Merge pull request #6102

86a5f4b Relocate calls to CheckDiskSpace (Alex Morcos)
67708ac Write block index more frequently than cache flushes (Pieter Wuille)
b3ed423 Cache tweak and logging improvements (Pieter Wuille)
fc684ad Use accurate memory for flushing decisions (Pieter Wuille)
046392d Keep track of memory usage in CCoinsViewCache (Pieter Wuille)
540629c Add memusage.h (Pieter Wuille)

9 files changed, 243 insertions, 42 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 1621b2dcd0..91d530222f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -100,6 +100,7 @@ BITCOIN_CORE_H = \
   leveldbwrapper.h \
   limitedmap.h \
   main.h \
+  memusage.h \
   merkleblock.h \
   miner.h \
   mruset.h \
diff --git a/src/coins.cpp b/src/coins.cpp
index d79e29951b..a41d5a310d 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -4,6 +4,7 @@
 
 #include "coins.h"
 
+#include "memusage.h"
 #include "random.h"
 
 #include <assert.h>
@@ -57,13 +58,17 @@ bool CCoinsViewBacked::GetStats(CCoinsStats &stats) const { return base->GetStat
 
 CCoinsKeyHasher::CCoinsKeyHasher() : salt(GetRandHash()) {}
 
-CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), hasModifier(false) { }
+CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), hasModifier(false), cachedCoinsUsage(0) { }
 
 CCoinsViewCache::~CCoinsViewCache()
 {
     assert(!hasModifier);
 }
 
+size_t CCoinsViewCache::DynamicMemoryUsage() const {
+    return memusage::DynamicUsage(cacheCoins) + cachedCoinsUsage;
+}
+
 CCoinsMap::const_iterator CCoinsViewCache::FetchCoins(const uint256 &txid) const {
     CCoinsMap::iterator it = cacheCoins.find(txid);
     if (it != cacheCoins.end())
@@ -78,6 +83,7 @@ CCoinsMap::const_iterator CCoinsViewCache::FetchCoins(const uint256 &txid) const
         // version as fresh.
         ret->second.flags = CCoinsCacheEntry::FRESH;
     }
+    cachedCoinsUsage += memusage::DynamicUsage(ret->second.coins);
     return ret;
 }
 
@@ -93,6 +99,7 @@ bool CCoinsViewCache::GetCoins(const uint256 &txid, CCoins &coins) const {
 CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) {
     assert(!hasModifier);
     std::pair<CCoinsMap::iterator, bool> ret = cacheCoins.insert(std::make_pair(txid, CCoinsCacheEntry()));
+    size_t cachedCoinUsage = 0;
     if (ret.second) {
         if (!base->GetCoins(txid, ret.first->second.coins)) {
             // The parent view does not have this entry; mark it as fresh.
@@ -102,10 +109,12 @@ CCoinsModifier CCoinsViewCache::ModifyCoins(const uint256 &txid) {
             // The parent view only has a pruned entry for this; mark it as fresh.
             ret.first->second.flags = CCoinsCacheEntry::FRESH;
         }
+    } else {
+        cachedCoinUsage = memusage::DynamicUsage(ret.first->second.coins);
     }
     // Assume that whenever ModifyCoins is called, the entry will be modified.
     ret.first->second.flags |= CCoinsCacheEntry::DIRTY;
-    return CCoinsModifier(*this, ret.first);
+    return CCoinsModifier(*this, ret.first, cachedCoinUsage);
 }
 
 const CCoins* CCoinsViewCache::AccessCoins(const uint256 &txid) const {
@@ -150,6 +159,7 @@ bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn
                     assert(it->second.flags & CCoinsCacheEntry::FRESH);
                     CCoinsCacheEntry& entry = cacheCoins[it->first];
                     entry.coins.swap(it->second.coins);
+                    cachedCoinsUsage += memusage::DynamicUsage(entry.coins);
                     entry.flags = CCoinsCacheEntry::DIRTY | CCoinsCacheEntry::FRESH;
                 }
             } else {
@@ -157,10 +167,13 @@ bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn
                     // The grandparent does not have an entry, and the child is
                     // modified and being pruned. This means we can just delete
                     // it from the parent.
+                    cachedCoinsUsage -= memusage::DynamicUsage(itUs->second.coins);
                     cacheCoins.erase(itUs);
                 } else {
                     // A normal modification.
+                    cachedCoinsUsage -= memusage::DynamicUsage(itUs->second.coins);
                     itUs->second.coins.swap(it->second.coins);
+                    cachedCoinsUsage += memusage::DynamicUsage(itUs->second.coins);
                     itUs->second.flags |= CCoinsCacheEntry::DIRTY;
                 }
             }
@@ -175,6 +188,7 @@ bool CCoinsViewCache::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlockIn
 bool CCoinsViewCache::Flush() {
     bool fOk = base->BatchWrite(cacheCoins, hashBlock);
     cacheCoins.clear();
+    cachedCoinsUsage = 0;
     return fOk;
 }
 
