Reset the GCM store to recover from it when it is busted

google_apis/gcm/engine/gcm_store_impl.cc

 // Copyright 2014 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 "google_apis/gcm/engine/gcm_store_impl.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/sequenced_task_runner.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_tokenizer.h"
 #include "base/time/time.h"
 #include "base/tracked_objects.h"
 #include "google_apis/gcm/base/encryptor.h"
 #include "google_apis/gcm/base/mcs_message.h"
 #include "google_apis/gcm/base/mcs_util.h"
 #include "google_apis/gcm/protocol/mcs.pb.h"
 #include "third_party/leveldatabase/src/include/leveldb/db.h"
 #include "third_party/leveldatabase/src/include/leveldb/write_batch.h"
 
 namespace gcm {
 
 namespace {
 
+// This enum is used in an UMA histogram (GCMLoadStatus enum defined in
+// tools/metrics/histograms/histogram.xml). Hence the entries here shouldn't
+// be deleted or re-ordered and new ones should be added to the end.
+enum LoadStatus {
+  LOADING_SUCCEEDED,
+  RELOADING_OPEN_STORE,
+  OPENING_STORE_FAILED,
+  LOADING_DEVICE_CREDENTIALS_FAILED,
+  LOADING_REGISTRATION_FAILED,
+  LOADING_INCOMING_MESSAGES_FAILED,
+  LOADING_OUTGOING_MESSAGES_FAILED,
+  LOADING_LAST_CHECKIN_INFO_FAILED,
+  LOADING_GSERVICE_SETTINGS_FAILED,
+  LOADING_ACCOUNT_MAPPING_FAILED,
+  LOADING_LAST_TOKEN_TIME_FAILED,
+
+  // NOTE: always keep this entry at the end. Add new status types only
+  // immediately above this line. Make sure to update the corresponding
+  // histogram enum accordingly.
+  LOAD_STATUS_COUNT
+};
+
 // Limit to the number of outstanding messages per app.
 const int kMessagesPerAppLimit = 20;
 
 // ---- LevelDB keys. ----
 // Key for this device's android id.
 const char kDeviceAIDKey[] = "device_aid_key";
 // Key for this device's android security token.
 const char kDeviceTokenKey[] = "device_token_key";
 // Lowest lexicographically ordered app ids.
 // Used for prefixing app id.
@@ skipping 128 matching lines @@
   void SetLastTokenFetchTime(const base::Time& time,
                              const UpdateCallback& callback);
   void SetValue(const std::string& key,
                 const std::string& value,
                 const UpdateCallback& callback);
 
  private:
   friend class base::RefCountedThreadSafe<Backend>;
   ~Backend();
 
+  LoadStatus OpenStoreAndLoadData(LoadResult* result);
   bool LoadDeviceCredentials(uint64* android_id, uint64* security_token);
   bool LoadRegistrations(RegistrationInfoMap* registrations);
   bool LoadIncomingMessages(std::vector<std::string>* incoming_messages);
   bool LoadOutgoingMessages(OutgoingMessageMap* outgoing_messages);
   bool LoadLastCheckinInfo(base::Time* last_checkin_time,
                            std::set<std::string>* accounts);
   bool LoadGServicesSettings(std::map<std::string, std::string>* settings,
                              std::string* digest);
   bool LoadAccountMappingInfo(AccountMappings* account_mappings);
   bool LoadLastTokenFetchTime(base::Time* last_token_fetch_time);
 
   const base::FilePath path_;
   scoped_refptr<base::SequencedTaskRunner> foreground_task_runner_;
   scoped_ptr<Encryptor> encryptor_;
 
   scoped_ptr<leveldb::DB> db_;
 };
 
 GCMStoreImpl::Backend::Backend(
     const base::FilePath& path,
     scoped_refptr<base::SequencedTaskRunner> foreground_task_runner,
     scoped_ptr<Encryptor> encryptor)
     : path_(path),
       foreground_task_runner_(foreground_task_runner),
       encryptor_(encryptor.Pass()) {
 }
 
