Module memory_events 

Opt-in allocation-change accounting and callbacks (include/mimalloc/memory-events.h).

Independent of the sampled profiler, and opt-in at compile time since 0.12.0 (#414): the C side is built only with the memory-events cargo feature (which dhat implies). Without it the per-allocation hook sites are compiled out – they were measured at 9-13 instructions per malloc/free pair, 18-26% of the pair, even with tracking disabled – and every function here links but reports the subsystem off ([set_enabled] returns false, [snapshot] returns None). With the feature on, tracking is still off until [set_enabled] or MIMALLOC_MEMORY_EVENTS=1.

use mimalloc_pprof::{memory_events, MiMalloc};

// The counters only move for allocations that actually reach mimalloc, so this
// example is only meaningful once mimalloc is the global allocator.
#[global_allocator]
static ALLOCATOR: MiMalloc = MiMalloc;

fn main() {
    if !memory_events::set_enabled(true) {
        return; // built without the `memory-events` feature: the API is a stub
    }
    let before = memory_events::snapshot().expect("snapshot").accum_count;
    let v = vec![0_u8; 4096];
    std::hint::black_box(&v);
    let after = memory_events::snapshot().expect("snapshot").accum_count;
    assert!(after > before);
    memory_events::set_enabled(false);
}

Structs

Callbacks

Handlers to install with set_callbacks, one per ChangeKind.

Change

One observed allocation change, copied out of mi_memory_change_t.

Snapshot

Running totals maintained while tracking is enabled.

Enums

ChangeKind

Which kind of change a Change describes.

Functions

clear_callbacks

Remove every installed callback. Accounting (and snapshot) keeps working.

is_enabled

Whether tracking is on.

set_callbacks

Install callbacks, replacing any previous table. Returns false if the C library refused the table.

set_enabled

Enable or disable tracking; returns the previous state.

snapshot

Read the running totals.

visit_live_allocations^⚠

Walk the live allocations this thread may safely observe, calling visitor with each one’s address and usable size. Return false from visitor to stop early.