Pass the CMake bit width setting to compile flags for blockchain_import
and blockchain_converter.
For LMDB on 32-bit, hyc has found that batch size of 100 appears to be a
good default.
3b13a74 Shutup about VERSION 0 (Howard Chu)
1537477 Use cursor in get_output_key (Howard Chu)
f2faf8c Use MDB_APPEND mode where possible (Howard Chu)
090b548 Use cursors in write txns (Howard Chu)
ed08d21 Keep a running blocksize count (Howard Chu)
0fc9334 Win32 import batchsize tweaks (Howard Chu)
27f76e2 blockchain_import: Build string for db type list (warptangent)
1aa8a9d blockchain_import: Add mode argument representing multiple DB flags (warptangent)
cffc411 blockchain_import: Support BerkeleyDB (warptangent)
19c1aaa blockchain_import: Add database type argument (warptangent)
0fedce0 blockchain_import: Make LMDB-specific names general (warptangent)
When keys are contiguous and monotonically increasing, this gets
denser page utilization (doesn't leave padding in page splits).
Can't be used for keys that are inserted in random order (e.g. hashes)
In total this only saves around 1.5% of space compared to original
DB code. The previous patch accounted for 0.8% savings on its own;
the blocks tables just aren't that big.
These modes match those optionally provided as part of the daemon's
--db-type argument.
Argument after the # is interpreted as a composite mode if there's only
one (no comma separated arguments).
Sample usage:
blockchain_import --database lmdb#fastest
blockchain_import --database berkeley#fastest
Multiple specific DB flags are still supported, e.g.
blockchain_import --database lmdb#nosync,nordahead
blockchain_import --database berkeley#txn_nosync
1995923 BlockchainLMDB: Deal with DB exceptions at block level with particularity (warptangent)
c16cc20 BlockchainLMDB: Add sanity check for inconsistent state (warptangent)
9118d0a BlockchainLMDB: Call destructor on allocated txn if setup fails (warptangent)
f5581c3 BlockchainLMDB: Replace remaining txn pointer NULLs with nullptr (warptangent)
c7e6b77 crypto: only check MONERO_USE_SOFTWARE_AES once (moneromooo-monero)
74aef21 crypto: use software AES based on the MONERO_USE_SOFTWARE_AES env var (moneromooo-monero)
Add another DB error exception type to distinguish failed txn setup from
general use of txn.
This keeps the error handling flow the same as before the block-level
txn setup changes that moved control up a layer to BlockchainDB.
Remove LINK_SEARCH_START_STATIC and LINK_SEARCH_END_STATIC. This is more
appropriate when the compiler flag -static is used.
This had been causing CMake to omit the linker flags necesssary to
distinguish static and dynamic library linking. CMake had assumed static
linking for the target, causing it to omit explicit static link flags.
That is problematic without the -static compile flag being set.
With a library located in system directories, like libboost_date_time,
the full static path (.a), though found correctly by CMake, was treated
by the linker as a dynamic library. This is because
target_link_libraries() transforms the full path to -l<libname> if it's
in a system directory. Without -static or explicit linker flags, the
dynamic library (.so) is linked.
Removing the above two properties removes the assumption of static. So
-Wl;-Bstatic is inserted where needed. This causes -l<libname> to
properly refer to the static library instead of dynamic.
Setting to no or 0 also works. If set, any other value enables it.
Useful for running with valgrind in cases where it fails at
properly implementing AES-NI.
We also replace the --fakechain option with an optional structure
containing details about configuration for the core/blockchain,
for test purposes. This seems more future friendly.
7658ac0 blockchain: revert handle_get_objects adding block id on tx not found (moneromooo-monero)
3a0f4d8 berkeleydb: fix delete/free mismatch (moneromooo-monero)
1642be2 minor bugfixes and refactoring (Thomas Winget)
098dcf2 unit_tests: fix mnemonics unit test testing invalid seeds (moneromooo-monero)
If it is, it points to reuse of a tx key, which isn't meant to happen.
If it does, a key image collision means that only one of those
outputs is spendable, so the wallet selects the larger amount,
unless that output was spent already.
This causes a discrepancy betewen reported received inputs and
payment total.
Since tx keys are 256 bits, this should never happen except if
done on purpose, or if a sender uses a bad PRNG.
