feat: show flow's mem usage in INFORMATION_SCHEMA.FLOWS (#4890)

* feat: add flow mem size to sys table

* chore: rm dup def

* chore: remove unused variant

* chore: minor refactor

* refactor: per review

src/catalog/src/error.rs

@@ -64,6 +64,13 @@ pub enum Error {
         source: BoxedError,
     },
 
+    #[snafu(display("Failed to list flow stats"))]
+    ListFlowStats {
+        #[snafu(implicit)]
+        location: Location,
+        source: BoxedError,
+    },
+
     #[snafu(display("Failed to list flows in catalog {catalog}"))]
     ListFlows {
         #[snafu(implicit)]
@@ -326,6 +333,7 @@ impl ErrorExt for Error {
             | Error::ListSchemas { source, .. }
             | Error::ListTables { source, .. }
             | Error::ListFlows { source, .. }
+            | Error::ListFlowStats { source, .. }
             | Error::ListProcedures { source, .. }
             | Error::ListRegionStats { source, .. }
             | Error::ConvertProtoData { source, .. } => source.status_code(),

src/catalog/src/information_extension.rs

@@ -17,6 +17,7 @@ use common_error::ext::BoxedError;
 use common_meta::cluster::{ClusterInfo, NodeInfo};
 use common_meta::datanode::RegionStat;
 use common_meta::ddl::{ExecutorContext, ProcedureExecutor};
+use common_meta::key::flow::flow_state::FlowStat;
 use common_meta::rpc::procedure;
 use common_procedure::{ProcedureInfo, ProcedureState};
 use meta_client::MetaClientRef;
@@ -89,4 +90,12 @@ impl InformationExtension for DistributedInformationExtension {
             .map_err(BoxedError::new)
             .context(error::ListRegionStatsSnafu)
     }
+
+    async fn flow_stats(&self) -> std::result::Result<Option<FlowStat>, Self::Error> {
+        self.meta_client
+            .list_flow_stats()
+            .await
+            .map_err(BoxedError::new)
+            .context(crate::error::ListFlowStatsSnafu)
+    }
 }

src/catalog/src/system_schema/information_schema.rs

@@ -35,6 +35,7 @@ use common_catalog::consts::{self, DEFAULT_CATALOG_NAME, INFORMATION_SCHEMA_NAME
 use common_error::ext::ErrorExt;
 use common_meta::cluster::NodeInfo;
 use common_meta::datanode::RegionStat;
+use common_meta::key::flow::flow_state::FlowStat;
 use common_meta::key::flow::FlowMetadataManager;
 use common_procedure::ProcedureInfo;
 use common_recordbatch::SendableRecordBatchStream;
@@ -192,6 +193,7 @@ impl SystemSchemaProviderInner for InformationSchemaProvider {
             )) as _),
             FLOWS => Some(Arc::new(InformationSchemaFlows::new(
                 self.catalog_name.clone(),
+                self.catalog_manager.clone(),
                 self.flow_metadata_manager.clone(),
             )) as _),
             PROCEDURE_INFO => Some(
@@ -338,6 +340,9 @@ pub trait InformationExtension {
 
     /// Gets the region statistics.
     async fn region_stats(&self) -> std::result::Result<Vec<RegionStat>, Self::Error>;
+
+    /// Get the flow statistics. If no flownode is available, return `None`.
+    async fn flow_stats(&self) -> std::result::Result<Option<FlowStat>, Self::Error>;
 }
 
 pub struct NoopInformationExtension;
@@ -357,4 +362,8 @@ impl InformationExtension for NoopInformationExtension {
     async fn region_stats(&self) -> std::result::Result<Vec<RegionStat>, Self::Error> {
         Ok(vec![])
     }
+
+    async fn flow_stats(&self) -> std::result::Result<Option<FlowStat>, Self::Error> {
+        Ok(None)
+    }
 }