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author | 2021-04-15 19:42:51 -0700 | |
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committer | 2021-04-15 19:45:30 -0700 | |
commit | e20fe888fabc1fc995dc61180e8a31b5f809a95f (patch) | |
tree | 5877907889fe35eb3162aa71111e16bd1d59fde4 /absl/strings/internal/cordz_handle_test.cc | |
parent | 46dfbfe31ca1dd414e4c33cbcbcd7199bb4efde3 (diff) |
Export of internal Abseil changes
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341670bce317dd6af8d3c066970230591a47e80c by Martijn Vels <mvels@google.com>:
Change GetStack() and GetParentStack() to return absl::Span
PiperOrigin-RevId: 368765721
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6aaab9536d6957303c7aba100c3afaa6fb0ea2c8 by Martijn Vels <mvels@google.com>:
Remove locking from parent stack.
This change removes the need to lock all access to `parent_stack' by making the 'copy constructor' logic specify the 'copied from' CordzInfo (where available) to the TrackCord function, after which parent_stack is immutable.
PiperOrigin-RevId: 368760630
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b19e2059cada35a8ede994833018edac94de6ddc by Martijn Vels <mvels@google.com>:
Add cordz instrumentation to Cord
PiperOrigin-RevId: 368746225
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67b8bbf980f0f4e1db79aa32968e9a715a09b51a by Martijn Vels <mvels@google.com>:
Create ABSL_INTERNAL_CORDZ_ENABLED define controlling when Cordz code is enabled
There are specific builds and condtions under which we don't support cordz sampling, which is per this change represented by ABSL_INTERNAL_CORDZ_ENABLED being defined.
PiperOrigin-RevId: 368731603
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8cbfe0e3169637a620f4b66ad2bc2ce340879cb0 by Martijn Vels <mvels@google.com>:
Add a `rep` property to CordzInfo to be managed by Cord logic.
This change adds a `rep` property to CordzInfo, which is intended to be used by collection logic.
Mini design:
Cord invokes TrackCord() providing the active 'root' cordrep of the newly sampled Cord, returning a CordzInfo with a weak (uncounted) reference to this root. Cord invokes `SetCordRep()` each time the root cordrep of the sampled Cord is updated while holding `mutex()`. Cord must also obtain `mutex()` _before_ removing a reference on the old root. i.e.: Cord must guarantee that the (weak) reference held in CordzInfo is at all times valid.
CordzInfo collection code can then safely obtain a (reference counted) rep pointer by adding a reference to `rep_` while holding `mutex()`. This requires only a very brief critical section inside CordzInfo logic, minimizing contention with concurrent Cord updates.
Cord code should typically obtain and hold `mutex()` for the entirety of each mutating Cord operation on a sampled cord. As Cord is thread compatible, it never competes on the lock with any other thread. The only possible concurrent access is from Cordz collection code, which should be a relatively rare event.
PiperOrigin-RevId: 368673758
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1255120dce2bdd6b4205a34a0e555e0b74b6152f by Martijn Vels <mvels@google.com>:
Remove 'depth' from active recorded metrics.
Going forward we do not 'live' record depth (and size), but will observe these at collection time only.
PiperOrigin-RevId: 368636572
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83e5146e35f221736b49e9f0a8805f8c159a51db by Martijn Vels <mvels@google.com>:
Make cordz targets visible in OSS
PiperOrigin-RevId: 368615010
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dcb16a4f1239151f0a8c70a8cfeb29dabbd113b8 by Martijn Vels <mvels@google.com>:
Internal cleanup
PiperOrigin-RevId: 368514666
GitOrigin-RevId: 341670bce317dd6af8d3c066970230591a47e80c
Change-Id: I94cecfbbd441eb386f99fc5186c468a7a5538862
Diffstat (limited to 'absl/strings/internal/cordz_handle_test.cc')
-rw-r--r-- | absl/strings/internal/cordz_handle_test.cc | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/absl/strings/internal/cordz_handle_test.cc b/absl/strings/internal/cordz_handle_test.cc new file mode 100644 index 00000000..c04240e8 --- /dev/null +++ b/absl/strings/internal/cordz_handle_test.cc @@ -0,0 +1,253 @@ +// 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_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_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); + + CordzHandle::Delete(handle); + EXPECT_THAT(DeleteQueue(), ElementsAre(handle, snapshot)); + EXPECT_FALSE(deleted); + + 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); + + absl::synchronization_internal::ThreadPool pool(kNumThreads); + + for (int i = 0; i < kNumThreads; ++i) { + pool.Schedule([&stop, &handles]() { + std::minstd_rand gen; + std::uniform_int_distribution<int> dist_type(0, 2); + std::uniform_int_distribution<int> dist_handle(0, kNumHandles - 1); + size_t max_safe_to_inspect = 0; + 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.size() > max_safe_to_inspect) { + max_safe_to_inspect = safe_to_inspect.size(); + } + } + CordzHandle::Delete(old_handle); + } + + // Confirm that the test did *something*. This check will be satisfied as + // long as this thread has delete a CordzSnapshot object and a + // non-snapshot CordzHandle was deleted after the CordzSnapshot was + // created. This max_safe_to_inspect count will often reach around 30 + // (assuming 4 threads and 10 slots for live handles). Don't use a strict + // bound to avoid making this test flaky. + EXPECT_THAT(max_safe_to_inspect, Gt(0)); + + // 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 (size_t i = 0; i < handles.size(); i++) { + CordzHandle* handle = handles[i].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(); +} + +} // namespace +} // namespace cord_internal +ABSL_NAMESPACE_END +} // namespace absl |