Implement Phase 0b base project against the frozen test contract
All seven services (gateway, ledger, fraud, sanctions, insights, notifier, audit), db/schema.sql plus optional_indexes.sql, scripts/seed.py and smoke.py, the gateway-served frontend, and docker-compose.yml. Plain-text stdlib logging and a weak manual X-Request-Id only -- no observability yet, by design, per test_no_observability.py. Implements all 13 named chaos-flag pathologies from docs/PATHOLOGIES.md behind Redis-backed runtime flags. make smoke and make test-contract pass; make test-baseline and make test-pathology pass except for a handful of load-sensitive tests documented in tests/README.md rather than papered over.
This commit is contained in:
Movses Aslanyan
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from fastapi import FastAPI, Request
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from fastapi.responses import JSONResponse
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from pydantic import BaseModel, field_validator
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from common.logging_config import configure_logging
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from . import chaos
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from .db import normal_engine, session_factory
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from . import repository
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SERVICE_NAME = "ledger"
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logger = configure_logging(SERVICE_NAME)
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app = FastAPI(title=SERVICE_NAME)
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class CreateTransactionRequest(BaseModel):
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account_id: str
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kind: str
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amount_minor: int
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currency: str
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merchant_name: str
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category_id: int | None = None
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request_id: str = "unknown"
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@field_validator("amount_minor")
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@classmethod
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def deposit_amount_must_be_non_negative(cls, v, info):
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kind = info.data.get("kind")
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if kind == "deposit" and v < 0:
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raise ValueError("amount_minor must be non-negative for a deposit")
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return v
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class SettleRequest(BaseModel):
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risk_score: float
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request_id: str = "unknown"
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@app.exception_handler(Exception)
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async def unhandled_exception_handler(request: Request, exc: Exception):
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logger.exception(f"unhandled exception on {request.url.path}: {exc}")
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return JSONResponse(status_code=500, content={"error": "internal error"})
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@app.get("/")
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async def root():
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return {"service": SERVICE_NAME, "version": "0.1.0"}
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@app.get("/healthz")
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async def healthz(request: Request):
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if request.headers.get("X-Ledgerline-Probe") == "chatty-health":
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logger.info("received chatty-health healthz probe from gateway")
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return {"status": "ok", "service": SERVICE_NAME}
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@app.get("/readyz")
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async def readyz():
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try:
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async with normal_engine.connect() as conn:
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await conn.exec_driver_sql("SELECT 1")
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except Exception as exc:
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logger.exception(f"readyz check failed: {exc}")
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return JSONResponse(status_code=503, content={"status": "unavailable"})
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return {"status": "ok"}
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@app.get("/internal/accounts")
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async def list_accounts():
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async with session_factory(starved=False) as session:
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rows = await repository.list_accounts(session)
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return [dict(row) for row in rows]
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@app.post("/internal/transactions")
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async def create_transaction(body: CreateTransactionRequest):
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logger.info(f"processing tx for account {body.account_id}, amount {body.amount_minor} request_id={body.request_id}")
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starved = await chaos.pool_starvation_enabled()
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poison_enabled = await chaos.poison_data_enabled()
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poison_tx_id = await chaos.find_poison_transaction_id(body.account_id)
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async with session_factory(starved=starved) as session:
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account = await repository.get_account(session, body.account_id)
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if account is None:
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return JSONResponse(status_code=404, content={"error": "account not found"})
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if poison_tx_id is not None and poison_enabled:
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poison_row = await repository.get_transaction_currency(session, poison_tx_id)
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# poison_data: skip input validation on the seeded malformed rows
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# (§8) -- this naive access raises on the NULL currency on purpose.
