go/src/internal/trace/order_test.go

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internal/trace/v2: clean up the ordering interface This change cleans up the ordering interface in several ways. First, it resolves a TODO about using a proper queue of events for extra events produced while performing ordering. This will be necessary for a follow-up change to handle coroutine switch events. Next, it simplifies the ordering.advance method's signature by not returning a schedCtx. Instead, ordering.advance will take responsibility for constructing the final Event instead of the caller, and places it on its own internal queue (in addition to any other Events generated). The caller is then responsible for taking events off of the queue with a new method Next. Finally, hand-in-hand with the signature change, the implementation of ordering.advance no longer forces each switch case to return but instead has them converge past the switch. This has two effects. One is that we eliminate the deferred call to update the M state. Using a defer here is technically incorrect, because we might end up changing the M state even if we don't advance the event! We got lucky here that curCtx == newCtx in all such cases, but there may have been a subtle bug lurking here. Unfortunately because of the queue's semantics however, we can't actually avoid pushing into the queue at every possible successful exit out of the switch. Hopefully this can become less error-prone in the future by splitting up the switch into a dispatch of different functions, instead of everything living in one giant function. This cleanup will happen in a follow-up change. Change-Id: Ifebbbf14e8ed5c08be5c1b0fadc2e5df3915c656 Reviewed-on: https://go-review.googlesource.com/c/go/+/565936 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Pratt <mpratt@google.com> Auto-Submit: Michael Knyszek <mknyszek@google.com>
2024-02-20 20:58:18 +00:00
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package trace
import "testing"
func TestQueue(t *testing.T) {
var q queue[int]
check := func(name string, exp []int) {
for _, v := range exp {
q.push(v)
}
for i, want := range exp {
if got, ok := q.pop(); !ok {
t.Fatalf("check %q: expected to be able to pop after %d pops", name, i+1)
} else if got != want {
t.Fatalf("check %q: expected value %d after on pop %d, got %d", name, want, i+1, got)
}
}
if _, ok := q.pop(); ok {
t.Fatalf("check %q: did not expect to be able to pop more values", name)
}
if _, ok := q.pop(); ok {
t.Fatalf("check %q: did not expect to be able to pop more values a second time", name)
}
}
check("one element", []int{4})
check("two elements", []int{64, 12})
check("six elements", []int{55, 16423, 2352, 644, 12874, 9372})
check("one element again", []int{7})
check("two elements again", []int{77, 6336})
}