Decred's serialized format for transactions split the 32-bit version
field into two 16-bit components such that the upper bits are used to
encode a serialization type and the lower 16 bits are the actual
transaction version.
Unfortunately, when this was done, the in-memory transaction struct was
not also updated to hide this complexity, which means that callers
currently have to understand and take special care when dealing with the
version field of the transaction.
Since the main purpose of the wire package is precisely to hide these
details, this remedies the situation by introducing a new field on the
in-memory transaction struct named SerType which houses the
serialization type and changes the Version field back to having the
desired semantics of actually being the real transaction version. Also,
since the maximum version can only be a 16-bit value, the Version field
has been changed to a uint16 to properly reflect this.
The serialization and deserialization functions now deal with properly
converting to and from these fields to the actual serialized format as
intended.
Finally, these changes also include a fairly significant amount of
related code cleanup and optimization along with some bug fixes in order
to allow the transaction version to be bumped as intended.
The following is an overview of all changes:
- Introduce new SerType field to MsgTx to specify the serialization type
- Change MsgTx.Version to a uint16 to properly reflect its maximum
allowed value
- Change the semantics of MsgTx.Version to be the actual transaction
version as intended
- Update all callers that had special code to deal with the previous
Version field semantics to use the new semantics
- Switch all of the code that deals with encoding and decoding the
serialized version field to use more efficient masks and shifts
instead of binary writes into buffers which cause allocations
- Correct several issues that would prevent producing expected
serializations for transactions with actual transaction versions that
are not 1
- Simplify the various serialize functions to use a single func which
accepts the serialization type to reduce code duplication
- Make serialization type switch usage more consistent with the rest of
the code base
- Update the utxoview and related code to use uint16s for the
transaction version as well since it should not care about the
serialization type due to using its own
- Make code more consistent in how it uses bytes.Buffer
- Clean up several of the comments regarding hashes and add some new
comments to better describe the serialization types
Contains the following commits:
- 711f33450c
- b6b1e55d1e
- Reverted because Travis is already at a more recent version
- bd4e64d1d4
Also, the merge commit contains the necessary decred-specific
alterations, converts all other references to sha to hash to keep with
the spirit of the merged commits, and various other cleanup intended to
bring the code bases more in line with one another.
Bump block version and add stake version to wire. Currently
StakeVersions are unused and once the enforcement logic goes in the
versions will bump again.
This fixes#435
This commit is the first stage of several that are planned to convert
the blockchain package into a concurrent safe package that will
ultimately allow support for multi-peer download and concurrent chain
processing. The goal is to update btcd proper after each step so it can
take advantage of the enhancements as they are developed.
In addition to the aforementioned benefit, this staged approach has been
chosen since it is absolutely critical to maintain consensus.
Separating the changes into several stages makes it easier for reviewers
to logically follow what is happening and therefore helps prevent
consensus bugs. Naturally there are significant automated tests to help
prevent consensus issues as well.
The main focus of this stage is to convert the blockchain package to use
the new database interface and implement the chain-related functionality
which it no longer handles. It also aims to improve efficiency in
various areas by making use of the new database and chain capabilities.
The following is an overview of the chain changes:
- Update to use the new database interface
- Add chain-related functionality that the old database used to handle
- Main chain structure and state
- Transaction spend tracking
- Implement a new pruned unspent transaction output (utxo) set
- Provides efficient direct access to the unspent transaction outputs
- Uses a domain specific compression algorithm that understands the
standard transaction scripts in order to significantly compress them
- Removes reliance on the transaction index and paves the way toward
eventually enabling block pruning
- Modify the New function to accept a Config struct instead of
inidividual parameters
- Replace the old TxStore type with a new UtxoViewpoint type that makes
use of the new pruned utxo set
- Convert code to treat the new UtxoViewpoint as a rolling view that is
used between connects and disconnects to improve efficiency
- Make best chain state always set when the chain instance is created
- Remove now unnecessary logic for dealing with unset best state
- Make all exported functions concurrent safe
- Currently using a single chain state lock as it provides a straight
forward and easy to review path forward however this can be improved
with more fine grained locking
- Optimize various cases where full blocks were being loaded when only
the header is needed to help reduce the I/O load
- Add the ability for callers to get a snapshot of the current best
chain stats in a concurrent safe fashion
- Does not block callers while new blocks are being processed
- Make error messages that reference transaction outputs consistently
use <transaction hash>:<output index>
- Introduce a new AssertError type an convert internal consistency
checks to use it
- Update tests and examples to reflect the changes
- Add a full suite of tests to ensure correct functionality of the new
code
The following is an overview of the btcd changes:
- Update to use the new database and chain interfaces
- Temporarily remove all code related to the transaction index
- Temporarily remove all code related to the address index
- Convert all code that uses transaction stores to use the new utxo
view
- Rework several calls that required the block manager for safe
concurrency to use the chain package directly now that it is
concurrent safe
- Change all calls to obtain the best hash to use the new best state
snapshot capability from the chain package
- Remove workaround for limits on fetching height ranges since the new
database interface no longer imposes them
- Correct the gettxout RPC handler to return the best chain hash as
opposed the hash the txout was found in
- Optimize various RPC handlers:
- Change several of the RPC handlers to use the new chain snapshot
capability to avoid needlessly loading data
- Update several handlers to use new functionality to avoid accessing
the block manager so they are able to return the data without
blocking when the server is busy processing blocks
- Update non-verbose getblock to avoid deserialization and
serialization overhead
- Update getblockheader to request the block height directly from
chain and only load the header
- Update getdifficulty to use the new cached data from chain
- Update getmininginfo to use the new cached data from chain
- Update non-verbose getrawtransaction to avoid deserialization and
serialization overhead
- Update gettxout to use the new utxo store versus loading
full transactions using the transaction index
The following is an overview of the utility changes:
- Update addblock to use the new database and chain interfaces
- Update findcheckpoint to use the new database and chain interfaces
- Remove the dropafter utility which is no longer supported
NOTE: The transaction index and address index will be reimplemented in
another commit.
Putting the test code in the same package makes it easier for forks
since they don't have to change the import paths as much and it also
gets rid of the need for internal_test.go to bridge.
This same thing should probably be done for the majority of the code
base.
At the current time, there is no difference between the wire encoding
at protocol version 0 and the stable long-term storage format. These
methods are simply for consistency with the other types.
At the current time, there is no difference between the wire encoding
at protocol version 0 and the stable long-term storage format. These
methods are simply for consistency with the other types.
This commit contains the entire btcwire repository along with several
changes needed to move all of the files into the wire directory in
order to prepare it for merging. This does NOT update btcd or any of the
other packages to use the new location as that will be done separately.
- All import paths in the old btcwire test files have been changed to the
new location
- All references to btcwire as the package name have been chagned to
wire
- The coveralls badge has been removed since it unfortunately doesn't
support coverage of sub-packages
This is ongoing work toward #214.
