This commit implements pruning for the block nodes that form the memory
chain which are no longer needed. The validation of a block only requires
information from a set number of previous nodes. The initial code did not
prune old nodes as they were no longer needed, but the vast majority of
the infrastructure to support it was already in place as that was always
the goal. This commit finishes implementing the missing bits to make it
a reality.
Previously, the code was using big rational numbers for work values which
resulted in carrying way too much precision around (and ultimately a lot
of extra memory and computation to carry that precision). This commit
converts the work values to big integers and calculates them with integer
division. This is acceptable because the numerator is multiplied by 2^256
which is higher than the maximum possible proof of work. Therefore
anything after the decimal is superfluous precision for the purposes of
chain selection.
Also, add a check for negative difficulty values when calculating the work
value. Negative values won't occur in practice with valid blocks, but
it's possible an invalid block could trigger the code path, so be safe and
check for it.
Previously the main network checkpoints were being used for unrecognized
networks. This commit changes the code so that no checkpoints are used in
that scenario.
Rather than converting the proof of work limit to its compact
representation multiple times during operation, do it once at package
initialization time and export it via the chain parameters.
This commit adds info level log statements when a block causes a chain
fork, extends a side chain (fork), or causes a reorganize. When a reorg
happens, the new and old chain heads along with the fork point are logged.
Even though the code currently makes heavy use of nodes which will have
the appropriate height, blocks which did not come from the database will
not have a height set. As a result, this could possibly result in a
height of 0 being used when unintended. By setting the block height in
the block as soon as its known (regardless of the source), we can future
proof against bugs that would likely be hard to track down.
The btcscript API for GetSigOpCount and GetPreciseSigOpCount
recently changed to no longer return an error. This change was necessary
to mirror the behavior of bitcoind signature operations counting. This
commit modifies the code accordingly to use the new API.
We do this by allowing the parser to return the list of parsed objects
(it is an internal only api anyway) and then we use this in the sigops
counting and ignore the error. This change due to bitcoind
compatability.
It is acceptable for a transaction input in a block to reference the
output of another transaction in the same block only if the referenced
transaction comes before the transaction referencing it.
This commit modifies the way initial database creation is handled.
Previously, the genesis for the main chain was inserted automatically upon
creation of the database. However, that approach caused an issue since
other networks such as the test network don't use the same genesis block
as the main network.
The new approach introduced by this commit is to leave it up to the caller
to insert the desired genesis block. In order to support this, the
InsertBlock function has been modified to allow the first (and only the
first) block to be inserted without having an existing parent. Also, the
NewestSha function has been modified to return a zero hash, -1 for the
height, and no error when the database does not yet have any blocks. This
allows the caller to determine the difference between no blocks and only
the genesis block (in which case the return values would be the genesis
hash and 0 for the height).
The go vet command complains about untagged struct initializers when
defining a ShaHash directly. This seems to be a limitation where go vet
does not exclude the warning for types which are a constant size byte array
like it does for normal constant size byte array definition.
This commit simply modifies the tests to use a constant definition cast to a
ShaHash to overcome the limitation of go vet.
This commit modifies the double spend detection to handle double spends
within the same block as well as side chains when doing the checks before
reorganizing the chain.
There was not much documentation about the difference between testnet and
testnet3, so make it clear that testnet is used for regression tests and
testnet3 is the public test network (version 3).
In addition to returning errors to the caller, log the error with a prefix
in a few key places that helps identify the origin for errors. In some
cases, the underlying error comes from a different subsystem such as the
SQL database driver and the error messages can be fairly generic.
This commit modifies the code to use params based on the active network
which paves the way for supporting the special rules and different genesis
blocks used by the test networks.
Since the same coinbase transaction is used for the genesis blocks of
all three currently supposed networks, separate it into its own var and
use a reference to it in each of the genesis block defintions.
