From 28a6267c056d43cdbf8cd3e10e69d8ab113e74f8 Mon Sep 17 00:00:00 2001
From: Michal Srb <michal@redhat.com>
Date: Tue, 7 Sep 2021 21:31:21 +0200
Subject: [PATCH] [rhbz] Retry XML-RPC calls when uploading attachments

If there is a bot that automatically modifies newly opened bugs, then
it can lead to "query serialization error" from Bugzilla. Retry should
help us here.

Signed-off-by: Michal Srb <michal@redhat.com>
---
 src/lib/abrt_xmlrpc.c     | 34 ++++++++++++++++++++++++++++++++++
 src/lib/abrt_xmlrpc.h     |  5 +++++
 src/lib/libreport-web.sym |  1 +
 src/plugins/rhbz.c        |  4 +++-
 4 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/src/lib/abrt_xmlrpc.c b/src/lib/abrt_xmlrpc.c
index 7cac9253..4c3b469a 100644
--- a/src/lib/abrt_xmlrpc.c
+++ b/src/lib/abrt_xmlrpc.c
@@ -16,6 +16,7 @@
     with this program; if not, write to the Free Software Foundation, Inc.,
     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
+#include <unistd.h>
 #include "internal_libreport.h"
 #include "abrt_xmlrpc.h"
 #include "proxies.h"
@@ -301,3 +302,36 @@ xmlrpc_value *abrt_xmlrpc_call(struct abrt_xmlrpc *ax,
 
     return result;
 }
+
+/* die eventually or return expected results; retry up to 5 times if the error is known */
+xmlrpc_value *abrt_xmlrpc_call_with_retry(const char *fault_substring,
+                                          struct abrt_xmlrpc *ax,
+                                          const char *method,
+                                          const char *format, ...)
+{
+    int retry_counter = 0;
+    xmlrpc_env env;
+
+    va_list args;
+
+    do {
+        // sleep, if this is not the first try;
+        // sleep() can be interrupted, but that's not a big deal here
+        if (retry_counter)
+            sleep(retry_counter);
+
+        va_start(args, format);
+        xmlrpc_value *result = abrt_xmlrpc_call_full_va(&env, ax, method, format, args);
+        va_end(args);
+
+        if (!env.fault_occurred)
+            return result;  // success!
+
+        if (env.fault_string && !strstr(env.fault_string, fault_substring)) {
+            // unknown error, don't bother retrying...
+            abrt_xmlrpc_die(&env);
+        }
+    } while (++retry_counter <= 5);
+
+    abrt_xmlrpc_die(&env);
+}
diff --git a/src/lib/abrt_xmlrpc.h b/src/lib/abrt_xmlrpc.h
index 31768ffc..8ddcfc54 100644
--- a/src/lib/abrt_xmlrpc.h
+++ b/src/lib/abrt_xmlrpc.h
@@ -63,6 +63,11 @@ xmlrpc_value *abrt_xmlrpc_call_params(xmlrpc_env *env, struct abrt_xmlrpc *ax,
 xmlrpc_value *abrt_xmlrpc_call_full(xmlrpc_env *enf, struct abrt_xmlrpc *ax,
                                    const char *method, const char *format, ...);
 
+xmlrpc_value *abrt_xmlrpc_call_with_retry(const char *fault_substring,
+                                          struct abrt_xmlrpc *ax,
+                                          const char *method,
+                                          const char *format, ...);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/lib/libreport-web.sym b/src/lib/libreport-web.sym
index 44f5244d..9ab88d3e 100644
--- a/src/lib/libreport-web.sym
+++ b/src/lib/libreport-web.sym
@@ -51,6 +51,7 @@ global:
     abrt_xmlrpc_call;
     abrt_xmlrpc_call_params;
     abrt_xmlrpc_call_full;
+    abrt_xmlrpc_call_with_retry;
 
     /* internal_libreport.h - these symbols are only to be used by libreport developers */
     libreport_trim_all_whitespace;
diff --git a/src/plugins/rhbz.c b/src/plugins/rhbz.c
index 0dae1e93..f252f914 100644
--- a/src/plugins/rhbz.c
+++ b/src/plugins/rhbz.c
@@ -643,8 +643,10 @@ int rhbz_attach_blob(struct abrt_xmlrpc *ax, const char *bug_id,
      *   i -> integer, single argument (int value)
      *   6 -> base64,  two arguments (char* plain data which will be encoded by xmlrpc-c to base64,
      *                                size_t number of bytes to encode)
+     *
+     * Retry if another user/bot attempted to change the same data.
      */
-    result = abrt_xmlrpc_call(ax, "Bug.add_attachment", "{s:(s),s:s,s:s,s:s,s:6,s:i}",
+    result = abrt_xmlrpc_call_with_retry("query serialization error", ax, "Bug.add_attachment", "{s:(s),s:s,s:s,s:s,s:6,s:i}",
                 "ids", bug_id,
                 "summary", fn,
                 "file_name", filename,
-- 
2.31.1