Buffered log-callback.

Allow a particular set of log messages to be retained indefinitely, for (presumably) later display somehow, such as in the GUI.

simgear/debug/logstream.cxx

@@ -27,6 +27,7 @@
 
 #include <boost/foreach.hpp>
 
+#include <simgear/sg_inlines.h>
 #include <simgear/threads/SGThread.hxx>
 #include <simgear/threads/SGQueue.hxx>
 #include <simgear/threads/SGGuard.hxx>
@@ -112,7 +113,55 @@ public:
 private:
     
 };
+
+namespace simgear
+{
+ 
+class BufferedLogCallback::BufferedLogCallbackPrivate
+{
+public:
+    SGMutex m_mutex;
+    sgDebugClass m_class;
+    sgDebugPriority m_priority;
+    string_list m_buffer;
+};
    
+BufferedLogCallback::BufferedLogCallback(sgDebugClass c, sgDebugPriority p) :
+    d(new BufferedLogCallbackPrivate)
+{
+    d->m_class = c;
+    d->m_priority = p;
+}
+
+BufferedLogCallback::~BufferedLogCallback()
+{
+}
+ 
+void BufferedLogCallback::operator()(sgDebugClass c, sgDebugPriority p, 
+        const char* file, int line, const std::string& aMessage)
+{
+    SG_UNUSED(file);
+    SG_UNUSED(line);
+    
+    if ((c & d->m_class) == 0 || p < d->m_priority) return;
+    
+    SGGuard<SGMutex> g(d->m_mutex);
+    d->m_buffer.push_back(aMessage);
+}
+ 
+void BufferedLogCallback::threadsafeCopy(string_list& aOutput)
+{
+    aOutput.clear();
+    SGGuard<SGMutex> g(d->m_mutex);
+    size_t sz = d->m_buffer.size();
+    aOutput.resize(sz);
+    for (unsigned int i=0; i<sz; ++i) {
+        aOutput[i] = d->m_buffer[i];
+    }
+} 
+
+} // of namespace simgear
+
 class LogStreamPrivate : public SGThread
 {
 private: