Make SignalHandler a singleton.

There can only be one SignalHandler object per application. This allows AddHandler to be a static method so it can be used outside the main initialization. Since AddHandler doesn't actually chain handlers as suggested by it's name this also renames the method to SetHandler. This also adds a lock for m_sigMap so we can call SetHandler in a thread other than the main thread. Finally, this allows a handler to be added for SIGINT and SIGKILL.
MythTV · Jul 30, 2012 · f3fb6f0 · f3fb6f0
1 parent 292323d
commit f3fb6f0
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Showing 20 changed files with 147 additions and 41 deletions.
diff --git a/mythtv/libs/libmythbase/signalhandling.cpp b/mythtv/libs/libmythbase/signalhandling.cpp
@@ -22,6 +22,8 @@ using namespace std;
 
 int SignalHandler::sigFd[2];
 volatile bool SignalHandler::s_exit_program = false;
+QMutex SignalHandler::s_singletonLock;
+SignalHandler *SignalHandler::s_singleton;
 
 // We may need to write out signal info using just the write() function
 // so we create an array of C strings + measure their lengths.
@@ -87,13 +89,15 @@ SignalHandler::SignalHandler(QList<int> &signallist, QObject *parent) :
             continue;
         }
 
-        AddHandler(signum, NULL);
+        SetHandlerPrivate(signum, NULL);
     }
 #endif
 }
 
 SignalHandler::~SignalHandler()
 {
+    s_singleton = NULL;
+
 #ifndef _WIN32
     if (m_notifier)
     {
@@ -102,6 +106,7 @@ SignalHandler::~SignalHandler()
         delete m_notifier;
     }
 
+    QMutexLocker locker(&m_sigMapLock);
     QMap<int, void (*)(void)>::iterator it = m_sigMap.begin();
     for ( ; it != m_sigMap.end(); ++it)
     {
@@ -113,23 +118,61 @@ SignalHandler::~SignalHandler()
 #endif
 }
 
-void SignalHandler::AddHandler(int signum, void (*handler)(void))
+void SignalHandler::Init(QList<int> &signallist, QObject *parent)
 {
-#ifndef _WIN32
-    struct sigaction sa;
-    sa.sa_handler = SignalHandler::signalHandler;
-    sigemptyset(&sa.sa_mask);
-    sa.sa_flags = SA_RESTART;
+    QMutexLocker locker(&s_singletonLock);
+    if (!s_singleton)
+        s_singleton = new SignalHandler(signallist, parent);
+}
+
+void SignalHandler::Done(void)
+{
+    QMutexLocker locker(&s_singletonLock);
+    if (s_singleton)
+        delete s_singleton;
+}
+
 
+void SignalHandler::SetHandler(int signum, void (*handler)(void))
+{
+    QMutexLocker locker(&s_singletonLock);
+    if (s_singleton)
+        s_singleton->SetHandlerPrivate(signum, handler);
+}
+
+void SignalHandler::SetHandlerPrivate(int signum, void (*handler)(void))
+{
+#ifndef _WIN32
     const char *signame = strsignal(signum);
-    signame = strdup(signame ? signame : "Unknown");
+    QString signal_name = signame ?
+        QString(signame) : QString("Unknown(%1)").arg(signum);
+
+    bool sa_handler_already_set = false;
+    {
+        QMutexLocker locker(&m_sigMapLock);
+        sa_handler_already_set = m_sigMap.contains(signum);
+        if (m_sigMap.value(signum, NULL) && (handler != NULL))
+        {
+            LOG(VB_GENERAL, LOG_WARNING, 
+                QString("Warning %1 signal handler overridden")
+                .arg(signal_name));
+        }
+        m_sigMap[signum] = handler;
+    }
 
-    sig_str_init(signum, signame);
-    sigaction(signum, &sa, NULL);
-    m_sigMap.insert(signum, handler);
-    LOG(VB_GENERAL, LOG_INFO, QString("Setup %1 handler").arg(signame));
+    if (!sa_handler_already_set)
+    {
+        struct sigaction sa;
+        sa.sa_handler = SignalHandler::signalHandler;
+        sigemptyset(&sa.sa_mask);
+        sa.sa_flags = SA_RESTART;
 
-    free((void *)signame);
+        sig_str_init(signum, qPrintable(signal_name));
+
+        sigaction(signum, &sa, NULL);
+    }
+
+    LOG(VB_GENERAL, LOG_INFO, QString("Setup %1 handler").arg(signal_name));
 #endif
 }
 
@@ -204,11 +247,20 @@ void SignalHandler::handleSignal(void)
     LOG(VB_GENERAL, LOG_CRIT, QString("Received %1").arg(signame));
     free((void *)signame);
 
