⚡️ Speed up method poloniex.parse_leverage by 123%

[codeflash-ai]

📄 123% (1.23x) speedup for poloniex.parse_leverage in python/ccxt/poloniex.py

⏱️ Runtime : 4.90 milliseconds → 2.20 milliseconds (best of 86 runs)

📝 Explanation and details

The optimized code achieves a 122% speedup (from 4.90ms to 2.20ms) through two key optimizations to the safe_string and safe_integer methods in the Exchange base class:

1. Exception-based key lookup optimization: The original code used a helper method Exchange.key_exists() to check dictionary keys before accessing them, which involved multiple function calls and redundant key lookups. The optimized version uses a direct try/except pattern that attempts the key access immediately and catches exceptions, eliminating the double lookup overhead.

2. Streamlined exception handling: In safe_integer, the optimized version consolidates exception types into a single catch block (KeyError, TypeError, IndexError) instead of separate checks, reducing branching overhead.

Performance impact analysis:

• The safe_string method shows the most dramatic improvement - from 15.6ms total time to 8.47ms (46% faster per call)
• The safe_integer method improves from 8.15ms to 4.33ms (47% faster per call)
• These methods are called extensively in the parse_leverage function (13,868 calls to safe_string and 4,542 calls to safe_integer)

Why this optimization works: In Python, the try/except pattern for dictionary access is generally faster than explicit key checking when keys exist most of the time (which is the common case). The "Easier to Ask for Forgiveness than Permission" (EAFP) approach avoids the overhead of multiple dictionary lookups and method calls.

Test case benefits: The optimization is particularly effective for large-scale test cases - the 1000-entry performance test shows 176% speedup, and tests with invalid entries show 88-174% improvements, indicating the optimization scales well with data volume and handles edge cases efficiently.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 63 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	100.0%

🌀 Generated Regression Tests and Runtime

import pytest
from ccxt.poloniex import poloniex

Minimal stub for poloniex class with required methods for parse_leverage

class PoloniexStub:
# Helper methods as per Exchange base class
@staticmethod
def key_exists(dictionary, key):
if hasattr(dictionary, 'getitem') and not isinstance(dictionary, str):
if isinstance(dictionary, list) and type(key) is not int:
return False
try:
value = dictionary[key]
return value is not None and value != ''
except LookupError:
return False
return False

@staticmethod
def safe_string(dictionary, key, default_value=None):
    return str(dictionary[key]) if PoloniexStub.key_exists(dictionary, key) else default_value

@staticmethod
def safe_integer(dictionary, key, default_value=None):
    if not PoloniexStub.key_exists(dictionary, key):
        return default_value
    value = dictionary[key]
    try:
        return int(float(value))
    except ValueError:
        return default_value
    except TypeError:
        return default_value

@staticmethod
def safe_list(dictionaryOrList, key, defaultValue=None):
    if PoloniexStub.key_exists(dictionaryOrList, key):
        value = dictionaryOrList[key]
        if isinstance(value, list):
            return value
    return defaultValue if defaultValue is not None else []

@staticmethod
def safe_symbol(marketId, market=None, delimiter=None, marketType=None):
    # For our tests, just return marketId or market['symbol'] if market is provided
    if market is not None and 'symbol' in market:
        return market['symbol']
    return marketId

# The function under test
def parse_leverage(self, leverage: dict, market: dict = None):
    shortLeverage = None
    longLeverage = None
    marketId = None
    marginMode = None
    data = self.safe_list(leverage, 'data')
    for i in range(0, len(data)):
        entry = data[i]
        marketId = self.safe_string(entry, 'symbol')
        marginMode = self.safe_string(entry, 'mgnMode')
        lever = self.safe_integer(entry, 'lever')
        posSide = self.safe_string(entry, 'posSide')
        if posSide == 'LONG':
            longLeverage = lever
        elif posSide == 'SHORT':
            shortLeverage = lever
        else:
            longLeverage = lever
            shortLeverage = lever
    return {
        'info': leverage,
        'symbol': self.safe_symbol(marketId, market),
        'marginMode': marginMode,
        'longLeverage': longLeverage,
        'shortLeverage': shortLeverage,
    }

from ccxt.poloniex import poloniex

--------------------------

BASIC TEST CASES

--------------------------

#------------------------------------------------
import pytest
from ccxt.poloniex import poloniex

Function under test: poloniex.parse_leverage and supporting minimal class structure

class DummyExchange:
# Minimal safe_string implementation
@staticmethod
def key_exists(dictionary, key):
if hasattr(dictionary, 'getitem') and not isinstance(dictionary, str):
if isinstance(dictionary, list) and type(key) is not int:
return False
try:
value = dictionary[key]
return value is not None and value != ''
except LookupError:
return False
return False

@staticmethod
def safe_string(dictionary, key, default_value=None):
    return str(dictionary[key]) if DummyExchange.key_exists(dictionary, key) else default_value

@staticmethod
def safe_integer(dictionary, key, default_value=None):
    if not DummyExchange.key_exists(dictionary, key):
        return default_value
    value = dictionary[key]
    try:
        return int(float(value))
    except (ValueError, TypeError):
        return default_value

