SERVER-4739 use a thread for logRotate signal instead of a signal handler

Conflicts:
	src/mongo/db/db.cpp
	src/mongo/s/server.cpp

5 files changed, 64 insertions, 25 deletions

diff --git a/src/mongo/db/db.cpp b/src/mongo/db/db.cpp
index 12037d0b6a8..def2e459c70 100644
--- a/src/mongo/db/db.cpp
+++ b/src/mongo/db/db.cpp
@@ -80,8 +80,8 @@ namespace mongo {
     extern string repairpath;
 
     static void setupSignalHandlers();
-    static void startInterruptThread();
     void startReplication();
+    static void startSignalProcessingThread();
     void exitCleanly( ExitCode code );
 
 #ifdef _WIN32
@@ -1280,9 +1280,9 @@ static int mongoDbMain(int argc, char* argv[], char **envp) {
     if (!initializeServerGlobalState())
         ::_exit(EXIT_FAILURE);
 
-    // Per SERVER-7434, startInterruptThread() must run after any forks
+    // Per SERVER-7434, startSignalProcessingThread() must run after any forks
     // (initializeServerGlobalState()) and before creation of any other threads.
-    startInterruptThread();
+    startSignalProcessingThread();
 
     dataFileSync.go();
 
@@ -1350,15 +1350,27 @@ namespace mongo {
     }
 
     sigset_t asyncSignals;
-    // The above signals will be processed by this thread only, in order to
+    // The signals in asyncSignals will be processed by this thread only, in order to
     // ensure the db and log mutexes aren't held.
-    void interruptThread() {
-        int actualSignal;
-        sigwait( &asyncSignals, &actualSignal );
-        log() << "got signal " << actualSignal << " (" << strsignal( actualSignal )
-              << "), will terminate after current cmd ends" << endl;
-        Client::initThread( "interruptThread" );
-        exitCleanly( EXIT_CLEAN );
+    void signalProcessingThread() {
+        while (true) {
+            int actualSignal = 0;
+            int status = sigwait( &asyncSignals, &actualSignal );
+            fassert(16781, status == 0);
+            switch (actualSignal) {
+            case SIGUSR1:
+                // log rotate signal
+                fassert(16782, rotateLogs());
+                break;
+            default:
+                // interrupt/terminate signal
+                Client::initThread( "signalProcessingThread" );
+                log() << "got signal " << actualSignal << " (" << strsignal( actualSignal )
+                      << "), will terminate after current cmd ends" << endl;
+                exitCleanly( EXIT_CLEAN );
+                break;
+            }
+        }
     }
 
     // this will be called in certain c++ error cases, for example if there are two active
@@ -1399,19 +1411,20 @@ namespace mongo {
         setupSIGTRAPforGDB();
 
         // asyncSignals is a global variable listing the signals that should be handled by the
-        // interrupt thread, once it is started via startInterruptThread().
+        // interrupt thread, once it is started via startSignalProcessingThread().
         sigemptyset( &asyncSignals );
         sigaddset( &asyncSignals, SIGHUP );
         sigaddset( &asyncSignals, SIGINT );
         sigaddset( &asyncSignals, SIGTERM );
+        sigaddset( &asyncSignals, SIGUSR1 );
 
         set_terminate( myterminate );
         set_new_handler( my_new_handler );
     }
 
-    void startInterruptThread() {
+    void startSignalProcessingThread() {
         verify( pthread_sigmask( SIG_SETMASK, &asyncSignals, 0 ) == 0 );
-        boost::thread it( interruptThread );
+        boost::thread it( signalProcessingThread );
     }
 
 #else   // WIN32
@@ -1486,7 +1499,7 @@ namespace mongo {
         _set_purecall_handler( myPurecallHandler );
     }
 
-    void startInterruptThread() {}
+    void startSignalProcessingThread() {}
 
 #endif  // if !defined(_WIN32)
 
diff --git a/src/mongo/db/dbcommands_generic.cpp b/src/mongo/db/dbcommands_generic.cpp
index 7b8070d6fac..e4528e605ae 100644
--- a/src/mongo/db/dbcommands_generic.cpp
+++ b/src/mongo/db/dbcommands_generic.cpp
@@ -230,8 +230,7 @@ namespace mongo {
             out->push_back(Privilege(AuthorizationManager::SERVER_RESOURCE_NAME, actions));
         }
         virtual bool run(const string& ns, BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
-            fassert(16175, rotateLogs());
-            return 1;
+            return rotateLogs();
         }
 
