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From c21bb5220a3ae835a5183afd58c186ba21f6c93d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Vr=C3=A1til?= <dvratil@kde.org>
Date: Fri, 28 Jun 2019 17:10:04 +0200
Subject: Fix race-condition on akonadi_control start
Summary:
Check that there are no other akonadi_control instances running as the
very first thing on startup. Previously this check would happen after
AkApplication initialization, which contains some potential race-
conditions, like rotating log files.
The situation when akonadi_control is launched multiple times can occur
on session startup, when multiple different components will attempt to
launch Akonadi if its not yet running.
BUG: 392092
FIXED-IN: 19.04.3
Reviewers: #kde_pim, vkrause
Reviewed By: #kde_pim, vkrause
Subscribers: kde-pim
Tags: #kde_pim
Differential Revision: https://phabricator.kde.org/D22092
---
src/akonadicontrol/main.cpp | 16 ++-------------
src/shared/akapplication.cpp | 7 +++----
src/shared/akapplication.h | 49 ++++++++++++++++++++++++++++++++++++++------
3 files changed, 48 insertions(+), 24 deletions(-)
diff --git a/src/akonadicontrol/main.cpp b/src/akonadicontrol/main.cpp
index 19bebb8..7dba85b 100644
--- a/src/akonadicontrol/main.cpp
+++ b/src/akonadicontrol/main.cpp
@@ -52,7 +52,7 @@ void crashHandler(int)
int main(int argc, char **argv)
{
- AkGuiApplication app(argc, argv, AKONADICONTROL_LOG());
+ AkUniqueGuiApplication app(argc, argv, Akonadi::DBus::serviceName(Akonadi::DBus::ControlLock), AKONADICONTROL_LOG());
app.setDescription(QStringLiteral("Akonadi Control Process\nDo not run this manually, use 'akonadictl' instead to start/stop Akonadi."));
KAboutData aboutData(QStringLiteral("akonadi_control"),
@@ -64,20 +64,8 @@ int main(int argc, char **argv)
app.parseCommandLine();
- // try to acquire the lock first, that means there is no second instance trying to start up at the same time
- // registering the real service name happens in AgentManager::continueStartup(), when everything is in fact up and running
- if (!QDBusConnection::sessionBus().registerService(Akonadi::DBus::serviceName(Akonadi::DBus::ControlLock))) {
- // We couldn't register. Most likely, it's already running.
- const QString lastError = QDBusConnection::sessionBus().lastError().message();
- if (lastError.isEmpty()) {
- qCWarning(AKONADICONTROL_LOG) << "Unable to register service as" << Akonadi::DBus::serviceName(Akonadi::DBus::ControlLock) << "Maybe it's already running?";
- } else {
- qCWarning(AKONADICONTROL_LOG) << "Unable to register service as" << Akonadi::DBus::serviceName(Akonadi::DBus::ControlLock) << "Error was:" << lastError;
- }
- return -1;
- }
-
// older Akonadi server versions don't use the lock service yet, so check if one is already running before we try to start another one
+ // TODO: Remove this legacy check?
