When RingCT is enabled, outputs from coinbase transactions
are created as a single output, and stored as RingCT output,
with a fake mask. Their amount is not hidden on the blockchain
itself, but they are then able to be used as fake inputs in
a RingCT ring. Since the output amounts are hidden, their
"dustiness" is not an obstacle anymore to mixing, and this
makes the coinbase transactions a lot smaller, as well as
helping the TXO set to grow more slowly.
Also add a new "Null" type of rct signature, which decreases
the size required when no signatures are to be stored, as
in a coinbase tx.
Since these are needed at the same time as the output pubkeys,
this is a whole lot faster, and takes less space. Only outputs
of 0 amount store the commitment. When reading other outputs,
a fake commitment is regenerated on the fly. This avoids having
to rewrite the database to add space for fake commitments for
existing outputs.
This code relies on two things:
- LMDB must support fixed size records per key, rather than
per database (ie, all records on key 0 are the same size, all
records for non 0 keys are same size, but records from key 0
and non 0 keys do have different sizes).
- the commitment must be directly after the rest of the data
in outkey and output_data_t.
This constrains the number of instances of any amount
to the unlocked ones (as defined by the default unlock time
setting: outputs with non default unlock time are not
considered, so may be counted as unlocked even if they are
not actually unlocked).
It sets the max number of threads to use for a parallel job.
This is different that the number of total threads, since monero
binaries typically start a lot of them.
Also bumped DB VERSION to 1
Another significant speedup and space savings:
Get rid of global_output_indices, remove indirection from output to keys
This is the change warptangent described on irc but never got to finish.
This speeds up wallet refresh by directly retrieving a tx's amount output indices.
It removes the indirection and walking the amount output duplicate list
for every amount in each requested tx.
"tx_outputs" is used by:
Amount output indices are needed for wallet refresh.
Global output indices are needed for removing a tx.
Both amount output indices and global output indices are now stored in
an array of 64-bit unsigned ints:
tx_outputs[<tx_hash>] -> [ <a1_oi, a1_gi, a2_oi, a2_gi, ...> ]
Previously it was:
tx_outputs[<tx_hash>] -> duplicate list of <a1_gi, a2_gi, a3_gi, ...>
The amount output list had to be walked for every amount in order to
find each amount's output index, by comparing the amount's global output
index with each one in the duplicate list until a match was found.
See also d045dfa7ce
This is a list of existing output amounts along with the number
of outputs of that amount in the blockchain.
The daemon command takes:
- no parameters: all outputs with at least 3 instances
- one parameter: all outputs with at least that many instances
- two parameters: all outputs within that many instances
The default starts at 3 to avoid massive spamming of all dust
outputs in the blockchain, and is the current minimum mixin
requirement.
An optional vector of amounts may be passed, to request
histogram only for those outputs.
bdec7cb BlockchainLMDB: Use DB error helper consistently (warptangent)
c5932eb BlockchainLMDB: Add DB error to exception (warptangent)
a49c355 Blockchain: Omit verbose time stats messages by default (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.
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)
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.
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