     } logRotateCmd;
diff --git a/src/mongo/db/initialize_server_global_state.cpp b/src/mongo/db/initialize_server_global_state.cpp
index 120a733d10d..f439c9e8a79 100644
--- a/src/mongo/db/initialize_server_global_state.cpp
+++ b/src/mongo/db/initialize_server_global_state.cpp
@@ -193,14 +193,10 @@ namespace mongo {
 
     static void ignoreSignal( int sig ) {}
 
-    static void rotateLogsOrDie(int sig) {
-        fassert(16176, rotateLogs());
-    }
-
     void setupCoreSignals() {
 #if !defined(_WIN32)
-        verify( signal(SIGUSR1 , rotateLogsOrDie ) != SIG_ERR );
         verify( signal(SIGHUP , ignoreSignal ) != SIG_ERR );
+        verify( signal(SIGUSR2, ignoreSignal ) != SIG_ERR );
 #endif
     }
 
diff --git a/src/mongo/s/server.cpp b/src/mongo/s/server.cpp
index f7e647662f9..165bf7a7ef7 100644
--- a/src/mongo/s/server.cpp
+++ b/src/mongo/s/server.cpp
@@ -163,6 +163,33 @@ namespace mongo {
         ::_exit(EXIT_ABRUPT);
     }
 
+    sigset_t asyncSignals;
+
+    void signalProcessingThread() {
+        while (true) {
+            int actualSignal = 0;
+            int status = sigwait( &asyncSignals, &actualSignal );
+            fassert(16779, status == 0);
+            switch (actualSignal) {
+            case SIGUSR1:
+                // log rotate signal
+                fassert(16780, rotateLogs());
+                break;
+            default:
+                // no one else should be here
+                fassertFailed(16778);
+                break;
+            }
+        }
+    }
+
+    void startSignalProcessingThread() {
+#ifndef _WIN32
+        verify( pthread_sigmask( SIG_SETMASK, &asyncSignals, 0 ) == 0 );
+        boost::thread it( signalProcessingThread );
+#endif
+    }
+
     void setupSignalHandlers() {
         setupSIGTRAPforGDB();
         setupCoreSignals();
@@ -183,6 +210,10 @@ namespace mongo {
         signal( SIGPIPE , SIG_IGN );
 #endif
 
+        sigemptyset( &asyncSignals );
+        sigaddset( &asyncSignals, SIGUSR1 );
+        startSignalProcessingThread();
+
         setWindowsUnhandledExceptionFilter();
         set_new_handler( my_new_handler );
     }
diff --git a/src/mongo/util/log.cpp b/src/mongo/util/log.cpp
index f69ffbd5450..00845d07da1 100644
--- a/src/mongo/util/log.cpp
+++ b/src/mongo/util/log.cpp
@@ -141,7 +141,7 @@ namespace mongo {
 
         bool rotate() {
             if ( ! _enabled ) {
-                cout << "LoggingManager not enabled" << endl;
+                cout << "logRotate is not possible: loggingManager not enabled" << endl;
                 return true;
             }
 
@@ -156,7 +156,7 @@ namespace mongo {
                 ss << _path << "." << terseCurrentTime( false );
                 string s = ss.str();
                 if (0 != rename(_path.c_str(), s.c_str())) {
-                    error() << "Failed to rename '" << _path
+                    error() << "failed to rename '" << _path
                             << "' to '" << s
                             << "': " << errnoWithDescription() << endl;
                     return false;
@@ -187,7 +187,7 @@ namespace mongo {
             tmp = freopen(_path.c_str(), _append ? "a" : "w", stdout);
 #endif
             if ( !tmp ) {
-                cerr << "can't open: " << _path.c_str() << " for log file" << endl;
+                error() << "can't open: " << _path.c_str() << " for log file" << endl;
                 return false;
             }