Size based gc trigger (#197)

- Feature: Disk size triggered GC, a soft disk usage limit for cache data.
- Feature: New option `--gc-disk-size-soft-limit` (command line), `gc.cache.disksizesoftlimit` (lua config) controlling limit for soft disk usage limit. Defaults to zero which disables soft disk usage limit.
- Improvement: Disk write pressure in GC log and cleaned up clutter in GC logging.

1 files changed, 10 insertions, 18 deletions

diff --git a/zenserver/cache/structuredcachestore.cpp b/zenserver/cache/structuredcachestore.cpp
index 91ae452a8..c20e40655 100644
--- a/zenserver/cache/structuredcachestore.cpp
+++ b/zenserver/cache/structuredcachestore.cpp
@@ -1213,8 +1213,7 @@ ZenCacheDiskLayer::CacheBucket::GatherReferences(GcContext& GcCtx)
 				  NiceLatencyNs(ReadBlockLongestTimeUs));
 	});
 
-	const GcClock::TimePoint ExpireTime =
-		GcCtx.MaxCacheDuration() == GcClock::Duration::max() ? GcClock::TimePoint::min() : GcCtx.Time() - GcCtx.MaxCacheDuration();
+	const GcClock::TimePoint ExpireTime = GcCtx.ExpireTime();
 
 	const GcClock::Tick ExpireTicks = ExpireTime.time_since_epoch().count();
 
@@ -1310,7 +1309,7 @@ ZenCacheDiskLayer::CacheBucket::CollectGarbage(GcContext& GcCtx)
 	uint64_t MovedCount	  = 0;
 
 	const auto _ = MakeGuard([&] {
-		ZEN_INFO(
+		ZEN_DEBUG(
 			"garbage collect from '{}' DONE after {}, write lock: {} ({}), read lock: {} ({}), collected {} bytes, deleted #{} and moved "
 			"#{} "
 			"of #{} "
@@ -2379,8 +2378,7 @@ TEST_CASE("z$.gc")
 										 GcClock::Duration		 MaxDuration,
 										 std::span<const IoHash> Cids,
 										 std::vector<IoHash>&	 OutKeep) {
-			GcContext GcCtx(Time);
-			GcCtx.MaxCacheDuration(MaxDuration);
+			GcContext GcCtx(Time - MaxDuration);
 			Gc.CollectGarbage(GcCtx);
 			OutKeep.clear();
 			GcCtx.FilterCids(Cids, [&OutKeep](const IoHash& Hash) { OutKeep.push_back(Hash); });
@@ -2459,8 +2457,7 @@ TEST_CASE("z$.gc")
 		}
 
 		{
-			GcContext GcCtx;
-			GcCtx.MaxCacheDuration(std::chrono::hours(46));
+			GcContext GcCtx(CurrentTime - std::chrono::hours(46));
 
 			Gc.CollectGarbage(GcCtx);
 
@@ -2474,9 +2471,7 @@ TEST_CASE("z$.gc")
 
 		// Move forward in time and collect again
 		{
-			GcContext GcCtx(CurrentTime + std::chrono::hours(46));
-			GcCtx.MaxCacheDuration(std::chrono::minutes(2));
-
+			GcContext GcCtx(CurrentTime + std::chrono::minutes(2));
 			Gc.CollectGarbage(GcCtx);
 
 			for (const auto& Key : Keys)
@@ -2495,8 +2490,7 @@ TEST_CASE("z$.gc")
 		ScopedTemporaryDirectory TempDir;
 		GcManager				 Gc;
 		ZenCacheNamespace		 Zcs(Gc, TempDir.Path() / "cache");
-		const auto				 Bucket		 = "rightintwo"sv;
-		const GcClock::TimePoint CurrentTime = GcClock::Now();
+		const auto				 Bucket = "rightintwo"sv;
 
 		std::vector<IoHash> Keys{CreateKey(1), CreateKey(2), CreateKey(3)};
 
@@ -2507,8 +2501,7 @@ TEST_CASE("z$.gc")
 		}
 
 		{
-			GcContext GcCtx;
-			GcCtx.MaxCacheDuration(std::chrono::hours(2));
+			GcContext GcCtx(GcClock::Now() - std::chrono::hours(2));
 			GcCtx.CollectSmallObjects(true);
 
 			Gc.CollectGarbage(GcCtx);
@@ -2523,8 +2516,7 @@ TEST_CASE("z$.gc")
 
 		// Move forward in time and collect again
 		{
-			GcContext GcCtx(CurrentTime + std::chrono::hours(2));
-			GcCtx.MaxCacheDuration(std::chrono::minutes(2));
+			GcContext GcCtx(GcClock::Now() + std::chrono::minutes(2));
 			GcCtx.CollectSmallObjects(true);
 
 			Zcs.Flush();
@@ -2713,7 +2705,7 @@ TEST_CASE("z$.threadedinsert")	// * doctest::skip(true))
 					C++;
 				}
 
-				GcContext GcCtx;
+				GcContext GcCtx(GcClock::Now() - std::chrono::hours(24));
 				GcCtx.CollectSmallObjects(true);
 				GcCtx.AddRetainedCids(KeepHashes);
 				Zcs.CollectGarbage(GcCtx);
@@ -2761,7 +2753,7 @@ TEST_CASE("z$.threadedinsert")	// * doctest::skip(true))
 					C++;
 				}
 
-				GcContext GcCtx;
+				GcContext GcCtx(GcClock::Now() - std::chrono::hours(24));
 				GcCtx.CollectSmallObjects(true);
 				GcCtx.AddRetainedCids(KeepHashes);
 				Zcs.CollectGarbage(GcCtx);