Create "persistent memory allocator" for persisting and sharing objects.

base/memory/shared_memory_allocator_unittest.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/memory/shared_memory_allocator.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "base/rand_util.h"
+#include "base/threading/simple_thread.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+namespace {
+
+const int32_t TEST_MEMORY_SIZE = 1 << 20;  // 1 MiB
+const int32_t TEST_MEMORY_PAGE = 64 << 10;  // 64 KiB
+
+}  // namespace
+
+namespace base {
+
+class SharedMemoryAllocatorTest : public testing::Test {
+ public:
+  struct TestObject1 {
+    int32_t onething;
+    char oranother;
+  };
+
+  struct TestObject2 {
+    int thiis;
+    long that;
+    float andthe;
+    char other;
+    double thing;
+  };
+
+  SharedMemoryAllocatorTest() {
+    mem_segment_.reset(new char[TEST_MEMORY_SIZE]);
+  }
+
+  void SetUp() override {
+    allocator_.reset();
+    memset(mem_segment_.get(), 0, TEST_MEMORY_SIZE);
+    allocator_.reset(new SharedMemoryAllocator(mem_segment_.get(),
+                                               TEST_MEMORY_SIZE,
+                                               TEST_MEMORY_PAGE));
+  }
+
+  void TearDown() override {
+    allocator_.reset();
+  }
+
+  int CountIterables() {
+    SharedMemoryAllocator::Iterator iter;
+    int32_t type;
+    int count = 0;
+    for (allocator_->CreateIterator(&iter);
+         allocator_->GetNextIterable(&iter, &type) != 0;) {
+      count++;
+    }
+    return count;
+  }
+
+  scoped_ptr<char[]> mem_segment_;
+  scoped_ptr<SharedMemoryAllocator> allocator_;
+};
+
+TEST_F(SharedMemoryAllocatorTest, AllocateAndIterate) {
+  SharedMemoryAllocator::MemoryInfo meminfo0;
+  allocator_->GetMemoryInfo(&meminfo0);
+  EXPECT_EQ(TEST_MEMORY_SIZE, meminfo0.total);
+  EXPECT_GT(meminfo0.total, meminfo0.free);
+
+  int32_t block1 = allocator_->Allocate(sizeof(TestObject1), 1);
+  EXPECT_NE(0, block1);
+  EXPECT_NE(nullptr, allocator_->GetType<TestObject1>(block1, 1));
+  EXPECT_EQ(nullptr, allocator_->GetType<TestObject2>(block1, 1));
+  SharedMemoryAllocator::MemoryInfo meminfo1;
+  allocator_->GetMemoryInfo(&meminfo1);
+  EXPECT_EQ(meminfo0.total, meminfo1.total);
+  EXPECT_GT(meminfo0.free, meminfo1.free);
+
+  SharedMemoryAllocator::Iterator iter;
+  int32_t type;
+  allocator_->CreateIterator(&iter);
+  EXPECT_EQ(0, allocator_->GetNextIterable(&iter, &type));
+  allocator_->MakeIterable(block1);
+  EXPECT_EQ(block1, allocator_->GetNextIterable(&iter, &type));
+  EXPECT_EQ(1, type);
+  EXPECT_EQ(0, allocator_->GetNextIterable(&iter, &type));
+
+  int32_t block2 = allocator_->Allocate(sizeof(TestObject2), 2);
+  EXPECT_NE(0, block2);
+  EXPECT_NE(nullptr, allocator_->GetType<TestObject2>(block2, 2));
+  EXPECT_EQ(nullptr, allocator_->GetType<TestObject2>(block2, 1));
+  SharedMemoryAllocator::MemoryInfo meminfo2;
+  allocator_->GetMemoryInfo(&meminfo2);
+  EXPECT_EQ(meminfo1.total, meminfo2.total);
+  EXPECT_GT(meminfo1.free, meminfo2.free);
+
+  allocator_->MakeIterable(block2);
+  EXPECT_EQ(block2, allocator_->GetNextIterable(&iter, &type));
+  EXPECT_EQ(2, type);
+  EXPECT_EQ(0, allocator_->GetNextIterable(&iter, &type));
+
+  EXPECT_FALSE(allocator_->IsFull());
+  EXPECT_FALSE(allocator_->IsCorrupted());
+}
+
+TEST_F(SharedMemoryAllocatorTest, PageTest) {
+  int32_t block1 = allocator_->Allocate(TEST_MEMORY_PAGE / 2, 1);
+  EXPECT_LT(0, block1);
+  EXPECT_GT(TEST_MEMORY_PAGE, block1);
+
+  int32_t block2 = allocator_->Allocate(TEST_MEMORY_PAGE - 16, 2);
+  EXPECT_EQ(TEST_MEMORY_PAGE, block2);
+
+  int32_t block3 = allocator_->Allocate(99, 3);
+  EXPECT_EQ(2 * TEST_MEMORY_PAGE, block3);
+}
+
+class AllocatorThread : public SimpleThread {
+ public:
+  AllocatorThread(const std::string& name, void* base, int32_t size,
+                  int32_t page_size)
+    : SimpleThread(name, Options()),
+      count_(0),
+      iterable_(0),
+      allocator_(base, size, page_size) {
+  }
+
+  void Run() override {
+    for (;;) {
+      int32_t size = (int32_t)base::RandInt(1, 99);
+      int32_t type = (int32_t)base::RandInt(100, 999);
+      int32_t block = allocator_.Allocate(size, type);
+      if (!block)
+        break;
+
+      count_++;
+      if (base::RandInt(0, 1)) {
+        allocator_.MakeIterable(block);
+        iterable_++;
+      }
+    }
+  }
+
+  int count_;
+  int iterable_;
+
+ private:
+  SharedMemoryAllocator allocator_;
+};
+
+TEST_F(SharedMemoryAllocatorTest, ParallelismTest) {
+  void* memory = mem_segment_.get();
+  AllocatorThread t1("t1", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);
+  AllocatorThread t2("t2", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);
+  AllocatorThread t3("t3", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);
+  AllocatorThread t4("t4", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);
+  AllocatorThread t5("t5", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);

