astreum 0.4.0

Python library to interact with the Astreum blockchain and its virtual machine.

lib

Python library to interact with the Astreum blockchain and its virtual machine.

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Configuration

When initializing an astreum.Node, pass a dictionary with any of the options below. Only the parameters you want to override need to be present – everything else falls back to its default.

Core Configuration

Parameter	Type	Default	Description
chain	string	"test"	Chain name ("main" or "test"). If chain_id is omitted, main maps to 1; all other values default to test (0).
chain_id	int	0	Chain identifier used for validation (0 = test, 1 = main). If chain is omitted, chain is derived from this value (1 => main, otherwise test).
hot_storage_limit	int	1073741824	Maximum bytes kept in the hot cache before new atoms are skipped (1 GiB).
cold_storage_limit	int	10737418240	Cold storage write threshold (10 GiB by default); set to 0 to skip the limit.
cold_storage_path	string	None	Directory where persisted atoms live; Astreum creates it on startup and skips cold storage when unset.
cold_storage_scale	string	"MB"	Base unit for cold storage roll-up thresholds (KB, MB, or GB). This sets the derived cold_storage_base_size used for level_0 collation and higher-level merges.
atom_fetch_interval	float	0.25	Poll interval (seconds) while waiting for missing atoms in get_atom_list_from_storage; 0 disables waiting.
atom_fetch_retries	int	8	Number of poll attempts for missing atoms; max wait is roughly interval * retries, 0 disables waiting.
verify_blockchain_interval	float	10.0	Delay (seconds) between consensus verification worker iterations. Defaults to peer_timeout_interval when not explicitly set.
verification_max_stale_seconds	int	10	Ignore otherwise-valid candidate heads whose block timestamp is older than this many seconds when selecting the latest verified chain head.
verification_max_future_skew	int	2	Ignore candidate heads whose block timestamp is more than this many seconds in the future when selecting the latest verified chain head.
latest_block_hash	hex string	None	Optional 32-byte block-hash override used to preload the node's starting latest_block_hash from config.
verified_up_to	hex string	None	Optional 32-byte hash override used to preload the verification anchor (node.verified_up_to) from config.
logging_enabled	bool	True	When False, disable logger setup entirely, including file creation and the background logging listener thread.
logging_retention_days	int	7	Number of days to keep rotated log files (daily gzip).
verbose	bool	False	When True, also mirror JSON logs to stdout with a human-readable format.

Communication

Parameter	Type	Default	Description
relay_secret_key	hex string	Auto-generated	X25519 private key used for the relay route; a new keypair is created when this field is omitted.
relay_payment_secret_key	hex string	None	Optional Ed25519 private key used for relay/storage payment channels; when set, the node can advertise a relay payment public key for paid objects.
validation_secret_key	hex string	None	Optional Ed25519 key that lets the node join the validation route; leave blank to opt out of validation.
use_ipv6	bool	False	Bind the incoming/outgoing sockets on IPv6 (the OS still listens on IPv4 if a peer speaks both).
incoming_port	int	52780	UDP port the relay binds to; pass 0 or omit to let the OS pick an ephemeral port.
default_seed	string	"bootstrap.astreum.org:52780"	Default address to ping before joining; set to None to disable the built-in default.
additional_seeds	list[str]	[]	Extra addresses appended to the bootstrap list; each must look like host:port or [ipv6]:port.
peer_timeout	int	900	Evict peers that have not been seen within this many seconds (15 minutes).
peer_timeout_interval	int	10	How often (seconds) the peer manager checks for stale peers.
bootstrap_retry_interval	int	30	How often (seconds) to retry bootstrapping when the peer list is empty.
storage_index_interval	int	600	How often (seconds) to re-advertise entries in node.atom_advertisments to the closest known peer.
storage_request_minimum_price	int	1	Floor price for storage/object requests; the dynamic storage request price never drops below this value.
storage_request_price_interval	float	5.0	How often (seconds) the storage thread recomputes request pricing from inbound queue pressure.
fair_use_limit	int	1048576	Bytes a peer may receive via shared object uploads before fair-use ratio enforcement begins (1 MiB by default).
fair_use_ratio	float	0.5	Minimum download/upload ratio a peer must maintain after fair_use_limit is exceeded; set 0 to disable the fair-use gate.
incoming_queue_size_limit	int	67108864	Soft cap (bytes) for inbound queue usage tracked by enqueue_incoming; set to 0 to disable.
incoming_queue_timeout	float	1.0	When > 0, enqueue_incoming waits up to this many seconds for space before dropping the payload.

