gc_collect_cycles() may interfere with using foreach to iterate objects

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    • Type: Bug
    • Resolution: Unresolved
    • Priority: Minor - P4
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    • Affects Version/s: None
    • Component/s: None
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    • PHP Drivers
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      1. What would you like to communicate to the user about this feature? 2. Would you like the user to see examples of the syntax and/or executable code and its output? 3. Which versions of the driver/connector does this apply to?
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      As reported in mongodb/mongo-php-driver#1776, calling gc_collect_cycles() may impact how properties of PHPC objects are reported when using foreach.

      To test this, I modified php_phongo_objectid_get_properties_hash() to print the value of is_temp each time it is called. I then ran the following:

      <?php

$oid = new MongoDB\BSON\ObjectId;

echo "foreach ObjectId:\n";
foreach ($oid as $k => $v) {
	printf("%s: %s\n", $k, $v);
}

printf("\ngc_collect_cycles: %d\n", gc_collect_cycles());

echo "\nforeach ObjectId:\n";
foreach ($oid as $k => $v) {
	printf("%s: %s\n", $k, $v);
}

echo "\nvar_dump() ObjectId:\n";
var_dump($oid);

echo "\nget_object_vars() ObjectId\n";
var_dump(get_object_vars($oid));

      Output:

      foreach ObjectId:
php_phongo_objectid_get_properties_hash is_temp: 0
php_phongo_objectid_get_properties_hash is_temp: 0
oid: 67a0e8dcff929c245f0786c0
php_phongo_objectid_get_properties_hash is_temp: 0

gc_collect_cycles: 0

foreach ObjectId:

var_dump() ObjectId:
php_phongo_objectid_get_properties_hash is_temp: 1
object(MongoDB\BSON\ObjectId)#1 (1) {
  ["oid"]=>
  string(24) "67a0e8dcff929c245f0786c0"
}

get_object_vars() ObjectId
php_phongo_objectid_get_properties_hash is_temp: 0
array(1) {
  ["oid"]=>
  string(24) "67a0e8dcff929c245f0786c0"
}

      var_dump() calls the get_debug_info handler, which sets is_temp: true, as expected. get_object_vars() uses the get_properties handler, which is also expected.

      It is unclear why the first foreach calls the get_properties handler three times, and then omits it entirely after the call to gc_collect_cycles.

              Assignee:
              Jeremy Mikola
              Reporter:
              Jeremy Mikola
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                Created:
                Updated: