MB-42607 [1/2]: Make bio_drain_buffer_sz dynamic

Modify Settings.bio_drain_buffer_sz to allow it to be changed
dynamically (only affects TLS connections created after it is
changed).

Change-Id: I6b2ea398e66716f7eb54db466c33026354a58b3e
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/139893
Tested-by: Build Bot <[email protected]>
Reviewed-by: James Harrison <[email protected]>
Reviewed-by: Trond Norbye <[email protected]>
Well-Formed: Build Bot <[email protected]>

Author: daverigby

daemon/settings.cc

@@ -803,12 +803,6 @@ void Settings::updateSettings(const Settings& other, bool apply) {
             throw std::invalid_argument("audit can't be changed dynamically");
         }
     }
-    if (other.has.bio_drain_buffer_sz) {
-        if (other.bio_drain_buffer_sz != bio_drain_buffer_sz) {
-            throw std::invalid_argument(
-                "bio_drain_buffer_sz can't be changed dynamically");
-        }
-    }
     if (other.has.datatype_json) {
         if (other.datatype_json != datatype_json) {
             throw std::invalid_argument(
@@ -901,6 +895,15 @@ void Settings::updateSettings(const Settings& other, bool apply) {
         }
     }
 
+    if (other.has.bio_drain_buffer_sz) {
+        if (other.bio_drain_buffer_sz != bio_drain_buffer_sz) {
+            LOG_INFO("Change BIO drain buffer size from {} to {}",
+                     bio_drain_buffer_sz,
+                     other.bio_drain_buffer_sz);
+            setBioDrainBufferSize(other.bio_drain_buffer_sz);
+        }
+    }
+
     if (other.has.reqs_per_event_high_priority) {
         if (other.reqs_per_event_high_priority !=
             reqs_per_event_high_priority) {

tests/config_parse_test/config_parse_test.cc

@@ -1358,18 +1358,17 @@ TEST(SettingsUpdateTest, ConnectionIdleTimeIsDynamic) {
               settings.getConnectionIdleTime());
 }
 
-TEST(SettingsUpdateTest, BioDrainBufferSzIsNotDynamic) {
+TEST(SettingsUpdateTest, BioDrainBufferSzIsDynamic) {
     Settings updated;
     Settings settings;
     // setting it to the same value should work
     auto old = settings.getBioDrainBufferSize();
     updated.setBioDrainBufferSize(old);
     EXPECT_NO_THROW(settings.updateSettings(updated, false));
 
-    // changing it should not work
+    // changing it should work
     updated.setBioDrainBufferSize(old + 10);
-    EXPECT_THROW(settings.updateSettings(updated, false),
-                 std::invalid_argument);
+    EXPECT_NO_THROW(settings.updateSettings(updated, false));
 }
 
 TEST(SettingsUpdateTest, DatatypeJsonIsNotDynamic) {