NTPSnippetsService: Garbage collect orphaned images at startup.

components/ntp_snippets/remote/ntp_snippets_database.cc

 // Copyright 2016 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 "components/ntp_snippets/remote/ntp_snippets_database.h"
 
 #include <utility>
 
 #include "base/files/file_path.h"
 #include "components/leveldb_proto/proto_database_impl.h"
@@ skipping 66 matching lines @@
 }
 
 void NTPSnippetsDatabase::SaveSnippets(const NTPSnippet::PtrVector& snippets) {
   std::unique_ptr<KeyEntryVector> entries_to_save(new KeyEntryVector());
   for (const std::unique_ptr<NTPSnippet>& snippet : snippets)
     entries_to_save->emplace_back(snippet->id(), snippet->ToProto());
   SaveSnippetsImpl(std::move(entries_to_save));
 }
 
 void NTPSnippetsDatabase::DeleteSnippet(const std::string& snippet_id) {
-  DeleteSnippetsImpl(base::MakeUnique<std::vector<std::string>>(1, snippet_id));
+  DeleteSnippets(base::MakeUnique<std::vector<std::string>>(1, snippet_id));
 }
 
 void NTPSnippetsDatabase::DeleteSnippets(
-    const NTPSnippet::PtrVector& snippets) {
-  std::unique_ptr<std::vector<std::string>> keys_to_remove(
-      new std::vector<std::string>());
-  for (const std::unique_ptr<NTPSnippet>& snippet : snippets)
-    keys_to_remove->emplace_back(snippet->id());
-  DeleteSnippetsImpl(std::move(keys_to_remove));
+    std::unique_ptr<std::vector<std::string>> keys_to_remove) {
+  DCHECK(IsInitialized());
+
+  std::unique_ptr<KeyEntryVector> entries_to_save(new KeyEntryVector());
+  database_->UpdateEntries(std::move(entries_to_save),
+                           std::move(keys_to_remove),
+                           base::Bind(&NTPSnippetsDatabase::OnDatabaseSaved,
+                                      weak_ptr_factory_.GetWeakPtr()));
 }
 
 void NTPSnippetsDatabase::LoadImage(const std::string& snippet_id,
                                     const SnippetImageCallback& callback) {
   if (IsInitialized())
     LoadImageImpl(snippet_id, callback);
   else
     pending_image_callbacks_.emplace_back(snippet_id, callback);
 }
 
 void NTPSnippetsDatabase::SaveImage(const std::string& snippet_id,
                                     const std::string& image_data) {
   DCHECK(IsInitialized());
 
   SnippetImageProto image_proto;
   image_proto.set_data(image_data);
 
   std::unique_ptr<ImageKeyEntryVector> entries_to_save(
       new ImageKeyEntryVector());
   entries_to_save->emplace_back(snippet_id, std::move(image_proto));
 
   image_database_->UpdateEntries(
       std::move(entries_to_save), base::MakeUnique<std::vector<std::string>>(),
       base::Bind(&NTPSnippetsDatabase::OnImageDatabaseSaved,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 void NTPSnippetsDatabase::DeleteImage(const std::string& snippet_id) {
-  DeleteImagesImpl(base::MakeUnique<std::vector<std::string>>(1, snippet_id));
+  DeleteImages(base::MakeUnique<std::vector<std::string>>(1, snippet_id));
 }
 
-void NTPSnippetsDatabase::DeleteImages(const NTPSnippet::PtrVector& snippets) {
-  std::unique_ptr<std::vector<std::string>> keys_to_remove(
-      new std::vector<std::string>());
-  for (const std::unique_ptr<NTPSnippet>& snippet : snippets)
-    keys_to_remove->emplace_back(snippet->id());
-  DeleteImagesImpl(std::move(keys_to_remove));
+void NTPSnippetsDatabase::DeleteImages(
+    std::unique_ptr<std::vector<std::string>> keys_to_remove) {
+  DCHECK(IsInitialized());
+  image_database_->UpdateEntries(
+      base::MakeUnique<ImageKeyEntryVector>(), std::move(keys_to_remove),
+      base::Bind(&NTPSnippetsDatabase::OnImageDatabaseSaved,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void NTPSnippetsDatabase::GarbageCollectImages(
+    std::unique_ptr<std::set<std::string>> alive_snippet_ids) {
+  DCHECK(image_database_initialized_);
+  image_database_->LoadKeys(
+      base::Bind(&NTPSnippetsDatabase::DeleteUnreferencedImages,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 base::Passed(std::move(alive_snippet_ids))));
 }
 
