#2373 Build index for small segment waste time on waiting background index thread finish (#2482)

* #2349 Drop collection timeout if too many partitions created on collection
Signed-off-by: Ngroot <yihua.mo@zilliz.com>

* changelog
Signed-off-by: Nyhmo <yihua.mo@zilliz.com>

* #2373 Build index for small segment waste time on waiting background index thread finish
Signed-off-by: Nyhmo <yihua.mo@zilliz.com>

CHANGELOG.md

@@ -5,6 +5,7 @@ Please mark all change in change log and use the issue from GitHub
 
 ## Bug
 -   \#2367 Fix inconsistent reading and writing when using mishards
+-   \#2373 Build index for small segment waste time on waiting background index thread finish
 -   \#2394 Drop collection timeout if too many partitions created on collection
 
 ## Feature

core/src/db/DBImpl.cpp

@@ -2377,17 +2377,16 @@ DBImpl::WaitCollectionIndexRecursively(const std::shared_ptr<server::Context>& c
                 }
             }
 
-            index_req_swn_.Wait_For(std::chrono::seconds(1));
-
+            auto ret = index_req_swn_.Wait_For(std::chrono::seconds(1));
             // client break the connection, no need to block, check every 1 second
             if (context && context->IsConnectionBroken()) {
                 LOG_ENGINE_DEBUG_ << "Client connection broken, build index in background";
                 break;  // just break, not return, continue to update partitions files to to_index
             }
 
-            // check to_index files every 5 seconds
+            // check to_index files every 5 seconds or background index thread finished
             repeat++;
-            if (repeat % WAIT_BUILD_INDEX_INTERVAL == 0) {
+            if ((ret == std::cv_status::no_timeout) || (repeat % WAIT_BUILD_INDEX_INTERVAL == 0)) {
                 GetFilesToBuildIndex(collection_id, file_types, files_holder);
                 ++times;
             }

core/src/db/DBImpl.h

@@ -310,22 +310,26 @@ class DBImpl : public DB, public server::CacheConfigHandler, public server::Engi
             notified_ = false;
         }
 
-        void
+        std::cv_status
         Wait_Until(const std::chrono::system_clock::time_point& tm_pint) {
             std::unique_lock<std::mutex> lck(mutex_);
+            std::cv_status ret = std::cv_status::timeout;
             if (!notified_) {
-                cv_.wait_until(lck, tm_pint);
+                ret = cv_.wait_until(lck, tm_pint);
             }
             notified_ = false;
+            return ret;
         }
 
-        void
+        std::cv_status
         Wait_For(const std::chrono::system_clock::duration& tm_dur) {
             std::unique_lock<std::mutex> lck(mutex_);
+            std::cv_status ret = std::cv_status::timeout;
             if (!notified_) {
-                cv_.wait_for(lck, tm_dur);
+                ret = cv_.wait_for(lck, tm_dur);
             }
             notified_ = false;
+            return ret;
         }
 
         void