@staticmethod
def safe_list(dictionaryOrList, key, defaultValue=None):
    # Only supports dicts
    if isinstance(dictionaryOrList, dict) and key in dictionaryOrList:
        value = dictionaryOrList[key]
        if isinstance(value, list):
            return value
    return defaultValue if defaultValue is not None else []

@staticmethod
def safe_symbol(marketId, market=None, delimiter=None, marketType=None):
    # For test, just return marketId if present, else None
    return marketId

from ccxt.poloniex import poloniex

Test suite for poloniex.parse_leverage

@pytest.fixture
def poloniex_instance():
return poloniex()

-------------------------------

1. Basic Test Cases

-------------------------------

def test_basic_long_and_short_leverage(poloniex_instance):
# Standard input with both LONG and SHORT entries
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 5, "posSide": "LONG"},
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 3, "posSide": "SHORT"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 16.4μs -> 14.1μs (16.0% faster)

def test_basic_single_entry_no_posside(poloniex_instance):
# Entry with no posSide (should set both long and short to lever)
leverage = {
"data": [
{"symbol": "DOGE/USDT", "mgnMode": "isolated", "lever": 7},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 15.1μs -> 13.9μs (9.00% faster)

def test_basic_multiple_entries_last_wins(poloniex_instance):
# Multiple entries for the same posSide, last one should win
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 3, "posSide": "LONG"},
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 5, "posSide": "LONG"},
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 2, "posSide": "SHORT"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 17.0μs -> 14.2μs (19.6% faster)

-------------------------------

2. Edge Test Cases

-------------------------------

def test_edge_entry_lever_is_string(poloniex_instance):
# 'lever' is a string
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": "8", "posSide": "LONG"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 15.0μs -> 13.6μs (10.3% faster)

def test_edge_entry_lever_is_float_string(poloniex_instance):
# 'lever' is a float string, should be converted to int
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": "4.0", "posSide": "SHORT"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 15.0μs -> 13.8μs (8.74% faster)

def test_edge_entry_lever_is_invalid(poloniex_instance):
# 'lever' is a non-numeric string, should become None
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": "abc", "posSide": "LONG"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 16.6μs -> 15.1μs (9.86% faster)

def test_edge_entry_missing_symbol_and_mgnMode(poloniex_instance):
# Entry missing 'symbol' and 'mgnMode'
leverage = {
"data": [
{"lever": 5, "posSide": "LONG"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 15.0μs -> 13.8μs (8.81% faster)

def test_edge_entry_posside_unexpected_value(poloniex_instance):
# Entry with unexpected posSide value (should set both)
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 6, "posSide": "BOTH"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 15.1μs -> 13.4μs (12.8% faster)

def test_edge_multiple_symbols_last_symbol_used(poloniex_instance):
# Multiple entries with different symbols, last symbol should be used
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 3, "posSide": "LONG"},
{"symbol": "ETH/USDT", "mgnMode": "isolated", "lever": 2, "posSide": "SHORT"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 16.1μs -> 13.5μs (19.2% faster)

def test_edge_none_lever_value(poloniex_instance):
# lever is None
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": None, "posSide": "LONG"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 14.0μs -> 14.7μs (4.47% slower)

def test_edge_none_posside_value(poloniex_instance):
# posSide is None (should set both)
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 9, "posSide": None},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 14.7μs -> 13.4μs (9.80% faster)

def test_edge_lever_zero(poloniex_instance):
# lever is zero
leverage = {
"data": [
{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 0, "posSide": "LONG"},
]
}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 14.8μs -> 13.3μs (11.6% faster)

-------------------------------

3. Large Scale Test Cases

-------------------------------

def test_large_scale_mixed_symbols(poloniex_instance):
# Many entries with different symbols, last entry's symbol/marginMode/leverage should be used
data = []
for i in range(500):
data.append({"symbol": f"SYM{i}/USDT", "mgnMode": "cross", "lever": i, "posSide": "LONG"})
data.append({"symbol": "FINAL/USDT", "mgnMode": "isolated", "lever": 42, "posSide": "SHORT"})
leverage = {"data": data}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 469μs -> 171μs (174% faster)

def test_large_scale_many_invalid_entries(poloniex_instance):
# Many entries with invalid lever, only last valid one should be used
data = [{"symbol": "BTC/USDT", "mgnMode": "cross", "lever": "bad", "posSide": "LONG"} for _ in range(999)]
data.append({"symbol": "BTC/USDT", "mgnMode": "cross", "lever": 77, "posSide": "LONG"})
leverage = {"data": data}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 1.27ms -> 677μs (88.2% faster)

def test_large_scale_performance(poloniex_instance):
# Performance: 1000 entries, all valid, alternating posSide
data = []
for i in range(1000):
data.append({"symbol": "BTC/USDT", "mgnMode": "cross", "lever": i, "posSide": "LONG" if i % 2 == 0 else "SHORT"})
leverage = {"data": data}
codeflash_output = poloniex_instance.parse_leverage(leverage); result = codeflash_output # 946μs -> 343μs (176% faster)

codeflash_output is used to check that the output of the original code is the same as that of the optimized code.

To edit these changes git checkout codeflash/optimize-poloniex.parse_leverage-mhurfxuj and push.