On Mar 22, 2013, Chris Mason <clmason@xxxxxxxxxxxx> wrote:
> Quoting Samuel Just (2013-03-22 13:06:41)
>> Incomplete writes for leveldb should just result in lost updates, not
>> corruption.
> In this case, I think Alexandre is scanning for zeros in the file.
Yup, the symptom is zeros at the end of a page, with nonzeros on the
subsequent page, which indicates that the writes to the previous page
were dropped.
What I actually do is to iterate over the entire database, which will
error out when the block header is found to be corrupted. I use this
program I wrote (also hereby provided under GNU GPLv3+) to check the
database for corruption.
#include <assert.h>
#include <iostream>
#include "leveldb/db.h"
int main(int argc, char *argv[]) {
bool paranoid = false;
bool dump = false;
bool repair = false;
bool quiet = false;
int i = 0;
int errors = 0;
if (argc == 1) {
usage:
std::cout << "usage: [flags] dbname [flags] ..." << std::endl
<< "-d --dump dump database contents" << std::endl
<< "-r --repair repair database" << std::endl
<< "-p --paranoid enable paranoid mode" << std::endl
<< "-l --lax disable paranoid mode (default)" << std::endl
<< "-q --quiet enable quiet mode" << std::endl
<< "-v --verbose disable quiet mode (default)" << std::endl
<< "-h --help show this message and exit" << std::endl
<< "dbname check, dump and repair" << std::endl
<< std::endl
<< "exit status is the number of errors" << std::endl;
return errors;
}
for (i++; i < argc; i++) {
if (argv[i][0] == '-') {
if (strcmp (argv[i], "--dump") == 0
|| strcmp (argv[i], "-d") == 0)
dump = true;
else if (strcmp (argv[i], "--repair") == 0
|| strcmp (argv[i], "-r") == 0)
repair = true;
else if (strcmp (argv[i], "--paranoid") == 0
|| strcmp (argv[i], "-p") == 0)
paranoid = true;
else if (strcmp (argv[i], "--lax") == 0
|| strcmp (argv[i], "-l") == 0)
paranoid = false;
else if (strcmp (argv[i], "--quiet") == 0
|| strcmp (argv[i], "-q") == 0)
quiet = true;
else if (strcmp (argv[i], "--verbose") == 0
|| strcmp (argv[i], "-v") == 0)
quiet = false;
else if (strcmp (argv[i], "--help") == 0
|| strcmp (argv[i], "-h") == 0)
goto usage;
else {
std::cerr << "unrecognized option: " << argv[i] << std::endl;
goto usage;
}
} else {
if (!quiet)
std::cout << argv[i] << std::endl;
leveldb::DB* db;
leveldb::Options options;
options.paranoid_checks = paranoid;
leveldb::Status status = leveldb::DB::Open(options, argv[i], &db);
bool bad = false;
if (!status.ok()) {
std::cerr << status.ToString() << std::endl;
bad = true;
} else {
leveldb::ReadOptions rdopt;
rdopt.verify_checksums = paranoid;
rdopt.fill_cache = false;
leveldb::Iterator* it = db->NewIterator(rdopt);
int count = 0;
try {
for (it->SeekToFirst(); it->Valid(); it->Next()) {
count++;
if (dump)
std::cout << it->key().ToString() << ": "
<< it->value().ToString() << std::endl;
else if (!quiet && count % 1000 == 0)
std::cout << count << " entries\r" << std::flush;
}
if (!it->status().ok()) {
std::cerr << it->status().ToString() << std::endl;
bad = true;
}
} catch (...) {
std::cerr << "caught an exception" << std::endl;
}
delete it;
if (!quiet)
std::cout << count << " entries" << std::endl;
}
delete db;
if (bad) {
errors++;
if (repair) {
if (!quiet)
std::cout << "repairing..." << std::endl;
status = RepairDB(argv[i], options);
if (!status.ok()) {
std::cerr << status.ToString() << std::endl;
errors++;
}
} else if (!quiet)
std::cout << "use --repair to repair" << std::endl;
}
}
}
return errors;
}
--
Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/ FSF Latin America board member
Free Software Evangelist Red Hat Brazil Compiler Engineer