+    void (*handler)(void) = NULL;
+
     switch (signum)
     {
     case SIGINT:
     case SIGTERM:
-        qApp->quit();
+        m_sigMapLock.lock();
+        handler = m_sigMap.value(signum, NULL);
+        m_sigMapLock.unlock();
+
+        if (handler)
+            handler();
+        else
+            QCoreApplication::exit(0);
         s_exit_program = true;
         break;
     case SIGSEGV:
@@ -220,7 +272,9 @@ void SignalHandler::handleSignal(void)
         s_exit_program = true;
         break;
     default:
-        void (*handler)(void) = m_sigMap.value(signum, NULL);
+        m_sigMapLock.lock();
+        handler = m_sigMap.value(signum, NULL);
+        m_sigMapLock.unlock();
         if (handler)
         {
             handler();

diff --git a/mythtv/libs/libmythbase/signalhandling.h b/mythtv/libs/libmythbase/signalhandling.h
@@ -3,6 +3,7 @@
 
 #include <QObject>
 #include <QSocketNotifier>
+#include <QMutex>
 #include <QList>
 #include <QMap>
 
@@ -19,10 +20,10 @@ class MBASE_PUBLIC SignalHandler: public QObject
     Q_OBJECT
 
   public:
-    SignalHandler(QList<int> &signallist, QObject *parent = NULL);
-    ~SignalHandler();
+    static void Init(QList<int> &signallist, QObject *parent = NULL);
+    static void Done(void);
 
-    void AddHandler(int signal, void (*handler)(void));
+    static void SetHandler(int signal, void (*handler)(void));
 
     static bool IsExiting(void) { return s_exit_program; }
 
@@ -34,12 +35,20 @@ class MBASE_PUBLIC SignalHandler: public QObject
     void handleSignal(void);
 
   private:
+    SignalHandler(QList<int> &signallist, QObject *parent);
+    ~SignalHandler();
+    void SetHandlerPrivate(int signal, void (*handler)(void));
+
     static int sigFd[2];
     static volatile bool s_exit_program;
     QSocketNotifier *m_notifier;
 
+    QMutex m_sigMapLock;
     QMap<int, void (*)(void)> m_sigMap;
     static QList<int> s_defaultHandlerList;
+
+    static QMutex s_singletonLock;
+    static SignalHandler *s_singleton;
 };
 
 #endif

diff --git a/mythtv/programs/mythavtest/main.cpp b/mythtv/programs/mythavtest/main.cpp
@@ -225,6 +225,14 @@ int main(int argc, char *argv[])
     MythMainWindow *mainWindow = GetMythMainWindow();
     mainWindow->Init();
 
+#ifndef _WIN32
+    QList<int> signallist;
+    signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
+               << SIGILL;
+    SignalHandler::Init(signallist);
+    signal(SIGHUP, SIG_IGN);
+#endif
+
     if (cmdline.toBool("test"))
     {
         int seconds = 5;
@@ -261,6 +269,8 @@ int main(int argc, char *argv[])
 
     delete gContext;
 
+    SignalHandler::Done();
+
     return GENERIC_EXIT_OK;
 }
 

diff --git a/mythtv/programs/mythbackend/main.cpp b/mythtv/programs/mythbackend/main.cpp
@@ -104,7 +104,7 @@ int main(int argc, char **argv)
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
+    SignalHandler::Init(signallist);
     signal(SIGHUP, SIG_IGN);
 #endif
 

diff --git a/mythtv/programs/mythbackend/main_helpers.cpp b/mythtv/programs/mythbackend/main_helpers.cpp
@@ -50,6 +50,7 @@
 #include "backendcontext.h"
 #include "mythtranslation.h"
 #include "mythtimezone.h"
+#include "signalhandling.h"
 
 #include "mediaserver.h"
 #include "httpstatus.h"
@@ -268,6 +269,8 @@ void cleanup(void)
         unlink(pidfile.toAscii().constData());
         pidfile.clear();
     }
+
+    SignalHandler::Done();
 }
 
 int handle_command(const MythBackendCommandLineParser &cmdline)

diff --git a/mythtv/programs/mythccextractor/main.cpp b/mythtv/programs/mythccextractor/main.cpp
@@ -25,6 +25,7 @@ namespace {
     {
         delete gContext;
         gContext = NULL;
+        SignalHandler::Done();
     }
 
     class CleanupGuard
@@ -145,7 +146,7 @@ int main(int argc, char *argv[])
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
+    SignalHandler::Init(signallist);
     signal(SIGHUP, SIG_IGN);
 #endif
 

