[#2438] prevent MySQL lease counters from going negative

src/bin/admin/tests/mysql_tests.sh.in

@@ -618,12 +618,59 @@ mysql_upgrade_13_to_14_test() {
         assert_str_eq '' "${OUTPUT}" "${query}: expected output %s, returned %s"
     done
 
-    # Clean up.
+    # Check that leases counters cannot go negative.
-    query='DELETE FROM lease4; DELETE FROM lease6;'
+    for v in 4 6; do
-    run_command \
+        query="SELECT leases FROM lease${v}_stat WHERE subnet_id = 1 AND state = 0 LIMIT 1"
-        mysql_execute "${query}"
+        run_command \
-    assert_eq 0 "${EXIT_CODE}" "${query}: expected %d, returned %d"
+            mysql_execute "${query}"
-    assert_str_eq "" "${OUTPUT}" "${query}: expected output %s, returned %s"
+        assert_eq 0 "${EXIT_CODE}" "${query}: expected %d, returned %d"
+        assert_str_eq '2' "${OUTPUT}" "${query}: expected output %s, returned %s"
+
+        # Artifically change the subnet counter from 2 down to 1.
+        query="UPDATE lease${v}_stat SET leases = 1 WHERE subnet_id = 1 AND state = 0"
+        run_command \
+            mysql_execute "${query}"
+        assert_eq 0 "${EXIT_CODE}" "${query}: expected %d, returned %d"
+        assert_str_eq '' "${OUTPUT}" "${query}: expected output %s, returned %s"
+
+        if test "${json_supported}" = 1; then
+            query="SELECT leases FROM lease${v}_stat_by_client_class WHERE client_class = 'foo' LIMIT 1"
+            run_command \
+                mysql_execute "${query}"
+            assert_eq 0 "${EXIT_CODE}" "${query}: expected %d, returned %d"
+            assert_str_eq '2' "${OUTPUT}" "${query}: expected output %s, returned %s"
+
+            # Artifically change the client class counter from 2 down to 1.
+            query="UPDATE lease${v}_stat SET leases = 1 WHERE client_class = 'foo'"
+            run_command \
+                mysql_execute "${query}"
+            assert_eq 0 "${EXIT_CODE}" "${query}: expected %d, returned %d"
+            assert_str_eq '' "${OUTPUT}" "${query}: expected output %s, returned %s"
+        fi
+
+        # Clean up.
+        query="DELETE FROM lease${v}"
+        run_command \
+            mysql_execute "${query}"
+        assert_eq 0 "${EXIT_CODE}" "${query}: expected %d, returned %d"
+        assert_str_eq '' "${OUTPUT}" "${query}: expected output %s, returned %s"
+
+        # SELECT should finish succesfully and the subnet counter should be 0.
+        query="SELECT leases FROM lease${v}_stat WHERE subnet_id = 1 AND state = 0 LIMIT 1"
+        run_command \
+            mysql_execute "${query}"
+        assert_eq 0 "${EXIT_CODE}" "${query}: expected %d, returned %d"
+        assert_str_eq '0' "${OUTPUT}" "${query}: expected output %s, returned %s"
+
+        if test "${json_supported}" = 1; then
+            # SELECT should finish succesfully and the client class counter should be 0.
+            query="SELECT leases FROM lease${v}_stat_by_client_class WHERE client_class = 'foo' LIMIT 1"
+            run_command \
+                mysql_execute "${query}"
+            assert_eq 0 "${EXIT_CODE}" "${query}: expected %d, returned %d"
+            assert_str_eq '0' "${OUTPUT}" "${query}: expected output %s, returned %s"
+        fi
+    done
 }
 
 mysql_upgrade_test() {

src/share/database/scripts/mysql/dhcpdb_create.mysql

@@ -4521,7 +4521,8 @@ BEGIN
     DECLARE length INT;
     DECLARE i INT;
 
