I have one problem. In c++ app, I am using sd-bus and signal does not call my callback function.
I hooked to org.freedesktop.login1, interface is org.freedesktop.DBus.Properties, member is PropertiesChanged and path is /org/freedesktop/login1/seat/seat0
In my connect method I have this:
sd_bus_add_match(m_bus, NULL, "interface='org.freedesktop.DBus.Properties',member='PropertiesChanged',path='/org/freedesktop/login1/seat/seat0',type='signal'", on_properties_changed, NULL)
On properties changed method is this:
static int on_properties_changed(sd_bus_message *m, void *userdata, sd_bus_error *ret_error) {
printf("got some signal");
}
So, when I ran this program, I also ran following command in cmd:ΒΈ
gdbus monitor --system --dest org.freedesktop.login1 --object-path /org/freedesktop/login1/seat/seat0
However, when I switch from userA to userB, I got following line in cmd window:
/org/freedesktop/login1/seat/seat0: org.freedesktop.DBus.Properties.PropertiesChanged ('org.freedesktop.login1.Seat', {'ActiveSession': <('c7', objectpath '/org/freedesktop/login1/session/c7')>}, #as [])
Also when I tried this
busctl --system --match "interface='org.freedesktop.DBus.Properties',member='PropertiesChanged',path='/org/freedesktop/login1/seat/seat0',type='signal' monitor
then I also get proper response
Type=signal Endian=l Flags=1 Version=1 Priority=0 Cookie=2281
Sender=:1.0 Path=/org/freedesktop/login1/seat/seat0 Interface=org.freedesktop.DBus.Properties Member=PropertiesChanged
UniqueName=:1.0
MESSAGE "sa{sv}as" {
STRING "org.freedesktop.login1.Seat";
ARRAY "{sv}" {
DICT_ENTRY "sv" {
STRING "ActiveSession";
VARIANT "(so)" {
STRUCT "so" {
STRING "c2";
OBJECT_PATH "/org/freedesktop/login1/session/c2";
};
};
};
};
ARRAY "s" {
};
};
But in c++ that callback function is not called. Any idea why is it not called?
I am using Ubuntu 16.04 and my systemd version is 229.
I found a solution to this problem. Problem was that I wasn't hooked to any event loop.
So I created new function run() and in this function I say this:
while(m_running) {
sd_bus_message *m = NULL;
r = sd_bus_process(m_bus, &m);
if (r < 0) {
//error handling
}
r = sd_bus_wait(m_bus, (uint64_t)-1);
if (r < 0) {
//error handling
}
}
and now I call this function after I connect to signal, and callback function of sd_bus_add_match is normally called
Related
I am having issues in a code having structure similar to the following minimum example. There is only one instance of MainClass. It makes new instance of Classlet on each call to its MainClass::makeclasslet()
I have multiple classlets writing to a single list buffer. After some time I need to copy/ dump the values from list buffer (FIFO).
The problem is that I am getting the following output in MainClass::clearbuffer()
>>>>>>>>>> 704 >>>>>>>>>>>>>>>>>>> Buffer size: 65363..... 1
I am unable to understand why the std::list::empty() returns true even when the buffer is locked with an atomic bool flag.
I have tried moving the call to clearbuffer() (in addval()) to the main application thread so that not each Classlet event calls clearbuffer().
I have also tried adding delay QThread::msleep(10); after setting busy = true;.
But some time after the application starts, I am getting the output shown above. Instead of popping all 65363+704 values in the list, it only popped 704 and broke the loop on list::isempty() being true (apparently).
class MainClass : public QObject {
Q_OBJECT
private:
std:: list<int> alist;
std::atomic<bool> busy;
MainClass() {
busy = false;
}
~MainClass() {
// delete all classlets
}
void makeclasslet() {
Classlet newclasslet = new Classlet();
// store the reference
}
void addval(int val) {
alist.push_back(val);
if (alist.size() > 100)
{
if (!busy)
{
clearbuffer();
}
}
}
void clearbuffer() {
if (!busy)
{
busy = true;
int i = 0;
while (!alist.empty())
{
i = i + 1;
// save alist.front() to file
alist.pop_front();
}
printf(">>>>>>>>>> %d >>>>>>>>>>> Buffer size: %d ..... %d\n", i, m_lstCSVBuffer.size(), m_lstCSVBuffer.empty());
busy = false;
}
}
}
class Classlet {
private:
Mainclass* parent;
void onsomeevent(int val) {
parent->addval(val);
}
}
I am using qt5.9 on Ubuntu 18.04. GCC/ G++ 7.5.0
I'm trying to call a java function by C++. It is working perfectly fine in Eclipse IDE, but when i build war and running in tomcat. I'm able to call C++ function from Springboot application. But unable to call java function from C++. Since It is unable to find the class which i mentioned with package.
