lbcd/doc.go
Dave Collins 491acd4ca6 blockchain: Rework to use new db interface.
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.
2016-04-11 16:47:27 -05:00

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Go

// Copyright (c) 2013-2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
/*
btcd is a full-node bitcoin implementation written in Go.
The default options are sane for most users. This means btcd will work 'out of
the box' for most users. However, there are also a wide variety of flags that
can be used to control it.
The following section provides a usage overview which enumerates the flags. An
interesting point to note is that the long form of all of these options
(except -C) can be specified in a configuration file that is automatically
parsed when btcd starts up. By default, the configuration file is located at
~/.btcd/btcd.conf on POSIX-style operating systems and %LOCALAPPDATA%\btcd\btcd.conf
on Windows. The -C (--configfile) flag, as shown below, can be used to override
this location.
Usage:
btcd [OPTIONS]
Application Options:
-V, --version Display version information and exit
-C, --configfile= Path to configuration file
-b, --datadir= Directory to store data
--logdir= Directory to log output.
-a, --addpeer= Add a peer to connect with at startup
--connect= Connect only to the specified peers at startup
--nolisten Disable listening for incoming connections -- NOTE:
Listening is automatically disabled if the --connect
or --proxy options are used without also specifying
listen interfaces via --listen
--listen= Add an interface/port to listen for connections
(default all interfaces port: 8333, testnet: 18333)
--maxpeers= Max number of inbound and outbound peers (125)
--nobanning Disable banning of misbehaving peers
--banthreshold= Maximum allowed ban score before disconnecting and
banning misbehaving peers.
--banduration= How long to ban misbehaving peers. Valid time units
are {s, m, h}. Minimum 1 second (24h0m0s)
-u, --rpcuser= Username for RPC connections
-P, --rpcpass= Password for RPC connections
--rpclimituser= Username for limited RPC connections
--rpclimitpass= Password for limited RPC connections
--rpclisten= Add an interface/port to listen for RPC connections
(default port: 8334, testnet: 18334)
--rpccert= File containing the certificate file
--rpckey= File containing the certificate key
--rpcmaxclients= Max number of RPC clients for standard connections
(10)
--rpcmaxwebsockets= Max number of RPC websocket connections (25)
--norpc Disable built-in RPC server -- NOTE: The RPC server
is disabled by default if no rpcuser/rpcpass or
rpclimituser/rpclimitpass is specified
--notls Disable TLS for the RPC server -- NOTE: This is only
allowed if the RPC server is bound to localhost
--nodnsseed Disable DNS seeding for peers
--externalip= Add an ip to the list of local addresses we claim to
listen on to peers
--proxy= Connect via SOCKS5 proxy (eg. 127.0.0.1:9050)
--proxyuser= Username for proxy server
--proxypass= Password for proxy server
--onion= Connect to tor hidden services via SOCKS5 proxy
(eg. 127.0.0.1:9050)
--onionuser= Username for onion proxy server
--onionpass= Password for onion proxy server
--noonion Disable connecting to tor hidden services
--torisolation Enable Tor stream isolation by randomizing user
credentials for each connection.
--testnet Use the test network
--regtest Use the regression test network
--simnet Use the simulation test network
--nocheckpoints Disable built-in checkpoints. Don't do this unless
you know what you're doing.
--dbtype= Database backend to use for the Block Chain (ffldb)
--profile= Enable HTTP profiling on given port -- NOTE port
must be between 1024 and 65536
--cpuprofile= Write CPU profile to the specified file
-d, --debuglevel= Logging level for all subsystems {trace, debug,
info, warn, error, critical} -- You may also specify
<subsystem>=<level>,<subsystem2>=<level>,... to set
the log level for individual subsystems -- Use show
to list available subsystems (info)
--upnp Use UPnP to map our listening port outside of NAT
--minrelaytxfee= The minimum transaction fee in BTC/kB to be
considered a non-zero fee.
--limitfreerelay= Limit relay of transactions with no transaction fee
to the given amount in thousands of bytes per
minute (15)
--norelaypriority Do not require free or low-fee transactions to have
high priority for relaying
--maxorphantx= Max number of orphan transactions to keep in memory
(1000)
--generate Generate (mine) bitcoins using the CPU
--miningaddr= Add the specified payment address to the list of
addresses to use for generated blocks -- At least
one address is required if the generate option is
set
--blockminsize= Mininum block size in bytes to be used when creating
a block
--blockmaxsize= Maximum block size in bytes to be used when creating
a block (750000)
--blockprioritysize= Size in bytes for high-priority/low-fee transactions
when creating a block (50000)
--getworkkey= DEPRECATED -- Use the --miningaddr option instead
--nopeerbloomfilters Disable bloom filtering support.
--sigcachemaxsize= The maximum number of entries in the signature
verification cache.
--blocksonly Do not accept transactions from remote peers.
Help Options:
-h, --help Show this help message
*/
package main