Locking just one db turns out to not have been a good idea, since
the pool and p2p state fdles have to be used anyway.
Also ensure the directory exists before tring to lock.
- Blockchain should store if it's running on testnet or not
- moved loading compiled-in block hashes to its own function for clarity
- on handle_get_objects, should now correctly return false if a block's
transactions are missing
- replace instances of BOOST_FOREACH with C++11 for loops in Blockchain.
7fc6fa3 wallet: forbid dust altogether in output selection where appropriate (moneromooo-monero)
5e1a739 blockchain: log number of outputs available for a new tx (moneromooo-monero)
bcac101 daemon: fix a few issues reported by valgrind (moneromooo-monero)
a7e8174 tx_pool: fix serialization of new relayed data (moneromooo-monero)
601ad76 hardfork: fix mixup in indexing variable in get_voting_info (moneromooo-monero)
444e22f blockchain: remove unused timer (moneromooo-monero)
7edfdd8 blockchain: fix m_sync_counter uninitialized variable use (moneromooo-monero)
d97582c epee: use generate_random_bytes for new random uuids (moneromooo-monero)
17c7c9c epee: remove dodgy random code that nobody uses (moneromooo-monero)
A boost lock is used to determine whether more than one process
wants to access the database. The boost file_lock doesn't seem
to like locking directories, so we use an arbitrary file in it.
This allows to still run two daemons if they have different
database directories (ie, LMDB/BDB, different data directories).
In particular, ensure we check the status of RPC response structures,
as some functions will return success, but with a BUSY status, when
the daemon is not yet synced, and the response will not filled.
94b98fb tx_pool: do not accept txes not in a block if they timed out before (moneromooo-monero)
eadbdf3 tx_pool: fix use of invalidated iterator (moneromooo-monero)
3b1d7e0 Fix V1/V2 use of hard fork related parameters (moneromooo-monero)
This is intended to avoid cases where a timed out tx will be
re-relayed by another peer for which it has not timed out yet,
which would cause the tx to stay in the network's pool for a
long time (until all peers time it out before another one
tries to relay it again).
This improves blockchain reorganization time by allowing one of the more
expensive DB lookups when popping a block to not have to seek through a
long dup list in the "output_amounts" db. This is most noticeable for
HDDs.
See ffcf6bdb95
Data should be removed in the reverse order it was added.
This matches the order of removal in
blockchain_storage::pop_transaction_from_global_index.
See f11def012f
c5baf30 use load_file_to_string and exit with error on file read errors (Fabian Hirschmann)
7b2d27f remove new lines at the end of the password only (Fabian Hirschmann)
302cc9c add --password-file option (Fabian Hirschmann)
The value will be different depending on whether we've reached
the first hard fork, which allows a larger size, or not.
This fixes transactions being rejected by the daemon on mainnet
where the first hard fork is not yet active.
This ensures this will be done without fail, as the error prone
matching of every return with a call to KILL_IOSERVICE leads to
hard to debug corruption when one is missing.
- only try to stop if actually started
- print number of threads before zeroing it
This fixes the suspiciously doubled "Mining has been stopped"
message on exit.
Blockchain hashes and key images are flushed, and blocks are
pulled anew from the daemon.
The console command is shortened to match bc_height.
This should make it a lot easier on users who are currently
told to remove this particular cache file but keep the keys
one, etc, etc.
61ce8d6 wallet_rpc_server: exit async, so we reply to stop_wallet RPC (moneromooo-monero)
9847db6 wallet: do not return error if incoming_transfers finds none (moneromooo-monero)
b39aae7 Tweak 45800a25e9 (hyc)
4a5a5ff blockchain: always stop the ioservice before returning (moneromooo-monero)
78b65cf db_lmdb: safety close db at exit (moneromooo-monero)
45800a2 db_lmdb: fix a strdup/delete[] mistmatch (moneromooo-monero)
79beed2 tests: fix various tests by using parameters better suited to monero (moneromooo-monero)
d0a8362 tests: fix some double spending tests (moneromooo-monero)
2358d0d tests: use 255 as a "too high" block version (moneromooo-monero)
f33a88c blockchain: fix a few block addition bugs (moneromooo-monero)
a9ff11c blockchain: fix an off by one error in unlocked time check (moneromooo-monero)
f294be3 blockchain: reinstate double spending checks in check_tx_inputs (moneromooo-monero)
737b6d6 blockchain: make some flag twiddling code closer to the original (moneromooo-monero)
81cb0fc blockchain: fix bitflipping test with quantized block rewards (moneromooo-monero)
22ddf09 blockchain: add missing m_tx_pool.on_blockchain_dec (moneromooo-monero)
d837c0c blockchain: fix switch to alternative blockchain for more than one block (moneromooo-monero)
5cec076 blockchain: add a missing validity check to rollback_blockchain_switching (moneromooo-monero)
3cabdb5 core: catch exceptions from get_output_key (moneromooo-monero)
5eef645 db: throw when given a non txout_to_key output to add (moneromooo-monero)
If the block reward was too high, the verification failed flag
was set, but the function continued. The code which was supposed
to trap this flag and return failure failed to trap it, and,
while the block was not added to the chain, the function would
return success.
