CCBC-1616: apply wait_for_config check for all pipelines

When the connection is slow, or operation timeout is configured to
pretty low value, the SDK might not leave the event loop in case, when
lcb_wait() function is being used to execute IO operations. In this
case, regardless that actual data operation has been completed, and user
callback invoked, the library might have configuration update operation
running, and will wait for its completion, even though it is not
required to return control from lcb_wait() operation by default.

Change-Id: Ia58cb6632f3b4d17ac01b75e71b6baaddbbde2f6
Reviewed-on: https://review.couchbase.org/c/libcouchbase/+/198057
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>

Author: avsej

.gitignore

@@ -26,6 +26,7 @@
 .deps/
 .libs/
 /INSTALL
+/.cache
 /Makefile
 /Makefile.in
 /aclocal.m4

src/mcserver/mcserver.cc

@@ -1382,3 +1382,30 @@ bool Server::check_closed()
     finalize_errored_ctx();
     return true;
 }
+
+bool Server::has_pending(bool ignore_cfgreq) const
+{
+    if (ignore_cfgreq) {
+        sllist_node *ll;
+        SLLIST_FOREACH(&requests, ll)
+        {
+            const mc_PACKET *pkt = SLLIST_ITEM(ll, mc_PACKET, slnode);
+            protocol_binary_request_header hdr = {};
+            mcreq_read_hdr(pkt, &hdr);
+            /*
+             * return true immediately if there is a pending request, that is not related to
+             * configuration updates
+             */
+            if (hdr.request.opcode != PROTOCOL_BINARY_CMD_GET_CLUSTER_CONFIG &&
+                hdr.request.opcode != PROTOCOL_BINARY_CMD_SELECT_BUCKET) {
+                return true;
+            }
+        }
+        /*
+         * the pending requests list is empty or contains only configuration update requests
+         * in any case consider it empty, because of ignore_cfgreq flag
+         */
+        return false;
+    }
+    return !SLLIST_IS_EMPTY(&requests);
+}

src/mcserver/mcserver.h

@@ -81,10 +81,7 @@ class Server : public mc_PIPELINE
      * Returns true or false depending on whether there are pending commands on
      * this server
      */
-    bool has_pending() const
-    {
-        return !SLLIST_IS_EMPTY(&requests);
-    }
+    bool has_pending(bool ignore_cfgreq = false) const;
 
     int get_index() const
     {

src/wait.cc

@@ -32,7 +32,7 @@ static bool has_pending(lcb_INSTANCE *instance)
     }
 
     for (size_t ii = 0; ii < LCBT_NSERVERS(instance); ii++) {
-        if (instance->get_server(ii)->has_pending()) {
+        if (instance->get_server(ii)->has_pending(!LCBT_SETTING(instance, wait_for_config))) {
             return true;
         }
     }

tests/iotests/t_get.cc

@@ -583,6 +583,8 @@ TEST_F(GetUnitTest, testFailoverAndGetReplica)
     lcb_cntl(instance, LCB_CNTL_SET, LCB_CNTL_OP_TIMEOUT, &tmoval);
     // Reduce configuration poll interval to get new configuration sooner
     lcb_cntl(instance, LCB_CNTL_SET, LCB_CNTL_CONFIG_POLL_INTERVAL, &tmoval);
+    std::uint32_t yes = 1;
+    lcb_cntl(instance, LCB_CNTL_SET, LCB_CNTL_WAIT_FOR_CONFIG, &yes);
 
     // store keys
     size_t counter = 0;