trace-graph: Fix plots to show start bars in zoomed views.

Currently, if a zoomed view has events before the start of the view,
those events are not examined to determine if the bar of a graph should
be shown at the start.

This patch adds code to the cpu and task plots to look for events
that happened before the view to determine if a bar should be shown
or not.

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

1 files changed, 32 insertions, 0 deletions

diff --git a/trace-plot-cpu.c b/trace-plot-cpu.c
index 09b1690..d6800ef 100644
--- a/trace-plot-cpu.c
+++ b/trace-plot-cpu.c
@@ -27,6 +27,7 @@ struct cpu_plot_info {
         int                     cpu;
         unsigned long long      last_time;
         int                     last_pid;
+        struct record           *last_record;
 };
 
 static gint hash_pid(gint val)
@@ -192,6 +193,7 @@ static void cpu_plot_start(struct graph_info *ginfo, struct graph_plot *plot,
         cpu = cpu_info->cpu;
         cpu_info->last_time = 0ULL;
         cpu_info->last_pid = -1;
+        cpu_info->last_record = NULL;
 }
 
 static int cpu_plot_event(struct graph_info *ginfo,
@@ -200,6 +202,7 @@ static int cpu_plot_event(struct graph_info *ginfo,
                           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;
@@ -212,6 +215,11 @@ 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;
+                }
+
                 /* Finish a box if the last record was not idle */
                 if (cpu_info->last_pid > 0) {
                         info->box = TRUE;
@@ -222,6 +230,30 @@ static int cpu_plot_event(struct graph_info *ginfo,
                 return 0;
         }
 
+        /*
+         * 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);
+        }
+
+        free_record(cpu_info->last_record);
+        cpu_info->last_record = record;
+        tracecmd_record_ref(record);
+
         cpu = cpu_info->cpu;
 
         filter = filter_record(ginfo, record, &orig_pid, &sched_pid, &is_sched_switch);