-    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to function json_extract: "The document is empty." at position 0.
+    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to
+    --      function json_extract: "The document is empty." at position 0.
     -- Ignore ERROR 4037 (HY000): Unexpected end of JSON text in argument 1 to function 'json_extract'
     -- These situations are handled with a propagating NULL result from JSON_EXTRACT.
     DECLARE CONTINUE HANDLER FOR 3141 BEGIN END;
@@ -4578,7 +4579,7 @@ BEGIN
                 SET class = JSON_UNQUOTE(JSON_EXTRACT(old_client_classes, CONCAT('\$[', i, ']')));
 
                 -- Decrement the lease count if the record exists.
-                UPDATE lease4_stat_by_client_class SET leases = leases - 1
+                UPDATE lease4_stat_by_client_class SET leases = IF(leases > 0, leases - 1, 0)
                     WHERE client_class = class;
 
                 SET i = i + 1;
@@ -4618,7 +4619,8 @@ BEGIN
     DECLARE length INT;
     DECLARE i INT;
 
-    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to function json_extract: "The document is empty." at position 0.
+    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to
+    --      function json_extract: "The document is empty." at position 0.
     -- Ignore ERROR 4037 (HY000): Unexpected end of JSON text in argument 1 to function 'json_extract'
     -- These situations are handled with a propagating NULL result from JSON_EXTRACT.
     DECLARE CONTINUE HANDLER FOR 3141 BEGIN END;
@@ -4635,7 +4637,7 @@ BEGIN
             SET class = JSON_UNQUOTE(JSON_EXTRACT(client_classes, CONCAT('\$[', i, ']')));
 
             -- Decrement the lease count if the record exists.
-            UPDATE lease4_stat_by_client_class SET leases = leases - 1
+            UPDATE lease4_stat_by_client_class SET leases = IF(leases > 0, leases - 1, 0)
                 WHERE client_class = class;
 
             SET i = i + 1;
@@ -4656,7 +4658,8 @@ BEGIN
     DECLARE length INT;
     DECLARE i INT;
 
-    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to function json_extract: "The document is empty." at position 0.
+    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to
+    --      function json_extract: "The document is empty." at position 0.
     -- Ignore ERROR 4037 (HY000): Unexpected end of JSON text in argument 1 to function 'json_extract'
     -- These situations are handled with a propagating NULL result from JSON_EXTRACT.
     DECLARE CONTINUE HANDLER FOR 3141 BEGIN END;
@@ -4714,7 +4717,7 @@ BEGIN
                 SET class = JSON_UNQUOTE(JSON_EXTRACT(old_client_classes, CONCAT('\$[', i, ']')));
 
                 -- Decrement the lease count if the record exists.
-                UPDATE lease6_stat_by_client_class SET leases = leases - 1
+                UPDATE lease6_stat_by_client_class SET leases = IF(leases > 0, leases - 1, 0)
                     WHERE client_class = class AND lease_type = old_lease_type;
 
                 SET i = i + 1;
@@ -4755,7 +4758,8 @@ BEGIN
     DECLARE length INT;
     DECLARE i INT;
 
-    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to function json_extract: "The document is empty." at position 0.
+    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to
+    --      function json_extract: "The document is empty." at position 0.
     -- Ignore ERROR 4037 (HY000): Unexpected end of JSON text in argument 1 to function 'json_extract'
     -- These situations are handled with a propagating NULL result from JSON_EXTRACT.
     DECLARE CONTINUE HANDLER FOR 3141 BEGIN END;
@@ -4772,7 +4776,7 @@ BEGIN
             SET class = JSON_UNQUOTE(JSON_EXTRACT(client_classes, CONCAT('\$[', i, ']')));
 
             -- Decrement the lease count if the record exists.
-            UPDATE lease6_stat_by_client_class SET leases = leases - 1
+            UPDATE lease6_stat_by_client_class SET leases = IF(leases > 0, leases - 1, 0)
                 WHERE client_class = class AND lease_type = old_lease_type;
 
             SET i = i + 1;

src/share/database/scripts/mysql/upgrade_013_to_014.sh.in

@@ -283,7 +283,8 @@ BEGIN
     DECLARE length INT;
     DECLARE i INT;
 
