[Sync] Add support for loading, updating and querying delete journals in

sync/syncable/directory.cc

Index: sync/syncable/directory.cc
diff --git a/sync/syncable/directory.cc b/sync/syncable/directory.cc
index 21e05ebe23e7f06309a43d1c0ce0496422793ad4..71217efc4b9e75eee802c9a993a5b3dd2ba5c785 100644
--- a/sync/syncable/directory.cc
+++ b/sync/syncable/directory.cc
@@ -101,7 +101,10 @@ Directory::SaveChangesSnapshot::SaveChangesSnapshot()
     : kernel_info_status(KERNEL_SHARE_INFO_INVALID) {
 }
 
-Directory::SaveChangesSnapshot::~SaveChangesSnapshot() {}
+Directory::SaveChangesSnapshot::~SaveChangesSnapshot() {
+  STLDeleteElements(&dirty_metas);
+  STLDeleteElements(&delete_journals);
+}
 
 Directory::Kernel::Kernel(
     const std::string& name,
@@ -121,7 +124,9 @@ Directory::Kernel::Kernel(
       cache_guid(info.cache_guid),
       next_metahandle(info.max_metahandle + 1),
       delegate(delegate),
-      transaction_observer(transaction_observer) {
+      transaction_observer(transaction_observer),
+      delete_journals_(new Directory::IdsIndex),
+      delete_journals_to_purge_(new MetahandleSet) {
   DCHECK(delegate);
   DCHECK(transaction_observer.IsInitialized());
 }
@@ -135,6 +140,9 @@ Directory::Kernel::~Kernel() {
   delete ids_index;
   STLDeleteElements(metahandles_index);
   delete metahandles_index;
+  STLDeleteElements(delete_journals_);
+  delete delete_journals_;
+  delete delete_journals_to_purge_;
 }
 
 Directory::Directory(
@@ -196,17 +204,19 @@ DirOpenResult Directory::OpenImpl(
     DirectoryChangeDelegate* delegate,
     const WeakHandle<TransactionObserver>&
         transaction_observer) {
-
   KernelLoadInfo info;
   // Temporary indices before kernel_ initialized in case Load fails. We 0(1)
   // swap these later.
   MetahandlesIndex metas_bucket;
-  DirOpenResult result = store_->Load(&metas_bucket, &info);
+  IdsIndex delete_journals;
+
+  DirOpenResult result = store_->Load(&metas_bucket, &delete_journals, &info);
   if (OPENED != result)
     return result;
 
   kernel_ = new Kernel(name, info, delegate, transaction_observer);
   kernel_->metahandles_index->swap(metas_bucket);
+  kernel_->delete_journals_->swap(delete_journals);
   InitializeIndices();
 
   // Write back the share info to reserve some space in 'next_id'.  This will
@@ -236,6 +246,75 @@ void Directory::OnUnrecoverableError(const BaseTransaction* trans,
                                                      message);
 }
 
+void Directory::UpdateDeleteJournalForServerDelete(BaseTransaction* trans,
+                                                   bool was_deleted,
+                                                   const EntryKernel& entry) {
+  if (!(IsDeleteJournalEnabled(entry.GetServerModelType()) ||
+      IsDeleteJournalEnabled(
+          GetModelTypeFromSpecifics(entry.ref(SPECIFICS))))) {

[tim (not reviewing), 2012/12/14 20:12:38]

Can you add the comment from your reply in here explaining why we check both?

[haitaol1, 2012/12/14 23:15:36]

Done.

+    return;
+  }
+
+  ScopedKernelLock lock(this);
+  kernel_->needle.put(ID, entry.ref(ID));
+  IdsIndex::const_iterator it =
+      kernel_->delete_journals_->find(&kernel_->needle);
+
+  if (entry.ref(SERVER_IS_DEL)) {
+    if (it == kernel_->delete_journals_->end()) {
+      // New delete.
+      EntryKernel* t = new EntryKernel(entry);
+      kernel_->delete_journals_->insert(t);
+      kernel_->delete_journals_to_purge_->erase(t->ref(META_HANDLE));
+    }
+  } else {
+    // Undelete. This could happen in two cases:
+    // * An entry was actually deleted and undeleted: was_deleted = true.
+    // * A data type was broken, i.e. encountered unrecoverable error, in last
+    //   sync session and all its entries were duplicated in delete journals.
+    //   On restart, entries are recreated from downloads and recreation calls
+    //   UpdateDeleteJournals() to remove live entries from delete journals,
+    //   thus only deleted entries remain in journals.
+    if (it != kernel_->delete_journals_->end()) {
+      kernel_->delete_journals_to_purge_->insert((*it)->ref(META_HANDLE));
+      delete *it;
+      kernel_->delete_journals_->erase(it);
+    } else if (was_deleted) {
+      kernel_->delete_journals_to_purge_->insert((*it)->ref(META_HANDLE));
+    }
+  }
+}
+
+void Directory::GetDeleteJournals(BaseTransaction* trans,
+                                  ModelType type,
+                                  EntryKernelSet* deleted_entries) {
+  ScopedKernelLock lock(this);
+  DCHECK(!passive_delete_journal_types_.Has(type));
+  for (IdsIndex::const_iterator it = kernel_->delete_journals_->begin();
+      it != kernel_->delete_journals_->end(); ++it) {
+    if ((*it)->GetServerModelType() == type ||
+        GetModelTypeFromSpecifics((*it)->ref(SPECIFICS)) == type) {
+      deleted_entries->insert(*it);
+    }
+  }
+  passive_delete_journal_types_.Put(type);
+}
+
+void Directory::PurgeDeleteJournals(BaseTransaction* trans,
+                                    const MetahandleSet& to_purge) {
+  ScopedKernelLock lock(this);
+  IdsIndex::const_iterator it = kernel_->delete_journals_->begin();
+  while (it != kernel_->delete_journals_->end()) {
+    int64 handle = (*it)->ref(META_HANDLE);
+    if (to_purge.count(handle)) {
+      delete *it;
+      kernel_->delete_journals_->erase(it++);
+    } else {
+      ++it;
+    }
+  }
+  kernel_->delete_journals_to_purge_->insert(to_purge.begin(), to_purge.end());
+}
 