[Dmitry Vyukov, 2015/11/03 14:06:46]

Also run iteration thread concurrently.

[bcwhite, 2015/11/03 16:28:20]

The test thread is doing that concurrently with the separate allocator threads. 
Is there a benefit to spawning another thread to concentrate on that?

+
+  t1.Start();
+  t2.Start();
+  t3.Start();
+  t4.Start();
+  t5.Start();
+
+  int last_count = 0;
+  do {
+    int count = CountIterables();
+    EXPECT_LE(last_count, count);
+  } while (!allocator_->IsCorrupted() && !allocator_->IsFull());
+
+  t1.Join();
+  t2.Join();
+  t3.Join();
+  t4.Join();
+  t5.Join();
+
+  EXPECT_FALSE(allocator_->IsCorrupted());
+  EXPECT_EQ(CountIterables(),
+            t1.iterable_ + t2.iterable_ + t3.iterable_ + t4.iterable_ +
+            t5.iterable_);
+}
+
+// This test doesn't verify anything other than it doesn't crash.
+TEST_F(SharedMemoryAllocatorTest, CorruptionTest) {
+  char* memory = mem_segment_.get();
+  AllocatorThread t1("t1", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);
+  AllocatorThread t2("t2", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);
+  AllocatorThread t3("t3", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);
+  AllocatorThread t4("t4", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);
+  AllocatorThread t5("t5", memory, TEST_MEMORY_SIZE, TEST_MEMORY_PAGE);

[Dmitry Vyukov, 2015/11/03 14:06:46]

Also run iteration thread concurrently.

+
+  t1.Start();
+  t2.Start();
+  t3.Start();
+  t4.Start();
+  t5.Start();
+
+  do {
+    size_t offset = base::RandInt(0, TEST_MEMORY_SIZE - 1);
+    char value = base::RandInt(0, 255);
+    memory[offset] = value;
+  } while (!allocator_->IsCorrupted() && !allocator_->IsFull());
+
+  t1.Join();
+  t2.Join();
+  t3.Join();
+  t4.Join();
+  t5.Join();
+
+  CountIterables();
+}
+
+// Attempt to cause crashes or loops by expressly creating dangerous coditions.
+TEST_F(SharedMemoryAllocatorTest, MaliciousTest) {
+  int32_t block1 = allocator_->Allocate(sizeof(TestObject1), 1);
+  int32_t block2 = allocator_->Allocate(sizeof(TestObject1), 2);
+  int32_t block3 = allocator_->Allocate(sizeof(TestObject1), 3);
+  int32_t block4 = allocator_->Allocate(sizeof(TestObject1), 3);
+  int32_t block5 = allocator_->Allocate(sizeof(TestObject1), 3);
+  allocator_->MakeIterable(block1);
+  allocator_->MakeIterable(block2);
+  allocator_->MakeIterable(block3);
+  allocator_->MakeIterable(block4);
+  allocator_->MakeIterable(block5);
+  EXPECT_EQ(5, CountIterables());
+  EXPECT_FALSE(allocator_->IsCorrupted());
+
+  // Create loop in iterable list and ensure it doesn't hang.
+  int32_t* header4 = (int32_t*)(mem_segment_.get() + block4);
+  EXPECT_EQ(block5, header4[3]);
+  header4[3] = block3;
+  CountIterables();  // loop: 1-2-3-4-3
+  header4[3] = block2;
+  CountIterables();  // loop: 1-2-3-4-2
+  header4[3] = block1;
+  CountIterables();  // loop: 1-2-3-4-1
+  EXPECT_TRUE(allocator_->IsCorrupted());
+}
+
+}  // namespace base