stoolap-jemalloc 0.1.5

A jemalloc-style memory allocator written in pure Rust, with a built-in pprof heap profiler
Documentation 
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// Copyright 2026 Stoolap Contributors
//
// Licensed 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.

//! Process-wide counters, updated only on slow paths

use core::sync::atomic::{AtomicUsize, Ordering::Relaxed};

pub(crate) static CHUNK_BYTES: Counter = Counter::new();
pub(crate) static HUGE_BYTES: Counter = Counter::new();
pub(crate) static HUGE_CACHED_BYTES: Counter = Counter::new();
pub(crate) static METADATA_BYTES: Counter = Counter::new();

/// Memory the allocator holds from the OS, in bytes
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
pub struct Stats {
    /// Chunks that hold small and large allocations
    pub chunks: usize,
    /// Mappings of huge allocations that are in use
    pub huge: usize,
    /// Freed huge mappings kept for reuse
    pub huge_cached: usize,
    /// The allocator's own metadata, including the heap profiler's
    pub metadata: usize,
}

impl Stats {
    /// All memory mapped from the OS
    #[must_use]
    pub fn mapped(&self) -> usize {
        self.chunks + self.huge + self.huge_cached + self.metadata
    }
}

/// A snapshot of the allocator's counters
pub fn stats() -> Stats {
    Stats {
        chunks: CHUNK_BYTES.get(),
        huge: HUGE_BYTES.get(),
        huge_cached: HUGE_CACHED_BYTES.get(),
        metadata: METADATA_BYTES.get(),
    }
}

/// A counter of bytes. Additions and subtractions are separate so that no
/// size needs a sign: on 32-bit targets a mapping can exceed `isize::MAX`.
pub(crate) struct Counter(AtomicUsize);

impl Counter {
    const fn new() -> Self {
        Counter(AtomicUsize::new(0))
    }

    fn get(&self) -> usize {
        self.0.load(Relaxed)
    }

    pub(crate) fn add(&self, n: usize) {
        self.0.fetch_add(n, Relaxed);
    }

    pub(crate) fn sub(&self, n: usize) {
        self.0.fetch_sub(n, Relaxed);
    }
}