 EntryKernel* Directory::GetEntryById(const Id& id) {
   ScopedKernelLock lock(this);
@@ -466,7 +545,8 @@ void Directory::TakeSnapshotForSaveChanges(SaveChangesSnapshot* snapshot) {
     // Skip over false positives; it happens relatively infrequently.
     if (!entry->is_dirty())
       continue;
-    snapshot->dirty_metas.insert(snapshot->dirty_metas.end(), *entry);
+    snapshot->dirty_metas.insert(snapshot->dirty_metas.end(),
+                                 new EntryKernel(*entry));
     DCHECK_EQ(1U, kernel_->dirty_metahandles->count(*i));
     // We don't bother removing from the index here as we blow the entire thing
     // in a moment, and it unnecessarily complicates iteration.
@@ -488,6 +568,22 @@ void Directory::TakeSnapshotForSaveChanges(SaveChangesSnapshot* snapshot) {
   snapshot->kernel_info_status = kernel_->info_status;
   // This one we reset on failure.
   kernel_->info_status = KERNEL_SHARE_INFO_VALID;
+
+  // Move passive delete journals to snapshot. Will copy back if snapshot fails
+  // to save.
+  MetahandlesIndex::const_iterator it = kernel_->delete_journals_->begin();
+  while (it != kernel_->delete_journals_->end()) {
+    if (passive_delete_journal_types_.Has((*it)->GetServerModelType()) ||
+        passive_delete_journal_types_.Has(GetModelTypeFromSpecifics(
+            (*it)->ref(SPECIFICS)))) {
+      snapshot->delete_journals.insert(*it);
+      kernel_->delete_journals_->erase(it++);
+    } else {
+      ++it;
+    }
+  }
+  snapshot->delete_journals_to_purge.swap(
+      *kernel_->delete_journals_to_purge_);
 }
 
 bool Directory::SaveChanges() {
@@ -518,7 +614,7 @@ bool Directory::VacuumAfterSaveChanges(const SaveChangesSnapshot& snapshot) {
   // Now drop everything we can out of memory.
   for (EntryKernelSet::const_iterator i = snapshot.dirty_metas.begin();
        i != snapshot.dirty_metas.end(); ++i) {
-    kernel_->needle.put(META_HANDLE, i->ref(META_HANDLE));
+    kernel_->needle.put(META_HANDLE, (*i)->ref(META_HANDLE));
     MetahandlesIndex::iterator found =
         kernel_->metahandles_index->find(&kernel_->needle);
     EntryKernel* entry = (found == kernel_->metahandles_index->end() ?
@@ -616,7 +712,7 @@ void Directory::HandleSaveChangesFailure(const SaveChangesSnapshot& snapshot) {
   // that SaveChanges will at least try again later.
   for (EntryKernelSet::const_iterator i = snapshot.dirty_metas.begin();
        i != snapshot.dirty_metas.end(); ++i) {
-    kernel_->needle.put(META_HANDLE, i->ref(META_HANDLE));
+    kernel_->needle.put(META_HANDLE, (*i)->ref(META_HANDLE));
     MetahandlesIndex::iterator found =
         kernel_->metahandles_index->find(&kernel_->needle);
     if (found != kernel_->metahandles_index->end()) {
@@ -626,6 +722,20 @@ void Directory::HandleSaveChangesFailure(const SaveChangesSnapshot& snapshot) {
 
   kernel_->metahandles_to_purge->insert(snapshot.metahandles_to_purge.begin(),
                                         snapshot.metahandles_to_purge.end());
+
+  // Restore delete journals.
+  for (EntryKernelSet::const_iterator i = snapshot.delete_journals.begin();
+       i != snapshot.delete_journals.end(); ++i) {
+    kernel_->needle.put(ID, (*i)->ref(ID));
+    if (kernel_->delete_journals_->find(&kernel_->needle) ==
+        kernel_->delete_journals_->end()) {
+      kernel_->delete_journals_->insert(new EntryKernel(**i));
+    }
+  }
+  kernel_->delete_journals_to_purge_->insert(
+      snapshot.delete_journals_to_purge.begin(),
+      snapshot.delete_journals_to_purge.end());
+
 }
 
 void Directory::GetDownloadProgress(
@@ -1268,6 +1378,16 @@ EntryKernel* Directory::GetPossibleFirstChild(
   return NULL;
 }
 
+/* static */
+bool Directory::IsDeleteJournalEnabled(ModelType type) {
+  switch (type) {
+    case BOOKMARKS:
+      return true;
+    default:
+      return false;
+  }
+}
+
 ScopedKernelLock::ScopedKernelLock(const Directory* dir)
   :  scoped_lock_(dir->kernel_->mutex), dir_(const_cast<Directory*>(dir)) {
 }