ServiceWorker: Migrate the script cache backend from BlockFile to Simple

content/browser/service_worker/service_worker_database.cc

Index: content/browser/service_worker/service_worker_database.cc
diff --git a/content/browser/service_worker/service_worker_database.cc b/content/browser/service_worker/service_worker_database.cc
index 842080ac0bb624840707d4b0ef28cac5beb3f94f..d328e9689afd2f7485c19c01f71c9a28bced02f1 100644
--- a/content/browser/service_worker/service_worker_database.cc
+++ b/content/browser/service_worker/service_worker_database.cc
@@ -73,6 +73,16 @@
 //
 //   key: "REGID_TO_ORIGIN:" + <int64 'registration_id'>
 //   value: <GURL 'origin'>
+//
+//   key: "INITDATA_DISKCACHE_MIGRATED"
+//   value: <empty>
+//     - This entry represents that the diskcache was migrated from BlockFile
+//       backend to Simple backend (http://crbug.com/487482).
+//
+//   key: "INITDATA_OLD_DISKCACHE_EXISTS"
+//   value: <empty>
+//     - This entry represents that the diskcahes was migrate, but the old
+//       BlockFile diskcache still exists (http://crbug.com/487482).
 namespace content {
 
 namespace {
@@ -82,6 +92,8 @@ const char kNextRegIdKey[] = "INITDATA_NEXT_REGISTRATION_ID";
 const char kNextResIdKey[] = "INITDATA_NEXT_RESOURCE_ID";
 const char kNextVerIdKey[] = "INITDATA_NEXT_VERSION_ID";
 const char kUniqueOriginKey[] = "INITDATA_UNIQUE_ORIGIN:";
+const char kDiskCacheMigratedKey[] = "INITDATA_DISKCACHE_MIGRATED";
+const char kOldDiskCacheExistsKey[] = "INITDATA_OLD_DISKCACHE_EXISTS";
 
 const char kRegKeyPrefix[] = "REG:";
 const char kRegUserDataKeyPrefix[] = "REG_USER_DATA:";
@@ -89,6 +101,7 @@ const char kRegHasUserDataKeyPrefix[] = "REG_HAS_USER_DATA:";
 const char kRegIdToOriginKeyPrefix[] = "REGID_TO_ORIGIN:";
 const char kResKeyPrefix[] = "RES:";
 const char kKeySeparator = '\x00';
+const char kEmptyValue[] = "";
 
 const char kUncommittedResIdKeyPrefix[] = "URES:";
 const char kPurgeableResIdKeyPrefix[] = "PRES:";
@@ -419,6 +432,65 @@ ServiceWorkerDatabase::Status ServiceWorkerDatabase::GetNextAvailableIds(
 }
 
 ServiceWorkerDatabase::Status
+ServiceWorkerDatabase::ReadDiskCacheMigrationState(
+    DiskCacheMigrationState* state) {
+  DCHECK(sequence_checker_.CalledOnValidSequencedThread());
+
+  Status status = LazyOpen(false);
+  if (IsNewOrNonexistentDatabase(status)) {
+    *state = DISKCACHE_NOT_USED;
+    return STATUS_OK;
+  }
+  if (status != STATUS_OK)
+    return status;
+
+  std::string value;
+  status = LevelDBStatusToStatus(
+      db_->Get(leveldb::ReadOptions(), kDiskCacheMigratedKey, &value));
+  if (status != STATUS_ERROR_NOT_FOUND) {
+    if (status == STATUS_OK)
+      *state = DISKCACHE_MIGRATED;
+    HandleReadResult(FROM_HERE, status);
+    return status;
+  }
+  HandleReadResult(FROM_HERE, STATUS_OK);
+
+  status = LevelDBStatusToStatus(
+      db_->Get(leveldb::ReadOptions(), kOldDiskCacheExistsKey, &value));
+  if (status != STATUS_ERROR_NOT_FOUND) {
+    if (status == STATUS_OK)
+      *state = DISKCACHE_NEEDS_TO_DELETE_OLD;
+    HandleReadResult(FROM_HERE, status);
+    return status;
+  }
+
+  *state = DISKCACHE_NEEDS_TO_MIGRATE;
+  HandleReadResult(FROM_HERE, STATUS_OK);
+  return STATUS_OK;
+}
+
+ServiceWorkerDatabase::Status
+ServiceWorkerDatabase::WriteDiskCacheMigrationState(
+    DiskCacheMigrationState state) {
+  DCHECK(sequence_checker_.CalledOnValidSequencedThread());
+  DCHECK(state == DISKCACHE_MIGRATED || state == DISKCACHE_NEEDS_TO_DELETE_OLD)
+      << state;
+
+  Status status = LazyOpen(true);
+  if (status != STATUS_OK)
+    return status;
+
+  leveldb::WriteBatch batch;
+  if (state == DISKCACHE_MIGRATED) {
+    batch.Put(kDiskCacheMigratedKey, kEmptyValue);
+    batch.Delete(kOldDiskCacheExistsKey);
+  } else if (state == DISKCACHE_NEEDS_TO_DELETE_OLD) {
+    batch.Put(kOldDiskCacheExistsKey, kEmptyValue);
+  }
+  return WriteBatch(&batch);
+}
+
+ServiceWorkerDatabase::Status
 ServiceWorkerDatabase::GetOriginsWithRegistrations(std::set<GURL>* origins) {
   DCHECK(sequence_checker_.CalledOnValidSequencedThread());
   DCHECK(origins->empty());