1// run
2
3// Copyright 2014 The Go Authors. All rights reserved.
4// Use of this source code is governed by a BSD-style
5// license that can be found in the LICENSE file.
6
7// Test finalizers work for tiny (combined) allocations.
8
9package main
10
11import (
12	"runtime"
13	"time"
14)
15
16func main() {
17	// Does not work on gccgo due to partially conservative GC.
18	// Try to enable when we have fully precise GC.
19	if runtime.Compiler == "gccgo" {
20		return
21	}
22	const N = 100
23	finalized := make(chan int32, N)
24	for i := 0; i < N; i++ {
25		x := new(int32) // subject to tiny alloc
26		*x = int32(i)
27		// the closure must be big enough to be combined
28		runtime.SetFinalizer(x, func(p *int32) {
29			finalized <- *p
30		})
31	}
32	runtime.GC()
33	count := 0
34	done := make([]bool, N)
35	timeout := time.After(5*time.Second)
36	for {
37		select {
38		case <-timeout:
39			println("timeout,", count, "finalized so far")
40			panic("not all finalizers are called")
41		case x := <-finalized:
42			// Check that p points to the correct subobject of the tiny allocation.
43			// It's a bit tricky, because we can't capture another variable
44			// with the expected value (it would be combined as well).
45			if x < 0 || x >= N {
46				println("got", x)
47				panic("corrupted")
48			}
49			if done[x] {
50				println("got", x)
51				panic("already finalized")
52			}
53			done[x] = true
54			count++
55			if count > N/10*9 {
56				// Some of the finalizers may not be executed,
57				// if the outermost allocations are combined with something persistent.
58				// Currently 4 int32's are combined into a 16-byte block,
59				// ensure that most of them are finalized.
60				return
61			}
62		}
63	}
64}
65