node: cap -dbcache to 1GiB on 32-bit architectures

32-bit architecture is limited to 4GiB, so it doesn't make sense to set a too
high value. Since this setting is performance critical, pick an arbitrary value
higher than for -maxmempool but still reasonable.

Author: darosior

src/node/caches.cpp

@@ -19,6 +19,8 @@
 static constexpr size_t MAX_TX_INDEX_CACHE{1024_MiB};
 //! Max memory allocated to all block filter index caches combined in bytes.
 static constexpr size_t MAX_FILTER_INDEX_CACHE{1024_MiB};
+//! Maximum dbcache size on 32-bit systems.
+static constexpr size_t MAX_32BIT_DBCACHE{1024_MiB};
 
 namespace node {
 CacheSizes CalculateCacheSizes(const ArgsManager& args, size_t n_indexes)
@@ -28,7 +30,8 @@ CacheSizes CalculateCacheSizes(const ArgsManager& args, size_t n_indexes)
     if (std::optional<int64_t> db_cache = args.GetIntArg("-dbcache")) {
         if (*db_cache < 0) db_cache = 0;
         uint64_t db_cache_bytes = SaturatingLeftShift<uint64_t>(*db_cache, 20);
-        total_cache = std::max<size_t>(MIN_DB_CACHE, std::min<uint64_t>(db_cache_bytes, std::numeric_limits<size_t>::max()));
+        constexpr auto max_db_cache{sizeof(void*) == 4 ? MAX_32BIT_DBCACHE : std::numeric_limits<size_t>::max()};
+        total_cache = std::max<size_t>(MIN_DB_CACHE, std::min<uint64_t>(db_cache_bytes, max_db_cache));
     }
 
     IndexCacheSizes index_sizes;