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// Copyright (c) 2024-present, fjall-rs
// This source code is licensed under both the Apache 2.0 and MIT License
// (found in the LICENSE-* files in the repository)
use std::sync::atomic::Ordering::Relaxed;
use std::sync::atomic::{AtomicU64, AtomicUsize};
/// Runtime metrics
///
/// Are not stored durably, so metrics will reset after a restart/crash.
#[derive(Debug, Default)]
pub struct Metrics {
/// Number of times a table file was opened using `fopen()`
pub(crate) table_file_opened_uncached: AtomicUsize,
/// Number of times a table file was retrieved from descriptor cache
pub(crate) table_file_opened_cached: AtomicUsize,
/// Number of index blocks that were actually read from disk
pub(crate) index_block_load_io: AtomicUsize,
/// Number of filter blocks that were actually read from disk
pub(crate) filter_block_load_io: AtomicUsize,
/// Number of blocks that were actually read from disk
pub(crate) data_block_load_io: AtomicUsize,
/// Number of blocks that were read from block cache
pub(crate) index_block_load_cached: AtomicUsize,
/// Number of blocks that were read from block cache
pub(crate) filter_block_load_cached: AtomicUsize,
/// Number of blocks that were read from block cache
pub(crate) data_block_load_cached: AtomicUsize,
/// Number of filter queries that were performed
pub(crate) filter_queries: AtomicUsize,
/// Number of IOs that were skipped due to filter
pub(crate) io_skipped_by_filter: AtomicUsize,
/// Number of data block bytes that were requested from OS or disk
pub(crate) data_block_io_requested: AtomicU64,
/// Number of index block bytes that were requested from OS or disk
pub(crate) index_block_io_requested: AtomicU64,
/// Number of filter block bytes that were requested from OS or disk
pub(crate) filter_block_io_requested: AtomicU64,
}
#[expect(
clippy::cast_precision_loss,
reason = "metrics can accept precision loss"
)]
impl Metrics {
/// Returns the cache hit rate for file descriptors in percent (0.0 - 1.0).
pub fn table_file_cache_hit_rate(&self) -> f64 {
let uncached = self.table_file_opened_uncached.load(Relaxed) as f64;
let cached = self.table_file_opened_cached.load(Relaxed) as f64;
if cached + uncached == 0.0 {
1.0
} else {
cached / (cached + uncached)
}
}
/// Number of I/O data block bytes transferred from disk or OS page cache.
pub fn data_block_io(&self) -> u64 {
self.data_block_io_requested.load(Relaxed)
}
/// Number of I/O index block bytes transferred from disk or OS page cache.
pub fn index_block_io(&self) -> u64 {
self.index_block_io_requested.load(Relaxed)
}
/// Number of I/O filter block bytes transferred from disk or OS page cache.
pub fn filter_block_io(&self) -> u64 {
self.filter_block_io_requested.load(Relaxed)
}
/// Number of I/O block bytes transferred from disk or OS page cache.
pub fn block_io(&self) -> u64 {
self.data_block_io_requested.load(Relaxed)
+ self.index_block_io_requested.load(Relaxed)
+ self.filter_block_io_requested.load(Relaxed)
}
/// Number of data blocks that were accessed.
pub fn data_block_load_count(&self) -> usize {
self.data_block_load_cached.load(Relaxed) + self.data_block_load_io.load(Relaxed)
}
/// Number of index blocks that were accessed.
pub fn index_block_load_count(&self) -> usize {
self.index_block_load_cached.load(Relaxed) + self.index_block_load_io.load(Relaxed)
}
/// Number of filter blocks that were accessed.
pub fn filter_block_load_count(&self) -> usize {
self.filter_block_load_cached.load(Relaxed) + self.filter_block_load_io.load(Relaxed)
}
/// Number of blocks that were loaded from disk or OS page cache.
pub fn block_load_io_count(&self) -> usize {
self.data_block_load_io.load(Relaxed)
+ self.index_block_load_io.load(Relaxed)
+ self.filter_block_load_io.load(Relaxed)
}
/// Number of data blocks that were loaded from disk or OS page cache.
pub fn data_block_load_cached_count(&self) -> usize {
self.data_block_load_cached.load(Relaxed)
}
/// Number of index blocks that were loaded from disk or OS page cache.
pub fn index_block_load_cached_count(&self) -> usize {
self.index_block_load_cached.load(Relaxed)
}
/// Number of filter blocks that were loaded from disk or OS page cache.
pub fn filter_block_load_cached_count(&self) -> usize {
self.filter_block_load_cached.load(Relaxed)
}
/// Number of blocks that were loaded from disk or OS page cache.
pub fn block_load_cached_count(&self) -> usize {
self.data_block_load_cached.load(Relaxed)
+ self.index_block_load_cached.load(Relaxed)
+ self.filter_block_load_cached.load(Relaxed)
}
/// Number of blocks that were accessed.
pub fn block_loads(&self) -> usize {
self.block_load_io_count() + self.block_load_cached_count()
}
/// Data block cache efficiency in percent (0.0 - 1.0).
pub fn data_block_cache_hit_rate(&self) -> f64 {
let queries = self.data_block_load_count() as f64;
let hits = self.data_block_load_cached_count() as f64;
if queries == 0.0 {
1.0
} else {
hits / queries
}
}
/// Filter block cache efficiency in percent (0.0 - 1.0).
pub fn filter_block_cache_hit_rate(&self) -> f64 {
let queries = self.filter_block_load_count() as f64;
let hits = self.filter_block_load_cached_count() as f64;
if queries == 0.0 {
1.0
} else {
hits / queries
}
}
/// Index block cache efficiency in percent (0.0 - 1.0).
pub fn index_block_cache_hit_rate(&self) -> f64 {
let queries = self.index_block_load_count() as f64;
let hits = self.index_block_load_cached_count() as f64;
if queries == 0.0 {
1.0
} else {
hits / queries
}
}
/// Block cache efficiency in percent (0.0 - 1.0).
pub fn block_cache_hit_rate(&self) -> f64 {
let queries = self.block_loads() as f64;
let hits = self.block_load_cached_count() as f64;
if queries == 0.0 {
1.0
} else {
hits / queries
}
}
/// Filter efficiency in percent (0.0 - 1.0).
///
/// Represents the ratio of I/O operations avoided due to filter.
pub fn filter_efficiency(&self) -> f64 {
let queries = self.filter_queries.load(Relaxed) as f64;
let io_skipped = self.io_skipped_by_filter.load(Relaxed) as f64;
if queries == 0.0 {
1.0
} else {
io_skipped / queries
}
}
/// Number of filter queries performed.
pub fn filter_queries(&self) -> usize {
self.filter_queries.load(Relaxed)
}
/// Number of I/O operations skipped by filter.
pub fn io_skipped_by_filter(&self) -> usize {
self.io_skipped_by_filter.load(Relaxed)
}
}