debug: hold trace file open while trace is enabled

this gives a substantial increase in responsiveness during
traceon sessions compared to opening and closing the file
for every log line

curspriv.h

@@ -51,7 +51,7 @@ typedef struct           /* structure for ripped off lines */
 #define _DLCHAR    0x15  /* Delete Line char (^U) */
 
 extern WINDOW *pdc_lastscr;
-extern bool pdc_trace_on;   /* tracing flag */
+extern FILE *pdc_dbfp;   /* tracing file pointer (NULL = off) */
 extern bool pdc_color_started;
 extern unsigned long pdc_key_modifiers;
 extern MOUSE_STATUS pdc_mouse_status;
@@ -106,7 +106,7 @@ size_t  PDC_wcstombs(char *, const wchar_t *, size_t);
 #endif
 
 #ifdef PDCDEBUG
-# define PDC_LOG(x) if (pdc_trace_on) PDC_debug x
+# define PDC_LOG(x) if (pdc_dbfp) PDC_debug x
 #else
 # define PDC_LOG(x)
 #endif

pdcurses/debug.c

@@ -35,49 +35,50 @@ debug
 #include <sys/types.h>
 #include <time.h>
 
-bool pdc_trace_on = FALSE;
+FILE *pdc_dbfp = NULL;
 
 void PDC_debug(const char *fmt, ...)
 {
     va_list args;
-    FILE *dbfp;
     char hms[9];
     time_t now;
 
-    if (!pdc_trace_on)
+    if (!pdc_dbfp)
         return; 
 
-    /* open debug log file append */
-
-    dbfp = fopen("trace", "a");
-    if (!dbfp)
-    {
-        fprintf(stderr,
-            "PDC_debug(): Unable to open debug log file\n");
-        return;
-    }
-
     time(&now);
     strftime(hms, 9, "%H:%M:%S", localtime(&now));
-    fprintf(dbfp, "At: %8.8ld - %s ", (long) clock(), hms);
+    fprintf(pdc_dbfp, "At: %8.8ld - %s ", (long) clock(), hms);
 
     va_start(args, fmt);
-    vfprintf(dbfp, fmt, args);
+    vfprintf(pdc_dbfp, fmt, args);
     va_end(args);
-
-    fclose(dbfp);
 }
 
 void traceon(void)
 {
-    pdc_trace_on = TRUE;
+    if (pdc_dbfp)
+        fclose(pdc_dbfp);
+
+    /* open debug log file append */
+    pdc_dbfp = fopen("trace", "a");
+    if (!pdc_dbfp)
+    {
+        fprintf(stderr,
+            "PDC_debug(): Unable to open debug log file\n");
+        return;
+    }
 
     PDC_LOG(("traceon() - called\n"));
 }
 
 void traceoff(void)
 {
+    if (!pdc_dbfp)
+        return;
+
     PDC_LOG(("traceoff() - called\n"));
 
-    pdc_trace_on = FALSE;
+    fclose(pdc_dbfp);
+    pdc_dbfp = NULL;
 }