In this commit, we update the glide.lock file to be pinned against the
latest btcutil commit hash. btcutil has recently been updated to pull in
all changes from roasbeef's fork. Notably, it now includes the code
necessary for creating GCS filters (BIP 158).
Go 1.10 made some changes such that json.Unmarshal can no longer
unmarshal into exported fields that are themselves embedded via an
uninitialized unexported pointer.
Since rpcclient previously relied on this behavior, this updates the
client to create the pointers before unmarshalling into the struct.
The block index now tracks the set of dirty block nodes with status
changes that haven't been persisted and flushes the changes to the DB
at the appropriate times.
Now that all headers are stored in the in-memory index, the database
bucket managed by blockchain, and in the flat files, it makes sense to
drop the redundant data from the block index bucket in ffldb.
To avoid modifying the database interface, this reimplements
FetchBlockHeader(s) to use header data stored in flat files. This can
be trivially implemented by delegating to FetchBlockRegion.
Currently only the blocks in the active chain are loaded into the
block index on initialization. This instead iterates over the entire
block index bucket in LevelDB and loads all nodes.
The bucket contains block headers keyed by the block height encoded as
big-endian concatenated with the block hash. This allows block headers
to be fetched from the DB in height order with a cursor.
These method allows safe concurrent access to reading and modifying
block node statuses. When block statuses get persisted in a later
change, the setter methods can be used to mark block nodes as dirty.
Each node in the block index records some flags about its validation
state. This is just stored in memory for now, but can save effort if
attempting to reconnect a block that failed validation or was
disconnected.