The reason for avoiding returning when the block reward problem
was detected was to be able to return any transactions to the
pool if needed. This is now mooted by moving the transaction
return code to a separate function, which is now called at all
appropriate points, making the logic much simpler, and hopefully
correct now.
We also move the hard fork version check after the prev_id check,
as block which does not go on the top of the chain might not
have the expected version there, without being invalid just for
this reason.
Last, we trap the case where a block fails to be added due to
using already spent key images, to set the verification failed
flag.
This fixes some double spending tests.
This may or may not be unneeded in normal (non test) circumstances,
to be determined later. Keeping these for now may be slower, but safer.
Block reward may now be less than the full amount allowed.
This was breaking the bitflipping test.
We now keep track of whether a block which was accepted by the core
has a lower than allowed block reward, and allow this in the test.
The check was explicit in the original version, so it seems
safer to make it explicit here, especially as it is now done
implicitely in a different place, away from the original check.
ffcf6bd BlockchainLMDB: When removing, find amount output index fast by starting at end (warptangent)
f11def0 BlockchainLMDB: Remove tx outputs in reverse order (warptangent)
Data should be removed in the reverse order it was added. Not doing so
breaks assumptions and can cause problems in other DB implementations.
This matches the order of tx removal in
blockchain_storage::purge_block_data_from_blockchain.
This improves blockchain reorganization time by allowing one of the more
expensive DB lookups when popping a block to not have to seek through a
long dup list in the "output_amounts" subdb. This is most noticeable for
HDDs.
As before, the dup list is still walked if necessary (but in reverse),
and the global output index still confirmed to be the one looked for.
But under proper use, the result will be found at the end of the dup
list, so we start there.
Removing an amount output index is always done in the context of popping
a block, so the global output index being looked for should be the last
one in that amount key's dup list. Even if the txs themselves aren't
removed in reverse order (supposed to be according to original
implementation), the specified amount output index will still be near
the end, because the txs are in the same block.
TEST:
Pop blocks with blockchain_import.
Blocks should be successfully removed with no errors shown.
bitmonerod should be able to start syncing from the reduced blockchain
height.
8ea7af1 Allow the wallet to access hard fork information (moneromooo-monero)
760331b epee: make log macros behave like statements (moneromooo-monero)
3f2970f Add missing semicolons after log statements (moneromooo-monero)
In particular, <boost/program_options.hpp> blows up daemon.cpp.obj,
making it too big to compile in debug mode on Win32. Even on a
release build it drops daemon.cpp.o on Linux from 31MB to 20MB.
This has no effect on the final linked binary size.
The version number passed to those data's serialize function
was always 0, not the wallet's version as I had expected.
A version number now exists for these structures so they're
versioned correctly.
9079a32 Fix typo (warptangent)
3796941 blockchain.cpp: Change indentation from 4 to 2 spaces (warptangent)
725acc7 Replace tabs with two spaces for consistency with rest of codebase (warptangent)
Sample use:
DNS_PUBLIC=tcp torsocks bin/bitmonerod --p2p-bind-ip 127.0.0.1
Test:
Run above with --log-level 4 with and without DNS_PUBLIC environment
variable set.
