[IndexedDB] Adding txn, value, and key size metrics

content/browser/indexed_db/leveldb/leveldb_transaction.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 "content/browser/indexed_db/leveldb/leveldb_transaction.h"
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/time/time.h"
@@ skipping 36 matching lines @@
                              std::string* value,
                              bool deleted) {
   DCHECK(!finished_);
   DataType::iterator it = data_.find(key);
 
   if (it == data_.end()) {
     std::unique_ptr<Record> record = base::MakeUnique<Record>();
     record->key.assign(key.begin(), key.end() - key.begin());
     record->value.swap(*value);
     record->deleted = deleted;
+    size_ += sizeof(Record) + key.size() * 2 + value->size();

[pwnall, 2017/05/23 23:01:09]

This book-keeping looks subtle enough to require tests. Can you add some quick
unit tests today? If not, it seems fine to land this now and potentially fix
later.

FWIW, I was about to suggest the following plan, and my idea fell flat on its
face because LevelDB doesn't report WriteBatch size.

1) Forward the WriteBatch size getter in LevelDBWriteBatch --
https://cs.chromium.org/chromium/src/content/browser/indexed_db/leveldb/level...

2) Change LevelDBTransaction::Commit to return the WriteBatch size in an
out-parameter --
https://cs.chromium.org/chromium/src/content/browser/indexed_db/leveldb/level...

3) Log the value in IndexedDBBackingStore::Transaction::CommitPhaseTwo
--https://cs.chromium.org/chromium/src/content/browser/indexed_db/indexed_db_backing_store.cc?l=4242

[dmurph, 2017/05/24 02:01:58]

BAsed on our convo, recording right before the journal commit, and I'll follow
up with blob metrics in a new CL.

     data_[record->key] = std::move(record);
     NotifyIterators();
     return;
   }
+  size_ += value->size();
   it->second->value.swap(*value);
+  size_ -= value->size();
   it->second->deleted = deleted;
 }
 
 void LevelDBTransaction::Put(const StringPiece& key, std::string* value) {
   Set(key, value, false);
 }
 
 void LevelDBTransaction::Remove(const StringPiece& key) {
   std::string empty;
   Set(key, &empty, true);
@@ skipping 296 matching lines @@
 }
 
 void LevelDBTransaction::TransactionIterator::DataChanged() {
   data_changed_ = true;
 }
 
 void LevelDBTransaction::TransactionIterator::Delete() {
   DCHECK(IsValid());
   if (current_ == data_iterator_.get()) {
     data_iterator_->Delete();
+    transaction_->size_ -= data_iterator_->Value().size();

[pwnall, 2017/05/23 23:01:10]

IIUC, this removes the record from the map, so I think you need to subtract
sizeof(Record) + key.size() * 2 + value->size().

[dmurph, 2017/05/24 02:01:58]

Added tests. Offline convo - record isn't removed from map, just the value.

   } else {
     std::unique_ptr<Record> record = base::MakeUnique<Record>();
     record->key = Key().as_string();
     record->deleted = true;
+    transaction_->size_ += sizeof(Record) + record->key.size() * 2;
     transaction_->data_[record->key] = std::move(record);
   }
 }
 
 void LevelDBTransaction::TransactionIterator::RefreshDataIterator() const {
   DCHECK(data_changed_);
 
   data_changed_ = false;
 
   if (data_iterator_->IsValid() && data_iterator_.get() == current_) {
@@ skipping 147 matching lines @@
 
   leveldb::Status s = db_->Write(*write_batch_);
   if (s.ok()) {
     finished_ = true;
     write_batch_->Clear();
   }
   return s;
 }
 
 }  // namespace content