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_ = poison_row.currency.upper()
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tx_id = await repository.create_transaction(
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session,
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account_id=body.account_id,
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kind=body.kind,
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amount_minor=body.amount_minor,
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currency=body.currency,
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merchant_name=body.merchant_name,
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category_id=body.category_id,
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)
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return JSONResponse(
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status_code=201,
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content={
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"transaction_id": tx_id,
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"account_id": body.account_id,
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"holder_name": account.holder_name,
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"kind": body.kind,
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"amount_minor": body.amount_minor,
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"category_id": body.category_id,
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"status": "pending",
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},
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)
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@app.post("/internal/transactions/{tx_id}/settle")
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async def settle(tx_id: str, body: SettleRequest):
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starved = await chaos.pool_starvation_enabled()
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row_lock = await chaos.row_lock_contention_enabled()
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async with session_factory(starved=starved) as session:
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tx = await repository.get_transaction(session, tx_id)
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if tx is None:
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return JSONResponse(status_code=404, content={"error": "transaction not found"})
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account = await repository.get_account(session, tx.account_id)
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use_lock = row_lock and bool(account.is_hot)
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balance = await repository.settle_transaction(session, tx=tx, risk_score=body.risk_score, use_row_lock=use_lock)
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logger.info(f"settled transaction {tx_id} request_id={body.request_id}")
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return {"status": "settled", "balance_minor": balance}
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@app.post("/internal/transactions/{tx_id}/reject")
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async def reject(tx_id: str, body: SettleRequest):
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starved = await chaos.pool_starvation_enabled()
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async with session_factory(starved=starved) as session:
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tx = await repository.get_transaction(session, tx_id)
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if tx is None:
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return JSONResponse(status_code=404, content={"error": "transaction not found"})
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balance = await repository.reject_transaction(session, tx=tx, risk_score=body.risk_score)
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logger.info(f"rejected transaction {tx_id} request_id={body.request_id}")
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return {"status": "rejected", "balance_minor": balance}
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"""pool_starvation, row_lock_contention, poison_data -- phase-0-base-project-spec.md
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§7. All three are owned by `ledger`.
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"""
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from common.chaos_flags import is_enabled
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from common.redis_client import redis_client
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# Populated once by scripts/seed.py: account_id -> id of that account's one
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# deliberately NULL-currency transaction (§8). A Redis hash lookup, not a
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# `transactions` scan by account_id -- that column has no supporting index
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# on purpose (§5), and the poison_data pathology shouldn't have to pay for a
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# full-table seq scan on every single request just to find its own trigger.
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POISON_TX_KEY = "poison:tx_by_account"
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async def pool_starvation_enabled() -> bool:
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return await is_enabled("pool_starvation")
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async def row_lock_contention_enabled() -> bool:
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return await is_enabled("row_lock_contention")
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async def poison_data_enabled() -> bool:
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return await is_enabled("poison_data")
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async def find_poison_transaction_id(account_id: str) -> str | None:
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return await redis_client.hget(POISON_TX_KEY, account_id)
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"""Two pre-built engines so pool_starvation (phase-0-base-project-spec.md §7)
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can be toggled live, with no restart: the flag picks which already-initialised
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pool a request borrows a connection from, rather than resizing a pool in
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place (SQLAlchemy pools aren't resizable live)."""
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from sqlalchemy.ext.asyncio import async_sessionmaker
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from common.db import make_engine
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normal_engine = make_engine(pool_size=20, max_overflow=10)
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starved_engine = make_engine(pool_size=2, max_overflow=0, pool_timeout=10)
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NormalSession = async_sessionmaker(normal_engine, expire_on_commit=False)
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StarvedSession = async_sessionmaker(starved_engine, expire_on_commit=False)
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def session_factory(starved: bool):
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return StarvedSession() if starved else NormalSession()
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import asyncio
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import uuid
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import sqlalchemy as sa
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KIND_SIGN = {"deposit": 1, "withdrawal": -1, "purchase": -1}
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ROW_LOCK_HOLD_SECONDS = 0.15
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async def get_account(session, account_id: str):
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result = await session.execute(
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sa.text("SELECT id, holder_name, currency, balance_minor, is_hot FROM accounts WHERE id = :id"),
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{"id": account_id},
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)
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return result.first()
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async def list_accounts(session, limit: int = 1000):
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result = await session.execute(
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sa.text(
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"SELECT id, holder_name, currency, balance_minor FROM accounts ORDER BY created_at LIMIT :limit"
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),
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{"limit": limit},
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)
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return result.mappings().all()
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async def get_transaction_currency(session, tx_id: str):
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"""Backs the poison_data pathology: fetches one known-malformed transaction
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(NULL currency, §8) by primary key -- a cheap, always-fast lookup regardless
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of the deliberately-missing account_id index, since which transaction to
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fetch is looked up by account_id in Redis first (chaos.py's
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find_poison_transaction_id), not by scanning `transactions` here."""
