// Copyright 2019 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "absl/strings/internal/cordz_handle.h"
#include <random>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/memory/memory.h"
#include "absl/synchronization/internal/thread_pool.h"
#include "absl/synchronization/notification.h"
#include "absl/time/clock.h"
#include "absl/time/time.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace cord_internal {
namespace {
using ::testing::ElementsAre;
using ::testing::Gt;
using ::testing::IsEmpty;
using ::testing::SizeIs;
// Local less verbose helper
std::vector<const CordzHandle*> DeleteQueue() {
return CordzHandle::DiagnosticsGetDeleteQueue();
}
struct CordzHandleDeleteTracker : public CordzHandle {
bool* deleted;
explicit CordzHandleDeleteTracker(bool* deleted) : deleted(deleted) {}
~CordzHandleDeleteTracker() override { *deleted = true; }
};
TEST(CordzHandleTest, DeleteQueueIsEmpty) {
EXPECT_THAT(DeleteQueue(), SizeIs(0));
}
TEST(CordzHandleTest, CordzHandleCreateDelete) {
bool deleted = false;
auto* handle = new CordzHandleDeleteTracker(&deleted);
EXPECT_FALSE(handle->is_snapshot());
EXPECT_TRUE(handle->SafeToDelete());
EXPECT_THAT(DeleteQueue(), SizeIs(0));
CordzHandle::Delete(handle);
EXPECT_THAT(DeleteQueue(), SizeIs(0));
EXPECT_TRUE(deleted);
}
TEST(CordzHandleTest, CordzSnapshotCreateDelete) {
auto* snapshot = new CordzSnapshot();
EXPECT_TRUE(snapshot->is_snapshot());
EXPECT_TRUE(snapshot->SafeToDelete());
EXPECT_THAT(DeleteQueue(), ElementsAre(snapshot));
delete snapshot;
EXPECT_THAT(DeleteQueue(), SizeIs(0));
}
TEST(CordzHandleTest, CordzHandleCreateDeleteWithSnapshot) {
bool deleted = false;
auto* snapshot = new CordzSnapshot();
auto* handle = new CordzHandleDeleteTracker(&deleted);
EXPECT_FALSE(handle->SafeToDelete());
CordzHandle::Delete(handle);
EXPECT_THAT(DeleteQueue(), ElementsAre(handle, snapshot));
EXPECT_FALSE(deleted);
EXPECT_FALSE(handle->SafeToDelete());
delete snapshot;
EXPECT_THAT(DeleteQueue(), SizeIs(0));
EXPECT_TRUE(deleted);
}
TEST(CordzHandleTest, MultiSnapshot) {
bool deleted[3] = {false, false, false};
CordzSnapshot* snapshot[3];
CordzHandleDeleteTracker* handle[3];
for (int i = 0; i < 3; ++i) {
snapshot[i] = new CordzSnapshot();
handle[i] = new CordzHandleDeleteTracker(&deleted[i]);
CordzHandle::Delete(handle[i]);
}
EXPECT_THAT(DeleteQueue(), ElementsAre(handle[2], snapshot[2], handle[1],
snapshot[1], handle[0], snapshot[0]));
EXPECT_THAT(deleted, ElementsAre(false, false, false));
delete snapshot[1];
EXPECT_THAT(DeleteQueue(), ElementsAre(handle[2], snapshot[2], handle[1],
handle[0], snapshot[0]));
EXPECT_THAT(deleted, ElementsAre(false, false, false));
delete snapshot[0];
EXPECT_THAT(DeleteQueue(), ElementsAre(handle[2], snapshot[2]));
EXPECT_THAT(deleted, ElementsAre(true, true, false));
delete snapshot[2];
EXPECT_THAT(DeleteQueue(), SizeIs(0));
EXPECT_THAT(deleted, ElementsAre(true, true, deleted));
}
TEST(CordzHandleTest, DiagnosticsHandleIsSafeToInspect) {
CordzSnapshot snapshot1;
EXPECT_TRUE(snapshot1.DiagnosticsHandleIsSafeToInspect(nullptr));
auto* handle1 = new CordzHandle();
EXPECT_TRUE(snapshot1.DiagnosticsHandleIsSafeToInspect(handle1));
CordzHandle::Delete(handle1);
EXPECT_TRUE(snapshot1.DiagnosticsHandleIsSafeToInspect(handle1));
CordzSnapshot snapshot2;
auto* handle2 = new CordzHandle();
EXPECT_TRUE(snapshot1.DiagnosticsHandleIsSafeToInspect(handle1));
EXPECT_TRUE(snapshot1.DiagnosticsHandleIsSafeToInspect(handle2));
EXPECT_FALSE(snapshot2.DiagnosticsHandleIsSafeToInspect(handle1));
EXPECT_TRUE(snapshot2.DiagnosticsHandleIsSafeToInspect(handle2));
CordzHandle::Delete(handle2);
EXPECT_TRUE(snapshot1.DiagnosticsHandleIsSafeToInspect(handle1));
}
TEST(CordzHandleTest, DiagnosticsGetSafeToInspectDeletedHandles) {
EXPECT_THAT(DeleteQueue(), IsEmpty());
auto* handle = new CordzHandle();
auto* snapshot1 = new CordzSnapshot();
// snapshot1 should be able to see handle.
