Fixes #66. (#70)

* Fixes #66.

1. Introduce `hz` flag to control the frequency of periodically running tasks.
2. Update helio dependency.

* Fix CI caching for PRs.

.github/workflows/ci.yml

@@ -43,9 +43,9 @@ jobs:
         path: |
           ~/.ccache
           ${{github.workspace}}/build/_deps
-        key: ${{ runner.os }}-deps-${{ github.sha }}
+        key: ${{ runner.os }}-deps-${{ github.base_ref }}-${{ github.sha }}
         restore-keys: |
-          ${{ runner.os }}-deps-
+          ${{ runner.os }}-deps-${{ github.base_ref }}-
           
     - name: Configure CMake
       # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.

helio

@@ -1 +1 @@
-Subproject commit 490814e3f0586e6974a462ddfe42905b71b90c3b
+Subproject commit 439b47b13ac5260ce0ba094e8166c2170965387b

src/server/engine_shard_set.cc

@@ -21,6 +21,12 @@ extern "C" {
 using namespace std;
 
 ABSL_FLAG(string, backing_prefix, "", "");
+
+ABSL_FLAG(uint32_t, hz, 1000,
+          "Base frequency at which the server updates its expiry clock "
+          "and performs other background tasks. Warning: not advised to decrease in production, "
+          "because it can affect expiry precision for PSETEX etc.");
+
 ABSL_DECLARE_FLAG(bool, cache_mode);
 
 namespace dfly {
@@ -28,6 +34,7 @@ namespace dfly {
 using namespace util;
 namespace this_fiber = ::boost::this_fiber;
 namespace fibers = ::boost::fibers;
+using absl::GetFlag;
 
 namespace {
 
@@ -48,16 +55,18 @@ EngineShard::Stats& EngineShard::Stats::operator+=(const EngineShard::Stats& o)
 
 EngineShard::EngineShard(util::ProactorBase* pb, bool update_db_time, mi_heap_t* heap)
     : queue_(kQueueLen), txq_([](const Transaction* t) { return t->txid(); }), mi_resource_(heap),
-      db_slice_(pb->GetIndex(), absl::GetFlag(FLAGS_cache_mode), this) {
+      db_slice_(pb->GetIndex(), GetFlag(FLAGS_cache_mode), this) {
   fiber_q_ = fibers::fiber([this, index = pb->GetIndex()] {
     this_fiber::properties<FiberProps>().set_name(absl::StrCat("shard_queue", index));
     queue_.Run();
   });
 
   if (update_db_time) {
-    constexpr uint32_t kClockCycleMs = 1;
+    uint32_t clock_cycle_ms = 1000 / std::max<uint32_t>(1, GetFlag(FLAGS_hz));
+    if (clock_cycle_ms == 0)
+      clock_cycle_ms = 1;
 
-    periodic_task_ = pb->AddPeriodic(kClockCycleMs, [this] { Heartbeat(); });
+    periodic_task_ = pb->AddPeriodic(clock_cycle_ms, [this] { Heartbeat(); });
   }
 
   tmp_str1 = sdsempty();
@@ -92,7 +101,7 @@ void EngineShard::InitThreadLocal(ProactorBase* pb, bool update_db_time) {
   CompactObj::InitThreadLocal(shard_->memory_resource());
   SmallString::InitThreadLocal(data_heap);
 
-  string backing_prefix = absl::GetFlag(FLAGS_backing_prefix);
+  string backing_prefix = GetFlag(FLAGS_backing_prefix);
   if (!backing_prefix.empty()) {
     string fn =
         absl::StrCat(backing_prefix, "-", absl::Dec(pb->GetIndex(), absl::kZeroPad4), ".ssd");

src/server/server_family.cc

@@ -33,9 +33,9 @@ extern "C" {
 #include "server/replica.h"
 #include "server/script_mgr.h"
 #include "server/server_state.h"
-#include "server/version.h"
 #include "server/tiered_storage.h"
 #include "server/transaction.h"
+#include "server/version.h"
 #include "strings/human_readable.h"
 #include "util/accept_server.h"
 #include "util/uring/uring_file.h"
@@ -48,6 +48,7 @@ ABSL_FLAG(string, requirepass, "", "password for AUTH authentication");
 
 ABSL_DECLARE_FLAG(uint32_t, port);
 ABSL_DECLARE_FLAG(bool, cache_mode);
+ABSL_DECLARE_FLAG(uint32_t, hz);
 
 extern "C" mi_stats_t _mi_stats_main;
 
@@ -56,10 +57,10 @@ namespace dfly {
 using namespace util;
 namespace fibers = ::boost::fibers;
 namespace fs = std::filesystem;
+using absl::GetFlag;
 using absl::StrCat;
 using facade::MCReplyBuilder;
 using strings::HumanReadableNumBytes;
-using absl::GetFlag;
 
 namespace {
 
@@ -170,7 +171,10 @@ void ServerFamily::Init(util::AcceptServer* acceptor, util::ListenerInterface* m
       used_mem_peak.store(sum, memory_order_relaxed);
   };
 
-  task_10ms_ = pb_task_->AwaitBrief([&] { return pb_task_->AddPeriodic(10, cache_cb); });
+  uint32_t cache_hz = max(GetFlag(FLAGS_hz) / 10, 1u);
+  uint32_t period_ms = max(1u, 1000 / cache_hz);
+  stats_caching_task_ =
+      pb_task_->AwaitBrief([&] { return pb_task_->AddPeriodic(period_ms, cache_cb); });
 
   fs::path data_folder = fs::current_path();
   const auto& dir = GetFlag(FLAGS_dir);
@@ -197,8 +201,8 @@ void ServerFamily::Shutdown() {
     load_fiber_.join();
 
   pb_task_->Await([this] {
-    pb_task_->CancelPeriodic(task_10ms_);
+    pb_task_->CancelPeriodic(stats_caching_task_);
-    task_10ms_ = 0;
+    stats_caching_task_ = 0;
 
     unique_lock lk(replicaof_mu_);
     if (replica_) {

src/server/server_family.h

@@ -114,7 +114,7 @@ class ServerFamily {
 
   boost::fibers::fiber load_fiber_;
 
-  uint32_t task_10ms_ = 0;
+  uint32_t stats_caching_task_ = 0;
   Service& service_;
 
   util::AcceptServer* acceptor_ = nullptr;