From ed03c3985d1fc73b71fca8f0ab2a2301eba12675 Mon Sep 17 00:00:00 2001
From: Lily Ballard <lily@ballards.net>
Date: Sun, 16 Feb 2025 22:27:33 -0800
Subject: [PATCH] libstore: use monotonic clock for SQLITE_BUSY warnings

Using time_t meant a warning could be printed arbitrarily soon depending
on when the second rolled over relative to when the SQLite transaction
was attempted.

Change-Id: I93401aea65f90e37cd450a293c4dd4d64fba7628
---
 lix/libstore/sqlite.cc | 10 +++++-----
 lix/libstore/sqlite.hh |  9 +++++----
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/lix/libstore/sqlite.cc b/lix/libstore/sqlite.cc
index 666d12945..8b19c18f7 100644
--- a/lix/libstore/sqlite.cc
+++ b/lix/libstore/sqlite.cc
@@ -278,11 +278,11 @@ void SQLiteTxn::Rollback::operator()(sqlite3 * db)
 }
 
 [[nodiscard]]
-static std::chrono::milliseconds handleSQLiteBusyCommon(const SQLiteBusy & e, time_t & nextWarning)
+static std::chrono::milliseconds handleSQLiteBusyCommon(const SQLiteBusy & e, std::chrono::time_point<std::chrono::steady_clock> & nextWarning)
 {
-    time_t now = time(0);
+    auto now = std::chrono::steady_clock::now();
     if (now > nextWarning) {
-        nextWarning = now + 10;
+        nextWarning = now + std::chrono::seconds(10);
         logWarning({
             .msg = HintFmt(e.what())
         });
@@ -297,12 +297,12 @@ static std::chrono::milliseconds handleSQLiteBusyCommon(const SQLiteBusy & e, ti
     return std::chrono::milliseconds { uniform_dist(generator) };
 }
 
-void handleSQLiteBusy(const SQLiteBusy & e, time_t & nextWarning)
+void handleSQLiteBusy(const SQLiteBusy & e, std::chrono::time_point<std::chrono::steady_clock> & nextWarning)
 {
     std::this_thread::sleep_for(handleSQLiteBusyCommon(e, nextWarning));
 }
 
-kj::Promise<Result<void>> handleSQLiteBusyAsync(const SQLiteBusy & e, time_t & nextWarning)
+kj::Promise<Result<void>> handleSQLiteBusyAsync(const SQLiteBusy & e, std::chrono::time_point<std::chrono::steady_clock> & nextWarning)
 try {
     std::chrono::milliseconds delay_ms = handleSQLiteBusyCommon(e, nextWarning);
     co_await AIO().provider.getTimer().afterDelay(delay_ms.count() * kj::MILLISECONDS);
diff --git a/lix/libstore/sqlite.hh b/lix/libstore/sqlite.hh
index 75f8681e8..e4122e957 100644
--- a/lix/libstore/sqlite.hh
+++ b/lix/libstore/sqlite.hh
@@ -1,6 +1,7 @@
 #pragma once
 ///@file
 
+#include <chrono>
 #include <kj/async.h>
 #include <string>
 #include <type_traits>
@@ -190,8 +191,8 @@ protected:
 
 MakeError(SQLiteBusy, SQLiteError);
 
-void handleSQLiteBusy(const SQLiteBusy & e, time_t & nextWarning);
-kj::Promise<Result<void>> handleSQLiteBusyAsync(const SQLiteBusy & e, time_t & nextWarning);
+void handleSQLiteBusy(const SQLiteBusy & e, std::chrono::time_point<std::chrono::steady_clock> & nextWarning);
+kj::Promise<Result<void>> handleSQLiteBusyAsync(const SQLiteBusy & e, std::chrono::time_point<std::chrono::steady_clock> & nextWarning);
 
 /**
  * Convenience function for retrying a SQLite transaction when the
@@ -200,10 +201,10 @@ kj::Promise<Result<void>> handleSQLiteBusyAsync(const SQLiteBusy & e, time_t & n
 template<typename F>
 auto retrySQLite(F fun)
 {
-    time_t nextWarning = time(0) + 1;
+    auto nextWarning = std::chrono::steady_clock::now() + std::chrono::seconds(1);
 
     if constexpr (requires (F f) { []<typename T>(kj::Promise<Result<T>>){}(f()); }) {
-        return [](time_t nextWarning, F fun) -> decltype(fun()) {
+        return [](std::chrono::time_point<std::chrono::steady_clock> nextWarning, F fun) -> decltype(fun()) {
             while (true) {
                 kj::Promise<Result<void>> handleBusy{nullptr};
                 try {