EXPECT_THAT(DeleteQueue(), ElementsAre(snapshot1));
EXPECT_TRUE(snapshot1->DiagnosticsHandleIsSafeToInspect(handle));
EXPECT_THAT(snapshot1->DiagnosticsGetSafeToInspectDeletedHandles(),
IsEmpty());
// This handle will be safe to inspect as long as snapshot1 is alive. However,
// since only snapshot1 can prove that it's alive, it will be hidden from
// snapshot2.
CordzHandle::Delete(handle);
// This snapshot shouldn't be able to see handle because handle was already
// sent to Delete.
auto* snapshot2 = new CordzSnapshot();
// DeleteQueue elements are LIFO order.
EXPECT_THAT(DeleteQueue(), ElementsAre(snapshot2, handle, snapshot1));
EXPECT_TRUE(snapshot1->DiagnosticsHandleIsSafeToInspect(handle));
EXPECT_FALSE(snapshot2->DiagnosticsHandleIsSafeToInspect(handle));
EXPECT_THAT(snapshot1->DiagnosticsGetSafeToInspectDeletedHandles(),
ElementsAre(handle));
EXPECT_THAT(snapshot2->DiagnosticsGetSafeToInspectDeletedHandles(),
IsEmpty());
CordzHandle::Delete(snapshot1);
EXPECT_THAT(DeleteQueue(), ElementsAre(snapshot2));
CordzHandle::Delete(snapshot2);
EXPECT_THAT(DeleteQueue(), IsEmpty());
}
// Create and delete CordzHandle and CordzSnapshot objects in multiple threads
// so that tsan has some time to chew on it and look for memory problems.
TEST(CordzHandleTest, MultiThreaded) {
Notification stop;
static constexpr int kNumThreads = 4;
// Keep the number of handles relatively small so that the test will naturally
// transition to an empty delete queue during the test. If there are, say, 100
// handles, that will virtually never happen. With 10 handles and around 50k
// iterations in each of 4 threads, the delete queue appears to become empty
// around 200 times.
static constexpr int kNumHandles = 10;
// Each thread is going to pick a random index and atomically swap its
// CordzHandle with one in handles. This way, each thread can avoid
// manipulating a CordzHandle that might be operated upon in another thread.
std::vector<std::atomic<CordzHandle*>> handles(kNumHandles);
// global bool which is set when any thread did get some 'safe to inspect'
// handles. On some platforms and OSS tests, we might risk that some pool
// threads are starved, stalled, or just got a few unlikely random 'handle'
// coin tosses, so we satisfy this test with simply observing 'some' thread
// did something meaningful, which should minimize the potential for flakes.
std::atomic<bool> found_safe_to_inspect(false);
{
absl::synchronization_internal::ThreadPool pool(kNumThreads);
for (int i = 0; i < kNumThreads; ++i) {
pool.Schedule([&stop, &handles, &found_safe_to_inspect]() {
std::minstd_rand gen;
std::uniform_int_distribution<int> dist_type(0, 2);
std::uniform_int_distribution<int> dist_handle(0, kNumHandles - 1);
while (!stop.HasBeenNotified()) {
CordzHandle* handle;
switch (dist_type(gen)) {
case 0:
handle = new CordzHandle();
break;
case 1:
handle = new CordzSnapshot();
break;
default:
handle = nullptr;
break;
}
CordzHandle* old_handle = handles[dist_handle(gen)].exchange(handle);
if (old_handle != nullptr) {
std::vector<const CordzHandle*> safe_to_inspect =
old_handle->DiagnosticsGetSafeToInspectDeletedHandles();
for (const CordzHandle* handle : safe_to_inspect) {
// We're in a tight loop, so don't generate too many error
// messages.
ASSERT_FALSE(handle->is_snapshot());
}
if (!safe_to_inspect.empty()) {
found_safe_to_inspect.store(true);
}
CordzHandle::Delete(old_handle);
}
}
// Have each thread attempt to clean up everything. Some thread will be
// the last to reach this cleanup code, and it will be guaranteed to
// clean up everything because nothing remains to create new handles.
for (auto& h : handles) {
if (CordzHandle* handle = h.exchange(nullptr)) {
CordzHandle::Delete(handle);
}
}
});
}
// The threads will hammer away. Give it a little bit of time for tsan to
// spot errors.
absl::SleepFor(absl::Seconds(3));
stop.Notify();
}
// Confirm that the test did *something*. This check will be satisfied as
// long as any thread has deleted a CordzSnapshot object and a non-snapshot
// CordzHandle was deleted after the CordzSnapshot was created.
// See also comments on `found_safe_to_inspect`
EXPECT_TRUE(found_safe_to_inspect.load());
}
} // namespace
} // namespace cord_internal
ABSL_NAMESPACE_END
} // namespace absl
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