-    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to function json_extract: "The document is empty." at position 0.
+    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to
+    --      function json_extract: "The document is empty." at position 0.
     -- Ignore ERROR 4037 (HY000): Unexpected end of JSON text in argument 1 to function 'json_extract'
     -- These situations are handled with a propagating NULL result from JSON_EXTRACT.
     DECLARE CONTINUE HANDLER FOR 3141 BEGIN END;
@@ -340,7 +341,7 @@ BEGIN
                 SET class = JSON_UNQUOTE(JSON_EXTRACT(old_client_classes, CONCAT('\$[', i, ']')));
 
                 -- Decrement the lease count if the record exists.
-                UPDATE lease4_stat_by_client_class SET leases = leases - 1
+                UPDATE lease4_stat_by_client_class SET leases = IF(leases > 0, leases - 1, 0)
                     WHERE client_class = class;
 
                 SET i = i + 1;
@@ -380,7 +381,8 @@ BEGIN
     DECLARE length INT;
     DECLARE i INT;
 
-    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to function json_extract: "The document is empty." at position 0.
+    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to
+    --      function json_extract: "The document is empty." at position 0.
     -- Ignore ERROR 4037 (HY000): Unexpected end of JSON text in argument 1 to function 'json_extract'
     -- These situations are handled with a propagating NULL result from JSON_EXTRACT.
     DECLARE CONTINUE HANDLER FOR 3141 BEGIN END;
@@ -397,7 +399,7 @@ BEGIN
             SET class = JSON_UNQUOTE(JSON_EXTRACT(client_classes, CONCAT('\$[', i, ']')));
 
             -- Decrement the lease count if the record exists.
-            UPDATE lease4_stat_by_client_class SET leases = leases - 1
+            UPDATE lease4_stat_by_client_class SET leases = IF(leases > 0, leases - 1, 0)
                 WHERE client_class = class;
 
             SET i = i + 1;
@@ -418,7 +420,8 @@ BEGIN
     DECLARE length INT;
     DECLARE i INT;
 
-    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to function json_extract: "The document is empty." at position 0.
+    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to
+    --      function json_extract: "The document is empty." at position 0.
     -- Ignore ERROR 4037 (HY000): Unexpected end of JSON text in argument 1 to function 'json_extract'
     -- These situations are handled with a propagating NULL result from JSON_EXTRACT.
     DECLARE CONTINUE HANDLER FOR 3141 BEGIN END;
@@ -476,7 +479,7 @@ BEGIN
                 SET class = JSON_UNQUOTE(JSON_EXTRACT(old_client_classes, CONCAT('\$[', i, ']')));
 
                 -- Decrement the lease count if the record exists.
-                UPDATE lease6_stat_by_client_class SET leases = leases - 1
+                UPDATE lease6_stat_by_client_class SET leases = IF(leases > 0, leases - 1, 0)
                     WHERE client_class = class AND lease_type = old_lease_type;
 
                 SET i = i + 1;
@@ -517,7 +520,8 @@ BEGIN
     DECLARE length INT;
     DECLARE i INT;
 
-    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to function json_extract: "The document is empty." at position 0.
+    -- Ignore ERROR 3141 (22032) at line 1: Invalid JSON text in argument 1 to
+    --      function json_extract: "The document is empty." at position 0.
     -- Ignore ERROR 4037 (HY000): Unexpected end of JSON text in argument 1 to function 'json_extract'
     -- These situations are handled with a propagating NULL result from JSON_EXTRACT.
     DECLARE CONTINUE HANDLER FOR 3141 BEGIN END;
@@ -534,7 +538,7 @@ BEGIN
             SET class = JSON_UNQUOTE(JSON_EXTRACT(client_classes, CONCAT('\$[', i, ']')));
 
             -- Decrement the lease count if the record exists.
-            UPDATE lease6_stat_by_client_class SET leases = leases - 1
+            UPDATE lease6_stat_by_client_class SET leases = IF(leases > 0, leases - 1, 0)
                 WHERE client_class = class AND lease_type = old_lease_type;
 
             SET i = i + 1;