Random db flush crash simulator

contrib/devtools/check-doc.py

@@ -21,7 +21,7 @@ CMD_GREP_DOCS = r"egrep -r -I 'HelpMessageOpt\(\"\-[^\"=]+?(=|\")' %s" % (CMD_RO
 REGEX_ARG = re.compile(r'(?:map(?:Multi)?Args(?:\.count\(|\[)|Get(?:Bool)?Arg\()\"(\-[^\"]+?)\"')
 REGEX_DOC = re.compile(r'HelpMessageOpt\(\"(\-[^\"=]+?)(?:=|\")')
 # list unsupported, deprecated and duplicate args as they need no documentation
-SET_DOC_OPTIONAL = set(['-rpcssl', '-benchmark', '-h', '-help', '-socks', '-tor', '-debugnet', '-whitelistalwaysrelay', '-prematurewitness', '-walletprematurewitness', '-promiscuousmempoolflags', '-blockminsize'])
+SET_DOC_OPTIONAL = set(['-rpcssl', '-benchmark', '-h', '-help', '-socks', '-tor', '-debugnet', '-whitelistalwaysrelay', '-prematurewitness', '-walletprematurewitness', '-promiscuousmempoolflags', '-blockminsize', '-dbcrashratio'])
 
 def main():
   used = check_output(CMD_GREP_ARGS, shell=True)

src/txdb.cpp

@@ -7,8 +7,10 @@
 
 #include "chainparams.h"
 #include "hash.h"
+#include "random.h"
 #include "pow.h"
 #include "uint256.h"
+#include "util.h"
 
 #include <stdint.h>
 
@@ -82,7 +84,7 @@ bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) {
     size_t count = 0;
     size_t changed = 0;
     size_t batch_size = (size_t)GetArg("-dbbatchsize", nDefaultDbBatchSize);
-
+    int crash_simulate = GetArg("-dbcrashratio", 0);
 
     uint256 old_tip = GetBestBlock();
     if (old_tip.IsNull()) {
@@ -124,6 +126,13 @@ bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) {
             LogPrint(BCLog::COINDB, "Writing partial batch of %.2f MiB\n", batch.SizeEstimate() * (1.0 / 1048576.0));
             db.WriteBatch(batch);
             batch.Clear();
+            if (crash_simulate) {
+                static FastRandomContext rng;
+                if (rng.randrange(crash_simulate) == 0) {
+                    LogPrintf("Simulating a crash. Goodbye.\n");
+                    exit(0);
+                }
+            }
         }
     }