Below is my sample code. Is their is anyway to fix this?
my C++ code
void myClientEvents::SendEvents(const char* ack) {
//Get current thread JNIEnv
JNIEnv * ENV;
WriteLogFile("Get current thread JNIEnv");
try {
WriteLogFile(ack);
int stat = savedVM->GetEnv((void **)&ENV, JNI_VERSION_1_8);
WriteLogFile("stat");
if (stat == JNI_EDETACHED) //We are on a different thread, attach
{
WriteLogFile("We are on a different thread, attach");
savedVM->AttachCurrentThread((void **)&ENV, NULL);
}
if (ENV == NULL)
{
WriteLogFile("Cant attach to java, bail");
//Cant attach to java, bail
}
//Get the Listener class reference
if (saved_listener_instance != NULL) {
WriteLogFile("Get the Listener class reference");
jclass listenerClassRef = ENV->FindClass("org/trinity/serviceImpl/CadiAstroServiceImpl");
if (listenerClassRef==NULL)
{
WriteLogFile("Class Not found"); //This line is printing for tomcat
}
WriteLogFile("Use Listener class reference to load the eventOccurred method");
//Not moving forward from above log in tomcat
jmethodID ctor = ENV->GetMethodID(listenerClassRef, "<init>", "()V");
jobject object = ENV->NewObject(listenerClassRef, ctor);
//Use Listener class reference to load the eventOccurred method
jmethodID listenerEventOccured = ENV->GetMethodID(listenerClassRef, "eventOccurred", "(Ljava/lang/String;)V");
WriteLogFile("jmethodID created");
jstring jstr = ENV->NewStringUTF(ack);
WriteLogFile("invoke listener eventOccurred");
//invoke listener eventOccurred
ENV->CallVoidMethod(object, listenerEventOccured, jstr);
ENV->DeleteLocalRef(jstr);
ENV->DeleteLocalRef(object);
ENV->DeleteLocalRef(listenerClassRef);
}
else {
WriteLogFile("Error getting class");
}
}
catch (const char* msg) {
WriteLogFile(msg);
}
}
my java method in mentioned class
public void eventOccurred(String info) {
System.out.println(info);
}
i init CefResourceManager pointer in my handler class constructor,and call SetupResourceManager function immediately.
cefclient_handler::cefclient_handler(CefRefPtr<QCefPage> listner, CefRefPtr<CefRenderHandler> osrenderHandler)
: is_closing_(false), clientListner_(listner), osrenderHandler_(osrenderHandler){
resource_manager_ = new CefResourceManager();
SetupResourceManager(resource_manager_ ,"file:///D:/test/test.zip")
}
void SetupResourceManager(CefRefPtr<CefResourceManager> resource_manager,std::string resource_dir) {
if (!CefCurrentlyOn(TID_IO)) {
// Execute on the browser IO thread.
CefPostTask(TID_IO, base::Bind(SetupResourceManager, resource_manager, resource_dir));
return;
}
resource_manager->AddArchiveProvider("https://***.net", resource_dir,"", 0,
std::string());
}
it works well.
But in the current business needs, when the handler is initialized, the resource (zip file) is not ready, so I try to call CreateBrowser first, and then call AddArchiveProvider in my handler class when the resource file is downloaded, like this.
void cefclient_handler::AddArchiveProvider(const std::string& url_path, const std::string& archive_path, const std::string& password, int order, const std::string& identifier)
{
if (!CefCurrentlyOn(TID_IO)) {
// Execute on the browser IO thread.
CefPostTask(TID_IO, base::Bind(&cefclient_handler::AddArchiveProvider, this, url_path, archive_path, password, order, identifier));
return;
}
if (resource_manager_.get())
{
resource_manager_->AddArchiveProvider(url_path, archive_path, "", 0,
std::string());
}
}
It doesn't work anymore.
I'm currently working on a project with MFC and I noticed something weird that apparently has been there for a couple of years. When I launch the .exe of the program, it will do n number of things including reading a .DAT file and storing it as well. If the file doesn't exists, the program will try to find it with no luck throwing this CFile exception: The file could not be located. Which is correct because it doesn't exists. I have to do some operations first to generate that file, the storing process works fine. When the file exists and I run the program again, it's supposed read the file but this CArchive exception shows up: Invalid file format. And I don't understand why.
