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"
 #include "base/test/test_suite.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/leveldatabase/env_chromium.h"
 #include "third_party/leveldatabase/src/include/leveldb/db.h"
 
 #define FPL FILE_PATH_LITERAL
 
 using leveldb::DB;
 using leveldb::Env;
 using leveldb::Options;
 using leveldb::ReadOptions;
 using leveldb::Slice;
 using leveldb::Status;
 using leveldb::WritableFile;
 using leveldb::WriteOptions;
 using leveldb_env::ChromiumEnv;
 using leveldb_env::MethodID;
 
+namespace leveldb_env {
+extern size_t WriteBufferSize(int64_t disk_space);

[michaeln, 2016/08/16 00:28:05]

Is including env_chromium.h not enough, the function is declared in there?

[cmumford, 2016/08/16 00:54:26]

I overloaded WriteBuferSize and this is the version that takes the disk space
(not the file/dir path). I did that to keep the public API clean. Still OK with
this approach, or do you think making this a public function is better?

[michaeln, 2016/08/16 19:41:23]

or maybe expose both functions in the .h file instead and give them different
names? WriteBufferSizeForDiskSize and WriteBufferSizeForPath or something like
that?

+}
+
 TEST(ErrorEncoding, OnlyAMethod) {
   const MethodID in_method = leveldb_env::kSequentialFileRead;
   const Status s = MakeIOError("Somefile.txt", "message", in_method);
   MethodID method;
   base::File::Error error = base::File::FILE_ERROR_MAX;
   EXPECT_EQ(leveldb_env::METHOD_ONLY, ParseMethodAndError(s, &method, &error));
   EXPECT_EQ(in_method, method);
   EXPECT_EQ(base::File::FILE_ERROR_MAX, error);
 }
 
@@ skipping 123 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(); }