatastoreError::from(ViewError::SerializeRow))?;
             self.insert(tx, table_id, &row_bytes)?;
         }
 

crates/core/src/db/relational_db.rs

@@ -8,7 +8,7 @@ use hex::FromHexError;
 use spacetimedb_commitlog::repo::TxOffset;
 use spacetimedb_durability::DurabilityExited;
 use spacetimedb_expr::errors::TypingError;
-use spacetimedb_lib::{AlgebraicType, Identity};
+use spacetimedb_lib::Identity;
 use spacetimedb_schema::error::ValidationErrors;
 use spacetimedb_snapshot::SnapshotError;
 use spacetimedb_table::table::ReadViaBsatnError;
@@ -147,8 +147,6 @@ pub enum DBError {
     RestoreSnapshot(#[from] RestoreSnapshotError),
     #[error(transparent)]
     DurabilityGone(#[from] DurabilityExited),
-    #[error("ViewError: {0}")]
-    View(#[from] ViewError),
 }
 
 impl DBError {
@@ -192,28 +190,6 @@ impl<'a, T: ?Sized + 'a> From<PoisonError<std::sync::MutexGuard<'a, T>>> for DBE
     }
 }
 
-#[derive(Error, Debug)]
-pub enum ViewError {
-    #[error("view '{0}' not found")]
-    ViewNotFound(String),
-    #[error("failed to deserialize view arguments from row")]
-    DeserializeArgs,
-    #[error("failed to deserialize view return value: {0}")]
-    DeserializeReturn(String),
-    #[error("failed to serialize row to BSATN")]
-    SerializeRow,
-    #[error("invalid return type: expected Array or Option, got {0:?}")]
-    InvalidReturnType(AlgebraicType),
-    #[error("return type is Array but deserialized value is not Array")]
-    TypeMismatchArray,
-    #[error("return type is Option but deserialized value is not Option")]
-    TypeMismatchOption,
-    #[error("expected ProductValue in view result")]
-    ExpectedProduct,
-    #[error("failed to serialize view arguments")]
-    SerializeArgs,
-}
-
 #[derive(Debug, Error)]
 pub enum LogReplayError {
     #[error(

crates/core/src/error.rs

@@ -27,7 +27,6 @@ use spacetimedb_data_structures::error_stream::ErrorStream;
 use spacetimedb_data_structures::map::IntMap;
 use spacetimedb_datastore::db_metrics::data_size::DATA_SIZE_METRICS;
 use spacetimedb_datastore::db_metrics::DB_METRICS;
-use spacetimedb_datastore::locking_tx_datastore::MutTxId;
 use spacetimedb_datastore::traits::Program;
 use spacetimedb_durability::{self as durability};
 use spacetimedb_lib::{hash_bytes, AlgebraicValue, Identity, Timestamp};
@@ -187,13 +186,6 @@ impl From<EventStatus> for ViewOutcome {
     }
 }
 
-pub struct ViewCallResult {
-    pub outcome: ViewOutcome,
-    pub tx: MutTxId,
-    pub energy_used: EnergyQuanta,
-    pub execution_duration: Duration,
-}
-
 #[derive(Clone, Debug)]
 pub struct ProcedureCallResult {
     pub return_val: AlgebraicValue,
@@ -893,8 +885,10 @@ impl Host {
         scheduler_starter.start(&module_host)?;
         let disk_metrics_recorder_task = tokio::spawn(metric_reporter(replica_ctx.clone())).abort_handle();
 
+        let module = watch::Sender::new(module_host);
+        replica_ctx.subscriptions.init(module.subscribe());
         Ok(Host {
-            module: watch::Sender::new(module_host),
+            module,
             replica_ctx,
             scheduler,
             disk_metrics_recorder_task,