[SyncFS] Introduce counters in LevelDBWrapper to count the number

of pending transactions for PUT/DELETE operations independently.
It means that both counters counts the operation for the entry, if an entry is put and deleted.


BUG=347425
TEST=./unit_tests --gtest_filter="LevelDBWrapper*"

Review URL: https://codereview.chromium.org/466373004

Cr-Commit-Position: refs/heads/master@{#289595}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289595 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.cc

@@ -78,6 +78,8 @@ void LevelDBWrapper::Iterator::Delete() {
   // update the value.
   map_iterator_->second = deletion;
 
+  ++(db_->num_deletes_);
+
   AdvanceIterators();
 }
 
@@ -142,19 +144,20 @@ void LevelDBWrapper::Iterator::AdvanceIterators() {
 // LevelDBWrapper class
 // ---------------------------------------------------------------------------
 LevelDBWrapper::LevelDBWrapper(scoped_ptr<leveldb::DB> db)
-    : db_(db.Pass()) {
+    : db_(db.Pass()), num_puts_(0), num_deletes_(0) {
   DCHECK(db_);
 }
 
 LevelDBWrapper::~LevelDBWrapper() {}
 
-void LevelDBWrapper::Put(const std::string& key,
-                         const std::string& value) {
+void LevelDBWrapper::Put(const std::string& key, const std::string& value) {
   pending_[key] = Transaction(PUT_OPERATION, value);
+  ++num_puts_;
 }
 
 void LevelDBWrapper::Delete(const std::string& key) {
   pending_[key] = Transaction(DELETE_OPERATION, std::string());
+  ++num_deletes_;
 }
 
 leveldb::Status LevelDBWrapper::Get(const std::string& key,
@@ -205,6 +208,8 @@ leveldb::Status LevelDBWrapper::Commit() {
 
 void LevelDBWrapper::Clear() {
   pending_.clear();
+  num_puts_ = 0;
+  num_deletes_ = 0;
 }
 
 leveldb::DB* LevelDBWrapper::GetLevelDB() {

chrome/browser/sync_file_system/drive_backend/leveldb_wrapper.h

@@ -89,6 +89,12 @@ class LevelDBWrapper {
   // Clears pending transactions.
   void Clear();
 
+  // Returns the number of pending PUT/DELETE operations.
+  // Each counter counts operations independently, so operations on a key
+  // may be counted more than once.
+  int64 num_puts() { return num_puts_; }
+  int64 num_deletes() { return num_deletes_; }
+
   // TODO(peria): Rename this method to GetLevelDBForTesting, after removing
   // usages of drive_backend::MigrateDatabaseFromVxToVy() under
   // drive_backend_v1/.
@@ -98,6 +104,8 @@ class LevelDBWrapper {
   scoped_ptr<leveldb::DB> db_;
 
   PendingOperationMap pending_;
+  int64 num_puts_;
+  int64 num_deletes_;
 
   DISALLOW_COPY_AND_ASSIGN(LevelDBWrapper);
 };

chrome/browser/sync_file_system/drive_backend/leveldb_wrapper_unittest.cc

@@ -128,6 +128,9 @@ TEST_F(LevelDBWrapperTest, IteratorTest) {
   EXPECT_TRUE(itr->Valid());
   EXPECT_EQ("ab", itr->key().ToString());
   EXPECT_EQ("0", itr->value().ToString());
+
+  EXPECT_EQ(0, GetDB()->num_puts());
+  EXPECT_EQ(1, GetDB()->num_deletes());
 }
 
 TEST_F(LevelDBWrapperTest, Iterator2Test) {
@@ -151,6 +154,9 @@ TEST_F(LevelDBWrapperTest, Iterator2Test) {
   EXPECT_EQ(3, loop_counter);
   EXPECT_EQ("c", prev_key);
   EXPECT_EQ("3", prev_value);
+
+  EXPECT_EQ(3, GetDB()->num_puts());
+  EXPECT_EQ(0, GetDB()->num_deletes());
 }
 
 TEST_F(LevelDBWrapperTest, PutTest) {
@@ -168,8 +174,10 @@ TEST_F(LevelDBWrapperTest, PutTest) {
   SCOPED_TRACE("PutTest_Pending");
   CheckDBContents(merged_data, arraysize(merged_data));
 
+  EXPECT_EQ(3, GetDB()->num_puts());
   // Remove all pending transactions.
   GetDB()->Clear();
+  EXPECT_EQ(0, GetDB()->num_puts());
 
   SCOPED_TRACE("PutTest_Clear");
   CheckDBContents(orig_data, arraysize(orig_data));
@@ -178,7 +186,9 @@ TEST_F(LevelDBWrapperTest, PutTest) {
   GetDB()->Put("aa", "new0");
   GetDB()->Put("c", "new1");
   GetDB()->Put("bb", "new2");
+  EXPECT_EQ(3, GetDB()->num_puts());
   GetDB()->Commit();
+  EXPECT_EQ(0, GetDB()->num_puts());
   GetDB()->Clear();  // Clear just in case.
 
   SCOPED_TRACE("PutTest_Commit");
@@ -199,6 +209,9 @@ TEST_F(LevelDBWrapperTest, DeleteTest) {
   GetDB()->Delete("c");        // Remove a pending entry.
   GetDB()->Delete("ab");       // Remove a committed entry.
 
+  EXPECT_EQ(3, GetDB()->num_puts());
+  EXPECT_EQ(2, GetDB()->num_deletes());
+
   SCOPED_TRACE("DeleteTest_Pending");
   CheckDBContents(merged_data, arraysize(merged_data));
 
@@ -217,6 +230,9 @@ TEST_F(LevelDBWrapperTest, DeleteTest) {
   GetDB()->Commit();
   GetDB()->Clear();
 
+  EXPECT_EQ(0, GetDB()->num_puts());
+  EXPECT_EQ(0, GetDB()->num_deletes());
+
   SCOPED_TRACE("DeleteTest_Commit");
   CheckDBContents(merged_data, arraysize(merged_data));
 }