1 files changed, 51 insertions, 23 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 9a3c272e0e..794edc30fb 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -57,7 +57,7 @@ bool fPruneMode = false;
 bool fIsBareMultisigStd = true;
 bool fCheckBlockIndex = false;
 bool fCheckpointsEnabled = true;
-unsigned int nCoinCacheSize = 5000;
+size_t nCoinCacheUsage = 5000 * 300;
 uint64_t nPruneTarget = 0;
 
 /** Fees smaller than this (in satoshi) are considered zero fee (for relaying and mining) */
@@ -1880,6 +1880,8 @@ enum FlushStateMode {
 bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode) {
     LOCK2(cs_main, cs_LastBlockFile);
     static int64_t nLastWrite = 0;
+    static int64_t nLastFlush = 0;
+    static int64_t nLastSetChain = 0;
     std::set<int> setFilesToPrune;
     bool fFlushForPrune = false;
     try {
@@ -1893,16 +1895,32 @@ bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode) {
             }
         }
     }
-    if ((mode == FLUSH_STATE_ALWAYS) ||
-        ((mode == FLUSH_STATE_PERIODIC || mode == FLUSH_STATE_IF_NEEDED) && pcoinsTip->GetCacheSize() > nCoinCacheSize) ||
-        (mode == FLUSH_STATE_PERIODIC && GetTimeMicros() > nLastWrite + DATABASE_WRITE_INTERVAL * 1000000) ||
-        fFlushForPrune) {
-        // Typical CCoins structures on disk are around 100 bytes in size.
-        // Pushing a new one to the database can cause it to be written
-        // twice (once in the log, and once in the tables). This is already
-        // an overestimation, as most will delete an existing entry or
-        // overwrite one. Still, use a conservative safety factor of 2.
-        if (!CheckDiskSpace(100 * 2 * 2 * pcoinsTip->GetCacheSize()))
+    int64_t nNow = GetTimeMicros();
+    // Avoid writing/flushing immediately after startup.
+    if (nLastWrite == 0) {
+        nLastWrite = nNow;
+    }
+    if (nLastFlush == 0) {
+        nLastFlush = nNow;
+    }
+    if (nLastSetChain == 0) {
+        nLastSetChain = nNow;
+    }
+    size_t cacheSize = pcoinsTip->DynamicMemoryUsage();
+    // The cache is large and close to the limit, but we have time now (not in the middle of a block processing).
+    bool fCacheLarge = mode == FLUSH_STATE_PERIODIC && cacheSize * (10.0/9) > nCoinCacheUsage;
+    // The cache is over the limit, we have to write now.
+    bool fCacheCritical = mode == FLUSH_STATE_IF_NEEDED && cacheSize > nCoinCacheUsage;
+    // It's been a while since we wrote the block index to disk. Do this frequently, so we don't need to redownload after a crash.
+    bool fPeriodicWrite = mode == FLUSH_STATE_PERIODIC && nNow > nLastWrite + (int64_t)DATABASE_WRITE_INTERVAL * 1000000;
+    // It's been very long since we flushed the cache. Do this infrequently, to optimize cache usage.
+    bool fPeriodicFlush = mode == FLUSH_STATE_PERIODIC && nNow > nLastFlush + (int64_t)DATABASE_FLUSH_INTERVAL * 1000000;
+    // Combine all conditions that result in a full cache flush.
+    bool fDoFullFlush = (mode == FLUSH_STATE_ALWAYS) || fCacheLarge || fCacheCritical || fPeriodicFlush || fFlushForPrune;
+    // Write blocks and block index to disk.
+    if (fDoFullFlush || fPeriodicWrite) {
+        // Depend on nMinDiskSpace to ensure we can write block index
+        if (!CheckDiskSpace(0))
             return state.Error("out of disk space");
         // First make sure all block and undo data is flushed to disk.
         FlushBlockFile();
@@ -1924,21 +1942,31 @@ bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode) {
                 return state.Abort("Files to write to block index database");
             }
         }
-        // Flush the chainstate (which may refer to block index entries).
-        if (!pcoinsTip->Flush())
-            return state.Abort("Failed to write to coin database");
-
         // Finally remove any pruned files
         if (fFlushForPrune) {
             UnlinkPrunedFiles(setFilesToPrune);
             fCheckForPruning = false;
         }
-
+        nLastWrite = nNow;
+    }
+    // Flush best chain related state. This can only be done if the blocks / block index write was also done.
+    if (fDoFullFlush) {
+        // Typical CCoins structures on disk are around 128 bytes in size.
+        // Pushing a new one to the database can cause it to be written
+        // twice (once in the log, and once in the tables). This is already
+        // an overestimation, as most will delete an existing entry or
+        // overwrite one. Still, use a conservative safety factor of 2.
+        if (!CheckDiskSpace(128 * 2 * 2 * pcoinsTip->GetCacheSize()))
+            return state.Error("out of disk space");
+        // Flush the chainstate (which may refer to block index entries).
+        if (!pcoinsTip->Flush())
+            return state.Abort("Failed to write to coin database");
+        nLastFlush = nNow;
+    }
+    if ((mode == FLUSH_STATE_ALWAYS || mode == FLUSH_STATE_PERIODIC) && nNow > nLastSetChain + (int64_t)DATABASE_WRITE_INTERVAL * 1000000) {
         // Update best block in wallet (so we can detect restored wallets).
-        if (mode != FLUSH_STATE_IF_NEEDED) {
-            GetMainSignals().SetBestChain(chainActive.GetLocator());
-        }
-        nLastWrite = GetTimeMicros();
+        GetMainSignals().SetBestChain(chainActive.GetLocator());
+        nLastSetChain = nNow;
     }
     } catch (const std::runtime_error& e) {
         return state.Abort(std::string("System error while flushing: ") + e.what());
@@ -1966,10 +1994,10 @@ void static UpdateTip(CBlockIndex *pindexNew) {
     nTimeBestReceived = GetTime();
     mempool.AddTransactionsUpdated(1);
 
-    LogPrintf("%s: new best=%s  height=%d  log2_work=%.8g  tx=%lu  date=%s progress=%f  cache=%u\n", __func__,
+    LogPrintf("%s: new best=%s  height=%d  log2_work=%.8g  tx=%lu  date=%s progress=%f  cache=%.1fMiB(%utx)\n", __func__,
       chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(), log(chainActive.Tip()->nChainWork.getdouble())/log(2.0), (unsigned long)chainActive.Tip()->nChainTx,
       DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()),
-      Checkpoints::GuessVerificationProgress(chainParams.Checkpoints(), chainActive.Tip()), (unsigned int)pcoinsTip->GetCacheSize());
+      Checkpoints::GuessVerificationProgress(chainParams.Checkpoints(), chainActive.Tip()), pcoinsTip->DynamicMemoryUsage() * (1.0 / (1<<20)), pcoinsTip->GetCacheSize());
 
     cvBlockChange.notify_all();
 
@@ -3197,7 +3225,7 @@ bool CVerifyDB::VerifyDB(CCoinsView *coinsview, int nCheckLevel, int nCheckDepth
             }
         }
         // check level 3: check for inconsistencies during memory-only disconnect of tip blocks
-        if (nCheckLevel >= 3 && pindex == pindexState && (coins.GetCacheSize() + pcoinsTip->GetCacheSize()) <= nCoinCacheSize) {
+        if (nCheckLevel >= 3 && pindex == pindexState && (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <= nCoinCacheUsage) {
             bool fClean = true;
             if (!DisconnectBlock(block, state, pindex, coins, &fClean))
                 return error("VerifyDB(): *** irrecoverable inconsistency in block data at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());