DNS debugging info should show successful DNS lookups only when
DNS_PUBLIC is set to "tcp":
DNS lookup for seeds.moneroseeds.se: 17 results
DNS lookup for seeds.moneroseeds.ae.org: 17 results
DNS lookup for seeds.moneroseeds.ch: 12 results
DNS lookup for seeds.moneroseeds.li: 12 results
cbded43 core_tests: fix ring_signature_1 tests (moneromooo-monero)
c3d208f core_tests: bump default test fee to 0.02 monero (moneromooo-monero)
10da0a0 add a --fakechain argument for tests (moneromooo-monero)
eee44e6 unit_tests: fix block reward test using post hard fork settings (moneromooo-monero)
595893f blockchain: log block (not chain) height in "BLOCK SUCCESFULLY ADDED" (moneromooo-monero)
2369968 blockchain: fix off by one in get_blocks (moneromooo-monero)
8af913a db_lmdb: implement BlockchainLMDB::reset (moneromooo-monero)
4833f4f db_bdb: implement BlockchainBDB::reset (moneromooo-monero)
18bf06e tx_pool: fix "minumim" typo in message (moneromooo-monero)
44f1267 tests: fix a typo in test name (moneromooo-monero)
1494557 db_lmdb: create all needed directories, not just the leaf one (moneromooo-monero)
015b68a db_bdb: create all needed directories, not just the leaf one (moneromooo-monero)
f141869 tests: remove data-dir argument registration (moneromooo-monero)
This prevents the intermediate thread from exiting properly, as
fork creates a child process with only one thread, so any existing
data_logger thread will not be in the child. Since this thread
sets a flag the data_logger dtor blocks on, all children threads
will hang on exit.
When throwing an exception from being unable to begin an LMDB
transaction, include the reason.
It's often been due to a write transaction attempted within a write
transaction (batch mode), but there can be other reasons such as write
transaction attempted while database was opened read only, or
environment's map needs to be resized.
The core tests use the blockchain, and reset it to be able
to add test data to it. This does not play nice with the
databases, since those will save that data without an explicit
save call.
We add a fakechain flag that the tests will set, which tells
the core and blockchain code to use a separate database, as
well as skip a few things like checkpoints and fixup, which
only make sense for real data.
Data is only guaranteed to be valid within the lifetime of a txn.
You cannot use data returned from LMDB after the txn ends.
Also, fixed a missing txn.commit BlockchainLMDB::get_tx_unlock_time()
This fixes coretests, which does not register daemon specific arguments,
but uses core, which uses those arguments. Also gets rid of an unwanted
dependency on daemon code from core.
This is a precaution for older Berkeley DB versions.
- smooth reports an issue running with 4.7:
DB_ENV->log_set_config: DB_LOG_IN_MEMORY: method not permitted
after handle's open method
- this works just fine with 5.3
- we do not use DB_LOG_IN_MEMORY, but we use DB_LOG_AUTO_REMOVE
- libdb docs say some flags must be set before open, and some
may be set at any time, but never say some must be set after
open
- moving the call to log_set_config before open works with 5.3
Therefore, it seems best to move the call before open.
Early DB versions did not store key images for inputs if the
transaction spending them had no outputs (ie, all fee). This
is not correct, as this would allow these outputs to be double
spent. This was fixed in 533acc30ed
a few months ago, but databases having synced blocks 2021612 and
685498 with a faulty version will be missing those key images
in the spent keys database. This code checks for this, and adds
those key images if they are missing.
Berkeley DB uses 1 based indices for RECNO databases, and the
implementation of BlockchainDB for Berkeley DB assumes 1 based
indices are passed to the API, whereas the LMDB one assumes
0 based indices. This is all internally consisteny, but since
the BDB code stores 1 based indices in the database, external
users have to be aware of this, as the indices will be off by
one depending on which DB is used.
^C while in manual refresh will cancel the refresh, since that's
often an annoying thing to have to wait for. Also, a manual refresh
command will interrupt any running background refresh and take
over, rather than wait for the background refresh to be done, and
look to be hanging.
9ee48e9 wallet2: speed up wallet refresh for large miners (moneromooo-monero)
4905903 wallet2: parallelize pulling blocks and processing them on refresh (moneromooo-monero)
d0eaf1d wallet2: maintain the short chain manually when refreshing (moneromooo-monero)
a4e9506 wallet2: split pull blocks between pulling and processing (moneromooo-monero)
The daemon will be polled every 90 seconds for new blocks.
It is enabled by default, and can be turned on/off with
set auto-refresh 1 and set auto-refresh 0 in the wallet.
