bitfinex v2 fetch_ohlcv empty / null response handling

[ralondo]

It seems, that bitfinex v2 fetch_ohlcv sometimes returns empty / null responses. I guess some problems on bitfinexs side. I get these warnings in my errorlog:
PHP Warning: array_key_exists() expects parameter 2 to be array, null given in /srv/www/htdocs/crypt/includes/classes/ccxt.php on line 4772
PHP Warning: array_values() expects parameter 1 to be array, null given in /srv/www/htdocs/crypt/includes/classes/ccxt.php on line 917
PHP Warning: Invalid argument supplied for foreach() in /srv/www/htdocs/crypt/includes/classes/ccxt.php on line 918

The $response in line 4771 is empty, the parameters for the fetch2 call are:
$body: (is empty)
$path:candles/trade:{timeframe}:{symbol}/hist
$params (print_r): Array\n(\n [symbol] => tBTCUSD\n [timeframe] => 1m\n)\n

Would it be possible to have some kind of handling there for empty responses?

[kroitor]

@ralondo hi! Thanks for reporting! I'll take a look into it. In the meantime, can you show your code, please? These symptoms may indicate that you are hitting their rate limit... Do you actually throttle your requests?

[ralondo]

What code do you need? How can I check with ccxt if I hit the rate limit? Anyway, I do throttle my requests by having my own scheduler, in average only one call every 12 seconds to bitfinex. According to their API-docs the the rate limit on the REST-API is 10-90 calls per minute, so I could make at least 1 call every 6 seconds.
The warning doesn't always come, only every few minutes. I lowered my rate now a little bit to a max. of one call every 14 seconds. Maybe it will help.

[kroitor]

@ralondo ok, no need for the code... Unfortunately, they state it clear, v2 is beta. We will add more checks to handle for empty responses. Thx!

[ralondo]

No problem. I just changed the code for me a bit to get rid of those annoying warnings:
if (!is_array($response)) { logtext($response." BODY:".$body." PATH:".$path." PARAMS:".print_r($params,true)); $response = array(); } else { if (array_key_exists ('message', $response)) { if (mb_strpos ($response['message'], 'not enough exchange balance') !== false) throw new InsufficientFunds ($this->id . ' ' . $this->json ($response)); throw new ExchangeError ($this->id . ' ' . $this->json ($response)); } }
I just don't have to forget to reinsert this code after upgrading ccxt ;)

[kroitor]

With examples/php/bitfinex2-fetch-ohlcv.php I'm also having some errors from Bitfinex v2:

...
2017-10-25T14:32:00.000+00:00	120
2017-10-25T14:32:00.000+00:00	120
2017-10-25T14:33:00.000+00:00	120
PHP Fatal error:  Uncaught exception 'ccxt\RequestTimeout' with message 'bitfinex2 GET https://api.bitfinex.com/v2/candles/trade:1m:tBTCUSD/hist 28 Operation timed out after 10000 milliseconds with 0 bytes received' in /Users/igorkroitor/ccxt/build/ccxt.php:629
Stack trace:
#0 /Users/igorkroitor/ccxt/build/ccxt.php(765): ccxt\Exchange->raise_error('RequestTimeout', 'https://api.bit...', 'GET', 28, 'Operation timed...')
#1 /Users/igorkroitor/ccxt/build/ccxt.php(650): ccxt\Exchange->fetch('https://api.bit...', 'GET', NULL, NULL)
#2 /Users/igorkroitor/ccxt/build/ccxt.php(4771): ccxt\Exchange->fetch2('candles/trade:{...', 'public', 'GET', Array, NULL, NULL)
#3 [internal function]: ccxt\bitfinex2->request('candles/trade:{...', 'public', 'GET', Array)
#4 /Users/igorkroitor/ccxt/build/ccxt.php(593): call_user_func(Array, 'candles/trade:{...', 'public', 'GET', Array)
#5 [internal function]: ccxt\Exchange->ccxt\{closure}(Array)
#6 /Users/igorkroitor/ccxt/build/ccxt.php(1327): call_user_func_array(Object(Closure), Array)
#7 /Users/igork in /Users/igorkroitor/ccxt/build/ccxt.php on line 629
mbp:ccxt igorkroitor$ 

So, yes, I am adding the handling for it now.

[kroitor]

This issue was addressed and fixed in 1.9.262. Thx again for your feedback! Really appreciate it!