Make changing a record's type an atomic operation.

base/metrics/persistent_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/metrics/persistent_memory_allocator.h"
 
 #include <memory>
 
 #include "base/files/file.h"
 #include "base/files/file_util.h"
@@ skipping 163 matching lines @@
   EXPECT_EQ(1, allocs_samples->GetCount(sizeof(TestObject2)));
 #if !DCHECK_IS_ON()  // DCHECK builds will die at a NOTREACHED().
   EXPECT_EQ(0U, allocator_->Allocate(TEST_MEMORY_SIZE + 1, 0));
   allocs_samples = allocator_->allocs_histogram_->SnapshotSamples();
   EXPECT_EQ(3, allocs_samples->TotalCount());
   EXPECT_EQ(1, allocs_samples->GetCount(0));
 #endif
 
   // Check that an objcet's type can be changed.
   EXPECT_EQ(2U, allocator_->GetType(block2));
-  allocator_->SetType(block2, 3);
+  allocator_->ChangeType(block2, 3, 2);
   EXPECT_EQ(3U, allocator_->GetType(block2));
-  allocator_->SetType(block2, 2);
+  allocator_->ChangeType(block2, 2, 3);
   EXPECT_EQ(2U, allocator_->GetType(block2));
 
   // Create second allocator (read/write) using the same memory segment.
   std::unique_ptr<PersistentMemoryAllocator> allocator2(
       new PersistentMemoryAllocator(mem_segment_.get(), TEST_MEMORY_SIZE,
                                     TEST_MEMORY_PAGE, 0, "", false));
   EXPECT_EQ(TEST_ID, allocator2->Id());
   EXPECT_FALSE(allocator2->used_histogram_);
   EXPECT_FALSE(allocator2->allocs_histogram_);
   EXPECT_NE(allocator2->allocs_histogram_, allocator_->allocs_histogram_);
@@ skipping 307 matching lines @@
   {
     std::unique_ptr<SharedMemory> shmem1(new SharedMemory());
     ASSERT_TRUE(shmem1->CreateAndMapAnonymous(TEST_MEMORY_SIZE));
     SharedPersistentMemoryAllocator local(std::move(shmem1), TEST_ID, "",
                                           false);
     EXPECT_FALSE(local.IsReadonly());
     r123 = local.Allocate(123, 123);
     r456 = local.Allocate(456, 456);
     r789 = local.Allocate(789, 789);
     local.MakeIterable(r123);
-    local.SetType(r456, 654);
+    local.ChangeType(r456, 654, 456);
     local.MakeIterable(r789);
     local.GetMemoryInfo(&meminfo1);
     EXPECT_FALSE(local.IsFull());
     EXPECT_FALSE(local.IsCorrupt());
 
     ASSERT_TRUE(local.shared_memory()->ShareToProcess(
                     GetCurrentProcessHandle(),
                     &shared_handle));
   }
 
@@ skipping 66 matching lines @@
 
   PersistentMemoryAllocator::MemoryInfo meminfo1;
   Reference r123, r456, r789;
   {
     LocalPersistentMemoryAllocator local(TEST_MEMORY_SIZE, TEST_ID, "");
     EXPECT_FALSE(local.IsReadonly());
     r123 = local.Allocate(123, 123);
     r456 = local.Allocate(456, 456);
     r789 = local.Allocate(789, 789);
     local.MakeIterable(r123);
-    local.SetType(r456, 654);
+    local.ChangeType(r456, 654, 456);
     local.MakeIterable(r789);
     local.GetMemoryInfo(&meminfo1);
     EXPECT_FALSE(local.IsFull());
     EXPECT_FALSE(local.IsCorrupt());
 
     File writer(file_path, File::FLAG_CREATE | File::FLAG_WRITE);
     ASSERT_TRUE(writer.IsValid());
     writer.Write(0, (const char*)local.data(), local.used());
   }
 
@@ skipping 167 matching lines @@
     } else {
       // For filesize >= minsize, the file must be acceptable. This
       // else clause (file-not-acceptable) should be reached only if
       // filesize < minsize.
       EXPECT_GT(minsize, filesize);
     }
   }
 }
 
 }  // namespace base