Apply INSERTs in Event::AddFrames in batches to avoid excessive query length

src/zm_config.h.in

@@ -45,6 +45,7 @@
 #define ZM_SCALE_BASE			100					// The factor by which we bump up 'scale' to simulate FP
 #define ZM_RATE_BASE			100					// The factor by which we bump up 'rate' to simulate FP
 
+#define ZM_SQL_BATCH_SIZE       50                  // Limit the size of multi-row SQL statements
 #define ZM_SQL_SML_BUFSIZ       256                 // Size of SQL buffer
 #define ZM_SQL_MED_BUFSIZ       1024                // Size of SQL buffer
 #define ZM_SQL_LGE_BUFSIZ       8192                // Size of SQL buffer

src/zm_event.cpp

@@ -489,11 +489,18 @@ void Event::updateNotes( const StringSetMap &newNoteSetMap )
 }
 
 void Event::AddFrames( int n_frames, Image **images, struct timeval **timestamps )
+{
+    for (int i = 0; i < n_frames; i += ZM_SQL_BATCH_SIZE) {
+        AddFramesInternal(n_frames, i, images, timestamps);
+    }
+}
+
+void Event::AddFramesInternal( int n_frames, int start_frame, Image **images, struct timeval **timestamps )
 {
     static char sql[ZM_SQL_LGE_BUFSIZ];
     strncpy( sql, "insert into Frames ( EventId, FrameId, TimeStamp, Delta ) values ", sizeof(sql) );
     int frameCount = 0;
-    for ( int i = 0; i < n_frames; i++ )
+    for ( int i = start_frame; i < n_frames && i - start_frame < ZM_SQL_BATCH_SIZE; i++ )
     {
         if ( !timestamps[i]->tv_sec )
         {

src/zm_event.h

@@ -133,6 +133,9 @@ public:
 	void AddFrames( int n_frames, Image **images, struct timeval **timestamps );
 	void AddFrame( Image *image, struct timeval timestamp, int score=0, Image *alarm_frame=NULL );
 
+private:
+	void AddFramesInternal( int n_frames, int start_frame, Image **images, struct timeval **timestamps );
+
 public:
     static const char *getSubPath( struct tm *time )
     {