@@ -232,7 +246,7 @@ double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
     return tx.ComputePriority(dResult);
 }
 
-CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_) : cache(cache_), it(it_) {
+CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_, size_t usage) : cache(cache_), it(it_), cachedCoinUsage(usage) {
     assert(!cache.hasModifier);
     cache.hasModifier = true;
 }
@@ -242,7 +256,11 @@ CCoinsModifier::~CCoinsModifier()
     assert(cache.hasModifier);
     cache.hasModifier = false;
     it->second.coins.Cleanup();
+    cache.cachedCoinsUsage -= cachedCoinUsage; // Subtract the old usage
     if ((it->second.flags & CCoinsCacheEntry::FRESH) && it->second.coins.IsPruned()) {
         cache.cacheCoins.erase(it);
+    } else {
+        // If the coin still exists after the modification, add the new usage
+        cache.cachedCoinsUsage += memusage::DynamicUsage(it->second.coins);
     }
 }
diff --git a/src/coins.h b/src/coins.h
index fe2eaa08e5..a4671645df 100644
--- a/src/coins.h
+++ b/src/coins.h
@@ -7,6 +7,7 @@
 #define BITCOIN_COINS_H
 
 #include "compressor.h"
+#include "memusage.h"
 #include "serialize.h"
 #include "uint256.h"
 
@@ -252,6 +253,15 @@ public:
                 return false;
         return true;
     }
+
+    size_t DynamicMemoryUsage() const {
+        size_t ret = memusage::DynamicUsage(vout);
+        BOOST_FOREACH(const CTxOut &out, vout) {
+            const std::vector<unsigned char> *script = &out.scriptPubKey;
+            ret += memusage::DynamicUsage(*script);
+        }
+        return ret;
+    }
 };
 
 class CCoinsKeyHasher
@@ -356,7 +366,8 @@ class CCoinsModifier
 private:
     CCoinsViewCache& cache;
     CCoinsMap::iterator it;
-    CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_);
+    size_t cachedCoinUsage; // Cached memory usage of the CCoins object before modification
+    CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_, size_t usage);
 
 public:
     CCoins* operator->() { return &it->second.coins; }
@@ -372,6 +383,7 @@ protected:
     /* Whether this cache has an active modifier. */
     bool hasModifier;
 
+
     /**
      * Make mutable so that we can "fill the cache" even from Get-methods
      * declared as "const".  
@@ -379,6 +391,9 @@ protected:
     mutable uint256 hashBlock;
     mutable CCoinsMap cacheCoins;
 
+    /* Cached dynamic memory usage for the inner CCoins objects. */
+    mutable size_t cachedCoinsUsage;
+
 public:
     CCoinsViewCache(CCoinsView *baseIn);
     ~CCoinsViewCache();
@@ -414,6 +429,9 @@ public:
     //! Calculate the size of the cache (in number of transactions)
     unsigned int GetCacheSize() const;
 
+    //! Calculate the size of the cache (in bytes)
+    size_t DynamicMemoryUsage() const;
+
     /** 
      * Amount of bitcoins coming in to a transaction
      * Note that lightweight clients may not know anything besides the hash of previous transactions,
diff --git a/src/init.cpp b/src/init.cpp
index bacc938375..2d75850253 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1061,18 +1061,20 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     }
 
     // cache size calculations
-    size_t nTotalCache = (GetArg("-dbcache", nDefaultDbCache) << 20);
-    if (nTotalCache < (nMinDbCache << 20))
-        nTotalCache = (nMinDbCache << 20); // total cache cannot be less than nMinDbCache
-    else if (nTotalCache > (nMaxDbCache << 20))
-        nTotalCache = (nMaxDbCache << 20); // total cache cannot be greater than nMaxDbCache
-    size_t nBlockTreeDBCache = nTotalCache / 8;
+    int64_t nTotalCache = (GetArg("-dbcache", nDefaultDbCache) << 20);
+    nTotalCache = std::max(nTotalCache, nMinDbCache << 20); // total cache cannot be less than nMinDbCache
+    nTotalCache = std::min(nTotalCache, nMaxDbCache << 20); // total cache cannot be greated than nMaxDbcache
+    int64_t nBlockTreeDBCache = nTotalCache / 8;
     if (nBlockTreeDBCache > (1 << 21) && !GetBoolArg("-txindex", false))
         nBlockTreeDBCache = (1 << 21); // block tree db cache shouldn't be larger than 2 MiB
     nTotalCache -= nBlockTreeDBCache;
-    size_t nCoinDBCache = nTotalCache / 2; // use half of the remaining cache for coindb cache
+    int64_t nCoinDBCache = std::min(nTotalCache / 2, (nTotalCache / 4) + (1 << 23)); // use 25%-50% of the remainder for disk cache
     nTotalCache -= nCoinDBCache;
-    nCoinCacheSize = nTotalCache / 300; // coins in memory require around 300 bytes
+    nCoinCacheUsage = nTotalCache; // the rest goes to in-memory cache
+    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));
 