This is the Serialize():
//Fruits.cpp
void CFruits::Serialize(CArchive &ar)
{
int nVersion = 0;
CObject::Serialize(ar);
ar.SerializeClass(GetRuntimeClass());
if(ar.IsStoring())
{
ar.Write(&m_bInit,sizeof(bool));
ar.Write(&m_bYummy,sizeof(bool));
ar.Write(&m_bAcid, sizeof(bool));
ar.Write(&m_bFresh,sizeof(bool));
...
...
...
ar<<m_cType;
ar<<m_cColour;
ar<<m_cFlavor;
ar<<m_cPrice;
ar<<m_cQuantity;
}
else
{
nVersion = ar.GetObjectSchema();
ar.Read(&m_bInit,sizeof(bool));
ar.Read(&m_bYummy,sizeof(bool));
ar.Read(&m_bAcid, sizeof(bool));
ar.Read(&m_bFresh,sizeof(bool));
...
...
...
if( nVersion >= 2 || nVersion < 0)
ar<<m_cType;
else
m_cType=0;
if (nVersion >= 3 || nVersion < 0)
ar<<m_cColour;
else
m_cColour=0;
if (nVersion >= 4 || nVersion < 0)
ar<<m_cFlavor;
else
ar<<m_cFlavor=0;
if( nVersion >= 5 || nVersion < 0)
{
ar<<m_cPrice;
ar<<m_cQuantity;
}
else
{
m_cPrice=0;
m_cQuantity=0;
}
}
m_oSales.Serialize(ar);
m_oAdmin.Serialize(ar);
...
...
}
IMPLEMENT_SERIAL(CVehiculo,CObject,VERSIONABLE_SCHEMA | 6)
This is the SerializeElements:
//Fruits.cpp
void AFXAPI SerializeElements(CArchive &ar,CFruits * fruits,int ncount)
{
try
{
for(cont=0;cont<ncount;cont++)
fruits[cont].Serialize(ar);
}
catch(CArchiveException *AE)
{
//Here it stores the exception in a Log. Exception 5
}
}
The serializeElements is used to store and read the file n times, as declared here in the header file of fruits:
//Fruits.h
class CFruits : public CObject
{
public:
CFruits();
CFruits(const CFruits &O);
virtual ~CFruits();
void operator = (const CFruits &O);
void Serialize(CArchive &ar);
protected:
DECLARE_SERIAL(CFruits)
};
void AFXAPI SerializeElements(CArchive &ar,CFruits * fruits,int ncount);
typedef CArray<CFruits, CFruitso&> TArrayFruits;
The values of this Array, and the methods used to call the serialize are defined here in my main function:
//main.h
#include "CFruits.h"
class CMain : public CDialog
{
// Construction
public:
enum T_Fruits { eFruitsOnLine, eFruitsIng, eFruitsTra, eFruitsAnt, eFruitsP3, eFruitsP2, eFruitsP1, eFruitsC1, eFruitsC0, eFruitsEscape, eFruitsVideo};
private:
void StoreFruits();
void ReadFruits();
The SerializeElements for-loop is supposed to run 11 times, but I noticed that it only does it 1 time, then the Schema version changes to -1, (originally 6 cause I managed to trace the value). This happens only when reading the file.
I've tried the following:
I can't use debug so I have to use Logs, I placed a Log after every sentence in the Serialize() function, I found what seems to be the issue, this line:
ar.SerializeClass(GetRuntimeClass());
I used a try-catch and found that when that sentence happens, it throws the exception so, it doesn't continue reading. That is the moment where the version changes to -1. I tried to change that to:
ar.SerializeClass(RUNTIME_CLASS(CFruits));
Is the same result, I've read many forums trying to find the answer but I can't seem to do so. I've read the documentation and I found this here:
https://learn.microsoft.com/en-us/cpp/mfc/reference/carchive-class?view=vs-2019#serializeclass
Like ReadClass, SerializeClass verifies that the archived class
information is compatible with your runtime class. If it is not
compatible, SerializeClass will throw a CArchiveException.
But it doesn't make sense to me, because it doesn't fail storing. Should I look into something else?
Thank you
EDIT:
I'm posting the Store and Read methods
void CMain::ReadFruits()
{
CString CSerror, sFileName;
CString sDebug;
try
{
sFileName.Format("FRUITS%03d.DAT",GetNumT());
CFile fFruitsTag(sFileName,CFile::modeRead);
CArchive ar(&fFruitsTag,CArchive::load);
m_vFruits.Serialize(ar);
ar.Close();
fFruitsTag.Close();
}
catch(CFileException *FE)
{
...
}
catch(CArchiveException *AE)
{
...
