alamb commented on code in PR #25583: URL: https://github.com/apache/datafusion/pull/25583#discussion_r4122808396
########## datafusion/physical-expr-common/src/metrics/snapshot.rs: ########## @@ -0,0 +1,376 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +//! Metric [`Registry`] and [`Snapshot`] implementations. + +use super::Metric; +use parking_lot::Mutex; +use std::collections::HashMap; +use std::fmt; +use std::sync::{Arc, OnceLock}; + +#[derive(Debug, Default)] +pub(super) struct Registry { + metrics: Vec<Arc<Metric>>, + // Readers index each registration once, avoiding repeated full scans when + // reporting successive partitions. Registration itself only appends to metrics. + index: PartitionIndex, +} + +#[derive(Debug, Default)] +struct PartitionIndex { + // Number of registry entries already examined, including global metrics. + indexed: usize, + // Partition ID -> positions in Registry::metrics, in registration order. + // Positions also let older snapshots exclude later registrations. Storing + // handles here would duplicate Arc ownership and still require these positions. + positions: HashMap<usize, Vec<usize>>, +} + +impl Registry { + pub(super) fn new(metrics: Vec<Arc<Metric>>) -> Self { + Self { + metrics, + index: PartitionIndex::default(), + } + } + + pub(super) fn register(&mut self, metric: Arc<Metric>) { + self.metrics.push(metric); + } + + /// Select metrics whose partition ID equals `partition`. `end` is an exclusive + /// position in the full registration vector, including other partitions and + /// global metrics. It fixes the membership of the requesting snapshot. + fn select(&mut self, partition: usize, end: usize) -> Vec<Arc<Metric>> { + let index = &mut self.index; + for position in index.indexed..end { + if let Some(partition) = self.metrics[position].partition() { + index.positions.entry(partition).or_default().push(position); + } + } + index.indexed = index.indexed.max(end); + let Some(positions) = index.positions.get(&partition) else { + return Vec::new(); + }; + // Another snapshot may already have indexed registrations after our end. + let len = positions.partition_point(|&position| position < end); + positions[..len] + .iter() + .map(|&i| Arc::clone(&self.metrics[i])) + .collect() + } +} + +#[derive(Clone)] +pub(super) enum Snapshot { Review Comment: 👍 ########## datafusion/physical-expr-common/src/metrics/snapshot.rs: ########## @@ -0,0 +1,376 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +//! Metric [`Registry`] and [`Snapshot`] implementations. + +use super::Metric; +use parking_lot::Mutex; +use std::collections::HashMap; +use std::fmt; +use std::sync::{Arc, OnceLock}; + +#[derive(Debug, Default)] +pub(super) struct Registry { + metrics: Vec<Arc<Metric>>, + // Readers index each registration once, avoiding repeated full scans when + // reporting successive partitions. Registration itself only appends to metrics. + index: PartitionIndex, +} + +#[derive(Debug, Default)] +struct PartitionIndex { + // Number of registry entries already examined, including global metrics. + indexed: usize, + // Partition ID -> positions in Registry::metrics, in registration order. + // Positions also let older snapshots exclude later registrations. Storing + // handles here would duplicate Arc ownership and still require these positions. + positions: HashMap<usize, Vec<usize>>, +} + +impl Registry { + pub(super) fn new(metrics: Vec<Arc<Metric>>) -> Self { + Self { + metrics, + index: PartitionIndex::default(), + } + } + + pub(super) fn register(&mut self, metric: Arc<Metric>) { + self.metrics.push(metric); + } + + /// Select metrics whose partition ID equals `partition`. `end` is an exclusive + /// position in the full registration vector, including other partitions and + /// global metrics. It fixes the membership of the requesting snapshot. + fn select(&mut self, partition: usize, end: usize) -> Vec<Arc<Metric>> { + let index = &mut self.index; + for position in index.indexed..end { + if let Some(partition) = self.metrics[position].partition() { + index.positions.entry(partition).or_default().push(position); + } + } + index.indexed = index.indexed.max(end); + let Some(positions) = index.positions.get(&partition) else { + return Vec::new(); + }; + // Another snapshot may already have indexed registrations after our end. + let len = positions.partition_point(|&position| position < end); + positions[..len] + .iter() + .map(|&i| Arc::clone(&self.metrics[i])) + .collect() + } +} + +#[derive(Clone)] +pub(super) enum Snapshot { + /// All metrics registered before a fixed boundary; partition reads use the index. + All(Arc<AllMetrics>), + /// A selected partition, independent of the source registry. + Partition { + partition: usize, + metrics: Vec<Arc<Metric>>, + }, + /// An arbitrary collection created directly or detached by mutation. It has + /// no registry/index and may contain multiple partitions and global metrics. + Standalone(Vec<Arc<Metric>>), +} + +pub(super) struct AllMetrics { + registry: Arc<Mutex<Registry>>, + // Exclusive position in Registry::metrics, not a per-partition count. + end: usize, + flat: OnceLock<Vec<Arc<Metric>>>, Review Comment: what is the `flat` field for and how does it relate to `registry.metrics`? Perhaps we can document it -- it seems like maybe it is a cache to avoid copying registry.metrics ? ``` metrics: Vec<Arc<Metric>>, ``` ########## datafusion/physical-expr-common/src/metrics/snapshot.rs: ########## @@ -0,0 +1,376 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +//! Metric [`Registry`] and [`Snapshot`] implementations. + +use super::Metric; +use parking_lot::Mutex; +use std::collections::HashMap; +use std::fmt; +use std::sync::{Arc, OnceLock}; + +#[derive(Debug, Default)] +pub(super) struct Registry { + metrics: Vec<Arc<Metric>>, + // Readers index each registration once, avoiding repeated full scans when + // reporting successive partitions. Registration itself only appends to metrics. + index: PartitionIndex, +} + +#[derive(Debug, Default)] +struct PartitionIndex { + // Number of registry entries already examined, including global metrics. + indexed: usize, + // Partition ID -> positions in Registry::metrics, in registration order. + // Positions also let older snapshots exclude later registrations. Storing + // handles here would duplicate Arc ownership and still require these positions. + positions: HashMap<usize, Vec<usize>>, +} + +impl Registry { + pub(super) fn new(metrics: Vec<Arc<Metric>>) -> Self { + Self { + metrics, + index: PartitionIndex::default(), + } + } + + pub(super) fn register(&mut self, metric: Arc<Metric>) { + self.metrics.push(metric); + } + + /// Select metrics whose partition ID equals `partition`. `end` is an exclusive + /// position in the full registration vector, including other partitions and + /// global metrics. It fixes the membership of the requesting snapshot. + fn select(&mut self, partition: usize, end: usize) -> Vec<Arc<Metric>> { + let index = &mut self.index; + for position in index.indexed..end { + if let Some(partition) = self.metrics[position].partition() { + index.positions.entry(partition).or_default().push(position); + } + } + index.indexed = index.indexed.max(end); + let Some(positions) = index.positions.get(&partition) else { + return Vec::new(); + }; + // Another snapshot may already have indexed registrations after our end. + let len = positions.partition_point(|&position| position < end); + positions[..len] + .iter() + .map(|&i| Arc::clone(&self.metrics[i])) + .collect() + } +} + +#[derive(Clone)] +pub(super) enum Snapshot { + /// All metrics registered before a fixed boundary; partition reads use the index. + All(Arc<AllMetrics>), + /// A selected partition, independent of the source registry. + Partition { + partition: usize, + metrics: Vec<Arc<Metric>>, + }, + /// An arbitrary collection created directly or detached by mutation. It has + /// no registry/index and may contain multiple partitions and global metrics. + Standalone(Vec<Arc<Metric>>), +} + +pub(super) struct AllMetrics { + registry: Arc<Mutex<Registry>>, + // Exclusive position in Registry::metrics, not a per-partition count. + end: usize, + flat: OnceLock<Vec<Arc<Metric>>>, Review Comment: If the idea is to model a delayed mateiralization, Another way to model it that might be simpler could be to convert `Snapshot::All` --> `Snapshot::Standalone` on a call to `iter` 🤔 or maybe introduce a new variant like `Snapshot::AllMaterialized` ########## datafusion/physical-plan/tests/partition_metrics.rs: ########## @@ -0,0 +1,101 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +#[path = "metrics/plan.rs"] +mod plan; + +use std::sync::Arc; + +use arrow::array::Int32Array; +use datafusion_common::Result; +use datafusion_execution::TaskContext; +use futures::{FutureExt, StreamExt, TryStreamExt}; + +#[tokio::test(flavor = "multi_thread", worker_threads = 4)] Review Comment: I would prefer this NOT be its own test binary (as that adds several hundred MB of binary to `--workspace` builds). Can we add these tests to some existing end to end tests (perhaps in `core_integration`)? ########## datafusion/physical-expr-common/src/metrics/mod.rs: ########## @@ -228,9 +230,17 @@ impl Metric { } /// A snapshot of the metrics for a particular execution plan. +/// +/// The set's members remain fixed as execution registers more metrics, but their +/// values continue to reflect execution progress. Use [`Self::for_partition`] to +/// select the metrics belonging to one partition. +/// +/// Snapshots from [`ExecutionPlanMetricsSet::clone_inner`] retain the source Review Comment: I think this last paragraph in the comment is about internal implementation details and is confusing on `Metrics` -- maybe it would be better on `Snapshot` or just dropped entirely ########## datafusion/physical-expr-common/src/metrics/snapshot.rs: ########## @@ -0,0 +1,301 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +//! Fixed-membership snapshots of an append-only registry. +//! +//! Registration only appends to a vector. Partition readers share an index that +//! catches up with registration on demand; snapshots remember their original end +//! position even when a later reader has advanced the index past that position. + +use super::Metric; +use parking_lot::Mutex; +use std::collections::HashMap; +use std::fmt; +use std::sync::{Arc, OnceLock}; + +#[derive(Debug, Default)] +pub(super) struct Registry { + pub(super) metrics: Vec<Arc<Metric>>, + // No index allocation or maintenance on the registration path. + index: Option<Box<PartitionIndex>>, +} + +#[derive(Debug, Default)] +struct PartitionIndex { + // Number of registry entries already examined, including global metrics. + indexed: usize, + // Partition ID -> positions in Registry::metrics, in registration order. + positions: HashMap<usize, Vec<usize>>, Review Comment: The new comments help a lot. Thank you -- This is an automated message from the Apache Git Service. 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