From 54f8daf6b17a2dee4f7901fe94e1f46f41bd7673 Mon Sep 17 00:00:00 2001
From: Pierre Bourdon <delroth@gmail.com>
Date: Sat, 20 Apr 2024 16:53:52 +0200
Subject: [PATCH] queue-runner: remove id > X from new builds query

Running the query with/without it shows that it makes no difference to
postgres, since there's an index on finished=0 already. This allows a
few simplifications, but also paves the way towards running multiple
parallel monitor threads in the future.
---
 src/hydra-queue-runner/hydra-queue-runner.cc |  7 -------
 src/hydra-queue-runner/queue-monitor.cc      | 21 ++++----------------
 src/hydra-queue-runner/state.hh              |  4 +---
 3 files changed, 5 insertions(+), 27 deletions(-)

diff --git a/src/hydra-queue-runner/hydra-queue-runner.cc b/src/hydra-queue-runner/hydra-queue-runner.cc
index 0caea7d3..b6eca0d1 100644
--- a/src/hydra-queue-runner/hydra-queue-runner.cc
+++ b/src/hydra-queue-runner/hydra-queue-runner.cc
@@ -70,13 +70,6 @@ State::PromMetrics::PromMetrics()
             .Register(*registry)
             .Add({})
     )
-    , queue_max_id(
-        prometheus::BuildGauge()
-            .Name("hydraqueuerunner_queue_max_build_id_info")
-            .Help("Maximum build record ID in the queue")
-            .Register(*registry)
-            .Add({})
-    )
     , dispatcher_time_spent_running(
         prometheus::BuildCounter()
             .Name("hydraqueuerunner_dispatcher_time_spent_running")
diff --git a/src/hydra-queue-runner/queue-monitor.cc b/src/hydra-queue-runner/queue-monitor.cc
index 6b643ec3..702ccb33 100644
--- a/src/hydra-queue-runner/queue-monitor.cc
+++ b/src/hydra-queue-runner/queue-monitor.cc
@@ -37,15 +37,13 @@ void State::queueMonitorLoop(Connection & conn)
 
     auto destStore = getDestStore();
 
-    unsigned int lastBuildId = 0;
-
     bool quit = false;
     while (!quit) {
         auto t_before_work = std::chrono::steady_clock::now();
 
         localStore->clearPathInfoCache();
 
-        bool done = getQueuedBuilds(conn, destStore, lastBuildId);
+        bool done = getQueuedBuilds(conn, destStore);
 
         if (buildOne && buildOneDone) quit = true;
 
@@ -63,12 +61,10 @@ void State::queueMonitorLoop(Connection & conn)
             conn.get_notifs();
 
         if (auto lowestId = buildsAdded.get()) {
-            lastBuildId = std::min(lastBuildId, static_cast<unsigned>(std::stoul(*lowestId) - 1));
             printMsg(lvlTalkative, "got notification: new builds added to the queue");
         }
         if (buildsRestarted.get()) {
             printMsg(lvlTalkative, "got notification: builds restarted");
-            lastBuildId = 0; // check all builds
         }
         if (buildsCancelled.get() || buildsDeleted.get() || buildsBumped.get()) {
             printMsg(lvlTalkative, "got notification: builds cancelled or bumped");
@@ -95,11 +91,11 @@ struct PreviousFailure : public std::exception {
 
 
 bool State::getQueuedBuilds(Connection & conn,
-    ref<Store> destStore, unsigned int & lastBuildId)
+    ref<Store> destStore)
 {
     prom.queue_checks_started.Increment();
 
-    printInfo("checking the queue for builds > %d...", lastBuildId);
+    printInfo("checking the queue for builds...");
 
     /* Grab the queued builds from the database, but don't process
        them yet (since we don't want a long-running transaction). */
@@ -107,8 +103,6 @@ bool State::getQueuedBuilds(Connection & conn,
     std::map<BuildID, Build::ptr> newBuildsByID;
     std::multimap<StorePath, BuildID> newBuildsByPath;
 
-    unsigned int newLastBuildId = lastBuildId;
-
     {
         pqxx::work txn(conn);
 
@@ -117,17 +111,12 @@ bool State::getQueuedBuilds(Connection & conn,
              "jobsets.name as jobset, job, drvPath, maxsilent, timeout, timestamp, "
              "globalPriority, priority from Builds "
              "inner join jobsets on builds.jobset_id = jobsets.id "
-             "where builds.id > $1 and finished = 0 order by globalPriority desc, builds.id",
-            lastBuildId);
+             "where finished = 0 order by globalPriority desc, builds.id");
 
         for (auto const & row : res) {
             auto builds_(builds.lock());
             BuildID id = row["id"].as<BuildID>();
             if (buildOne && id != buildOne) continue;
-            if (id > newLastBuildId) {
-                newLastBuildId = id;
-                prom.queue_max_id.Set(id);
-            }
             if (builds_->count(id)) continue;
 
             auto build = std::make_shared<Build>(
@@ -336,8 +325,6 @@ bool State::getQueuedBuilds(Connection & conn,
     }
 
     prom.queue_checks_finished.Increment();
-
-    lastBuildId = newBuildsByID.empty() ? newLastBuildId : newBuildsByID.begin()->first - 1;
     return newBuildsByID.empty();
 }
 
diff --git a/src/hydra-queue-runner/state.hh b/src/hydra-queue-runner/state.hh
index 3fd57be3..922e61d5 100644
--- a/src/hydra-queue-runner/state.hh
+++ b/src/hydra-queue-runner/state.hh
@@ -490,7 +490,6 @@ private:
         prometheus::Counter& queue_steps_created;
         prometheus::Counter& queue_checks_early_exits;
         prometheus::Counter& queue_checks_finished;
-        prometheus::Gauge& queue_max_id;
 
         prometheus::Counter& dispatcher_time_spent_running;
         prometheus::Counter& dispatcher_time_spent_waiting;
@@ -546,8 +545,7 @@ private:
     void queueMonitorLoop(Connection & conn);
 
     /* Check the queue for new builds. */
-    bool getQueuedBuilds(Connection & conn,
-        nix::ref<nix::Store> destStore, unsigned int & lastBuildId);
+    bool getQueuedBuilds(Connection & conn, nix::ref<nix::Store> destStore);
 
     /* Handle cancellation, deletion and priority bumps. */
     void processQueueChange(Connection & conn);