parquet/arrow/async_reader/store.rs
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// 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.
use std::{ops::Range, sync::Arc};
use bytes::Bytes;
use futures::{future::BoxFuture, FutureExt, TryFutureExt};
use object_store::{path::Path, ObjectMeta, ObjectStore};
use tokio::runtime::Handle;
use crate::arrow::async_reader::AsyncFileReader;
use crate::errors::{ParquetError, Result};
use crate::file::metadata::{ParquetMetaData, ParquetMetaDataReader};
/// Reads Parquet files in object storage using [`ObjectStore`].
///
/// ```no_run
/// # use std::io::stdout;
/// # use std::sync::Arc;
/// # use object_store::azure::MicrosoftAzureBuilder;
/// # use object_store::ObjectStore;
/// # use object_store::path::Path;
/// # use parquet::arrow::async_reader::ParquetObjectReader;
/// # use parquet::arrow::ParquetRecordBatchStreamBuilder;
/// # use parquet::schema::printer::print_parquet_metadata;
/// # async fn run() {
/// // Populate configuration from environment
/// let storage_container = Arc::new(MicrosoftAzureBuilder::from_env().build().unwrap());
/// let location = Path::from("path/to/blob.parquet");
/// let meta = storage_container.head(&location).await.unwrap();
/// println!("Found Blob with {}B at {}", meta.size, meta.location);
///
/// // Show Parquet metadata
/// let reader = ParquetObjectReader::new(storage_container, meta);
/// let builder = ParquetRecordBatchStreamBuilder::new(reader).await.unwrap();
/// print_parquet_metadata(&mut stdout(), builder.metadata());
/// # }
/// ```
#[derive(Clone, Debug)]
pub struct ParquetObjectReader {
store: Arc<dyn ObjectStore>,
meta: ObjectMeta,
metadata_size_hint: Option<usize>,
preload_column_index: bool,
preload_offset_index: bool,
runtime: Option<Handle>,
}
impl ParquetObjectReader {
/// Creates a new [`ParquetObjectReader`] for the provided [`ObjectStore`] and [`ObjectMeta`]
///
/// [`ObjectMeta`] can be obtained using [`ObjectStore::list`] or [`ObjectStore::head`]
pub fn new(store: Arc<dyn ObjectStore>, meta: ObjectMeta) -> Self {
Self {
store,
meta,
metadata_size_hint: None,
preload_column_index: false,
preload_offset_index: false,
runtime: None,
}
}
/// Provide a hint as to the size of the parquet file's footer,
/// see [fetch_parquet_metadata](crate::arrow::async_reader::fetch_parquet_metadata)
pub fn with_footer_size_hint(self, hint: usize) -> Self {
Self {
metadata_size_hint: Some(hint),
..self
}
}
/// Load the Column Index as part of [`Self::get_metadata`]
pub fn with_preload_column_index(self, preload_column_index: bool) -> Self {
Self {
preload_column_index,
..self
}
}
/// Load the Offset Index as part of [`Self::get_metadata`]
pub fn with_preload_offset_index(self, preload_offset_index: bool) -> Self {
Self {
preload_offset_index,
..self
}
}
/// Perform IO on the provided tokio runtime
///
/// Tokio is a cooperative scheduler, and relies on tasks yielding in a timely manner
/// to service IO. Therefore, running IO and CPU-bound tasks, such as parquet decoding,
/// on the same tokio runtime can lead to degraded throughput, dropped connections and
/// other issues. For more information see [here].
///
/// [here]: https://www.influxdata.com/blog/using-rustlangs-async-tokio-runtime-for-cpu-bound-tasks/
pub fn with_runtime(self, handle: Handle) -> Self {
Self {
runtime: Some(handle),
..self
}
}
fn spawn<F, O, E>(&self, f: F) -> BoxFuture<'_, Result<O>>
where
F: for<'a> FnOnce(&'a Arc<dyn ObjectStore>, &'a Path) -> BoxFuture<'a, Result<O, E>>
+ Send
+ 'static,
O: Send + 'static,
E: Into<ParquetError> + Send + 'static,
{
match &self.runtime {
Some(handle) => {
let path = self.meta.location.clone();
let store = Arc::clone(&self.store);
handle
.spawn(async move { f(&store, &path).await })
.map_ok_or_else(
|e| match e.try_into_panic() {
Err(e) => Err(ParquetError::External(Box::new(e))),
Ok(p) => std::panic::resume_unwind(p),
},
|res| res.map_err(|e| e.into()),
)
.boxed()
}
None => f(&self.store, &self.meta.location)
.map_err(|e| e.into())
.boxed(),
}
}
}
impl AsyncFileReader for ParquetObjectReader {
fn get_bytes(&mut self, range: Range<usize>) -> BoxFuture<'_, Result<Bytes>> {
self.spawn(|store, path| store.get_range(path, range))
}
fn get_byte_ranges(&mut self, ranges: Vec<Range<usize>>) -> BoxFuture<'_, Result<Vec<Bytes>>>
where
Self: Send,
{
self.spawn(|store, path| async move { store.get_ranges(path, &ranges).await }.boxed())
}
// This method doesn't directly call `self.spawn` because all of the IO that is done down the
// line due to this method call is done through `self.get_bytes` and/or `self.get_byte_ranges`.
