grit-lib 0.5.29

Core library for the grit Git implementation
Documentation 
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//! Return freed heap pages to the operating system where supported.

/// Release memory the global allocator has freed but may still hold in arenas.
///
/// On Linux with glibc, this calls `malloc_trim(0)`, which returns unused arena
/// pages to the kernel. Live allocations are untouched. On musl, other operating
/// systems, and other targets this is a no-op.
///
/// Call after large, bursty allocations (for example pack generation) when no
/// concurrent work on the same thread needs the allocator — `malloc_trim` can
/// briefly lock every arena.
#[must_use]
pub fn release_unused_heap() -> bool {
    release_unused_heap_impl()
}

#[cfg(all(target_os = "linux", target_env = "gnu"))]
fn release_unused_heap_impl() -> bool {
    extern "C" {
        fn malloc_trim(pad: usize) -> i32;
    }
    // SAFETY: `malloc_trim` is a glibc extension on Linux; `pad` is 0 per man page.
    unsafe { malloc_trim(0) != 0 }
}

#[cfg(not(all(target_os = "linux", target_env = "gnu")))]
fn release_unused_heap_impl() -> bool {
    false
}