// Copyright 2019 The TCMalloc 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 <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <sys/mman.h>

#include <functional>
#include <memory>
#include <optional>
#include <string>

#include "tcmalloc/internal/profile.pb.h"
#include "gtest/gtest.h"
#include "absl/base/attributes.h"
#include "absl/base/const_init.h"
#include "absl/base/internal/low_level_alloc.h"
#include "absl/base/internal/spinlock.h"
#include "absl/base/thread_annotations.h"
#include "absl/container/flat_hash_set.h"
#include "absl/log/absl_check.h"
#include "absl/log/check.h"
#include "absl/status/statusor.h"
#include "absl/strings/str_format.h"
#include "absl/time/clock.h"
#include "absl/time/time.h"
#include "tcmalloc/internal/config.h"
#include "tcmalloc/internal/logging.h"
#include "tcmalloc/internal/profile_builder.h"
#include "tcmalloc/internal/sampled_allocation.h"
#include "tcmalloc/malloc_extension.h"
#include "tcmalloc/malloc_hook.h"
#include "tcmalloc/static_vars.h"
#include "tcmalloc/testing/test_allocator_harness.h"
#include "tcmalloc/testing/thread_manager.h"

namespace tcmalloc {
namespace {

using absl::base_internal::LowLevelAlloc;

auto process_start = absl::Now();

class HeapProfilingTest : public ::testing::TestWithParam<int64_t> {};

// Verify that heap profiling sessions concurrent with allocations/deallocations
// do not crash, as they all use `tc_globals.sampled_allocation_recorder_`. Also
// check that the data in the sample make sense. Here the
// allocations/deallocations can happen on the same thread or the object is
// allocated in one thread, transferred to another thread and deleted there.
TEST_P(HeapProfilingTest, GetHeapProfileWhileAllocAndDealloc) {
  ScopedProfileSamplingInterval s(GetParam());
  const int kThreads = 10;
  ThreadManager manager;
  AllocatorHarness harness(kThreads);

  // Some threads are busy with allocating and deallocating.
  manager.Start(kThreads, [&](int thread_id) { harness.Run(thread_id); });

  absl::Time test_start = absl::Now();
  // Another few threads busy with iterating different kinds of heap profiles.
  for (auto t : {
           ProfileType::kHeap,
           ProfileType::kFragmentation,
           ProfileType::kPeakHeap,
       }) {
    manager.Start(2, [&, t](int) {
      MallocExtension::SnapshotCurrent(t).Iterate(
          [&](const Profile::Sample& s) {
            // Inspect a few fields in the sample.
            CHECK_GE(s.sum, 0);
            CHECK_GT(s.depth, 0);
            CHECK_GT(s.requested_size, 0);
            CHECK_GT(s.allocated_size, 0);
            // Note: there may be few allocations that happened before
            // process_start initialization.
            CHECK_GT(s.allocation_time, process_start - absl::Seconds(10));
            CHECK_LT(s.allocation_time, test_start + absl::Seconds(20));
          });
    });
  }

  absl::SleepFor(absl::Milliseconds(100));
  manager.Stop();
}

// Test at different sampling rates, from always sampling to lower sampling
// probabilities. This is stress testing and attempts to expose potential
// failure modes when we only have sampled allocations and when we have a mix of
// sampled/unsampled allocations.
INSTANTIATE_TEST_SUITE_P(SamplingIntervals, HeapProfilingTest,
                         testing::Values(1, 1 << 7, 1 << 14, 1 << 21),
                         testing::PrintToStringParamName());

TEST(HeapProfilingTest, Timestamp) {
  const absl::Time now = absl::Now();

  auto converted_or = tcmalloc_internal::MakeProfileProto(
      MallocExtension::SnapshotCurrent(ProfileType::kHeap));
  if (tcmalloc_internal::kSanitizerPresent) {
    EXPECT_FALSE(converted_or.ok());
    return;
  }
  ASSERT_TRUE(converted_or.ok());
  const auto& converted = **converted_or;

  EXPECT_GE(converted.time_nanos(), absl::ToUnixNanos(now - absl::Seconds(10)));
  EXPECT_LE(converted.time_nanos(), absl::ToUnixNanos(now + absl::Seconds(10)));
}

TEST(HeapProfilingTest, AllocateDifferentSizes) {
  const int num_allocations = 1000;
  const size_t requested_size1 = (1 << 19) + 1;
  const size_t requested_size2 = (1 << 20) + 1;
  int requested_size1_count = 0;
  int requested_size2_count = 0;

  // First allocate some large objects at a specific size, verify through heap
  // profile, and deallocate them.
  void* allocations1[num_allocations];
  for (int i = 0; i < num_allocations; i++) {
    allocations1[i] = ::operator new(requested_size1);
  }

  MallocExtension::SnapshotCurrent(ProfileType::kHeap)
      .Iterate([&](const Profile::Sample& s) {
        if (s.requested_size == requested_size1) requested_size1_count++;
        if (s.requested_size == requested_size2) requested_size2_count++;
      });

  if (!tcmalloc_internal::kSanitizerPresent) {
    EXPECT_GT(requested_size1_count, 0);
    EXPECT_EQ(requested_size2_count, 0);
  }
  requested_size1_count = 0;

  for (int i = 0; i < num_allocations; i++) {
    ::operator delete(allocations1[i]);
  }

