mkleen commented on code in PR #20047: URL: https://github.com/apache/datafusion/pull/20047#discussion_r3159660521
########## datafusion/execution/src/cache/file_statistics_cache.rs: ########## @@ -0,0 +1,745 @@ +// 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 crate::cache::cache_manager::{ + CachedFileMetadata, FileStatisticsCache, FileStatisticsCacheEntry, +}; +use crate::cache::{CacheAccessor, TableScopedPath}; +use std::collections::HashMap; +use std::sync::Mutex; + +pub use crate::cache::DefaultFilesMetadataCache; +use crate::cache::lru_queue::LruQueue; +use datafusion_common::TableReference; +use datafusion_common::heap_size::{DFHeapSize, DFHeapSizeCtx}; + +/// Default implementation of [`FileStatisticsCache`] +/// +/// Stores cached file metadata (statistics and orderings) for files. +/// +/// The typical usage pattern is: +/// 1. Call `get(path)` to check for cached value +/// 2. If `Some(cached)`, validate with `cached.is_valid_for(¤t_meta)` +/// 3. If invalid or missing, compute new value and call `put(path, new_value)` +/// +/// # Internal details +/// +/// The `memory_limit` controls the maximum size of the cache, which uses a +/// Least Recently Used eviction algorithm. When adding a new entry, if the total +/// size of the cached entries exceeds `memory_limit`, the least recently used entries +/// are evicted until the total size is lower than `memory_limit`. +/// +/// +/// [`FileStatisticsCache`]: crate::cache::cache_manager::FileStatisticsCache +#[derive(Default)] +pub struct DefaultFileStatisticsCache { + state: Mutex<DefaultFileStatisticsCacheState>, +} + +impl DefaultFileStatisticsCache { + pub fn new(memory_limit: usize) -> Self { + Self { + state: Mutex::new(DefaultFileStatisticsCacheState::new(memory_limit)), + } + } + + /// Returns the size of the cached memory, in bytes. + pub fn memory_used(&self) -> usize { + let state = self.state.lock().unwrap(); + state.memory_used + } +} + +struct DefaultFileStatisticsCacheState { + lru_queue: LruQueue<TableScopedPath, CachedFileMetadata>, + memory_limit: usize, + memory_used: usize, +} + +pub const DEFAULT_FILE_STATISTICS_MEMORY_LIMIT: usize = 20 * 1024 * 1024; // 20MiB + +impl Default for DefaultFileStatisticsCacheState { + fn default() -> Self { + Self { + lru_queue: LruQueue::new(), + memory_limit: DEFAULT_FILE_STATISTICS_MEMORY_LIMIT, + memory_used: 0, + } + } +} + +impl DefaultFileStatisticsCacheState { + fn new(memory_limit: usize) -> Self { + Self { + lru_queue: LruQueue::new(), + memory_limit, + memory_used: 0, + } + } + fn get(&mut self, key: &TableScopedPath) -> Option<CachedFileMetadata> { + self.lru_queue.get(key).cloned() + } + + fn put( + &mut self, + key: &TableScopedPath, + value: CachedFileMetadata, + ) -> Option<CachedFileMetadata> { + let mut ctx = DFHeapSizeCtx::default(); Review Comment: Thank you, i made one more iteration to streamline the memory accounting for inserting. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