 void NTPSnippetsDatabase::OnDatabaseInited(bool success) {
   DCHECK(!database_initialized_);
   if (!success) {
     DVLOG(1) << "NTPSnippetsDatabase init failed.";
     OnDatabaseError();
     return;
   }
   database_initialized_ = true;
@@ skipping 23 matching lines @@
       LOG(WARNING) << "Invalid proto from DB " << proto.id();
       keys_to_remove->emplace_back(proto.id());
     }
   }
 
   callback.Run(std::move(snippets));
 
   // If any of the snippet protos couldn't be converted to actual snippets,
   // clean them up now.
   if (!keys_to_remove->empty())
-    DeleteSnippetsImpl(std::move(keys_to_remove));
+    DeleteSnippets(std::move(keys_to_remove));
 }
 
 void NTPSnippetsDatabase::OnDatabaseSaved(bool success) {
   if (!success) {
     DVLOG(1) << "NTPSnippetsDatabase save failed.";
     OnDatabaseError();
   }
 }
 
 void NTPSnippetsDatabase::OnImageDatabaseInited(bool success) {
@@ skipping 65 matching lines @@
   DCHECK(IsInitialized());
 
   std::unique_ptr<std::vector<std::string>> keys_to_remove(
       new std::vector<std::string>());
   database_->UpdateEntries(std::move(entries_to_save),
                            std::move(keys_to_remove),
                            base::Bind(&NTPSnippetsDatabase::OnDatabaseSaved,
                                       weak_ptr_factory_.GetWeakPtr()));
 }
 
-void NTPSnippetsDatabase::DeleteSnippetsImpl(
-    std::unique_ptr<std::vector<std::string>> keys_to_remove) {
-  DCHECK(IsInitialized());
-
-  std::unique_ptr<KeyEntryVector> entries_to_save(new KeyEntryVector());
-  database_->UpdateEntries(std::move(entries_to_save),
-                           std::move(keys_to_remove),
-                           base::Bind(&NTPSnippetsDatabase::OnDatabaseSaved,
-                                      weak_ptr_factory_.GetWeakPtr()));
-}
-
 void NTPSnippetsDatabase::LoadImageImpl(const std::string& snippet_id,
                                         const SnippetImageCallback& callback) {
   DCHECK(IsInitialized());
   image_database_->GetEntry(
       snippet_id,
       base::Bind(&NTPSnippetsDatabase::OnImageDatabaseLoaded,
                  weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
-void NTPSnippetsDatabase::DeleteImagesImpl(
-    std::unique_ptr<std::vector<std::string>> keys_to_remove) {
-  DCHECK(IsInitialized());
-
-  image_database_->UpdateEntries(
-      base::MakeUnique<ImageKeyEntryVector>(), std::move(keys_to_remove),
-      base::Bind(&NTPSnippetsDatabase::OnImageDatabaseSaved,
-                 weak_ptr_factory_.GetWeakPtr()));
+void NTPSnippetsDatabase::DeleteUnreferencedImages(
+    std::unique_ptr<std::set<std::string>> references,
+    bool load_keys_success,
+    std::unique_ptr<std::vector<std::string>> image_keys) {
+  if (!load_keys_success) {
+    DVLOG(1) << "NTPSnippetsDatabase garbage collection failed.";
+    OnDatabaseError();
+    return;
+  }
+  auto keys_to_remove = base::MakeUnique<std::vector<std::string>>();
+  for (const std::string& key : *image_keys) {
+    if (references->count(key) == 0) {
+      keys_to_remove->emplace_back(key);
+    }
+  }
+  DeleteImages(std::move(keys_to_remove));
 }
 
+
 }  // namespace ntp_snippets