Memcached corrupting JSON encoded data #250
Description
Problem
Running the following sample code, json_decoding the memcached value results in the following JSON error messages:
- Syntax error
- Control character error, possibly incorrectly encoded
- Malformed UTF-8 characters, possibly incorrectly encoded
The error message generated cycles through the above list once the JSON encoded string is larger than 2000 characters.
No error messages are generated by just JSON encoding and decoding directly. The only time errors occur is when the value being decoded is retrieve from memcache.
Sample code
<?php
$memcache = new Memcached;
$memcache->addServer('localhost', 11211);
echo "<pre>\n";
$arr = array();
for ($i = 0; $i < 1000; $i++) {
$arr[] = "abcdefghij";
$json_str_in = json_encode($arr);
if (FALSE === $memcache->set('test/jsondata', $json_str_in, 2)) {
echo "getResultCode = " . Memcached::getResultCode() . PHP_EOL;
exit;
}
$json_str_out = $memcache->get('test/jsondata');
json_decode($json_str_in, TRUE);
if (JSON_ERROR_NONE !== json_last_error()) {
printf(
'strlen of source value: %d, json_decode of source value: [%s]' . PHP_EOL,
strlen($json_str_in),
json_last_error_msg()
);
}
json_decode($json_str_out, TRUE);
if (JSON_ERROR_NONE !== json_last_error()) {
printf(
'strlen of memcached value: %d, json_decode of memcached value: [%s]' . PHP_EOL,
strlen($json_str_out),
json_last_error_msg()
);
}
}
PHP Version
PHP 7.0.5 (cli) (built: Apr 11 2016 15:53:52) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies
with Xdebug v2.4.0, Copyright (c) 2002-2016, by Derick Rethans
Memcached Config
memcached support => enabled
Version => 3.0.0-dev
libmemcached version => 1.0.18
SASL support => yes
Session support => yes
igbinary support => yes
json support => yes
msgpack support => yes
Directive => Local Value => Master Value
memcached.compression_factor => 1.3 => 1.3
memcached.compression_threshold => 2000 => 2000
memcached.compression_type => fastlz => fastlz
memcached.default_binary_protocol => 0 => 0
memcached.default_connect_timeout => 0 => 0
memcached.default_consistent_hash => 0 => 0
memcached.serializer => igbinary => igbinary
memcached.sess_binary_protocol => 1 => 1
memcached.sess_connect_timeout => 1000 => 1000
memcached.sess_consistent_hash => no value => no value
memcached.sess_lock_expire => 0 => 0
memcached.sess_lock_max_wait => not set => not set
memcached.sess_lock_retries => 5 => 5
memcached.sess_lock_wait => not set => not set
memcached.sess_lock_wait_max => 0 => 0
memcached.sess_lock_wait_min => 0 => 0
memcached.sess_locking => 1 => 1
memcached.sess_number_of_replicas => 0 => 0
memcached.sess_persistent => 0 => 0
memcached.sess_prefix => memc.sess.key. => memc.sess.key.
memcached.sess_randomize_replica_read => no value => no value
memcached.sess_remove_failed_servers => 0 => 0
memcached.sess_sasl_password => no value => no value
memcached.sess_sasl_username => no value => no value
memcached.sess_server_failure_limit => 0 => 0
memcached.store_retry_count => 2 => 2
Memcache Server Version
1.4.13