From e6918187568dbd01842d8d1d2c808ce16a894239 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 21 Apr 2024 13:54:28 +0200
Subject: Adding upstream version 18.2.2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 src/rocksdb/db/flush_scheduler.cc | 86 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 src/rocksdb/db/flush_scheduler.cc

(limited to 'src/rocksdb/db/flush_scheduler.cc')

diff --git a/src/rocksdb/db/flush_scheduler.cc b/src/rocksdb/db/flush_scheduler.cc
new file mode 100644
index 000000000..6f4d3e1a5
--- /dev/null
+++ b/src/rocksdb/db/flush_scheduler.cc
@@ -0,0 +1,86 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include "db/flush_scheduler.h"
+
+#include <cassert>
+
+#include "db/column_family.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+void FlushScheduler::ScheduleWork(ColumnFamilyData* cfd) {
+#ifndef NDEBUG
+  {
+    std::lock_guard<std::mutex> lock(checking_mutex_);
+    assert(checking_set_.count(cfd) == 0);
+    checking_set_.insert(cfd);
+  }
+#endif  // NDEBUG
+  cfd->Ref();
+// Suppress false positive clang analyzer warnings.
+#ifndef __clang_analyzer__
+  Node* node = new Node{cfd, head_.load(std::memory_order_relaxed)};
+  while (!head_.compare_exchange_strong(
+      node->next, node, std::memory_order_relaxed, std::memory_order_relaxed)) {
+    // failing CAS updates the first param, so we are already set for
+    // retry.  TakeNextColumnFamily won't happen until after another
+    // inter-thread synchronization, so we don't even need release
+    // semantics for this CAS
+  }
+#endif  // __clang_analyzer__
+}
+
+ColumnFamilyData* FlushScheduler::TakeNextColumnFamily() {
+  while (true) {
+    if (head_.load(std::memory_order_relaxed) == nullptr) {
+      return nullptr;
+    }
+
+    // dequeue the head
+    Node* node = head_.load(std::memory_order_relaxed);
+    head_.store(node->next, std::memory_order_relaxed);
+    ColumnFamilyData* cfd = node->column_family;
+    delete node;
+
+#ifndef NDEBUG
+    {
+      std::lock_guard<std::mutex> lock(checking_mutex_);
+      auto iter = checking_set_.find(cfd);
+      assert(iter != checking_set_.end());
+      checking_set_.erase(iter);
+    }
+#endif  // NDEBUG
+
+    if (!cfd->IsDropped()) {
+      // success
+      return cfd;
+    }
+
+    // no longer relevant, retry
+    cfd->UnrefAndTryDelete();
+  }
+}
+
+bool FlushScheduler::Empty() {
+  auto rv = head_.load(std::memory_order_relaxed) == nullptr;
+#ifndef NDEBUG
+  std::lock_guard<std::mutex> lock(checking_mutex_);
+  // Empty is allowed to be called concurrnetly with ScheduleFlush. It would
+  // only miss the recent schedules.
+  assert((rv == checking_set_.empty()) || rv);
+#endif  // NDEBUG
+  return rv;
+}
+
+void FlushScheduler::Clear() {
+  ColumnFamilyData* cfd;
+  while ((cfd = TakeNextColumnFamily()) != nullptr) {
+    cfd->UnrefAndTryDelete();
+  }
+  assert(head_.load(std::memory_order_relaxed) == nullptr);
+}
+
+}  // namespace ROCKSDB_NAMESPACE
-- 
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