Function test_try_shrink

datafusion/execution/src/memory_pool/mod.rs:632–662

()

    #[test]
    fn test_try_shrink() {
        let pool = Arc::new(GreedyMemoryPool::new(100)) as _;
        let r1 = MemoryConsumer::new("r1").register(&pool);

        r1.try_grow(50).unwrap();
        assert_eq!(r1.size(), 50);
        assert_eq!(pool.reserved(), 50);

        // Successful shrink returns new size and frees pool memory
        let new_size = r1.try_shrink(30).unwrap();
        assert_eq!(new_size, 20);
        assert_eq!(r1.size(), 20);
        assert_eq!(pool.reserved(), 20);

        // Freed pool memory is now available to other consumers
        let r2 = MemoryConsumer::new("r2").register(&pool);
        r2.try_grow(80).unwrap();
        assert_eq!(pool.reserved(), 100);

        // Shrinking more than allocated fails without changing state
        let err = r1.try_shrink(25);
        assert!(err.is_err());
        assert_eq!(r1.size(), 20);
        assert_eq!(pool.reserved(), 100);

        // Shrink to exactly zero
        let new_size = r1.try_shrink(20).unwrap();
        assert_eq!(new_size, 0);
        assert_eq!(r1.size(), 0);
        assert_eq!(pool.reserved(), 80);
    }
}