Add CChainState::ResizeCoinsCaches

Also adds CCoinsViewCache::ReallocateCache() to attempt to free
memory that the cacheCoins's allocator may be hanging onto when
downsizing the cache.

Adds `CChainState::m_coins{tip,db}_cache_size_bytes` data members
so that we can reference cache size on a per-chainstate basis for
flushing.

1 files changed, 37 insertions, 4 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index dbdf5028fd..1d7d85b751 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -135,7 +135,6 @@ bool fPruneMode = false;
 bool fRequireStandard = true;
 bool fCheckBlockIndex = false;
 bool fCheckpointsEnabled = DEFAULT_CHECKPOINTS_ENABLED;
-size_t nCoinCacheUsage = 5000 * 300;
 uint64_t nPruneTarget = 0;
 int64_t nMaxTipAge = DEFAULT_MAX_TIP_AGE;
 
@@ -1279,9 +1278,10 @@ void CChainState::InitCoinsDB(
         leveldb_name, cache_size_bytes, in_memory, should_wipe);
 }
 
-void CChainState::InitCoinsCache()
+void CChainState::InitCoinsCache(size_t cache_size_bytes)
 {
     assert(m_coins_views != nullptr);
+    m_coinstip_cache_size_bytes = cache_size_bytes;
     m_coins_views->InitCache();
 }
 
@@ -2228,7 +2228,7 @@ CoinsCacheSizeState CChainState::GetCoinsCacheSizeState(const CTxMemPool& tx_poo
 {
     return this->GetCoinsCacheSizeState(
         tx_pool,
-        nCoinCacheUsage,
+        m_coinstip_cache_size_bytes,
         gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000);
 }
 
@@ -4300,7 +4300,7 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
             }
         }
         // check level 3: check for inconsistencies during memory-only disconnect of tip blocks
-        if (nCheckLevel >= 3 && (coins.DynamicMemoryUsage() + ::ChainstateActive().CoinsTip().DynamicMemoryUsage()) <= nCoinCacheUsage) {
+        if (nCheckLevel >= 3 && (coins.DynamicMemoryUsage() + ::ChainstateActive().CoinsTip().DynamicMemoryUsage()) <= ::ChainstateActive().m_coinstip_cache_size_bytes) {
             assert(coins.GetBestBlock() == pindex->GetBlockHash());
             DisconnectResult res = ::ChainstateActive().DisconnectBlock(block, pindex, coins);
             if (res == DISCONNECT_FAILED) {
@@ -4965,6 +4965,39 @@ std::string CChainState::ToString()
         tip ? tip->nHeight : -1, tip ? tip->GetBlockHash().ToString() : "null");
 }
 
+bool CChainState::ResizeCoinsCaches(size_t coinstip_size, size_t coinsdb_size)
+{
+    if (coinstip_size == m_coinstip_cache_size_bytes &&
+            coinsdb_size == m_coinsdb_cache_size_bytes) {
+        // Cache sizes are unchanged, no need to continue.
+        return true;
+    }
+    size_t old_coinstip_size = m_coinstip_cache_size_bytes;
+    m_coinstip_cache_size_bytes = coinstip_size;
+    m_coinsdb_cache_size_bytes = coinsdb_size;
+    CoinsDB().ResizeCache(coinsdb_size);
+
+    LogPrintf("[%s] resized coinsdb cache to %.1f MiB\n",
+        this->ToString(), coinsdb_size * (1.0 / 1024 / 1024));
+    LogPrintf("[%s] resized coinstip cache to %.1f MiB\n",
+        this->ToString(), coinstip_size * (1.0 / 1024 / 1024));
+
+    BlockValidationState state;
+    const CChainParams& chainparams = Params();
+
+    bool ret;
+
+    if (coinstip_size > old_coinstip_size) {
+        // Likely no need to flush if cache sizes have grown.
+        ret = FlushStateToDisk(chainparams, state, FlushStateMode::IF_NEEDED);
+    } else {
+        // Otherwise, flush state to disk and deallocate the in-memory coins map.
+        ret = FlushStateToDisk(chainparams, state, FlushStateMode::ALWAYS);
+        CoinsTip().ReallocateCache();
+    }
+    return ret;
+}
+
 std::string CBlockFileInfo::ToString() const
 {
     return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, FormatISO8601Date(nTimeFirst), FormatISO8601Date(nTimeLast));