  // Next allocate some large objects at a different size, verify through heap
  // profile, and deallocate them.
  void* allocations2[num_allocations];
  for (int i = 0; i < num_allocations; i++) {
    allocations2[i] = ::operator new(requested_size2);
  }

  MallocExtension::SnapshotCurrent(ProfileType::kHeap)
      .Iterate([&](const Profile::Sample& s) {
        if (s.requested_size == requested_size1) requested_size1_count++;
        if (s.requested_size == requested_size2) requested_size2_count++;
      });

  if (!tcmalloc_internal::kSanitizerPresent) {
    EXPECT_EQ(requested_size1_count, 0);
    EXPECT_GT(requested_size2_count, 0);
  }

  for (int i = 0; i < num_allocations; i++) {
    ::operator delete(allocations2[i]);
  }
}

TEST(HeapProfilingTest, CheckResidency) {
  ScopedProfileSamplingInterval s(1);
  const int num_allocations = 1000;
  const size_t requested_size = (1 << 19) + 1;

  void* allocations[num_allocations];
  for (int i = 0; i < num_allocations; i++) {
    allocations[i] = ::operator new(requested_size);
  }

  bool mlock_failure = false;
  for (int i = 0; i < num_allocations; i++) {
    if (::mlock(allocations[i], requested_size) != 0) {
      mlock_failure = true;
      for (int j = 0; j < requested_size; ++j) {
        static_cast<volatile char*>(allocations[i])[j] = 0x20;
      }
    }
  }
  if (mlock_failure) {
    absl::FPrintF(
        stderr,
        "one or more mlocks failed, which could cause test flakiness\n");
  }

  // Collect the heap profile and look for residency info.
  auto converted_or = tcmalloc_internal::MakeProfileProto(
      MallocExtension::SnapshotCurrent(ProfileType::kHeap));
  if (tcmalloc_internal::kSanitizerPresent) {
    EXPECT_FALSE(converted_or.ok());
    return;
  }

  ASSERT_TRUE(converted_or.ok());
  const auto& converted = **converted_or;

  // Look for "sampled_resident_bytes" string in string table.
  std::optional<int> sampled_resident_bytes_id;
  std::optional<int> resident_space_id;
  for (int i = 0, n = converted.string_table().size(); i < n; ++i) {
    if (converted.string_table(i) == "sampled_resident_bytes") {
      sampled_resident_bytes_id = i;
    }
    if (converted.string_table(i) == "resident_space") {
      resident_space_id = i;
    }
  }
  EXPECT_FALSE(sampled_resident_bytes_id.has_value());
  ASSERT_TRUE(resident_space_id.has_value());

  std::optional<int> resident_value_index;
  for (int i = 0; i < converted.sample_type_size(); ++i) {
    if (converted.sample_type(i).type() == resident_space_id) {
      resident_value_index = i;
      break;
    }
  }

  ASSERT_TRUE(resident_value_index.has_value());

  size_t resident_size = 0;
  for (const auto& sample : converted.sample()) {
    resident_size += sample.value(*resident_value_index);
  }

  EXPECT_GE(resident_size, num_allocations * requested_size);
  EXPECT_LE(resident_size, num_allocations * requested_size * 2);

  for (int i = 0; i < num_allocations; i++) {
    // throw away the error
    ::munlock(allocations[i], requested_size);
  }
  for (int i = 0; i < num_allocations; i++) {
    ::operator delete(allocations[i]);
  }
}

// Make sure users can allocate when iterating over the heap samples. For now
// `MallocExtension::SnapshotCurrent()` uses `StackTraceTable` to make a copy of
// the sampled allocations from `tc_globals.sampled_allocation_recorder()` and
// then iterate from the `StackTraceTable`. Ideally, we would want to avoid the
// extra copy and iterate over sampled allocations directly. However, this would
// result in deadlocks for the test case below. If we `Iterate()` directly on
// `tc_globals.sampled_allocation_recorder()`, we hold the per-sample lock. As
// we add data to a hashtable that stores allocations (always sampled here), the
// hashtable can decide to `resize()`, deallocates the same sampled allocation
// it is iterating at, wants to get the per-sample lock and ends up with a
// deadlock. At the current state, making copies over sampled allocations and
// iterate over those copies would not deadlock and the test case below passes.
TEST(HeapProfilingTest, AllocateWhileIterating) {
  ScopedProfileSamplingInterval s(1);
  absl::flat_hash_set<void*> set;
  // This fills up the slots in hashtable and so there is a good chance it would
  // call `resize()` when inserting new entries later. This makes it easier for
  // the deadlock to happen (>95% of the cases when directly iterating over
  // `tc_globals.sampled_allocation_recorder()`).
  set.reserve(1);
  set.insert(::operator new(100));
  for (int i = 0; i < 3; i++) {
    MallocExtension::SnapshotCurrent(ProfileType::kHeap)
        .Iterate(
            [&](const Profile::Sample& s) { set.insert(::operator new(100)); });
  }
  for (void* obj : set) {
    ::operator delete(obj);
  }
}

