trace: separate trace event control and query routines from the simple backend

Generalize the 'st_print_trace_events' and 'st_change_trace_event_state' into
backend-specific 'trace_print_events' and 'trace_event_set_state' (respectively)
in the "trace/control.h" file.

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>

hmp-commands.hx

@@ -186,7 +186,7 @@ ETEXI
         .args_type  = "name:s,option:b",
         .params     = "name on|off",
         .help       = "changes status of a specific trace event",
-        .mhandler.cmd = do_change_trace_event_state,
+        .mhandler.cmd = do_trace_event_set_state,
     },
 
 STEXI

monitor.c

@@ -60,6 +60,7 @@
 #ifdef CONFIG_TRACE_SIMPLE
 #include "trace.h"
 #endif
+#include "trace/control.h"
 #include "ui/qemu-spice.h"
 
 //#define DEBUG
@@ -593,11 +594,11 @@ static void do_help_cmd(Monitor *mon, const QDict *qdict)
 }
 
 #ifdef CONFIG_TRACE_SIMPLE
-static void do_change_trace_event_state(Monitor *mon, const QDict *qdict)
+static void do_trace_event_set_state(Monitor *mon, const QDict *qdict)
 {
     const char *tp_name = qdict_get_str(qdict, "name");
     bool new_state = qdict_get_bool(qdict, "option");
-    int ret = st_change_trace_event_state(tp_name, new_state);
+    int ret = trace_event_set_state(tp_name, new_state);
 
     if (!ret) {
         monitor_printf(mon, "unknown event name \"%s\"\n", tp_name);
@@ -1002,9 +1003,9 @@ static void do_info_trace(Monitor *mon)
     st_print_trace((FILE *)mon, &monitor_fprintf);
 }
 
-static void do_info_trace_events(Monitor *mon)
+static void do_trace_print_events(Monitor *mon)
 {
-    st_print_trace_events((FILE *)mon, &monitor_fprintf);
+    trace_print_events((FILE *)mon, &monitor_fprintf);
 }
 #endif
 
@@ -3148,7 +3149,7 @@ static const mon_cmd_t info_cmds[] = {
         .args_type  = "",
         .params     = "",
         .help       = "show available trace-events & their state",
-        .mhandler.info = do_info_trace_events,
+        .mhandler.info = do_trace_print_events,
     },
 #endif
     {

trace/control.h

@@ -10,7 +10,16 @@
 #ifndef TRACE_CONTROL_H
 #define TRACE_CONTROL_H
 
-#include <stdbool.h>
+#include "qemu-common.h"
+
+
+/** Print the state of all events. */
+void trace_print_events(FILE *stream, fprintf_function stream_printf);
+/** Set the state of an event.
+ *
+ * @return Whether the state changed.
+ */
+bool trace_event_set_state(const char *name, bool state);
 
 
 /** Initialize the tracing backend.

trace/default.c

@@ -10,6 +10,21 @@
 #include "trace/control.h"
 
 
+void trace_print_events(FILE *stream, fprintf_function stream_printf)
+{
+    fprintf(stderr, "warning: "
+            "cannot print the trace events with the current backend\n");
+    stream_printf(stream, "error: "
+                  "operation not supported with the current backend\n");
+}
+
+bool trace_event_set_state(const char *name, bool state)
+{
+    fprintf(stderr, "warning: "
+            "cannot set the state of a trace event with the current backend\n");
+    return false;
+}
+
 bool trace_backend_init(const char *file)
 {
     if (file) {

trace/simple.c

@@ -303,7 +303,12 @@ void st_print_trace(FILE *stream, int (*stream_printf)(FILE *stream, const char
     }
 }
 
-void st_print_trace_events(FILE *stream, int (*stream_printf)(FILE *stream, const char *fmt, ...))
+void st_flush_trace_buffer(void)
+{
+    flush_trace_file(true);
+}
+
+void trace_print_events(FILE *stream, fprintf_function stream_printf)
 {
     unsigned int i;
 
@@ -313,24 +318,19 @@ void st_print_trace_events(FILE *stream, int (*stream_printf)(FILE *stream, cons
     }
 }
 
-bool st_change_trace_event_state(const char *name, bool enabled)
+bool trace_event_set_state(const char *name, bool state)
 {
     unsigned int i;
 
     for (i = 0; i < NR_TRACE_EVENTS; i++) {
         if (!strcmp(trace_list[i].tp_name, name)) {
-            trace_list[i].state = enabled;
+            trace_list[i].state = state;
             return true;
         }
     }
     return false;
 }
 
-void st_flush_trace_buffer(void)
-{
-    flush_trace_file(true);
-}
-
 bool trace_backend_init(const char *file)
 {
     pthread_t thread;

trace/simple.h

@@ -30,8 +30,6 @@ void trace4(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t
 void trace5(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5);
 void trace6(TraceEventID event, uint64_t x1, uint64_t x2, uint64_t x3, uint64_t x4, uint64_t x5, uint64_t x6);
 void st_print_trace(FILE *stream, fprintf_function stream_printf);
-void st_print_trace_events(FILE *stream, fprintf_function stream_printf);
-bool st_change_trace_event_state(const char *tname, bool tstate);
 void st_print_trace_file_status(FILE *stream, fprintf_function stream_printf);
 void st_set_trace_file_enabled(bool enable);
 bool st_set_trace_file(const char *file);