Ticket #12089: UpdateShutdownLock.patch.v0

diff --git a/mythtv/libs/libmythservicecontracts/services/mythServices.h b/mythtv/libs/libmythservicecontracts/services/mythServices.h
index 373d444..d0d0018 100644
--- a/mythtv/libs/libmythservicecontracts/services/mythServices.h
+++ b/mythtv/libs/libmythservicecontracts/services/mythServices.h
@@ -43,7 +43,7 @@
 class SERVICE_PUBLIC MythServices : public Service  //, public QScriptable ???
 {
     Q_OBJECT
-    Q_CLASSINFO( "version"    , "4.0" );
+    Q_CLASSINFO( "version"    , "4.1" );
     Q_CLASSINFO( "AddStorageGroupDir_Method",    "POST" )
     Q_CLASSINFO( "RemoveStorageGroupDir_Method", "POST" )
     Q_CLASSINFO( "PutSetting_Method",            "POST" )
@@ -55,6 +55,7 @@ class SERVICE_PUBLIC MythServices : public Service  //, public QScriptable ???
     Q_CLASSINFO( "CheckDatabase_Method",         "POST" )
     Q_CLASSINFO( "ProfileSubmit_Method",         "POST" )
     Q_CLASSINFO( "ProfileDelete_Method",         "POST" )
+    Q_CLASSINFO( "UpdateShutdownLock_Method",    "POST" )
 
     public:
 
@@ -167,6 +168,8 @@ class SERVICE_PUBLIC MythServices : public Service  //, public QScriptable ???
         virtual QString             ProfileUpdated      ( void ) = 0;
 
         virtual QString             ProfileText         ( void ) = 0;
+
+        virtual int                 UpdateShutdownLock  ( int   Increment ) = 0;
 };
 
 #endif
diff --git a/mythtv/programs/mythbackend/services/myth.cpp b/mythtv/programs/mythbackend/services/myth.cpp
index 811e87c..9da02dd 100644
--- a/mythtv/programs/mythbackend/services/myth.cpp
+++ b/mythtv/programs/mythbackend/services/myth.cpp
@@ -1055,3 +1055,77 @@ QString Myth::ProfileText()
     return sProfileText;
 }
 
+/////////////////////////////////////////////////////////////////////////////
+// UpdateShutdownLock( int Increment )
+// Input:  +/- value to add to the counter, typically 1 or -1, 0 is invalid.
+// Output: -1 for all failures, otherwise the new value of the ShutdownLock.
+/////////////////////////////////////////////////////////////////////////////
+
+int Myth::UpdateShutdownLock( int Increment )
+{
+    if ( Increment == 0 )
+    {
+        LOG(VB_GENERAL, LOG_ERR, "UpdateShutdownLock API, "
+            "Error: Increment is missing or equals 0.");
+        return -1;
+    }
+
+    MSqlQuery query(MSqlQuery::InitCon());
+
+    int tries = 0;
+    while (!query.exec("LOCK TABLE settings WRITE;") && tries < 5)
+    {
+        LOG(VB_GENERAL, LOG_INFO, "UpdateShutdownLock API, "
+            "Waiting for LOCK on settings table");
+        sleep(1);
+        tries++;
+    }
+
+    if (tries >= 5)
+    {
+        LOG(VB_GENERAL, LOG_ERR,
+            "UpdateShutdownLock API, too long to LOCK settings");
+        return -1;
+    }
+
+    query.prepare("SELECT data FROM settings "
+                  "WHERE value = 'MythShutdownLock' AND hostname IS NULL;");
+    if (!query.exec() || !query.next())
+    {
+        MythDB::DBError("UpdateShutdownLock API, SELECT", query);
+        return -1;
+    }
+
+    int data = 1;
+    if (query.size() < 1)
+    {
+        query.prepare("INSERT INTO settings (value, data) "
+                      "VALUES ('MythShutdownLock', '1');");
+        if (!query.exec())
+        {
+            MythDB::DBError("UpdateShutdownLock API, INSERT", query);
+            return -1;
+        }
+    }
+    else
+    {
+        data = query.value(0).toInt();
+        data += Increment;
+        if (data < 0)
+            data = 0;
+        query.prepare("UPDATE settings SET data = :DATA "
+                      "WHERE value = 'MythShutdownLock' "
+                      "AND hostname IS NULL;");
+        query.bindValue(":DATA", QString("%1").arg(data));
+        if (!query.exec())
+        {
+            MythDB::DBError("UpdateShutdownLock API, UPDATE", query);
+            return -1;
+        }
+    }
+
+    if (!query.exec("UNLOCK TABLES;"))
+        MythDB::DBError("UpdateShutdownLock API, UNLOCK settings", query);
+
+    return data;
+}
diff --git a/mythtv/programs/mythbackend/services/myth.h b/mythtv/programs/mythbackend/services/myth.h
index cfd50aa..f889c71 100644
--- a/mythtv/programs/mythbackend/services/myth.h
+++ b/mythtv/programs/mythbackend/services/myth.h
@@ -136,6 +136,8 @@ class Myth : public MythServices
         QString             ProfileUpdated      ( void );
 
         QString             ProfileText         ( void );
+
+        int                 UpdateShutdownLock  ( int Increment );
 };
 
 // --------------------------------------------------------------------------
@@ -377,6 +379,13 @@ class ScriptableMyth : public QObject
                 return m_obj.ProfileText();
             )
         }
+
+        int UpdateShutdownLock( int Increment )
+        {
+            SCRIPT_CATCH_EXCEPTION( false,
+                return m_obj.UpdateShutdownLock( Increment );
+            )
+        }
 };
 
 Q_SCRIPT_DECLARE_QMETAOBJECT_MYTHTV( ScriptableMyth, QObject*);