m_num_outputs keeps track of the number of outputs, which should
be the same as the size of both the output_txs and output_amounts
databases. If one goes out of sync, we need to throw to abort
whatever it is we were doing.
Add consts in a few places where it makes sense, avoid unnecessary
memory reallocation where we know the full size needed at the outset,
simplify and avoid memory copy.
25% of the outputs are selected from the last 5 days (if possible),
in order to avoid the common case of sending recently received
outputs again. 25% and 5 days are subject to review later, since
it's just a wallet level change.
Since this queries block heights for blocks that may or may not
exist, queries for non existing blocks would throw an exception,
and that would slow down the loop a lot. 7 seconds to go through
a 30 hash list.
Fix this by adding an optional return block height to block_exists
and using this instead. Actual errors will still throw an
exception.
This also cuts down on log exception spam.
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).
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.