     bool fLoaded = false;
     while (!fLoaded) {
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());
diff --git a/src/main.h b/src/main.h
index 90b809e85e..fcbc4075d2 100644
--- a/src/main.h
+++ b/src/main.h
@@ -82,8 +82,10 @@ static const unsigned int MAX_HEADERS_RESULTS = 2000;
  *  degree of disordering of blocks on disk (which make reindexing and in the future perhaps pruning
  *  harder). We'll probably want to make this a per-peer adaptive value at some point. */
 static const unsigned int BLOCK_DOWNLOAD_WINDOW = 1024;
-/** Time to wait (in seconds) between writing blockchain state to disk. */
-static const unsigned int DATABASE_WRITE_INTERVAL = 3600;
+/** Time to wait (in seconds) between writing blocks/block index to disk. */
+static const unsigned int DATABASE_WRITE_INTERVAL = 60 * 60;
+/** Time to wait (in seconds) between flushing chainstate to disk. */
+static const unsigned int DATABASE_FLUSH_INTERVAL = 24 * 60 * 60;
 /** Maximum length of reject messages. */
 static const unsigned int MAX_REJECT_MESSAGE_LENGTH = 111;
 
@@ -119,7 +121,7 @@ extern bool fTxIndex;
 extern bool fIsBareMultisigStd;
 extern bool fCheckBlockIndex;
 extern bool fCheckpointsEnabled;
-extern unsigned int nCoinCacheSize;
+extern size_t nCoinCacheUsage;
 extern CFeeRate minRelayTxFee;
 
 /** Best header we've seen so far (used for getheaders queries' starting points). */
diff --git a/src/memusage.h b/src/memusage.h
new file mode 100644
index 0000000000..9f7de9e2e1
--- /dev/null
+++ b/src/memusage.h
@@ -0,0 +1,111 @@
+// Copyright (c) 2015 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_MEMUSAGE_H
+#define BITCOIN_MEMUSAGE_H
+
+#include <stdlib.h>
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include <boost/unordered_set.hpp>
+#include <boost/unordered_map.hpp>
+
+namespace memusage
+{
+
+/** Compute the total memory used by allocating alloc bytes. */
+static size_t MallocUsage(size_t alloc);
+
+/** Compute the memory used for dynamically allocated but owned data structures.
+ *  For generic data types, this is *not* recursive. DynamicUsage(vector<vector<int> >)
+ *  will compute the memory used for the vector<int>'s, but not for the ints inside.
+ *  This is for efficiency reasons, as these functions are intended to be fast. If
+ *  application data structures require more accurate inner accounting, they should
+ *  do the recursion themselves, or use more efficient caching + updating on modification.
+ */
+template<typename X> static size_t DynamicUsage(const std::vector<X>& v);
+template<typename X> static size_t DynamicUsage(const std::set<X>& s);
+template<typename X, typename Y> static size_t DynamicUsage(const std::map<X, Y>& m);
+template<typename X, typename Y> static size_t DynamicUsage(const boost::unordered_set<X, Y>& s);
+template<typename X, typename Y, typename Z> static size_t DynamicUsage(const boost::unordered_map<X, Y, Z>& s);
+template<typename X> static size_t DynamicUsage(const X& x);
+
+static inline size_t MallocUsage(size_t alloc)
+{
+    // Measured on libc6 2.19 on Linux.
+    if (sizeof(void*) == 8) {
+        return ((alloc + 31) >> 4) << 4;
+    } else if (sizeof(void*) == 4) {
+        return ((alloc + 15) >> 3) << 3;
+    } else {
+        assert(0);
+    }
+}
+
+// STL data structures
+
+template<typename X>
+struct stl_tree_node
+{
+private:
+    int color;
+    void* parent;
+    void* left;
+    void* right;
+    X x;
+};
+
+template<typename X>
+static inline size_t DynamicUsage(const std::vector<X>& v)
+{
+    return MallocUsage(v.capacity() * sizeof(X));
+}
+
+template<typename X>
+static inline size_t DynamicUsage(const std::set<X>& s)
+{
+    return MallocUsage(sizeof(stl_tree_node<X>)) * s.size();
+}
+
+template<typename X, typename Y>
+static inline size_t DynamicUsage(const std::map<X, Y>& m)
+{
+    return MallocUsage(sizeof(stl_tree_node<std::pair<const X, Y> >)) * m.size();
+}
+
+// Boost data structures
+
+template<typename X>
+struct boost_unordered_node : private X
+{
+private:
+    void* ptr;
+};
+
+template<typename X, typename Y>
+static inline size_t DynamicUsage(const boost::unordered_set<X, Y>& s)
+{
+    return MallocUsage(sizeof(boost_unordered_node<X>)) * s.size() + MallocUsage(sizeof(void*) * s.bucket_count());
+}
+
+template<typename X, typename Y, typename Z>
+static inline size_t DynamicUsage(const boost::unordered_map<X, Y, Z>& m)
+{
+    return MallocUsage(sizeof(boost_unordered_node<std::pair<const X, Y> >)) * m.size() + MallocUsage(sizeof(void*) * m.bucket_count());
+}
+
+// Dispatch to class method as fallback
+
+template<typename X>
+static inline size_t DynamicUsage(const X& x)
+{
+    return x.DynamicMemoryUsage();
+}
+
+}
+
+#endif
diff --git a/src/test/coins_tests.cpp b/src/test/coins_tests.cpp
index 2e2cc2214b..34b311b804 100644
--- a/src/test/coins_tests.cpp
+++ b/src/test/coins_tests.cpp
@@ -59,6 +59,24 @@ public:
 