if (QDBusConnection::sessionBus().interface()->isServiceRegistered(Akonadi::DBus::serviceName(Akonadi::DBus::Control))) {
qCWarning(AKONADICONTROL_LOG) << "Another Akonadi control process is already running.";
return -1;
diff --git a/src/shared/akapplication.cpp b/src/shared/akapplication.cpp
index af860e5..b790b8d 100644
--- a/src/shared/akapplication.cpp
+++ b/src/shared/akapplication.cpp
@@ -32,10 +32,9 @@
AkApplicationBase *AkApplicationBase::sInstance = nullptr;
-AkApplicationBase::AkApplicationBase(int &argc, char **argv, const QLoggingCategory &loggingCategory)
+AkApplicationBase::AkApplicationBase(std::unique_ptr<QCoreApplication> app, const QLoggingCategory &loggingCategory)
: QObject(nullptr)
- , mArgc(argc)
- , mArgv(argv)
+ , mApp(std::move(app))
, mLoggingCategory(loggingCategory)
{
Q_ASSERT(!sInstance);
@@ -59,7 +58,7 @@ AkApplicationBase *AkApplicationBase::instance()
void AkApplicationBase::init()
{
- akInit(QString::fromLatin1(mArgv[0]));
+ akInit(mApp->applicationName());
akInitRemoteLog();
if (!QDBusConnection::sessionBus().isConnected()) {
diff --git a/src/shared/akapplication.h b/src/shared/akapplication.h
index aae7a99..433b725 100644
--- a/src/shared/akapplication.h
+++ b/src/shared/akapplication.h
@@ -23,6 +23,10 @@
#include <QObject>
#include <QCommandLineParser>
#include <QLoggingCategory>
+#include <QDBusConnection>
+#include <QDBusError>
+
+#include <memory>
class QCoreApplication;
class QApplication;
@@ -55,16 +59,15 @@ public:
int exec();
protected:
- AkApplicationBase(int &argc, char **argv, const QLoggingCategory &loggingCategory);
+ AkApplicationBase(std::unique_ptr<QCoreApplication> app, const QLoggingCategory &loggingCategory);
void init();
- QScopedPointer<QCoreApplication> mApp;
+
+ std::unique_ptr<QCoreApplication> mApp;
private Q_SLOTS:
void pollSessionBus() const;
private:
- int mArgc;
- char **mArgv;
QString mInstanceId;
const QLoggingCategory &mLoggingCategory;
static AkApplicationBase *sInstance;
@@ -77,13 +80,46 @@ class AkApplicationImpl : public AkApplicationBase
{
public:
AkApplicationImpl(int &argc, char **argv, const QLoggingCategory &loggingCategory = *QLoggingCategory::defaultCategory())
- : AkApplicationBase(argc, argv, loggingCategory)
+ : AkApplicationBase(std::make_unique<T>(argc, argv), loggingCategory)
{
- mApp.reset(new T(argc, argv));
init();
}
};
+template<typename T>
+class AkUniqueApplicationImpl : public AkApplicationBase
+{
+public:
+ AkUniqueApplicationImpl(int &argc, char **argv, const QString &serviceName, const QLoggingCategory &loggingCategory = *QLoggingCategory::defaultCategory())
+ : AkApplicationBase(std::make_unique<T>(argc, argv), loggingCategory)
+ {
+ registerUniqueServiceOrTerminate(serviceName, loggingCategory);
+ init();
+ }
+
+private:
+ void registerUniqueServiceOrTerminate(const QString &serviceName, const QLoggingCategory &log)
+ {
+ auto bus = QDBusConnection::sessionBus();
+ if (!bus.isConnected()) {
+ qCCritical(log, "Session bus not found. Is DBus running?");
+ exit(1);
+ }
+
+ if (!bus.registerService(serviceName)) {
+ // We couldn't register. Most likely, it's already running.
+ const QString lastError = bus.lastError().message();
+ if (lastError.isEmpty()) {
+ qCInfo(log, "Service %s already registered, terminating now.", qUtf8Printable(serviceName));
+ exit(0); // already running, so it's OK. Terminate now.
+ } else {
+ qCCritical(log, "Unable to register service as %s due to an error: %s", qUtf8Printable(serviceName), qUtf8Printable(lastError));
+ exit(1); // :(
+ }
+ }
+ }
+};
+
/**
* Returns the contents of @p name environment variable if it is defined,
* or @p defaultValue otherwise.
@@ -93,5 +129,6 @@ QString akGetEnv(const char *name, const QString &defaultValue = QString());
typedef AkApplicationImpl<QCoreApplication> AkCoreApplication;
typedef AkApplicationImpl<QApplication> AkApplication;
typedef AkApplicationImpl<QGuiApplication> AkGuiApplication;
+typedef AkUniqueApplicationImpl<QGuiApplication> AkUniqueGuiApplication;
#endif
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