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chore: Failed to create instance #202

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chore: Failed to create instance #202

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28 changes: 26 additions & 2 deletions singleapplication.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -72,8 +72,9 @@ SingleApplication::SingleApplication( int &argc, char *argv[], bool allowSeconda
#else
d->memory = new QSharedMemory( d->blockServerName );
#endif
d->memory->attach();
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When debugging and releasing, there is a high probability that this line will crash after a few more tries;

delete d->memory;
bool ok = d->memory->attach();
qCritical() << "d->memory->attach():" << ok;
if (ok) delete d->memory;
Comment on lines +75 to +77
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That first attach and delete are dummy operations. They are only there as I noticed that when there is orphaned shared memory after the original process has crashed, attaching and deleting clears it up. If it's not orphaned this is a no-op.

As such I didn't think I need to check their success status.

#endif
// Guarantee thread safe behaviour with a shared memory block.
#if QT_VERSION >= QT_VERSION_CHECK(6, 6, 0)
Expand All @@ -91,23 +92,46 @@ SingleApplication::SingleApplication( int &argc, char *argv[], bool allowSeconda
}
d->initializeMemoryBlock();
} else {

qCritical() << "Shared memory creation failed:" << d->memory->errorString();
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This is a valid code path when there is already an instance running. There is no need for qCritical here.


if( d->memory->error() == QSharedMemory::AlreadyExists ){
// Attempt to attach to the memory segment
if( ! d->memory->attach() ){
qCritical() << "SingleApplication: Unable to attach to shared memory block.";
abortSafely();
} else {
qCritical() << "Successfully attached to existing shared memory block";
}
if( ! d->memory->lock() ){
qCritical() << "SingleApplication: Unable to lock memory block after attach.";
abortSafely();
} else {
qCritical() << "Memory block successfully locked";
}

} else {
qCritical() << "SingleApplication: Unable to create block.";
abortSafely();
}
}

auto *inst = static_cast<InstancesInfo*>( d->memory->data() );

if (!inst) {
qCritical() << "Shared memory data is NULL!";
abortSafely();
} else {

qCritical() << "Shared memory data doesn't NULL!";
qCritical() << "Primary: " << inst->primary << QString::asprintf("0x%X", inst->primary);
qCritical() << "Secondary: " << inst->secondary << QString::asprintf("0x%X", inst->secondary);
qCritical() << "Primary PID: " << inst->primaryPid << QString::asprintf("0x%llX", inst->primaryPid);
qCritical() << "Checksum: " << inst->checksum << QString::asprintf("0x%X", inst->checksum);
qCritical() << "Primary User: " << inst->primaryUser;
}


QElapsedTimer time;
time.start();

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