Added support for 'spare' file that can be used at startup.

base/metrics/persistent_histogram_allocator_unittest.cc

 // Copyright 2016 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_histogram_allocator.h"
 
+#include "base/files/file.h"
+#include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/bucket_ranges.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/persistent_memory_allocator.h"
 #include "base/metrics/statistics_recorder.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
@@ skipping 28 matching lines @@
   }
 
   std::unique_ptr<StatisticsRecorder> statistics_recorder_;
   std::unique_ptr<char[]> allocator_memory_;
   PersistentMemoryAllocator* allocator_ = nullptr;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PersistentHistogramAllocatorTest);
 };
 
-TEST_F(PersistentHistogramAllocatorTest, CreateAndIterateTest) {
+TEST_F(PersistentHistogramAllocatorTest, CreateAndIterate) {
   PersistentMemoryAllocator::MemoryInfo meminfo0;
   allocator_->GetMemoryInfo(&meminfo0);
 
   // Try basic construction
   HistogramBase* histogram = Histogram::FactoryGet(
       "TestHistogram", 1, 1000, 10, HistogramBase::kIsPersistent);
   EXPECT_TRUE(histogram);
   histogram->CheckName("TestHistogram");
   PersistentMemoryAllocator::MemoryInfo meminfo1;
   allocator_->GetMemoryInfo(&meminfo1);
@@ skipping 53 matching lines @@
   recovered->CheckName("TestBooleanHistogram");
 
   recovered = histogram_iter.GetNext();
   ASSERT_TRUE(recovered);
   recovered->CheckName("TestCustomHistogram");
 
   recovered = histogram_iter.GetNext();
   EXPECT_FALSE(recovered);
 }
 
-TEST_F(PersistentHistogramAllocatorTest, CreateWithFileTest) {
+TEST_F(PersistentHistogramAllocatorTest, CreateWithFile) {
   const char temp_name[] = "CreateWithFileTest";
   ScopedTempDir temp_dir;
   ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
   FilePath temp_file = temp_dir.GetPath().AppendASCII(temp_name);
   const size_t temp_size = 64 << 10;  // 64 KiB
 
   // Test creation of a new file.
   GlobalHistogramAllocator::ReleaseForTesting();
   GlobalHistogramAllocator::CreateWithFile(temp_file, temp_size, 0, temp_name);
   EXPECT_EQ(std::string(temp_name),
             GlobalHistogramAllocator::Get()->memory_allocator()->Name());
 
   // Test re-open of a possibly-existing file.
   GlobalHistogramAllocator::ReleaseForTesting();
   GlobalHistogramAllocator::CreateWithFile(temp_file, temp_size, 0, "");
   EXPECT_EQ(std::string(temp_name),
             GlobalHistogramAllocator::Get()->memory_allocator()->Name());
 
   // Test re-open of an known-existing file.
   GlobalHistogramAllocator::ReleaseForTesting();
   GlobalHistogramAllocator::CreateWithFile(temp_file, 0, 0, "");
   EXPECT_EQ(std::string(temp_name),
             GlobalHistogramAllocator::Get()->memory_allocator()->Name());
 
   // Final release so file and temp-dir can be removed.
   GlobalHistogramAllocator::ReleaseForTesting();
 }
 
-TEST_F(PersistentHistogramAllocatorTest, StatisticsRecorderMergeTest) {
+TEST_F(PersistentHistogramAllocatorTest, CreateSpareFile) {
+  const char temp_name[] = "CreateSpareFileTest.pma";
+  ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  FilePath temp_file = temp_dir.GetPath().AppendASCII(temp_name);
+  const size_t temp_size = 64 << 10;  // 64 KiB
+
+  ASSERT_TRUE(GlobalHistogramAllocator::CreateSpareFile(temp_file, temp_size));
+
+  File file(temp_file, File::FLAG_OPEN | File::FLAG_READ);
+  ASSERT_TRUE(file.IsValid());
+  EXPECT_EQ(static_cast<int64_t>(temp_size), file.GetLength());
+
+  char buffer[256];
+  for (size_t pos = 0; pos < temp_size; pos += sizeof(buffer)) {
+    ASSERT_EQ(static_cast<int>(sizeof(buffer)),
+              file.ReadAtCurrentPos(buffer, sizeof(buffer)));
+    for (size_t i = 0; i < sizeof(buffer); ++i)
+      EXPECT_EQ(0, buffer[i]);
+  }
+}
+
+TEST_F(PersistentHistogramAllocatorTest, StatisticsRecorderMerge) {
   const char LinearHistogramName[] = "SRTLinearHistogram";
   const char SparseHistogramName[] = "SRTSparseHistogram";
   const size_t starting_sr_count = StatisticsRecorder::GetHistogramCount();
 
   // Create a local StatisticsRecorder in which the newly created histogram
   // will be recorded. The global allocator must be replaced after because the
   // act of releasing will cause the active SR to forget about all histograms
   // in the relased memory.
   std::unique_ptr<StatisticsRecorder> local_sr =
       StatisticsRecorder::CreateTemporaryForTesting();
@@ skipping 143 matching lines @@
 
   uint32_t* data1 =
       allocator_->GetAsArray<uint32_t>(ref1, 0, kRangesRefIndex + 1);
   uint32_t* data2 =
       allocator_->GetAsArray<uint32_t>(ref2, 0, kRangesRefIndex + 1);
   EXPECT_EQ(ranges_ref, data1[kRangesRefIndex]);
   EXPECT_EQ(ranges_ref, data2[kRangesRefIndex]);
 }
 
 }  // namespace base