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result = await session.execute(
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sa.text("SELECT currency FROM transactions WHERE id = :id"),
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{"id": tx_id},
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)
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return result.first()
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async def create_transaction(
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session, *, account_id, kind, amount_minor, currency, merchant_name, category_id
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):
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tx_id = str(uuid.uuid4())
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await session.execute(
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sa.text(
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"INSERT INTO transactions "
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"(id, account_id, kind, amount_minor, currency, merchant_name, category_id, status) "
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"VALUES (:id, :account_id, :kind, :amount_minor, :currency, :merchant_name, :category_id, 'pending')"
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),
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{
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"id": tx_id,
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"account_id": account_id,
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"kind": kind,
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"amount_minor": amount_minor,
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"currency": currency,
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"merchant_name": merchant_name,
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"category_id": category_id,
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},
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)
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await session.commit()
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return tx_id
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async def get_transaction(session, tx_id: str):
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result = await session.execute(
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sa.text(
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"SELECT id, account_id, kind, amount_minor, currency, merchant_name, "
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"category_id, status FROM transactions WHERE id = :id"
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),
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{"id": tx_id},
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)
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return result.first()
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async def settle_transaction(session, *, tx, risk_score, use_row_lock: bool):
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"""Applies the balance delta and marks the transaction settled. When
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use_row_lock is true (row_lock_contention on a hot account), takes
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SELECT ... FOR UPDATE and holds the transaction open for an extra 150ms
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before committing -- phase-0-base-project-spec.md §7."""
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delta = KIND_SIGN[tx.kind] * tx.amount_minor
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if use_row_lock:
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result = await session.execute(
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sa.text("SELECT balance_minor FROM accounts WHERE id = :id FOR UPDATE"),
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{"id": tx.account_id},
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)
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result.first()
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await session.execute(
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sa.text("UPDATE accounts SET balance_minor = balance_minor + :delta WHERE id = :id"),
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{"delta": delta, "id": tx.account_id},
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)
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await asyncio.sleep(ROW_LOCK_HOLD_SECONDS)
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else:
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await session.execute(
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sa.text("UPDATE accounts SET balance_minor = balance_minor + :delta WHERE id = :id"),
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{"delta": delta, "id": tx.account_id},
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)
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await session.execute(
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sa.text("UPDATE transactions SET status = 'settled', risk_score = :risk_score WHERE id = :id"),
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{"risk_score": risk_score, "id": tx.id},
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)
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await session.commit()
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result = await session.execute(
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sa.text("SELECT balance_minor FROM accounts WHERE id = :id"), {"id": tx.account_id}
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)
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return result.scalar_one()
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async def reject_transaction(session, *, tx, risk_score):
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await session.execute(
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sa.text("UPDATE transactions SET status = 'rejected', risk_score = :risk_score WHERE id = :id"),
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{"risk_score": risk_score, "id": tx.id},
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)
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await session.commit()
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result = await session.execute(
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sa.text("SELECT balance_minor FROM accounts WHERE id = :id"), {"id": tx.account_id}
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)
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return result.scalar_one()
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