This is the implementation of the primary and secondary blob journals for

content/browser/indexed_db/indexed_db_leveldb_coding.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/indexed_db_leveldb_coding.h"
 
 #include <iterator>
 #include <limits>
 
 #include "base/logging.h"
@@ skipping 357 matching lines @@
       size_t count = array.size();
       EncodeVarInt(count, into);
       for (size_t i = 0; i < count; ++i) {
         EncodeStringWithLength(array[i], into);
       }
       break;
     }
   }
 }
 
+void EncodeBlobJournal(const BlobJournalType& journal, std::string* into) {
+  BlobJournalType::const_iterator iter;
+  for (iter = journal.begin(); iter != journal.end(); ++iter) {

[cmumford, 2014/04/30 21:29:30]

If the journal is empty (which may not be possible?) is it OK to leave "into"
untouched?

[ericu, 2014/04/30 22:16:10]

Yes.  The convention in this file is that all EncodeXXX functions append, rather
than replacing.

+    EncodeVarInt(iter->first, into);
+    EncodeVarInt(iter->second, into);
+  }
+}
+
 bool DecodeByte(StringPiece* slice, unsigned char* value) {
   if (slice->empty())
     return false;
 
   *value = (*slice)[0];
   slice->remove_prefix(1);
   return true;
 }
 
 bool DecodeBool(StringPiece* slice, bool* value) {
@@ skipping 212 matching lines @@
       }
       DCHECK(slice->empty());
       *value = IndexedDBKeyPath(array);
       return true;
     }
   }
   NOTREACHED();
   return false;
 }
 
+bool DecodeBlobJournal(StringPiece* slice, BlobJournalType* journal) {
+  BlobJournalType output;

[cmumford, 2014/04/30 21:29:30]

Should an empty slice be considered an error?

[ericu, 2014/04/30 22:16:10]

No, that's an empty journal.

+  while (!slice->empty()) {
+    int64 database_id = -1;
+    int64 blob_key = -1;
+    if (!DecodeVarInt(slice, &database_id))
+      return false;
+    if (!KeyPrefix::IsValidDatabaseId(database_id))
+      return false;
+    if (!DecodeVarInt(slice, &blob_key))
+      return false;
+    if (!DatabaseMetaDataKey::IsValidBlobKey(blob_key) &&
+        (blob_key != DatabaseMetaDataKey::kAllBlobsKey)) {
+      return false;
+    }
+    output.push_back(std::make_pair(database_id, blob_key));
+  }
+  journal->swap(output);
+  return true;
+}
+
 bool ConsumeEncodedIDBKey(StringPiece* slice) {
   unsigned char type = (*slice)[0];
   slice->remove_prefix(1);
 
   switch (type) {
     case kIndexedDBKeyNullTypeByte:
     case kIndexedDBKeyMinKeyTypeByte:
       return true;
     case kIndexedDBKeyArrayTypeByte: {
       int64 length;
@@ skipping 1380 matching lines @@
 scoped_ptr<IndexedDBKey> IndexDataKey::primary_key() const {
   scoped_ptr<IndexedDBKey> key;
   StringPiece slice(encoded_primary_key_);
   if (!DecodeIDBKey(&slice, &key)) {
     // TODO(jsbell): Return error.
   }
   return key.Pass();
 }
 
 }  // namespace content