Share unused mempool memory with coincache

If the mempool is not completely full, treat the difference between
the maximum size and the actual usage as available for the coin cache.

This also changes the early flush trigger from (usage > 0.9 * space)
to (usage > 0.9 * space && usage > space - 100MB). This means we're not
permanently leaving 10% of the space unused when the space is large.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/init.cpp b/src/init.cpp
index e642729a9..0eb206ba8 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1330,10 +1330,11 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler)
     nCoinDBCache = std::min(nCoinDBCache, nMaxCoinsDBCache << 20); // cap total coins db cache
     nTotalCache -= nCoinDBCache;
     nCoinCacheUsage = nTotalCache; // the rest goes to in-memory cache
+    int64_t nMempoolSizeMax = GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
     LogPrintf("Cache configuration:\n");
     LogPrintf("* Using %.1fMiB for block index database\n", nBlockTreeDBCache * (1.0 / 1024 / 1024));
     LogPrintf("* Using %.1fMiB for chain state database\n", nCoinDBCache * (1.0 / 1024 / 1024));
-    LogPrintf("* Using %.1fMiB for in-memory UTXO set\n", nCoinCacheUsage * (1.0 / 1024 / 1024));
+    LogPrintf("* Using %.1fMiB for in-memory UTXO set (plus up to %.1fMiB of unused mempool space)\n", nCoinCacheUsage * (1.0 / 1024 / 1024), nMempoolSizeMax * (1.0 / 1024 / 1024));
 
     bool fLoaded = false;
     while (!fLoaded) {