Add JoinContext with JoinLeftData to TaskContext in HashJoinExec (#300)

* Add JoinContext with JoinLeftData to TaskContext in HashJoinExec

* Expose random state as const

* re-export ahash::RandomState

* JoinContext default impl

* Add debug log when setting join left data

Author: thinkharderdev

datafusion/physical-plan/src/joins/hash_join.rs

@@ -77,8 +77,26 @@ use arrow_buffer::BooleanBuffer;
 use datafusion_expr::Operator;
 use datafusion_physical_expr_common::datum::compare_op_for_nested;
 use futures::{ready, Stream, StreamExt, TryStreamExt};
+use log::debug;
 use parking_lot::Mutex;
 
+pub const RANDOM_STATE: RandomState = RandomState::with_seeds(0, 0, 0, 0);
+
+#[derive(Default)]
+pub struct JoinContext {
+    build_state: Mutex<Option<Arc<JoinLeftData>>>,
+}
+
+impl JoinContext {
+    pub fn set_build_state(&self, state: Arc<JoinLeftData>) {
+        self.build_state.lock().replace(state);
+    }
+
+    pub fn get_build_state(&self) -> Option<Arc<JoinLeftData>> {
+        self.build_state.lock().clone()
+    }
+}
+
 pub struct SharedJoinState {
     state_impl: Arc<dyn SharedJoinStateImpl>,
 }
@@ -128,7 +146,7 @@ pub trait SharedJoinStateImpl: Send + Sync + 'static {
 type SharedBitmapBuilder = Mutex<BooleanBufferBuilder>;
 
 /// HashTable and input data for the left (build side) of a join
-struct JoinLeftData {
+pub struct JoinLeftData {
     /// The hash table with indices into `batch`
     hash_map: JoinHashMap,
     /// The input rows for the build side
@@ -165,6 +183,10 @@ impl JoinLeftData {
         }
     }
 
+    pub fn contains_hash(&self, hash: u64) -> bool {
+        self.hash_map.contains_hash(hash)
+    }
+
     /// return a reference to the hash map
     fn hash_map(&self) -> &JoinHashMap {
         &self.hash_map
@@ -768,6 +790,7 @@ impl ExecutionPlan for HashJoinExec {
 
         let distributed_state =
             context.session_config().get_extension::<SharedJoinState>();
+        let join_context = context.session_config().get_extension::<JoinContext>();
 
         let join_metrics = BuildProbeJoinMetrics::new(partition, &self.metrics);
         let left_fut = match self.mode {
@@ -855,6 +878,7 @@ impl ExecutionPlan for HashJoinExec {
             batch_size,
             hashes_buffer: vec![],
             right_side_ordered: self.right.output_ordering().is_some(),
+            join_context,
         }))
     }
 
@@ -1187,6 +1211,7 @@ struct HashJoinStream {
     hashes_buffer: Vec<u64>,
     /// Specifies whether the right side has an ordering to potentially preserve
     right_side_ordered: bool,
+    join_context: Option<Arc<JoinContext>>,
 }
 
 impl RecordBatchStream for HashJoinStream {
@@ -1399,6 +1424,11 @@ impl HashJoinStream {
             .get_shared(cx))?;
         build_timer.done();
 
+        if let Some(ctx) = self.join_context.as_ref() {
+            debug!("setting join left data in join context");
+            ctx.set_build_state(Arc::clone(&left_data));
+        }
+
         self.state = HashJoinStreamState::FetchProbeBatch;
         self.build_side = BuildSide::Ready(BuildSideReadyState { left_data });
 

datafusion/physical-plan/src/joins/mod.rs

@@ -19,7 +19,8 @@
 
 pub use cross_join::CrossJoinExec;
 pub use hash_join::{
-    HashJoinExec, SharedJoinState, SharedJoinStateImpl, SharedProbeState,
+    HashJoinExec, JoinContext, JoinLeftData, SharedJoinState, SharedJoinStateImpl,
+    SharedProbeState, RANDOM_STATE,
 };
 pub use nested_loop_join::NestedLoopJoinExec;
 // Note: SortMergeJoin is not used in plans yet
@@ -33,6 +34,8 @@ mod stream_join_utils;
 mod symmetric_hash_join;
 pub mod utils;
 
+pub type RandomState = ahash::RandomState;
+
 #[cfg(test)]
 pub mod test_utils;
 

datafusion/physical-plan/src/joins/utils.rs

@@ -139,6 +139,10 @@ impl JoinHashMap {
             next: vec![0; capacity],
         }
     }
+
+    pub fn contains_hash(&self, hash: u64) -> bool {
+        self.map.find(hash, |(h, _)| *h == hash).is_some()
+    }
 }
 
 // Type of offsets for obtaining indices from JoinHashMap.