// When `self` is passed into `ParquetMetaDataReader::load_and_finish`, it treats it as
// an `impl MetadataFetch` and calls those methods to get data from it. Due to `Self`'s impl of
// `AsyncFileReader`, the calls to `MetadataFetch::fetch` are just delegated to
// `Self::get_bytes`.
fn get_metadata(&mut self) -> BoxFuture<'_, Result<Arc<ParquetMetaData>>> {
Box::pin(async move {
let file_size = self.meta.size;
let metadata = ParquetMetaDataReader::new()
.with_column_indexes(self.preload_column_index)
.with_offset_indexes(self.preload_offset_index)
.with_prefetch_hint(self.metadata_size_hint)
.load_and_finish(self, file_size)
.await?;
Ok(Arc::new(metadata))
})
}
}
#[cfg(test)]
mod tests {
use std::sync::{
atomic::{AtomicUsize, Ordering},
Arc,
};
use futures::TryStreamExt;
use arrow::util::test_util::parquet_test_data;
use futures::FutureExt;
use object_store::local::LocalFileSystem;
use object_store::path::Path;
use object_store::{ObjectMeta, ObjectStore};
use crate::arrow::async_reader::{AsyncFileReader, ParquetObjectReader};
use crate::arrow::ParquetRecordBatchStreamBuilder;
use crate::errors::ParquetError;
async fn get_meta_store() -> (ObjectMeta, Arc<dyn ObjectStore>) {
let res = parquet_test_data();
let store = LocalFileSystem::new_with_prefix(res).unwrap();
let meta = store
.head(&Path::from("alltypes_plain.parquet"))
.await
.unwrap();
(meta, Arc::new(store) as Arc<dyn ObjectStore>)
}
#[tokio::test]
async fn test_simple() {
let (meta, store) = get_meta_store().await;
let object_reader = ParquetObjectReader::new(store, meta);
let builder = ParquetRecordBatchStreamBuilder::new(object_reader)
.await
.unwrap();
let batches: Vec<_> = builder.build().unwrap().try_collect().await.unwrap();
assert_eq!(batches.len(), 1);
assert_eq!(batches[0].num_rows(), 8);
}
#[tokio::test]
async fn test_not_found() {
let (mut meta, store) = get_meta_store().await;
meta.location = Path::from("I don't exist.parquet");
let object_reader = ParquetObjectReader::new(store, meta);
// Cannot use unwrap_err as ParquetRecordBatchStreamBuilder: !Debug
match ParquetRecordBatchStreamBuilder::new(object_reader).await {
Ok(_) => panic!("expected failure"),
Err(e) => {
let err = e.to_string();
assert!(
err.contains("not found: No such file or directory (os error 2)"),
"{err}",
);
}
}
}
#[tokio::test]
async fn test_runtime_is_used() {
let num_actions = Arc::new(AtomicUsize::new(0));
let (a1, a2) = (num_actions.clone(), num_actions.clone());
let rt = tokio::runtime::Builder::new_multi_thread()
.on_thread_park(move || {
a1.fetch_add(1, Ordering::Relaxed);
})
.on_thread_unpark(move || {
a2.fetch_add(1, Ordering::Relaxed);
})
.build()
.unwrap();
let (meta, store) = get_meta_store().await;
let initial_actions = num_actions.load(Ordering::Relaxed);
let reader = ParquetObjectReader::new(store, meta).with_runtime(rt.handle().clone());
let builder = ParquetRecordBatchStreamBuilder::new(reader).await.unwrap();
let batches: Vec<_> = builder.build().unwrap().try_collect().await.unwrap();
// Just copied these assert_eqs from the `test_simple` above
assert_eq!(batches.len(), 1);
assert_eq!(batches[0].num_rows(), 8);
assert!(num_actions.load(Ordering::Relaxed) - initial_actions > 0);
// Runtimes have to be dropped in blocking contexts, so we need to move this one to a new
// blocking thread to drop it.
tokio::runtime::Handle::current().spawn_blocking(move || drop(rt));
}
/// Unit test that `ParquetObjectReader::spawn`spawns on the provided runtime
#[tokio::test]
async fn test_runtime_thread_id_different() {
let rt = tokio::runtime::Builder::new_multi_thread()
.worker_threads(1)
.build()
.unwrap();
let (meta, store) = get_meta_store().await;
let reader = ParquetObjectReader::new(store, meta).with_runtime(rt.handle().clone());
let current_id = std::thread::current().id();
let other_id = reader
.spawn(|_, _| async move { Ok::<_, ParquetError>(std::thread::current().id()) }.boxed())
.await
.unwrap();
assert_ne!(current_id, other_id);
tokio::runtime::Handle::current().spawn_blocking(move || drop(rt));
}
#[tokio::test]
async fn io_fails_on_shutdown_runtime() {
let rt = tokio::runtime::Builder::new_multi_thread()
.worker_threads(1)
.build()
.unwrap();
let (meta, store) = get_meta_store().await;
let mut reader = ParquetObjectReader::new(store, meta).with_runtime(rt.handle().clone());
rt.shutdown_background();
let err = reader.get_bytes(0..1).await.unwrap_err().to_string();
assert!(err.to_string().contains("was cancelled"));
}
}