Clean up useless variable (#419)

 

Signed-off-by: Connor1996 <zbk602423539@gmail.com>

Author: Connor1996

db/version_set.cc

@@ -4145,7 +4145,8 @@ VersionSet::~VersionSet() {
   }
   obsolete_files_.clear();
   io_status_.PermitUncheckedError();
-  // Shutdown the dedicated background deletion scheduler first
+  // Shutdown the dedicated background deletion scheduler and wait for it to
+  // finish
   if (deletion_scheduler_) {
     deletion_scheduler_->Shutdown();
   }

db/version_set_deletion_scheduler.cc

@@ -21,7 +21,6 @@ VersionSetDeletionScheduler::VersionSetDeletionScheduler(Logger* info_log)
       deletion_queue_(),
       bg_thread_(nullptr),
       shutting_down_(false),
-      pending_deletion_count_(0),
       info_log_(info_log) {
   // Start the background thread
   bg_thread_.reset(new port::Thread(
@@ -39,11 +38,11 @@ void VersionSetDeletionScheduler::ScheduleDeletion(
   MutexLock lock(&version_delete_mutex_);
 
   if (shutting_down_) {
+    delete storage_info;  // Delete synchronously if shutting down
     return;
   }
 
   deletion_queue_.push(storage_info);
-  pending_deletion_count_++;
 
   // Notify the background thread that work is available
   cv_.Signal();
@@ -76,10 +75,9 @@ void VersionSetDeletionScheduler::BackgroundDeletionThread() {
     }
 
     // Process all pending deletion operations
-    while (!deletion_queue_.empty() && !shutting_down_) {
+    while (!deletion_queue_.empty()) {
       VersionStorageInfo* storage_info = deletion_queue_.front();
       deletion_queue_.pop();
-      pending_deletion_count_--;
 
       // Unlock mutex while executing the deletion operation
       version_delete_mutex_.Unlock();

db/version_set_deletion_scheduler.h

@@ -18,14 +18,8 @@ class VersionStorageInfo;
 class Logger;
 
 // VersionSetDeletionScheduler provides a dedicated background thread for
-// handling VersionStorageInfo deletion operations that were previously executed
-// via env_->Schedule() in the LOW priority thread pool.
-//
-// This dedicated thread helps to:
-// 1. Isolate version storage deletion operations from other background work
-// 2. Avoid potential interference with other low-priority operations
-// 3. Provide better control over deletion timing and parallelism
-//
+// handling VersionStorageInfo deletion operations that would be time-consuming
+// when having a lot of SST files.
 class VersionSetDeletionScheduler {
  public:
   explicit VersionSetDeletionScheduler(Logger* info_log);
@@ -58,9 +52,6 @@ class VersionSetDeletionScheduler {
   // Flag to indicate shutdown
   bool shutting_down_;
 
-  // Number of pending deletion operations
-  int pending_deletion_count_;
-
   // Logger for debug/info messages
   Logger* info_log_;
 };