Merge pull request #1460 from nichtsfrei/gvmd-21.04

Add retry if a deadlock occurs on postgres within sql#sql

CHANGELOG.md

@@ -28,6 +28,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Limit "whole-only" config families to "growing" and "every nvt" [#1386](https://github.com/greenbone/gvmd/pull/1386)
 - Access current user with an SQL function [#1399](https://github.com/greenbone/gvmd/pull/1399)
 - Refactor modify_config, allowing multiple simultaneous changes [#1404](https://github.com/greenbone/gvmd/pull/1404)
+- Add retry on a deadlock within sql#sql [#1460](https://github.com/greenbone/gvmd/pull/1460)
 
 ### Fixed
 - Use GMP version with leading zero for feed dirs [#1287](https://github.com/greenbone/gvmd/pull/1287)

src/sql.c

@@ -39,6 +39,15 @@
  * @brief GLib log domain.
  */
 #define G_LOG_DOMAIN "md manage"
+/**
+ * @brief amount of ms sql should wait before retrying when a deadlock occured
+ */
+#define DEADLOCK_SLEEP 1000
+
+/**
+ * @brief defines the amount of retries after a deadlock is considered a warning 
+ */
+#define DEADLOCK_THRESHOLD 25
 
 
 /* Headers of internal symbols defined in backend files. */
@@ -206,6 +215,8 @@ sqlv (int retry, char* sql, va_list args)
         return -1;
       if (ret == -4)
         return 3;
+      if (ret == -5)
+        return 4;
       assert (ret == -1 || ret == 0);
       return ret;
     }
@@ -220,6 +231,7 @@ sqlv (int retry, char* sql, va_list args)
 void
 sql (char* sql, ...)
 {
+  unsigned int deadlock_amount =  0;
   while (1)
     {
       va_list args;
@@ -231,6 +243,15 @@ sql (char* sql, ...)
       if (ret == 1)
         /* Gave up with statement reset. */
         continue;
+      else if (ret == 4)
+        {
+            if (deadlock_amount++ > DEADLOCK_THRESHOLD)
+              {
+                  g_warning("%s: %d deadlocks detected, wating and retrying %s", __func__, deadlock_amount, sql);
+              } 
+            gvm_usleep (DEADLOCK_SLEEP);
+            continue;
+         }
       else if (ret)
         abort();
       break;

src/sql_pg.c

@@ -523,7 +523,15 @@ sql_exec_internal (int retry, sql_stmt_t *stmt)
               g_warning ("%s: SQL: %s", __func__, stmt->sql);
               return -4;
             }
-
+            else if (sqlstate && (strcmp (sqlstate, "40P01") == 0))
+              {
+                /* deadlock_detected */
+                g_debug ("%s: deadlock: %s",
+                         __func__,
+                         PQresultErrorMessage (result));
+                g_debug ("%s: SQL: %s", __func__, stmt->sql);
+                return -5;
+              }
           if (log_errors)
             {
               g_warning ("%s: PQexec failed: %s (%i)",