diff --git a/mythtv/programs/mythcommflag/main.cpp b/mythtv/programs/mythcommflag/main.cpp
@@ -57,7 +57,7 @@ namespace
     {
         delete gContext;
         gContext = NULL;
-
+        SignalHandler::Done();
     }
 
     class CleanupGuard
@@ -1127,7 +1127,7 @@ int main(int argc, char *argv[])
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
+    SignalHandler::Init(signallist);
     signal(SIGHUP, SIG_IGN);
 #endif
 

diff --git a/mythtv/programs/mythfilldatabase/main.cpp b/mythtv/programs/mythfilldatabase/main.cpp
@@ -38,7 +38,7 @@ namespace
     {
         delete gContext;
         gContext = NULL;
-
+        SignalHandler::Done();
     }
 
     class CleanupGuard
@@ -349,7 +349,7 @@ int main(int argc, char *argv[])
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
+    SignalHandler::Init(signallist);
     signal(SIGHUP, SIG_IGN);
 #endif
 

diff --git a/mythtv/programs/mythfrontend/main.cpp b/mythtv/programs/mythfrontend/main.cpp
@@ -267,6 +267,8 @@ namespace
         ReferenceCounter::PrintDebug();
 
         delete qApp;
+
+        SignalHandler::Done();
     }
 
     class CleanupGuard
@@ -1477,9 +1479,9 @@ int main(int argc, char **argv)
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
-    handler.AddHandler(SIGUSR1, handleSIGUSR1);
-    handler.AddHandler(SIGUSR2, handleSIGUSR2);
+    SignalHandler::Init(signallist);
+    SignalHandler::SetHandler(SIGUSR1, handleSIGUSR1);
+    SignalHandler::SetHandler(SIGUSR2, handleSIGUSR2);
     signal(SIGHUP, SIG_IGN);
 #endif
 

diff --git a/mythtv/programs/mythjobqueue/main.cpp b/mythtv/programs/mythjobqueue/main.cpp
@@ -50,6 +50,8 @@ static void cleanup(void)
         unlink(pidfile.toAscii().constData());
         pidfile.clear();
     }
+
+    SignalHandler::Done();
 }
 
 namespace
@@ -112,7 +114,7 @@ int main(int argc, char *argv[])
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
+    SignalHandler::Init(signallist);
     signal(SIGHUP, SIG_IGN);
 #endif
 

diff --git a/mythtv/programs/mythlcdserver/main.cpp b/mythtv/programs/mythlcdserver/main.cpp
@@ -101,7 +101,7 @@ int main(int argc, char **argv)
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
+    SignalHandler::Init(signallist);
     signal(SIGHUP, SIG_IGN);
 #endif
 
@@ -111,6 +111,7 @@ int main(int argc, char **argv)
     {
         LOG(VB_GENERAL, LOG_ERR,
             "lcdserver: Could not initialize MythContext. Exiting.");
+        SignalHandler::Done();
         return GENERIC_EXIT_NO_MYTHCONTEXT;
     }
 
@@ -130,6 +131,9 @@ int main(int argc, char **argv)
     a.exec();
 
     delete gContext;
+
+    SignalHandler::Done();
+
     return GENERIC_EXIT_OK;
 }
 
diff --git a/mythtv/programs/mythlogserver/main.cpp b/mythtv/programs/mythlogserver/main.cpp
@@ -106,8 +106,8 @@ int main(int argc, char *argv[])
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
-    handler.AddHandler(SIGHUP, logSigHup);
+    SignalHandler::Init(signallist);
+    SignalHandler::SetHandler(SIGHUP, logSigHup);
 #endif
 
     gContext = new MythContext(MYTH_BINARY_VERSION);
@@ -119,6 +119,8 @@ int main(int argc, char *argv[])
 
     qApp->exec();
 
+    SignalHandler::Done();
+
     return GENERIC_EXIT_OK;
 }
 

diff --git a/mythtv/programs/mythmediaserver/main.cpp b/mythtv/programs/mythmediaserver/main.cpp
@@ -48,6 +48,8 @@ static void cleanup(void)
         unlink(pidfile.toAscii().constData());
         pidfile.clear();
     }
+
+    SignalHandler::Done();
 }
 
 namespace
@@ -110,7 +112,7 @@ int main(int argc, char *argv[])
     QList<int> signallist;
     signallist << SIGINT << SIGTERM << SIGSEGV << SIGABRT << SIGBUS << SIGFPE
                << SIGILL;
-    SignalHandler handler(signallist);
+    SignalHandler::Init(signallist);
     signal(SIGHUP, SIG_IGN);
 #endif