Writing counterblock Plug-in Modules
counterblock
is a modular application that allows developers to turn on or off various bits of its out-of-the-box functionality, as well as extending it with new functionality, through its plug-in architecture.
This document introduces the built-in modules, as well as discussing how you can write your own custom modules for counterblock
that extend its functionality beyond what is possible out of the box.
Table of Contents
Built-in Modules
counterblock
ships with the following built-in modules:
assets
: Implements basic asset functionality, such as extended asset info parsing, basic asset-related APIs, and more.betting
: Implements betting-specific API calls, tasks, and more.dex
: Implements API methods, order book and market info parsing, and more for Counterparty’s distributed exchange. (Requires that theassets
module be loaded for use.)transaction_stats
: Handles the compliation of transaction statistics.counterwallet
: Implements Counterwallet-specific API calls, tasks, and more. (Requires that theassets
module be loaded for use.)
Any of these above modules may be enabled or disabled, allowing you to tune counterblock
to your exact needs out of the box.
Custom Module Development
A counterblock
module is simply a python module that utilizes a special plug-in API, to provide runtime integration into the counterblock
base code.
For some examples of modules in use, check out the modules directory of the counterblock
respository. These built-in modules are written just like any custom module would be, and provide a good launching point to see what is possible.
Processors: Hooking into runtime functionality
Most of the API functionality follows a specific Python decorator type syntax, to integrate into things like blockchain message processing, block level processing, startup/initialization processing and more. The general syntax is:
from lib.processor import <processor_name> @<processor_name>.subscribe(enabled=<bool>, priority=<int>) def my_function(param1, param2): bla = do_foo()
Some other notes on processors:
- If not specified, the defaults are
enabled=true, priority=0
. - When a processor is triggered methods are run in order of priority from highest to lowest.
- Please note that any priority less than
0
or greater than1000
is reserved for internalcounterblock
functionality, and custom plugins should only utilize priority settings under this number.
MessageProcessor
MessageProcessor
runs once for each message as obtained from the counterpartyd
message feed, for all activity that has been confirmed on the blockchain (i.e. at least 1 Bitcoin confirmation). msg
will pass the message in the same format as the get_messages
counterpartyd api method, msg_data corresponds to json.loads(msg['bindings'])
.
@MessageProcessor.subscribe(enabled=True, priority=90) def custom_received_xcp_alert(msg, msg_data): if msg['category'] != 'sends': return if message['status'] != 'valid': return if not msg_data['destination'] in MY_ADDRESS_LIST: return if not msg_data['asset'] == 'XCP': return print('Received %s XCP at My Address %s from %s' %( (float(msg_data['quantity'])/10**8), msg_data['destination'], msg_data['source'])) return
Note that with MessageProcessor
handlers, you can return 'ABORT_THIS_MESSAGE_PROCESSING'
to prevent the running of further MessageProcessors (i.e. of lesser priority than the current one) for the message being currently processed.
MempoolMessageProcessor
MempoolMessageProcessor
works similar to MessageProcessor
, however, for messages out the mempool (i.e.
that are not confirmed and included on the blockchain yet). The format of the data supplied to the processor is slightly different though, and looks like this:
@MempoolMessageProcessor.subscribe(enabled=True, priority=90) def custom_received_xcp_alert(msg, msg_data): assert msg['_message_index'] == 'mempool' assert msg['tx_hash'] assert msg['command'] assert msg['category'] assert msg_data #the actual message data assert msg['timestamp'] assert msg['viewed_in_block'] #prevent running of further MempoolMessageProcessor's of lesser priority for the message being processed return 'ABORT_THIS_MESSAGE_PROCESSING'
BlockProcessor
BlockProcessor
run once per new block, after all MessageProcessor
functions have completed.
@BlockProcessor.subscribe(priority=0) def alertBlock(): print('Finished processing messages for this block')
StartUpProcessor
StartUpProcessor
runs once on counterblock
startup.
@StartUpProcessor.subscribe() def my_db_config(): config.my_db = pymongo.Connection()['my_db']
CaughtUpProcessor
CaughtUpProcessor
runs once when counterblock
catches up to the latest Counterpartyd block.
@CaughtUpProcessor.subscribe() def caughtUpAlert(): print('counterblock is now caught up to Counterpartyd!')
RollbackProcessor
RollbackProcessor
runs whenever the counterblock
database is rolled back (either due to a blockchain
reorg, or an explicit rollback command being specified to counterblock
via the command line).
Note that if this processor runs and None
is passed as max_block_index
, it means that there was a reparse of
all block data.
@RollbackProcessor.subscribe() def rollbackAlert(max_block_index): print('counterblock block database rolled back! Anything newer than block index %i removed!' % max_block_index)
Other integration points
config.state
A number of internal state variables that a module may need to access are stored in config.state
.
For example, if you want to run a process for every new block (but not when counterblock is catching up):
@BlockProcessor.subscribe() def my_custom_block_event(): if not (config.state['cpd_latest_block_index'] - config.state['my_latest_block']['block_index']) == 1: return #Do stuff here
Enhancing the API
To add an API method for counterblock
to provide:
from lib.processor import API #(note that the dispatcher add_method does not take arguments) @API.add_method def my_foo_api_method(): return 'bar'
Upon doing the above, my_foo_api_method
is now a valid API method, and callable from any client that that utilizes your counterblock
JSON RPC API.
start_task
To start a task that runs in a seperate lightweight thread (either immediately, or with a delay), use start_task
:
from lib.processor import start_task def run_my_task(): print("Foo bar!!") #start again in 5 minutes start_task(run_my_task, delay=5*60) #start task the first time with no delay start_task(run_my_task)
Module configuration file
After creating your module, you will need to tell counterblock
about it, so that it can load it on startup. To do this, you should edit (or create) a file called modules.conf
(or modules.testnet.conf
for testnet), which should be located in the counterblock config-dir
(~xcp/.config/counterblock
on a federated node).
To load your custom module, specify the module’s path under [LoadModule]
relative to the counterblock base-dir
. i.e.:
[LoadModule] 'lib/vendor' = True
The above configuration would look for a vendor.py
, or vendor
folder (with required __init__.py
file present), and load the plugin code from there. Note that you should not include any .py
suffix on the filename.
To change the default behavior for counterblock
modules/events, change the corresponding processor config. For instance:
To disable a processor:
#(must be bool) [BlockProcessor] generate_wallet_stats = False
To change a processor’s priority:
#(must be int) [MessageProcessor] parse_issuance = 5
To change priority and enable:
#(tuple, order does not matter) [MessageProcessor] parse_issuance = 5, True parse_issuance = True, 5
Here’s an extensive counterblock
modules.conf
example config file:
[MessageProcessor] #Tweak core messaging processing # (don't use these unless you know what you're doing) handle_exceptional = True handle_invalid = True parse_insert = True handle_reorg = True parse_issuance = 10, True parse_balance_change = True parse_trade_book = True parse_broadcast = True [StartUpProcessor] #Enable/disable core functionality (all enabled by # default, don't use these unless you know what you're doing) start_cpd_blockfeed = True check_blockchain_service = True expire_stale_orders = True start_api = True [LoadModule] #Load custom modules lib/modules/reparse_timer = True
Please note that function names must be exact.
Command-line functions
Counterblock also provides the ability to load/unload/disable/etc modules via the command line. (Although, please note that we recommend manually editing the appropriate modules
config file(s), at least for starters.)
To enable a custom module, run the following command:
counterblock enmod 'lib/vendor'
To disable a loaded module:
counterblock dismod 'lib/vendor'
To list loaded modules and processors:
counterblock listmod