Limit size of memory cache layer (#423)

- Feature: Limit the size ZenCacheMemoryLayer may use
  - `--cache-memlayer-targetfootprint` option to set which size (in bytes) it should be limited to, zero to have it unbounded
  - `--cache-memlayer-maxage` option to set how long (in seconds) cache items should be kept in the memory cache

Do more "standard" GC rather than clearing everything.
Tries to purge memory on Get/Put on the fly if exceeding limit - not sure if we should have a polling thread instead of adding overhead to Get/Put (however light it may be).

1 files changed, 34 insertions, 5 deletions

diff --git a/src/zenserver/config.cpp b/src/zenserver/config.cpp
index 6daf7fe1c..5e24d174b 100644
--- a/src/zenserver/config.cpp
+++ b/src/zenserver/config.cpp
@@ -814,9 +814,17 @@ ParseConfigFile(const std::filesystem::path& Path,
 	LuaOptions.AddOption("trace.file"sv, ServerOptions.TraceFile, "tracefile"sv);
 
 	////// cache
-	LuaOptions.AddOption("cache.enable"sv, ServerOptions.StructuredCacheEnabled);
-	LuaOptions.AddOption("cache.writelog"sv, ServerOptions.StructuredCacheWriteLogEnabled);
-	LuaOptions.AddOption("cache.accesslog"sv, ServerOptions.StructuredCacheAccessLogEnabled);
+	LuaOptions.AddOption("cache.enable"sv, ServerOptions.StructuredCacheConfig.Enabled);
+	LuaOptions.AddOption("cache.writelog"sv, ServerOptions.StructuredCacheConfig.WriteLogEnabled, "cache-write-log");
+	LuaOptions.AddOption("cache.accesslog"sv, ServerOptions.StructuredCacheConfig.AccessLogEnabled, "cache-access-log");
+
+	LuaOptions.AddOption("cache.memlayer.targetfootprint"sv,
+						 ServerOptions.StructuredCacheConfig.MemTargetFootprintBytes,
+						 "cache-memlayer-targetfootprint");
+	LuaOptions.AddOption("cache.memlayer.triminterval"sv,
+						 ServerOptions.StructuredCacheConfig.MemTrimIntervalSeconds,
+						 "cache-memlayer-triminterval");
+	LuaOptions.AddOption("cache.memlayer.maxage"sv, ServerOptions.StructuredCacheConfig.MemMaxAgeSeconds, "cache-memlayer-maxage");
 
 	////// cache.upstream
 	LuaOptions.AddOption("cache.upstream.policy"sv, ServerOptions.UpstreamCacheConfig.CachePolicy, "upstream-cache-policy"sv);
@@ -1236,14 +1244,35 @@ ParseCliOptions(int argc, char* argv[], ZenServerOptions& ServerOptions)
 					   "",
 					   "cache-write-log",
 					   "Whether cache write log is enabled",
-					   cxxopts::value<bool>(ServerOptions.StructuredCacheWriteLogEnabled)->default_value("true"),
+					   cxxopts::value<bool>(ServerOptions.StructuredCacheConfig.WriteLogEnabled)->default_value("true"),
 					   "");
 
 	options.add_option("cache",
 					   "",
 					   "cache-access-log",
 					   "Whether cache access log is enabled",
-					   cxxopts::value<bool>(ServerOptions.StructuredCacheAccessLogEnabled)->default_value("true"),
+					   cxxopts::value<bool>(ServerOptions.StructuredCacheConfig.AccessLogEnabled)->default_value("true"),
+					   "");
+
+	options.add_option("cache",
+					   "",
+					   "cache-memlayer-targetfootprint",
+					   "Max allowed memory used by cache memory layer per namespace in bytes. Default set to 536870912 (512 Mb).",
+					   cxxopts::value<uint64_t>(ServerOptions.StructuredCacheConfig.MemTargetFootprintBytes)->default_value("536870912"),
+					   "");
+
+	options.add_option("cache",
+					   "",
+					   "cache-memlayer-triminterval",
+					   "Minimum time between each attempt to trim cache memory layers in seconds. Default set to 60 (1 min).",
+					   cxxopts::value<uint64_t>(ServerOptions.StructuredCacheConfig.MemTrimIntervalSeconds)->default_value("60"),
+					   "");
+
+	options.add_option("cache",
+					   "",
+					   "cache-memlayer-maxage",
+					   "Maximum age of payloads when trimming cache memory layers in seconds. Default set to 86400 (1 day).",
+					   cxxopts::value<uint64_t>(ServerOptions.StructuredCacheConfig.MemMaxAgeSeconds)->default_value("86400"),
 					   "");
 
 	options.add_option("compute",