 GCMStoreImpl::Backend::~Backend() {}
 
-void GCMStoreImpl::Backend::Load(const LoadCallback& callback) {
-  scoped_ptr<LoadResult> result(new LoadResult());
+LoadStatus GCMStoreImpl::Backend::OpenStoreAndLoadData(LoadResult* result) {
+  LoadStatus load_status;
   if (db_.get()) {
     LOG(ERROR) << "Attempting to reload open database.";
-    foreground_task_runner_->PostTask(FROM_HERE,
-                                      base::Bind(callback,
-                                                 base::Passed(&result)));
-    return;
+    return RELOADING_OPEN_STORE;
   }
 
   leveldb::Options options;
   options.create_if_missing = true;
   leveldb::DB* db;
   leveldb::Status status =
       leveldb::DB::Open(options, path_.AsUTF8Unsafe(), &db);
-  UMA_HISTOGRAM_BOOLEAN("GCM.LoadSucceeded", status.ok());
   if (!status.ok()) {
     LOG(ERROR) << "Failed to open database " << path_.value() << ": "
                << status.ToString();
-    foreground_task_runner_->PostTask(FROM_HERE,
-                                      base::Bind(callback,
-                                                 base::Passed(&result)));
-    return;
+    return OPENING_STORE_FAILED;
   }
+
   db_.reset(db);
+  if (!LoadDeviceCredentials(&result->device_android_id,
+                             &result->device_security_token)) {
+    return LOADING_DEVICE_CREDENTIALS_FAILED;
+  }
+  if (!LoadRegistrations(&result->registrations))
+    return LOADING_REGISTRATION_FAILED;
+  if (!LoadIncomingMessages(&result->incoming_messages))
+    return LOADING_INCOMING_MESSAGES_FAILED;
+  if (!LoadOutgoingMessages(&result->outgoing_messages))
+    return LOADING_OUTGOING_MESSAGES_FAILED;
+  if (!LoadLastCheckinInfo(&result->last_checkin_time,
+                           &result->last_checkin_accounts)) {
+    return LOADING_LAST_CHECKIN_INFO_FAILED;
+  }
+  if (!LoadGServicesSettings(&result->gservices_settings,
+                             &result->gservices_digest)) {
+    return load_status = LOADING_GSERVICE_SETTINGS_FAILED;
+  }
+  if (!LoadAccountMappingInfo(&result->account_mappings))
+    return LOADING_ACCOUNT_MAPPING_FAILED;
+  if (!LoadLastTokenFetchTime(&result->last_token_fetch_time))
+     return LOADING_LAST_TOKEN_TIME_FAILED;
 
-  if (!LoadDeviceCredentials(&result->device_android_id,
-                             &result->device_security_token) ||
-      !LoadRegistrations(&result->registrations) ||
-      !LoadIncomingMessages(&result->incoming_messages) ||
-      !LoadOutgoingMessages(&result->outgoing_messages) ||
-      !LoadLastCheckinInfo(&result->last_checkin_time,
-                           &result->last_checkin_accounts) ||
-      !LoadGServicesSettings(&result->gservices_settings,
-                             &result->gservices_digest) ||
-      !LoadAccountMappingInfo(&result->account_mappings) ||
-      !LoadLastTokenFetchTime(&result->last_token_fetch_time)) {
+  return LOADING_SUCCEEDED;
+}
+
+void GCMStoreImpl::Backend::Load(const LoadCallback& callback) {
+  scoped_ptr<LoadResult> result(new LoadResult());
+  LoadStatus load_status = OpenStoreAndLoadData(result.get());
+  if (load_status != LOADING_SUCCEEDED) {
+    UMA_HISTOGRAM_ENUMERATION("GCM.LoadStatus", load_status, LOAD_STATUS_COUNT);

[Nicolas Zea, 2015/02/10 21:07:37]

Did you not want to record success as well? If so, perhaps name this and
describe it differently to reflect that this is just a breakdown of the errors.

[jianli, 2015/02/10 21:11:53]

Good catch. I do want to record the success. Move the UMA code outside if. I
think LoadStatus mean both success and error.

     result->Reset();
     foreground_task_runner_->PostTask(FROM_HERE,
                                       base::Bind(callback,
                                                  base::Passed(&result)));
     return;
   }
 
   // Only record histograms if GCM had already been set up for this device.
   if (result->device_android_id != 0 && result->device_security_token != 0) {
     int64 file_size = 0;
@@ skipping 922 matching lines @@
            removed_message_counts.begin();
        iter != removed_message_counts.end(); ++iter) {
     DCHECK_NE(app_message_counts_.count(iter->first), 0U);
     app_message_counts_[iter->first] -= iter->second;
     DCHECK_GE(app_message_counts_[iter->first], 0);
   }
   callback.Run(true);
 }
 
 }  // namespace gcm