CR#1

db/column_family.cc

@@ -882,19 +882,30 @@ int GetL0ThresholdSpeedupCompaction(int level0_file_num_compaction_trigger,
 }  // namespace
 
 namespace {
-const uint64_t Gb = 1073741824u;
-const uint64_t Mb = 1048576u;
+const uint64_t Gb = 1ull << 30;
+const uint64_t Mb = 1ull << 20;
 const uint64_t kMinWriteRate = 16 * 1024u;  // Minimum write rate 16KB/s.
+const int kMemtablePenalty = 10;
+const int kNearStopPenalty = 4;
 }  // namespace
 
+double ColumnFamilyData::TEST_CalculateWriteDelayDivider(
+    uint64_t compaction_needed_bytes,
+    const MutableCFOptions& mutable_cf_options,
+    WriteStallCause& write_stall_cause) {
+  return CalculateWriteDelayDividerAndMaybeUpdateWriteStallCause(
+      compaction_needed_bytes, mutable_cf_options, write_stall_cause);
+}
+
 std::unique_ptr<WriteControllerToken> ColumnFamilyData::DynamicSetupDelay(
     WriteController* write_controller, uint64_t compaction_needed_bytes,
     const MutableCFOptions& mutable_cf_options,
     WriteStallCause& write_stall_cause) {
   uint64_t max_write_rate = write_controller->max_delayed_write_rate();
 
-  const double rate_divider = CalculateWriteDelayDivider(
-      compaction_needed_bytes, write_stall_cause, mutable_cf_options);
+  const double rate_divider =
+      CalculateWriteDelayDividerAndMaybeUpdateWriteStallCause(
+          compaction_needed_bytes, mutable_cf_options, write_stall_cause);
   assert(rate_divider >= 1);
   auto write_rate = static_cast<uint64_t>(max_write_rate / rate_divider);
   if (write_rate < kMinWriteRate) {
@@ -945,10 +956,11 @@ ColumnFamilyData::GetWriteStallConditionAndCause(
 // Delay divider is by how much we divide the users delayed_write_rate.
 // E.g. divider 10 will result in 10 Mb/s from users 100 Mb/s.
 // The rate is reduced linearly according to the range from slowdown to stop.
-double ColumnFamilyData::CalculateWriteDelayDivider(
+double
+ColumnFamilyData::CalculateWriteDelayDividerAndMaybeUpdateWriteStallCause(
     uint64_t compaction_needed_bytes,
-    ColumnFamilyData::WriteStallCause& write_stall_cause,
-    const MutableCFOptions& mutable_cf_options) {
+    const MutableCFOptions& mutable_cf_options,
+    ColumnFamilyData::WriteStallCause& write_stall_cause) {
   assert(current_ != nullptr);
 
   const auto* vstorage = current_->storage_info();
@@ -963,7 +975,7 @@ double ColumnFamilyData::CalculateWriteDelayDivider(
           mutable_cf_options.max_write_buffer_number - 1 &&
       num_unflushed_memtables - 1 >=
           ioptions_.min_write_buffer_number_to_merge) {
-    memtable_divider = 10;
+    memtable_divider = kMemtablePenalty;
   }
 
   // Pending Compaction Bytes
@@ -973,6 +985,7 @@ double ColumnFamilyData::CalculateWriteDelayDivider(
     auto hard_limit = mutable_cf_options.hard_pending_compaction_bytes_limit;
     // soft_limit != hard_limit here. we're in a kDelayed state here and not
     // stop.
+    assert(hard_limit > soft_limit);
     uint64_t soft_hard_range = hard_limit - soft_limit;
     // change rate every 1G change or 100Mb if soft_hard_range is too small.
     auto step_size = soft_hard_range > Gb ? Gb : 100 * Mb;

db/column_family.h

@@ -485,22 +485,22 @@ class ColumnFamilyData {
   WriteStallCondition RecalculateWriteStallConditions(
       const MutableCFOptions& mutable_cf_options);
 
+  // REQUIREMENT: db mutex must be held
   double TEST_CalculateWriteDelayDivider(
-      uint64_t compaction_needed_bytes, WriteStallCause& write_stall_cause,
-      const MutableCFOptions& mutable_cf_options) {
-    return CalculateWriteDelayDivider(compaction_needed_bytes,
-                                      write_stall_cause, mutable_cf_options);
-  }
+      uint64_t compaction_needed_bytes,
+      const MutableCFOptions& mutable_cf_options,
+      WriteStallCause& write_stall_cause);
 
  private:
   std::unique_ptr<WriteControllerToken> DynamicSetupDelay(
       WriteController* write_controller, uint64_t compaction_needed_bytes,
       const MutableCFOptions& mutable_cf_options,
       WriteStallCause& write_stall_cause);
 
-  double CalculateWriteDelayDivider(uint64_t compaction_needed_bytes,
-                                    WriteStallCause& write_stall_cause,
-                                    const MutableCFOptions& mutable_cf_options);
+  double CalculateWriteDelayDividerAndMaybeUpdateWriteStallCause(
+      uint64_t compaction_needed_bytes,
+      const MutableCFOptions& mutable_cf_options,
+      WriteStallCause& write_stall_cause);
 
  public:
   void set_initialized() { initialized_.store(true); }