}
}
void CMain::StoreFruits()
{
CString CSerror, sFileName;
try
{
if(!m_bStoringFruits)
{
sFileName.Format("FRUITS%03d.DAT",GetNumT());
m_bStoringFruits=true;
CFile fFruitsTag(sFileName,CFile::modeCreate|CFile::modeWrite);
CArchive ar(&fFruitsTag,CArchive::store);
m_vFruits.Serialize(ar);
ar.Close();
fFruitsTag.Close();
m_bStoringFruits=false;
}
}
catch(CFileException *FE)
{
...
}
catch(CArchiveException *AE)
{
...
}
catch(CException *e)
{
...
}
}
This question involves etcd specific stuff, but I think the question more related to work with gRPC in general.
I'm trying to create etcd Watch for some keys, since the documentation is sparse I had a look at Nokia implementation
It was easy to adapt code to my needs and I came up with first version which worked just fine, creating WatchCreateRequest, and firing callback on key update. So far so good. Then I've tried to add more than one key to watch. Fiasco! ClientAsyncReaderWriter is failing to Read/Write in such a case. Now to the question.
If I have following members in my class
Watch::Stub watchStub;
CompletionQueue completionQueue;
ClientContext context;
std::unique_ptr<ClientAsyncReaderWriter<WatchRequest, WatchResponse>> stream;
WatchResponse reply;
and I want to support multiple Watches added to my class, I guess I have to hold several variables per watch and not as class members.
First of all, I guess, WatchResponse reply should be one per Watch. I'm less sure about the stream, should I hold one per Watch? I'm almost sure that context could be reused for all Watches and 100% sure the stub and completionQueue can be reused for all Watches.
So the question is my guess-work right? Whats about thread safety? Didnt find any documentation describing what objects are safe to use from multiple thread and where I have to synchronize access.
Any link to documentation (not this one) will be appreciated!
Test code before I split members into single Watch property
(no proper shutdown, I know)
using namespace grpc;
class Watcher
{
public:
using Callback = std::function<void(const std::string&, const std::string&)>;
Watcher(std::shared_ptr<Channel> channel) : watchStub(channel)
{
stream = watchStub.AsyncWatch(&context, &completionQueue, (void*) "create");
eventPoller = std::thread([this]() { WaitForEvent(); });
}
void AddWatch(const std::string& key, Callback callback)
{
AddWatch(key, callback, false);
}
void AddWatches(const std::string& key, Callback callback)
{
AddWatch(key, callback, true);
}
private:
void AddWatch(const std::string& key, Callback callback, bool isRecursive)
{
auto insertionResult = callbacks.emplace(key, callback);
if (!insertionResult.second) {
throw std::runtime_error("Event handle already exist.");
}
WatchRequest watch_req;
WatchCreateRequest watch_create_req;
watch_create_req.set_key(key);
if (isRecursive) {
watch_create_req.set_range_end(key + "\xFF");
}
watch_req.mutable_create_request()->CopyFrom(watch_create_req);
stream->Write(watch_req, (void*) insertionResult.first->first.c_str());
stream->Read(&reply, (void*) insertionResult.first->first.c_str());
}
void WaitForEvent()
{
void* got_tag;
bool ok = false;
while (completionQueue.Next(&got_tag, &ok)) {
if (ok == false) {
break;
}
if (got_tag == (void*) "writes done") {
// Signal shutdown
}
else if (got_tag == (void*) "create") {
}
else if (got_tag == (void*) "write") {
}
else {
auto tag = std::string(reinterpret_cast<char*>(got_tag));
auto findIt = callbacks.find(tag);
if (findIt == callbacks.end()) {
throw std::runtime_error("Key \"" + tag + "\"not found");
}
if (reply.events_size()) {
ParseResponse(findIt->second);
}
stream->Read(&reply, got_tag);
}
}
}
void ParseResponse(Callback& callback)
{
for (int i = 0; i < reply.events_size(); ++i) {
auto event = reply.events(i);
auto key = event.kv().key();
callback(event.kv().key(), event.kv().value());
}
}
Watch::Stub watchStub;
CompletionQueue completionQueue;
ClientContext context;
std::unique_ptr<ClientAsyncReaderWriter<WatchRequest, WatchResponse>> stream;
WatchResponse reply;
std::unordered_map<std::string, Callback> callbacks;
std::thread eventPoller;
};
I'm sorry that I'm not very sure about the proper Watch design here. It's not very clear to me whether you want to create a gRPC call for each Watch.
Anyway, each gRPC call will have its own ClientContext, ClientAsyncReaderWriter. But stub and CompletionQueue is not per-call thing.
As far as I know, there is no central place to find the thread-safe classes. You may want to read the API document to have a correct expectation.
When I was writing the async server load reporting service, the only place I add synchronization myself is around CompletionQueue, so that I don't en-queue new tags to the cq if it's shut down.