Advertisements: node.atom_advertisments holds (atom_id, payload_type, expires_at) tuples. Use node.add_atom_advertisement or node.add_atom_advertisements to enqueue entries (expires_at=None keeps them indefinite). Validators automatically advertise block, transaction (main and detail lists), receipt, and account trie lists for 15 minutes by default.

Note The peer‑to‑peer route used for object discovery is always enabled. If validation_secret_key is provided the node automatically joins the validation route too.

Usage

from astreum.node import Node

config = {
    "relay_secret_key": "ab…cd",             # optional – hex encoded
    "validation_secret_key": "12…34",        # optional – validator
    "hot_storage_limit": 1073741824,         # cap hot cache at 1 GiB
    "cold_storage_limit": 10737418240,       # cap cold storage at 10 GiB
    "cold_storage_path": "./data/node1",
    "incoming_port": 52780,
    "use_ipv6": False,
    "default_seed": None,
    "additional_seeds": [
        "127.0.0.1:7374"
    ]
}

node = Node(config)
# … your code …

Validation Overview

Call node.verify() to connect the node, initialize fork tracking, and start the background consensus verification worker. The worker watches peer-reported block heads, verifies candidate forks, merges fully verified forks, and updates node.latest_block_hash / node.latest_block when a better verified head is available.

node.verify()

node.verify() is idempotent while the verification thread is already running.

To start creating blocks, call node.validate(validation_secret_key). Validation connects the node, prepares validator state, creates a genesis block when no latest block is configured, and starts the consensus validation worker.

from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey

validation_secret_key = Ed25519PrivateKey.generate()

node.validate(validation_secret_key)

The validation worker only creates blocks when this node is the scheduled validator for the current head. It applies queued transactions when available, can create empty blocks when the queue is empty, stores the new block atoms locally, advertises them to peers, and updates node.latest_block_hash / node.latest_block.

Transaction Overview

Use send_transaction(...) to atomize, store, advertise, and forward an already-signed transaction to available validators.

from astreum.consensus.transaction import (
    create_transaction,
    send_transaction,
)

tx = create_transaction(
    chain_id=node.config["chain_id"],
    amount=100,
    counter=sender_account.counter + 1,
    recipient=recipient_public_key,
    sender=sender_public_key,
)
tx.sign(sender_key)
tx_hash = send_transaction(node, tx)
print(tx_hash.hex())

The node must already be connected and have a latest_block; otherwise the function raises RuntimeError. It writes the transaction's atoms to local storage, advertises them on the P2P network, and sends the transaction hash to peers on the validation route.

Language Syntax

Astreum uses S-expressions with prefix notation. Expressions are either atoms or parenthesised lists. Lists are right-linked Link chains — (a b c) parses as Link(a, Link(b, c)).

Tokens

Token	Meaning
( )	Delimit a list expression.
'	Quote token — when alone, parses as the symbol '. Inside a list it's a regular symbol. The word quote in source also normalises to '.
123 -5	Integer literals. Parsed to Expr.Bytes as minimal-width signed two's complement, big-endian.
add def	Everything else is a symbol. Parsed to Expr.Symbol.
;	Line comment — skips to end of line.
#;	Expression skip — skips the next complete expression (including nested lists).

Expression types

Type	Class	Description
Symbol	Expr.Symbol(value: str)	A named identifier.
Bytes	Expr.Bytes(value: bytes)	Raw byte data. Integers in source are encoded as two's complement bytes.
Link	Expr.Link(head, tail)	A pair — the building block for lists. Link(None, None) is NIL.

Links form right-associated chains. (1 2 3) becomes:

Link(Bytes(b"\x01"), Link(Bytes(b"\x02"), Bytes(b"\x03")))

Environment

Env(data={}, parent=None) is a string-keyed binding store with parent-chain lookup. env.get(key) walks up parent environments. env.put(key, value) writes to the local environment only.

Machine Overview

The machine evaluates an expression tree against an environment, producing a result stack.

from astreum.machine.main import Machine
from astreum.machine import Env, Expr, tokenize, parse
from astreum.node import Node

node = Node()
machine = Machine(node)

# Parse source text and evaluate
tokens = tokenize("(1 2 +)")
expr, _ = parse(tokens)

env = Env()
stack = machine.run(expr, env)
# stack = [Bytes(b"\x03")]

machine.run(expr, env) walks the expression tree and pushes results onto a stack. Symbols that match operators pop arguments and push results. Non-operator symbols are looked up in the environment. Bytes values are pushed as-is.

Metering

Every Machine carries a Meter that tracks computation cost in bytes read:

machine = Machine(node, meter_enabled=True, meter_limit=1_000_000)
# MeterExceededError raised if limit is exceeded
machine.meter.used  # bytes consumed so far

Operators

Operators are symbols that pop arguments from the stack and push a result.

