SYSDB: Add systemtap probes to track sysdb transactions

Actually adds marks for sysdb transactions that receive the transaction
nesting level as an argument. The nesting is passed on from probes to
marks along with a human-friendly description.

The transaction commit is decorated with two probes, before and after.
This would allow the caller to distinguish between the time we spend in
the transaction (which might be important, because if a transaction is
active on an ldb context, even the readers are blocked before the
transaction completes) and the time we spend commiting the transaction
(which is important because that's when the disk writes occur)

The probes would be installed into /usr/share/systemtap/tapset on RHEL
and Fedora. This is in line with systemtap's paths which are described
in detail in "man 7 stappaths".

Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/db/sysdb.c b/src/db/sysdb.c
index 0d2f4f06d..80feb8266 100644
--- a/src/db/sysdb.c
+++ b/src/db/sysdb.c
@@ -26,6 +26,7 @@
 #include "util/crypto/sss_crypto.h"
 #include "db/sysdb_private.h"
 #include "confdb/confdb.h"
+#include "util/probes.h"
 #include <time.h>
 
 #define LDB_MODULES_PATH "LDB_MODULES_PATH"
@@ -918,6 +919,7 @@ int sysdb_transaction_start(struct sysdb_ctx *sysdb)
 
     ret = ldb_transaction_start(sysdb->ldb);
     if (ret == LDB_SUCCESS) {
+        PROBE(SYSDB_TRANSACTION_START, sysdb->transaction_nesting);
         sysdb->transaction_nesting++;
     } else {
         DEBUG(SSSDBG_CRIT_FAILURE,
@@ -929,10 +931,15 @@ int sysdb_transaction_start(struct sysdb_ctx *sysdb)
 int sysdb_transaction_commit(struct sysdb_ctx *sysdb)
 {
     int ret;
+#ifdef HAVE_SYSTEMTAP
+    int commit_nesting = sysdb->transaction_nesting-1;
+#endif
 
+    PROBE(SYSDB_TRANSACTION_COMMIT_BEFORE, commit_nesting);
     ret = ldb_transaction_commit(sysdb->ldb);
     if (ret == LDB_SUCCESS) {
         sysdb->transaction_nesting--;
+        PROBE(SYSDB_TRANSACTION_COMMIT_AFTER, sysdb->transaction_nesting);
     } else {
         DEBUG(SSSDBG_CRIT_FAILURE,
               "Failed to commit ldb transaction! (%d)\n", ret);
@@ -947,6 +954,7 @@ int sysdb_transaction_cancel(struct sysdb_ctx *sysdb)
     ret = ldb_transaction_cancel(sysdb->ldb);
     if (ret == LDB_SUCCESS) {
         sysdb->transaction_nesting--;
+        PROBE(SYSDB_TRANSACTION_CANCEL, sysdb->transaction_nesting);
     } else {
         DEBUG(SSSDBG_CRIT_FAILURE,
               "Failed to cancel ldb transaction! (%d)\n", ret);