LowLevelAlloc::Arena* arena() {
  static auto* arena = LowLevelAlloc::NewArena(0);
  return arena;
}

template <class T>
class TestAllocator {
 public:
  using value_type = T;
  TestAllocator() = default;
  template <typename U>
  TestAllocator(TestAllocator<U>) {}  // NOLINT

  static T* allocate(size_t size) {
    return reinterpret_cast<T*>(
        LowLevelAlloc::AllocWithArena(size * sizeof(T), arena()));
  }

  static void deallocate(T* ptr, size_t size) { LowLevelAlloc::Free(ptr); }
};

using AllocHandle = MallocHook::AllocHandle;
// We can't allocate memory from TCMalloc for the hash set here, otherwise,
// we will run into a deadlock.
using AllocHandles =
    absl::flat_hash_set<AllocHandle, absl::flat_hash_set<AllocHandle>::hasher,
                        std::equal_to<AllocHandle>, TestAllocator<AllocHandle>>;

class HeapAllocHandleTest : public ::testing::TestWithParam<int64_t> {
 public:
  HeapAllocHandleTest() {
    alloc_handles_ = new AllocHandles;
    ABSL_CHECK(
        MallocHook::AddSampledNewHook(&HeapAllocHandleTest::MemoryAllocated));
    ABSL_CHECK(MallocHook::AddSampledDeleteHook(
        &HeapAllocHandleTest::MemoryDeallocated));
  }

  ~HeapAllocHandleTest() override {
    ABSL_CHECK(MallocHook::RemoveSampledNewHook(
        &HeapAllocHandleTest::MemoryAllocated));
    ABSL_CHECK(MallocHook::RemoveSampledDeleteHook(
        &HeapAllocHandleTest::MemoryDeallocated));
    delete alloc_handles_;
  }

  static void MemoryAllocated(const MallocHook::SampledAlloc& sampled_alloc) {
    absl::base_internal::SpinLockHolder h(lock_);
    alloc_handles_->insert(sampled_alloc.handle);
  }

  static void MemoryDeallocated(
      const
      MallocHook::SampledAlloc& sampled_alloc) {
    absl::base_internal::SpinLockHolder h(lock_);
    alloc_handles_->erase(sampled_alloc.handle);
  }

  static absl::base_internal::SpinLock lock_;
  static AllocHandles* alloc_handles_ ABSL_PT_GUARDED_BY(lock_);
};

ABSL_CONST_INIT absl::base_internal::SpinLock HeapAllocHandleTest::lock_(
    absl::base_internal::SCHEDULE_KERNEL_ONLY);
AllocHandles* HeapAllocHandleTest::alloc_handles_;

// Verify that alloc handles in `tc_globals.sampled_allocation_recorder_` can be
// found in `alloc_handles_`, which manages the handle information through the
// malloc hook. Here the allocation/deallocation can happen on the same thread
// or the object is allocated in one thread, transferred to another thread and
// deleted there.
TEST_P(HeapAllocHandleTest, VerifyAllocHandles) {
  ScopedProfileSamplingInterval s(GetParam());
  const int kThreads = 2;
  ThreadManager manager;
  AllocatorHarness harness(kThreads);

  // First insert existing live alloc handles to `alloc_handles_`.
  tcmalloc_internal::tc_globals.sampled_allocation_recorder().Iterate(
      [&](const tcmalloc_internal::SampledAllocation& sampled_allocation) {
        absl::base_internal::SpinLockHolder h(lock_);
        alloc_handles_->insert(
            sampled_allocation.sampled_stack.sampled_alloc_handle);
      });

  // Set up some threads busy with allocating and deallocating.
  manager.Start(kThreads, [&](int thread_id) { harness.Run(thread_id); });

  // Set up some threads iterating over the sampled allocations and check if
  // their alloc handles are present in `alloc_handles_`.
  manager.Start(2, [&](int) {
    tcmalloc_internal::tc_globals.sampled_allocation_recorder().Iterate(
        [&](const tcmalloc_internal::SampledAllocation& sampled_allocation) {
          absl::base_internal::SpinLockHolder h(lock_);
          ABSL_CHECK(alloc_handles_->contains(
              sampled_allocation.sampled_stack.sampled_alloc_handle));
        });
  });

  absl::SleepFor(absl::Milliseconds(100));
  manager.Stop();
}

// Test at different sampling rates, from always sampling to lower sampling
// probabilities. This is stress testing and attempts to expose potential
// failure modes when we only have sampled allocations and when we have a mix of
// sampled/unsampled allocations.
INSTANTIATE_TEST_SUITE_P(SamplingIntervals, HeapAllocHandleTest,
                         testing::Values(1, 1 << 7, 1 << 14, 1 << 21),
                         testing::PrintToStringParamName());

}  // namespace
}  // namespace tcmalloc