Operator	Stack effect	Description
+	a b → a+b	Two's complement addition.
!&	a b → ~(a & b)	Bitwise NAND (functionally complete — all other bitwise ops derive from this).
!	a → ~a	Bitwise NOT (derived: a a !&).
link	head tail → Link(head, tail)	Construct a Link pair.
head	Link(h, t) → h	Extract the head of a Link.
tail	Link(h, t) → t	Extract the tail of a Link.
is_atom	expr → 0|1	Returns Bytes(b"\x01") if the value is Bytes or Symbol, else Bytes(b"\x00").
is_eq	a b → 0|1	Equality comparison. Bytes compared by value; Link by head+tail identity; different types never equal.
if	cond then else → result	If cond is truthy (non-zero Bytes or non-NIL Link), evaluate then branch; otherwise else.
fn	argN … arg1 params body → result	Pops params (a Link chain of Symbols), body, and N args. Binds args to param names in a child environment and evaluates body.
def	value name → —	Binds name (a Symbol) to value in the current environment.

Actor Model

The machine supports concurrent actors communicating via named mailboxes.

Operator	Stack effect	Description
spawn	body name → name|nil	Spawn a new actor thread running body in a child environment. name must be a Symbol. Returns name on success, NIL if the name is already taken or threading is disabled.
send	target msg → —	Send msg to the mailbox of actor target. Returns nothing. Drops silently if the mailbox doesn't exist.
receive	target → msg|nil	Block until a message arrives in the mailbox of actor target. Returns NIL if the mailbox doesn't exist.

Actors run on daemon threads with their own environment (parented to the spawner's environment). Threading can be disabled with Machine(node, allow_threading=False) — spawn, send, and receive then push NIL.

Quickstart Example

from astreum.machine.main import Machine
from astreum.machine import Env, Expr, tokenize, parse, Meter
from astreum.node import Node

node = Node()
machine = Machine(node)

# Define (add a b (+ a b)) and call (add 1 2)
src = "(((a b (+ a b)) (a b) fn) add def) (1 2 add +)"
tokens = tokenize(src)
expr, _ = parse(tokens)

env = Env()
stack = machine.run(expr, env)

# First value on stack is the result of (1 2 add +)
result = stack[0]
print(int.from_bytes(result.value, "big"))  # 3

Handling errors

tokenize and parse raise ParseError (from astreum.machine.parser) on malformed input:

from astreum.machine import tokenize, parse, ParseError

try:
    tokens = tokenize("(1 2")
    expr, _ = parse(tokens)
except ParseError as e:
    print("Parse failed:", e)

---

Logging

Every Node instance wires up structured logging automatically:

• Set config["logging_enabled"] = False to skip logging setup entirely. This bypasses log directory creation, file rotation, console mirroring, and the background listener thread.
• Logs land in per-instance files named node.csv under %LOCALAPPDATA%\Astreum\lib-py\logs/<instance_id> on Windows and $XDG_STATE_HOME (or ~/.local/state)/Astreum/lib-py/logs/<instance_id> on other platforms. The <instance_id> is the first 16 hex characters of a BLAKE3 hash of the caller's file path, so running the node from different entry points keeps their logs isolated.
• Files rotate at midnight UTC with gzip compression (node-YYYY-MM-DD.csv.gz) and retain 7 days by default. Override via config["logging_retention_days"].
• Each event is a single CSV row with columns ts, level, msg, module, and func.
• Set config["verbose"] = True to mirror logs to stdout in a human-friendly format like [2025-04-13-42-59] [info] Starting Astreum Node.
• The very first entry emitted is the banner Starting Astreum Node, signalling that the logging pipeline is live before other subsystems spin up.

Testing

python3 -m venv venv
source venv/bin/activate
pip install -e .

for all tests

python3 -m unittest discover -s tests

for individual tests

Test	Pass
python3 -m unittest tests.node.test_current_validator	✅
python3 -m unittest tests.node.test_node_connection	✅
python3 -m unittest tests.node.test_node_init
python3 -m unittest tests.node.test_node_validation
python3 -m unittest tests.node.machine.parser	✅
python3 -m unittest tests.communication.test_message_port
python3 -m unittest tests.communication.test_integration_port_handling
python3 -m unittest tests.storage.indexing
python3 -m unittest tests.storage.cold
python3 -m unittest tests.storage.utils
python3 -m unittest tests.models.test_merkle
python3 -m unittest tests.models.test_patricia
python3 -m unittest tests.block.atom
python3 -m unittest tests.block.nonce