From 9f5004faec796031a2a9e315554562f8c0222310 Mon Sep 17 00:00:00 2001
From: Yuval Ariel <yuval.ariel@redis.io>
Date: Sun, 14 Apr 2024 18:04:24 +0300
Subject: [PATCH] prettify

---
 db/db_impl/db_impl_write.cc            | 8 ++++++--
 include/rocksdb/write_buffer_manager.h | 8 +++++++-
 memtable/write_buffer_manager.cc       | 2 +-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/db/db_impl/db_impl_write.cc b/db/db_impl/db_impl_write.cc
index d63ab3fbda..ae0d68fbd4 100644
--- a/db/db_impl/db_impl_write.cc
+++ b/db/db_impl/db_impl_write.cc
@@ -1747,9 +1747,13 @@ Status DBImpl::HandleWriteBufferManagerFlush(WriteContext* write_context) {
   if (immutable_db_options_.atomic_flush) {
     SelectColumnFamiliesForAtomicFlush(&cfds);
   } else {
+    // As part of https://github.com/speedb-io/speedb/pull/859, theres a need to
+    // schedule more flushes since the cfd picked for flush was the oldest one
+    // and not necessarily enough to resolve the stall issue.
+    // For this reason, schedule enough flushes so that the memory usage is at
+    // least below the flush trigger (kMutableLimit * buffer_size)
     int64_t total_mem_to_free =
-        write_buffer_manager()->mutable_memtable_memory_usage() -
-        write_buffer_manager()->buffer_size() * 7 / 8;
+        write_buffer_manager()->memory_above_flush_trigger();
     for (auto cfd : *versions_->GetColumnFamilySet()) {
       if (cfd->IsDropped()) {
         continue;
diff --git a/include/rocksdb/write_buffer_manager.h b/include/rocksdb/write_buffer_manager.h
index 691280ca32..52eaf0b825 100644
--- a/include/rocksdb/write_buffer_manager.h
+++ b/include/rocksdb/write_buffer_manager.h
@@ -67,6 +67,8 @@ class WriteBufferManager final {
   static constexpr uint64_t kNoDelayedWriteFactor = 0U;
   static constexpr uint64_t kMaxDelayedWriteFactor = 100U;
   static constexpr uint64_t kStopDelayedWriteFactor = kMaxDelayedWriteFactor;
+  static constexpr double kMutableLimit = 0.875;
+
   enum class UsageState { kNone, kDelay, kStop };
 
  public:
@@ -152,6 +154,10 @@ class WriteBufferManager final {
     return ((inactive >= total) ? 0 : (total - inactive));
   }
 
+  int64_t memory_above_flush_trigger() {
+    return mutable_memtable_memory_usage() - buffer_size() * kMutableLimit;
+  }
+
   // Returns the total inactive memory used by memtables.
   size_t immmutable_memtable_memory_usage() const {
     return memory_inactive_.load(std::memory_order_relaxed);
@@ -180,7 +186,7 @@ class WriteBufferManager final {
     [[maybe_unused]] auto was_enabled = enabled();
 
     buffer_size_.store(new_size, std::memory_order_relaxed);
-    mutable_limit_.store(new_size * 7 / 8, std::memory_order_relaxed);
+    mutable_limit_.store(new_size * kMutableLimit, std::memory_order_relaxed);
 
     assert(was_enabled == enabled());
 
diff --git a/memtable/write_buffer_manager.cc b/memtable/write_buffer_manager.cc
index bdfc389798..87fb3cb656 100644
--- a/memtable/write_buffer_manager.cc
+++ b/memtable/write_buffer_manager.cc
@@ -54,7 +54,7 @@ WriteBufferManager::WriteBufferManager(
     const FlushInitiationOptions& flush_initiation_options,
     uint16_t start_delay_percent)
     : buffer_size_(_buffer_size),
-      mutable_limit_(buffer_size_ * 7 / 8),
+      mutable_limit_(buffer_size_ * kMutableLimit),
       memory_used_(0),
       memory_inactive_(0),
       memory_being_freed_(0U),