locks exhaustion fix

src/db.cpp

@@ -9,6 +9,7 @@
 #include "util.h"
 #include "main.h"
 #include "kernel.h"
+#include "ui_interface.h"
 #include <boost/version.hpp>
 #include <boost/filesystem.hpp>
 #include <boost/filesystem/fstream.hpp>
@@ -85,7 +86,11 @@ bool CDBEnv::Open(boost::filesystem::path pathEnv_)
     dbenv.set_cachesize(nDbCache / 1024, (nDbCache % 1024)*1048576, 1);
     dbenv.set_lg_bsize(1048576);
     dbenv.set_lg_max(10485760);
-    dbenv.set_lk_max_locks(10000);
+
+    // Bugfix: Bump lk_max_locks default to 537000, to safely handle reorgs with up to 5 blocks reversed
+    // dbenv.set_lk_max_locks(10000);
+    dbenv.set_lk_max_locks(537000);
+
     dbenv.set_lk_max_objects(10000);
     dbenv.set_errfile(fopen(pathErrorFile.string().c_str(), "a")); /// debug
     dbenv.set_flags(DB_AUTO_COMMIT, 1);
@@ -106,6 +111,30 @@ bool CDBEnv::Open(boost::filesystem::path pathEnv_)
 
     fDbEnvInit = true;
     fMockDb = false;
+
+    // Check that the number of locks is sufficient (to prevent chain fork possibility, read http://bitcoin.org/may15 for more info)
+    u_int32_t nMaxLocks;
+    if (!dbenv.get_lk_max_locks(&nMaxLocks))
+    {
+        int nBlocks, nDeepReorg;
+        std::string strMessage;
+
+        nBlocks = nMaxLocks / 48768;
+        nDeepReorg = (nBlocks - 1) / 2;
+
+        printf("Final lk_max_locks is %lu, sufficient for (worst case) %d block%s in a single transaction (up to a %d-deep reorganization)\n", (unsigned long)nMaxLocks, nBlocks, (nBlocks == 1) ? "" : "s", nDeepReorg);
+        if (nDeepReorg < 3)
+        {
+            if (nBlocks < 1)
+                strMessage = strprintf(_("Warning: DB_CONFIG has set_lk_max_locks %lu, which may be too low for a single block. If this limit is reached, NovaCoin may stop working."), (unsigned long)nMaxLocks);
+            else
+                strMessage = strprintf(_("Warning: DB_CONFIG has set_lk_max_locks %lu, which may be too low for a common blockchain reorganization. If this limit is reached, NovaCoin may stop working."), (unsigned long)nMaxLocks);
+
+            strMiscWarning = strMessage;
+            printf("*** %s\n", strMessage.c_str());
+        }
+    }
+
     return true;
 }