Use a two-part data format version in IndexedDB metadata.

content/browser/indexed_db/indexed_db_backing_store.cc

Index: content/browser/indexed_db/indexed_db_backing_store.cc
diff --git a/content/browser/indexed_db/indexed_db_backing_store.cc b/content/browser/indexed_db/indexed_db_backing_store.cc
index a05267af2ed2409edf8c62b1908c75fc1ed33681..40eb5a6015429ba1a16569b0a4b09cca5e4d6ca7 100644
--- a/content/browser/indexed_db/indexed_db_backing_store.cc
+++ b/content/browser/indexed_db/indexed_db_backing_store.cc
@@ -25,6 +25,7 @@
 #include "content/browser/indexed_db/indexed_db_blob_info.h"
 #include "content/browser/indexed_db/indexed_db_class_factory.h"
 #include "content/browser/indexed_db/indexed_db_context_impl.h"
+#include "content/browser/indexed_db/indexed_db_data_format_version.h"
 #include "content/browser/indexed_db/indexed_db_database_error.h"
 #include "content/browser/indexed_db/indexed_db_leveldb_coding.h"
 #include "content/browser/indexed_db/indexed_db_tracing.h"
@@ -46,7 +47,6 @@
 #include "storage/common/database/database_identifier.h"
 #include "storage/common/fileapi/file_system_mount_option.h"
 #include "third_party/WebKit/public/platform/modules/indexeddb/WebIDBTypes.h"
-#include "third_party/WebKit/public/web/WebSerializedScriptValueVersion.h"
 #include "third_party/leveldatabase/env_chromium.h"
 
 using base::FilePath;
@@ -335,24 +335,19 @@ WARN_UNUSED_RESULT bool IsSchemaKnown(LevelDBDatabase* db, bool* known) {
     return true;
   }
 
-  const uint32_t latest_known_data_version =
-      blink::kSerializedScriptValueVersion;
-  int64_t db_data_version = 0;
-  s = GetInt(db, DataVersionKey::Encode(), &db_data_version, &found);
+  int64_t raw_db_data_version = 0;
+  s = GetInt(db, DataVersionKey::Encode(), &raw_db_data_version, &found);
   if (!s.ok())
     return false;
   if (!found) {
     *known = true;
     return true;
   }
-  if (db_data_version < 0)
+  if (raw_db_data_version < 0)
     return false;  // Only corruption should cause this.
-  if (db_data_version > latest_known_data_version) {
-    *known = false;
-    return true;
-  }
 
-  *known = true;
+  *known = IndexedDBDataFormatVersion::GetCurrent().IsAtLeast(
+      IndexedDBDataFormatVersion::Decode(raw_db_data_version));
   return true;
 }
 
@@ -1143,8 +1138,8 @@ Status IndexedDBBackingStore::DestroyBackingStore(const FilePath& path_base,
 }
 
 WARN_UNUSED_RESULT Status IndexedDBBackingStore::SetUpMetadata() {

[cmumford, 2017/04/10 17:35:12]

The metadata version is set when the database is first created when
IndexedDBBackingStore::Create() calls IndexedDBBackingStore::SetUpMetadata() and
the metadata version isn't changed afterwards. If the serialized script version
is written at create time then new serialized scripts can be written later on
when that version has possibly changed.

Have I overlooked something?

[jbroman, 2017/04/11 15:09:20]

I'm mostly following the existing code, but my understanding is that
IndexedDBBackingStore::Create is called to create the backing store object in
memory, regardless of whether a new database is being created or an existing
database is being opened. If that were not the case, there's a great deal of
logic in SetUpMetadata that wouldn't apply.

-  const uint32_t latest_known_data_version =
-      blink::kSerializedScriptValueVersion;
+  const IndexedDBDataFormatVersion latest_known_data_version =
+      IndexedDBDataFormatVersion::GetCurrent();
   const std::string schema_version_key = SchemaVersionKey::Encode();
   const std::string data_version_key = DataVersionKey::Encode();
 
@@ -1152,7 +1147,7 @@ WARN_UNUSED_RESULT Status IndexedDBBackingStore::SetUpMetadata() {
       IndexedDBClassFactory::Get()->CreateLevelDBTransaction(db_.get());
 
   int64_t db_schema_version = 0;
-  int64_t db_data_version = 0;
+  IndexedDBDataFormatVersion db_data_version;
   bool found = false;
   Status s =
       GetInt(transaction.get(), schema_version_key, &db_schema_version, &found);
@@ -1165,7 +1160,7 @@ WARN_UNUSED_RESULT Status IndexedDBBackingStore::SetUpMetadata() {
     db_schema_version = kLatestKnownSchemaVersion;
     PutInt(transaction.get(), schema_version_key, db_schema_version);
     db_data_version = latest_known_data_version;
-    PutInt(transaction.get(), data_version_key, db_data_version);
+    PutInt(transaction.get(), data_version_key, db_data_version.Encode());
     // If a blob directory already exists for this database, blow it away.  It's
     // leftover from a partially-purged previous generation of data.
     if (!base::DeleteFile(blob_path_, true)) {
@@ -1206,8 +1201,8 @@ WARN_UNUSED_RESULT Status IndexedDBBackingStore::SetUpMetadata() {
     if (s.ok() && db_schema_version < 2) {
       db_schema_version = 2;
       PutInt(transaction.get(), schema_version_key, db_schema_version);
-      db_data_version = blink::kSerializedScriptValueVersion;
-      PutInt(transaction.get(), data_version_key, db_data_version);
+      db_data_version = latest_known_data_version;
+      PutInt(transaction.get(), data_version_key, db_data_version.Encode());
     }
     if (db_schema_version < 3) {
       db_schema_version = 3;
@@ -1225,7 +1220,8 @@ WARN_UNUSED_RESULT Status IndexedDBBackingStore::SetUpMetadata() {
 
   // All new values will be written using this serialization version.
   found = false;
-  s = GetInt(transaction.get(), data_version_key, &db_data_version, &found);
+  int64_t raw_db_data_version = 0;
+  s = GetInt(transaction.get(), data_version_key, &raw_db_data_version, &found);
   if (!s.ok()) {
     INTERNAL_READ_ERROR_UNTESTED(SET_UP_METADATA);
     return s;
@@ -1234,13 +1230,20 @@ WARN_UNUSED_RESULT Status IndexedDBBackingStore::SetUpMetadata() {
     INTERNAL_CONSISTENCY_ERROR_UNTESTED(SET_UP_METADATA);
     return InternalInconsistencyStatus();
   }
-  if (db_data_version < latest_known_data_version) {
+  db_data_version = IndexedDBDataFormatVersion::Decode(raw_db_data_version);
+  if (latest_known_data_version == db_data_version) {
+    // Up to date. Nothing to do.
+  } else if (latest_known_data_version.IsAtLeast(db_data_version)) {
     db_data_version = latest_known_data_version;
-    PutInt(transaction.get(), data_version_key, db_data_version);
+    PutInt(transaction.get(), data_version_key, db_data_version.Encode());
+  } else {
+    // |db_data_version| is in the future according to at least one component.
+    INTERNAL_CONSISTENCY_ERROR(SET_UP_METADATA);
+    return InternalInconsistencyStatus();
   }
 
   DCHECK_EQ(db_schema_version, kLatestKnownSchemaVersion);
-  DCHECK_EQ(db_data_version, latest_known_data_version);
+  DCHECK(db_data_version == latest_known_data_version);
 
   s = transaction->Commit();
   if (!s.ok())