This allows them to be saved as a fixed (one byte) chunk whatever
the value. Using a varint will use two bytes as the high bit gets
set.
This is backward compatible with current usage (0-2 values).
d887c18 hardfork: fix more major/minor issues (moneromooo-monero)
3b47ca2 hardfork: fix rescan on load (moneromooo-monero)
4cea2b1 Add IP blocking for misbehaving nodes (adapted from Boolberry) (Javier Smooth)
9c64b12 quiet down p2p logging a bit (Javier Smooth)
53c75ab blockchain: log versions as numbers, not characters (moneromooo-monero)
edade8d hardfork: fix actual/voting confusion (moneromooo-monero)
9b945f5 wallet: make the refresh optimizations selectable via command line (moneromooo-monero)
d2c0313 wallet: speedup refresh from daemon (moneromooo-monero)
ea707c7 wallet2: minor cleanup (moneromooo-monero)
55a2da7 wallet2: speedup refresh a bit (moneromooo-monero)
Also add some more tests, and rename some instances of
"version" and "add" for clarity.
NOTE: the starting height values are sometimes wrong.
I suspect this is due to the hard fork reorg code being
buggy, since they're good when syncing after the fact.
However, they're not actually used by the consensus code,
so I'm ignoring this for now, but this needs debugging.
Assume the whole of a coinbase goes to the same address (so that
if the first output isn't for us, none of it is), and only look
for payment id when we received something in the transaction.
Height seemed to be flying all over the place on a rescan here.
Logging to a file shows the heights are actually correct, and
this is some kind of screen refresh artifact. Flush after \r
and update less often to reduce this effect a lot.
f3724ae Fix startup crash when using a locale boost does not like (moneromooo-monero)
0c1dae3 i18n: allow language to be passed as a parameter (moneromooo-monero)
There are various locale related bugs in various versions of boost,
where exceptions are thrown in boost::filesystem APIs when the
current locale is not to boost's liking. It's not clear what "not
to boost's liking" means in detail, though "en" and "en_US.UTF-8"
are not to its liking.
Fix it by running a test function that's known to throw in such
a case, and resetting LANG and LC_ALL to C if an exception is
thrown. In simplewallet, the locale is queried before that so the
correct translations will still be used.
The last relayed time of a transaction is maintained, and
transactions will be relayed again if they are still in the
pool after a certain amount of time, which increases with
the transaction's age. All such transactions are resent,
whether or not they originated on the local node.
baf101e More changes for 2-min blocks Use the correct block time for realtime fuzz on locktime Use the correct block time to calculate next_difficulty on alt chains (will not work as-is with voting) Lock unit tests to original block time for now (Javier Smooth)
4fea1a5 Adjust difficulty target (2 min) and full reward zone (60 kbytes) for block version 2 (Javier Smooth)
It looks like some of the indices passed to the DB access functions
are already bumped by 1. Moreover, the existing code was not
throwing DB errors with 0 keys, and this is unlikely if it really
was using 0 keys. Last, this patch broke sync from scratch in at
least one case. So I'm calling it bad and reverting it.
This reverts commit bfc97401ae.
Use the correct block time for realtime fuzz on locktime
Use the correct block time to calculate next_difficulty on alt chains (will not work as-is with voting)
Lock unit tests to original block time for now
They check whether they're running on testnet by accessing the
m_rpc_server object, which does not exist when in RPC mode.
Also, fix hard_fork_info being called with the wrong API.
43bca0d blockchain_utilities: new blockchain_dump diagnostic tool (moneromooo-monero)
5f397e4 Add functions to iterate through blocks, txes, outputs, key images (moneromooo-monero)
0a5a5e8 db_bdb: record numbers for recno databases start at 1 (moneromooo-monero)
50dfdc0 db_bdb: DB_KEYEMPTY is also not found for non-top recon fields (moneromooo-monero)
572780e blockchain_db: use the DNE exceptions where appropriate (moneromooo-monero)
Displays current block height and target, net hash, hard fork
basic info, and connections.
Useful as a basic user friendly "what's going on here" command.
The wallet and the daemon applied different height considerations
when selecting outputs to use. This can leak information on which
input in a ring signature is the real one.
Found and originally fixed by smooth on Aeon.
Using major version would cause older daemons to reject those
blocks as they fail to deserialize blocks with a major version
which is not 1. There is no such restriction on the minor
version, so switching allows older daemons to coexist with
newer ones till the actual fork date, when most will hopefully
have updated already.
