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use std::alloc::{GlobalAlloc, Layout, System};
use std::cell::RefCell;
pub fn count<F: FnOnce()>(run_while_counting: F) -> u64 {
let initial_count = ALLOCATIONS.with(|f| *f.borrow());
run_while_counting();
ALLOCATIONS.with(|f| *f.borrow()) - initial_count
}
thread_local! {
static ALLOCATIONS: RefCell<u64> = RefCell::new(0);
}
struct CountingAllocator;
unsafe impl GlobalAlloc for CountingAllocator {
unsafe fn alloc(&self, l: Layout) -> *mut u8 {
ALLOCATIONS.with(|f| {
*f.borrow_mut() += 1;
});
System.alloc(l)
}
unsafe fn dealloc(&self, ptr: *mut u8, l: Layout) {
System.dealloc(ptr, l);
}
}
#[global_allocator]
static GLOBAL: CountingAllocator = CountingAllocator {};
#[test]
fn test_closure() {
let allocations = count(|| {
let mut v: Vec<u32> = Vec::new();
v.push(12);
assert_eq!(v.len(), 1);
});
assert_eq!(allocations, 1);
let allocations = count(|| {
let mut v: Vec<u32> = Vec::new();
v.push(12);
assert_eq!(v.len(), 1);
});
assert_eq!(allocations, 1);
let allocations = count(|| {
let mut v: Vec<u32> = Vec::new();
v.push(12);
assert_eq!(v.len(), 1);
let mut v: Vec<u32> = Vec::new();
v.push(12);
assert_eq!(v.len(), 1);
});
assert_eq!(allocations, 2);
}