Support writes during ingestion

Signed-off-by: hhwyt <[email protected]>

Author: hhwyt

db/db_impl/db_impl.cc

@@ -5735,6 +5735,16 @@ Status DBImpl::IngestExternalFiles(
   if (args.empty()) {
     return Status::InvalidArgument("ingestion arg list is empty");
   }
+  // Supported only when all args have the consistent `allow_write` behavior, as
+  // `allow_write` determines whether stopping writes to the DB affects all
+  // args.
+  bool allow_write = args[0].options.allow_write;
+  for (const auto& arg : args) {
+    if (arg.options.allow_write != allow_write) {
+      return Status::InvalidArgument(
+          "Inconsistent allow_writes values across ingestion arguments");
+    }
+  }
   {
     std::unordered_set<ColumnFamilyHandle*> unique_cfhs;
     for (const auto& arg : args) {
@@ -5858,6 +5868,17 @@ Status DBImpl::IngestExternalFiles(
     // So wait here to ensure there is no pending write to memtable.
     WaitForPendingWrites();
 
+    if (allow_write) {
+      // If allow_write is true, writes to the DB are resumed here,
+      // allowing users to write normally during the subsequent ingest process.
+      if (two_write_queues_) {
+        nonmem_write_thread_.ExitUnbatched(&nonmem_w);
+      }
+      write_thread_.ExitUnbatched(&w);
+    }
+    TEST_SYNC_POINT_CALLBACK("DBImpl::IngestExternalFile:AfterPendingWrites",
+                             nullptr);
+
     num_running_ingest_file_ += static_cast<int>(num_cfs);
     TEST_SYNC_POINT("DBImpl::IngestExternalFile:AfterIncIngestFileCounter");
 
@@ -5890,9 +5911,10 @@ Status DBImpl::IngestExternalFiles(
       flush_opts.check_if_compaction_disabled = true;
       if (immutable_db_options_.atomic_flush) {
         mutex_.Unlock();
-        status = AtomicFlushMemTables(
-            flush_opts, FlushReason::kExternalFileIngestion,
-            {} /* provided_candidate_cfds */, true /* entered_write_thread */);
+        status = AtomicFlushMemTables(flush_opts,
+                                      FlushReason::kExternalFileIngestion,
+                                      {} /* provided_candidate_cfds */,
+                                      !allow_write /* entered_write_thread */);
         mutex_.Lock();
       } else {
         for (size_t i = 0; i != num_cfs; ++i) {
@@ -5903,7 +5925,7 @@ Status DBImpl::IngestExternalFiles(
                     ->cfd();
             status = FlushMemTable(cfd, flush_opts,
                                    FlushReason::kExternalFileIngestion,
-                                   true /* entered_write_thread */);
+                                   !allow_write /* entered_write_thread */);
             mutex_.Lock();
             if (!status.ok()) {
               break;
@@ -6008,11 +6030,12 @@ Status DBImpl::IngestExternalFiles(
       error_handler_.SetBGError(io_s, BackgroundErrorReason::kManifestWrite);
     }
 
-    // Resume writes to the DB
-    if (two_write_queues_) {
-      nonmem_write_thread_.ExitUnbatched(&nonmem_w);
+    if (!allow_write) {
+      if (two_write_queues_) {
+        nonmem_write_thread_.ExitUnbatched(&nonmem_w);
+      }
+      write_thread_.ExitUnbatched(&w);
     }
-    write_thread_.ExitUnbatched(&w);
 
     if (status.ok()) {
       for (auto& job : ingestion_jobs) {