Also, for the same reason, we consider a vote for 0 to be a
vote for 1, since older daemons set minor version to 0.
33affd2 blockchain: on hardfork 2, require mixin 2 at least if possible (moneromooo-monero)
434e0f4 hardfork: make the voting window a week (moneromooo-monero)
0a7421b hardfork: rescan speedup (moneromooo-monero)
fec98b8 hardfork: remove use of GNU extension for initializing object (moneromooo-monero)
4bbf944 blockchain: on hardfork 2, allow miners to claim less money than allowed (moneromooo-monero)
088bc56 hardfork: change window semantics to not count the newly added block (moneromooo-monero)
198f557 blockchain: use different hard fork settings for testnet and mainnet (moneromooo-monero)
This allows knowing the hard fork a block must obey in order to be
added to the blockchain. The previous semantics would use that new
block's version vote to determine this hard fork, which made it
impossible to use the rules to validate transactions entering the
tx pool (and made it impossible to validate a block before adding
it to the blockchain).
3c10239 unbound: use the mini event fallback implementation (moneromooo-monero)
4e138a0 dns_utils: remove unnecessary string conversion (moneromooo-monero)
f928468 dns_utils: factor the fetching code for different DNS record types (moneromooo-monero)
4ef0da1 dns_utils: simplify string handling and fix leak (moneromooo-monero)
ae5f28c dns_utils: add a const where possible (moneromooo-monero)
f43d465 dns_utils: lock access to the singleton (moneromooo-monero)
5990344 dns: make ctor private (moneromooo-monero)
This ensures one can't instanciate a DNSResolver object by
mistake, but uses the singleton. A separate create static
function is added for cases where a new object is explicitely
needed.
0a4bc84 Added ref10 shen_ed25519_ref code, which includes code that can replace crypto-ops with a version straight from Bernstein's ref 10 (ShenNoether)
0d70fdc revert to 776b4fc91a (ShenNoether)
b01f286 Added shen_ed25519_ref to crypto ops subfolder, the point is to directly have bitmonero's crypto code come from bernstein et al's ref 10 code (ShenNoether)
f197599 wallet: encrypt the cache file (moneromooo-monero)
98c76a3 chacha8: add a key generation variant that take a pointer and size (moneromooo-monero)
It contains private data, such as a record of transactions.
The key is derived from the view and spend secret keys.
The encryption currently is one shot, so may require a lot of
memory for large wallet caches.
7c4d6f1 simplewallet: Use default log file name when executable's file path is unknown (warptangent)
b5b0f08 epee: Don't set log file name when process path name isn't found (warptangent)
Default to "simplewallet.log" in current directory when file path isn't
obtained from epee.
In this situation previously, it defaulted to the file name of ".log"
("" + ".log") in the current directory.
(Thanks to @sammy007 for reporting bug.)
An earlier version yet used "" + "/" + ".log" = "/.log", which resulted
in silently not logging in most cases, due to lack of permission.
Test:
PATH=$PATH:</path/to/simplewallet/folder> && simplewallet --wallet-file /dev/null
This results in epee not finding the executable's file path, so
simplewallet will now use a default log filename.
The height function apparently used to return the index of
the last block, rather than the height of the chain. This now
seems to be incorrect, judging the the code, so we remove the
now wrong comment, as well as a couple +/- 1 adjustments
which now cause the median calculation to differ from the
original blockchain_storage version.
This obsoletes the need for a lengthy blockchain rescan when
a transaction doesn't end up in the chain after being accepted
by the daemon, or any other reason why the wallet's idea of
spent and unspent outputs gets out of sync from the blockchain's.
The original code removed key images from a tx from the blockchain
when an non to-key nor gen input was found in that tx. Additionally,
the remainder of the tx data was added to the blockchain only after
the double spend check passed.
2634307 daemon: omit extra set of <> in error message (moneromooo-monero)
0822933 daemon: print a decoded tx in print_tx (moneromooo-monero)
1d678b1 daemon: fix print_tx not find transactions (moneromooo-monero)
It was only used by the older blockchain_storage.
We also move the code to the calling blockchain level, to avoid
replicating the code in every DB implementation. This also makes
the get_random_out method obsolete, and we delete it.