     bool GetStats(CCoinsStats& stats) const { return false; }
 };
+
+class CCoinsViewCacheTest : public CCoinsViewCache
+{
+public:
+    CCoinsViewCacheTest(CCoinsView* base) : CCoinsViewCache(base) {}
+
+    void SelfTest() const
+    {
+        // Manually recompute the dynamic usage of the whole data, and compare it.
+        size_t ret = memusage::DynamicUsage(cacheCoins);
+        for (CCoinsMap::iterator it = cacheCoins.begin(); it != cacheCoins.end(); it++) {
+            ret += memusage::DynamicUsage(it->second.coins);
+        }
+        BOOST_CHECK_EQUAL(memusage::DynamicUsage(*this), ret);
+    }
+
+};
+
 }
 
 BOOST_FIXTURE_TEST_SUITE(coins_tests, BasicTestingSetup)
@@ -90,8 +108,8 @@ BOOST_AUTO_TEST_CASE(coins_cache_simulation_test)
 
     // The cache stack.
     CCoinsViewTest base; // A CCoinsViewTest at the bottom.
-    std::vector<CCoinsViewCache*> stack; // A stack of CCoinsViewCaches on top.
-    stack.push_back(new CCoinsViewCache(&base)); // Start with one cache.
+    std::vector<CCoinsViewCacheTest*> stack; // A stack of CCoinsViewCaches on top.
+    stack.push_back(new CCoinsViewCacheTest(&base)); // Start with one cache.
 
     // Use a limited set of random transaction ids, so we do test overwriting entries.
     std::vector<uint256> txids;
@@ -136,6 +154,9 @@ BOOST_AUTO_TEST_CASE(coins_cache_simulation_test)
                     missed_an_entry = true;
                 }
             }
+            BOOST_FOREACH(const CCoinsViewCacheTest *test, stack) {
+                test->SelfTest();
+            }
         }
 
         if (insecure_rand() % 100 == 0) {
@@ -152,7 +173,7 @@ BOOST_AUTO_TEST_CASE(coins_cache_simulation_test)
                 } else {
                     removed_all_caches = true;
                 }
-                stack.push_back(new CCoinsViewCache(tip));
+                stack.push_back(new CCoinsViewCacheTest(tip));
                 if (stack.size() == 4) {
                     reached_4_caches = true;
                 }
diff --git a/src/txdb.h b/src/txdb.h
index 86e1c5d831..bef5dc9fd1 100644
--- a/src/txdb.h
+++ b/src/txdb.h
@@ -22,7 +22,7 @@ class uint256;
 //! -dbcache default (MiB)
 static const int64_t nDefaultDbCache = 100;
 //! max. -dbcache in (MiB)
-static const int64_t nMaxDbCache = sizeof(void*) > 4 ? 4096 : 1024;
+static const int64_t nMaxDbCache = sizeof(void*) > 4 ? 16384 : 1024;
 //! min. -dbcache in (MiB)
 static const int64_t nMinDbCache = 4;