[ovs-dev] [RFC 2/3] coverage: Add command for reading counter value

[Jakub Sitnicki]

Facilitate checking coverage counters from scripts and tests by
providing new "coverage/read-count" command that returns the value of a
given counter.

Same could be achieved by scraping the output of "coverage/show" command
but the difficulties there are that output is in human readable format
and zero-value counters are not included.

Signed-off-by: Jakub Sitnicki <jkbs at redhat.com>
---
 lib/coverage.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/lib/coverage.c b/lib/coverage.c
index 6cef82614..4aa283be8 100644
--- a/lib/coverage.c
+++ b/lib/coverage.c
@@ -44,6 +44,8 @@ static unsigned int idx_count = 0;
 static void coverage_read(struct svec *);
 static unsigned int coverage_array_sum(const unsigned int *arr,
                                        const unsigned int len);
+static bool coverage_get_count(const char *counter_name,
+                               unsigned long long int *count);

 /* Registers a coverage counter with the coverage core */
 void
@@ -72,11 +74,32 @@ coverage_unixctl_show(struct unixctl_conn *conn, int argc OVS_UNUSED,
     svec_destroy(&lines);
 }

+static void
+coverage_unixctl_read_count(struct unixctl_conn *conn, int argc OVS_UNUSED,
+                            const char *argv[], void *aux OVS_UNUSED)
+{
+    unsigned long long count;
+    char *reply;
+    bool ok;
+
+    ok = coverage_get_count(argv[1], &count);
+    if (!ok) {
+        unixctl_command_reply_error(conn, "No such counter");
+        return;
+    }
+
+    reply = xasprintf("%llu\n", count);
+    unixctl_command_reply(conn, reply);
+    free(reply);
+}
+
 void
 coverage_init(void)
 {
     unixctl_command_register("coverage/show", "", 0, 0,
                              coverage_unixctl_show, NULL);
+    unixctl_command_register("coverage/read-count", "COUNTER", 1, 1,
+                             coverage_unixctl_read_count, NULL);
 }

 /* Sorts coverage counters in descending order by total, within equal
@@ -372,3 +395,21 @@ coverage_array_sum(const unsigned int *arr, const unsigned int len)
     ovs_mutex_unlock(&coverage_mutex);
     return sum;
 }
+
+static bool
+coverage_get_count(const char *counter_name, unsigned long long int *count)
+{
+    for (size_t i = 0; i < n_coverage_counters; i++) {
+        struct coverage_counter *counter = coverage_counters[i];
+
+        if (!strcmp(counter->name, counter_name)) {
+            ovs_mutex_lock(&coverage_mutex);
+            *count = counter->total;
+            ovs_mutex_unlock(&coverage_mutex);
+
+            return true;
+        }
+    }
+
+    return false;
+}
--
2.14.3