IndexedDB: Limit the size of a leveldb write buffer to minimize disk space.

third_party/leveldatabase/env_chromium_unittest.cc

 // Copyright (c) 2013 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/files/file.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/lazy_instance.h"
@@ skipping 151 matching lines @@
   leveldb::Status status = env->GetChildren(dir.AsUTF8Unsafe(), &result);
   EXPECT_TRUE(status.ok());
   EXPECT_EQ(1U, result.size());
 
   // And a second time should also return one result
   status = env->GetChildren(dir.AsUTF8Unsafe(), &result);
   EXPECT_TRUE(status.ok());
   EXPECT_EQ(1U, result.size());
 }
 
+TEST(ChromiumEnv, TestWriteBufferSize) {
+  // If can't get disk size, use leveldb defaults.
+  const int64_t MB = 1024 * 1024;
+  EXPECT_EQ(size_t(4 * MB), leveldb_env::WriteBufferSize(-1));
+
+  // A very small disk (check lower clamp value).
+  EXPECT_EQ(size_t(1 * MB), leveldb_env::WriteBufferSize(1 * MB));
+
+  // Some value on the linear equation between min and max.
+  EXPECT_EQ(size_t(2.5 * MB), leveldb_env::WriteBufferSize(25 * MB));
+
+  // The disk size equating to the max buffer size
+  EXPECT_EQ(size_t(4 * MB), leveldb_env::WriteBufferSize(40 * MB));
+
+  // Make sure sizes larger than 40MB are clamped to max buffer size.
+  EXPECT_EQ(size_t(4 * MB), leveldb_env::WriteBufferSize(80 * MB));
+
+  // Check for very large disk size (catch overflow).
+  EXPECT_EQ(size_t(4 * MB), leveldb_env::WriteBufferSize(100 * MB * MB));
+}
+
 int main(int argc, char** argv) { return base::TestSuite(argc, argv).Run(); }