trace-graph: Make zooming in on CPU plots stay filled

Currently when you zoom into a CPU plot, when there are no events in
the viewable area, the line turns blank (as if it were just idle).

This patch keeps the plot with a bar even if no events are visible.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 56 insertions, 27 deletions

diff --git a/trace-plot-cpu.c b/trace-plot-cpu.c
index d6800ef..0e7f5e8 100644
--- a/trace-plot-cpu.c
+++ b/trace-plot-cpu.c
@@ -46,15 +46,10 @@ static void convert_nano(unsigned long long time, unsigned long *sec,
         *usec = (time / 1000) % 1000000;
 }
 
-static int cpu_plot_match_time(struct graph_info *ginfo, struct graph_plot *plot,
-                               unsigned long long time)
+static struct record *get_record_from_time(struct graph_info *ginfo, int cpu,
+                                           unsigned long long time)
 {
-        struct cpu_plot_info *cpu_info = plot->private;
         struct record *record;
-        long cpu;
-        int ret = 0;
-
-        cpu = cpu_info->cpu;
 
         tracecmd_set_cpu_to_timestamp(ginfo->handle, cpu, time);
         record = tracecmd_read_data(ginfo->handle, cpu);
@@ -62,6 +57,18 @@ static int cpu_plot_match_time(struct graph_info *ginfo, struct graph_plot *plot
                 free_record(record);
                 record = tracecmd_read_data(ginfo->handle, cpu);
         }
+
+        return record;
+}
+
+static int cpu_plot_match_time(struct graph_info *ginfo, struct graph_plot *plot,
+                               unsigned long long time)
+{
+        struct cpu_plot_info *cpu_info = plot->private;
+        struct record *record;
+        int ret = 0;
+
+        record = get_record_from_time(ginfo, cpu_info->cpu, time);
         if (record && record->ts == time)
                 ret = 1;
         free_record(record);
@@ -196,13 +203,46 @@ static void cpu_plot_start(struct graph_info *ginfo, struct graph_plot *plot,
         cpu_info->last_record = NULL;
 }
 
+static void update_last_record(struct graph_info *ginfo,
+                               struct cpu_plot_info *cpu_info,
+                               struct record *record)
+{
+        struct tracecmd_input *handle = ginfo->handle;
+        struct record *trecord;
+        int filter;
+        int sched_pid;
+        int orig_pid;
+        int is_sched_switch;
+
+        if (record)
+                tracecmd_record_ref(record);
+        else
+                record = get_record_from_time(ginfo, cpu_info->cpu,
+                                              ginfo->view_end_time);
+
+        trecord = tracecmd_read_prev(handle, record);
+        free_record(record);
+
+        if (!trecord)
+                return;
+
+        filter = filter_record(ginfo, trecord,
+                               &orig_pid, &sched_pid,
+                               &is_sched_switch);
+        cpu_info->last_pid = is_sched_switch ? sched_pid : orig_pid;
+        cpu_info->last_record = trecord;
+        cpu_info->last_time = trecord->ts;
+        /* We moved the cursor, put it back */
+        trecord = tracecmd_read_data(handle, cpu_info->cpu);
+        free_record(trecord);
+}
+
 static int cpu_plot_event(struct graph_info *ginfo,
                           struct graph_plot *plot,
                           struct record *record,
                           struct plot_info *info)
 {
         struct cpu_plot_info *cpu_info = plot->private;
-        struct tracecmd_input *handle = ginfo->handle;
         int sched_pid;
         int orig_pid;
         int is_sched_switch;
@@ -215,10 +255,8 @@ static int cpu_plot_event(struct graph_info *ginfo,
         cpu = cpu_info->cpu;
 
         if (!record) {
-                if (cpu_info->last_record) {
-                        free_record(cpu_info->last_record);
-                        cpu_info->last_record = NULL;
-                }
+                if (!cpu_info->last_record)
+                        update_last_record(ginfo, cpu_info, record);
 
                 /* Finish a box if the last record was not idle */
                 if (cpu_info->last_pid > 0) {
@@ -227,6 +265,10 @@ static int cpu_plot_event(struct graph_info *ginfo,
                         info->bend = ginfo->view_end_time;
                         info->bcolor = hash_pid(cpu_info->last_pid);
                 }
+                if (cpu_info->last_record) {
+                        free_record(cpu_info->last_record);
+                        cpu_info->last_record = NULL;
+                }
                 return 0;
         }
 
@@ -234,21 +276,8 @@ static int cpu_plot_event(struct graph_info *ginfo,
          * If last record is NULL, then it may exist off the
          * viewable range. Search to see if one exists.
          */
-        if (!cpu_info->last_record) {
-                struct record *trecord;
-
-                trecord = tracecmd_read_prev(handle, record);
-                if (trecord) {
-                        filter = filter_record(ginfo, trecord,
-                                               &orig_pid, &sched_pid,
-                                               &is_sched_switch);
-                        cpu_info->last_pid = is_sched_switch ? sched_pid : orig_pid;
-                }
-                cpu_info->last_record = trecord;
-                /* We moved the cursor, put it back */
-                trecord = tracecmd_read_data(handle, record->cpu);
-                free_record(trecord);
-        }
+        if (!cpu_info->last_record)
+                update_last_record(ginfo, cpu_info, record);
 
         free_record(cpu_info->last_record);
         cpu_info->last_record = record;