trace-cmd: Add ability to add new comms after first use

To speed up the reading of cmdlines to pid mappings, an unsorted list
is used first to register comms (cmdlines). Once the list is
used to seach, the list is converted to a sorted array to allow
for fast binary searches. But once this was done, there was no way
to add more cmdlines mappings.

This now adds a slower version to add new cmdlines after the list
has been made, but still makes it possible.

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

1 files changed, 43 insertions, 1 deletions

diff --git a/parse-events.c b/parse-events.c
index 424b367..818be40 100644
--- a/parse-events.c
+++ b/parse-events.c
@@ -135,7 +135,6 @@ int pevent_pid_is_registered(struct pevent *pevent, int pid)
         if (!pid)
                 return 1;
 
-
         if (!pevent->cmdlines)
                 cmdline_init(pevent);
 
@@ -149,6 +148,46 @@ int pevent_pid_is_registered(struct pevent *pevent, int pid)
         return 0;
 }
 
+/*
+ * If the command lines have been converted to an array, then
+ * we must add this pid. This is much slower than when cmdlines
+ * are added before the array is initialized.
+ */
+static int add_new_comm(struct pevent *pevent, char *comm, int pid)
+{
+        struct cmdline *cmdlines = pevent->cmdlines;
+        const struct cmdline *cmdline;
+        struct cmdline key;
+
+        if (!pid)
+                return 0;
+
+        /* avoid duplicates */
+        key.pid = pid;
+
+        cmdline = bsearch(&key, pevent->cmdlines, pevent->cmdline_count,
+                       sizeof(*pevent->cmdlines), cmdline_cmp);
+        if (cmdline) {
+                errno = EEXIST;
+                return -1;
+        }
+
+        cmdlines = realloc(cmdlines, sizeof(*cmdlines) * (pevent->cmdline_count + 1));
+        if (!cmdlines) {
+                errno = ENOMEM;
+                return -1;
+        }
+
+        cmdlines[pevent->cmdline_count].pid = pid;
+        cmdlines[pevent->cmdline_count].comm = comm;
+        pevent->cmdline_count++;
+
+        qsort(cmdlines, pevent->cmdline_count, sizeof(*cmdlines), cmdline_cmp);
+        pevent->cmdlines = cmdlines;
+
+        return 0;
+}
+
 /**
  * pevent_register_comm - register a pid / comm mapping
  * @pevent: handle for the pevent
@@ -163,6 +202,9 @@ int pevent_register_comm(struct pevent *pevent, char *comm, int pid)
 {
         struct cmdline_list *item;
 
+        if (pevent->cmdlines)
+                return add_new_comm(pevent, comm, pid);
+
         item = malloc_or_die(sizeof(*item));
         item->comm = comm;
         item->pid = pid;