support pushing to CappedMemoryCache

[icewind1991]

Support doing $cache[] = 'foo'

Only the CappedMemoryCache is ever used that way, since doing this doesn't make sense on "real" memecaches

[mention-bot]

@icewind1991, thanks for your PR! By analyzing the history of the files in this pull request, we identified @nickvergessen to be a potential reviewer.

[MorrisJobke]

What is the background of this?

[icewind1991]

The query logger (used mainly by xray) was switched to the capped cache to prevent memory issues on long running processes, but since that uses the push semantics it currently doesn't properly hold the logged queries

[MorrisJobke]

But there is no way to get the information out of the cache?

[MorrisJobke]

Ah found it - the offsetGet

[MorrisJobke]

A unit tests fails:

There was 1 failure:
1) Test\AppTest::testEnabledApps with data set #3 (null, array('files', 'app1', 'app3', 'appforgroup1', 'appforgroup12', 'appforgroup2', 'dav', 'federatedfilesharing', 'lookup_server_connector', 'provisioning_api', 'twofactor_backupcodes', 'workflowengine'), false)
Failed asserting that two arrays are equal.
--- Expected
+++ Actual
@@ @@
 Array (
     0 => 'files'
     1 => 'app1'
     2 => 'app3'
-    3 => 'appforgroup1'
-    4 => 'appforgroup12'
-    5 => 'appforgroup2'
-    6 => 'dav'
-    7 => 'federatedfilesharing'
-    8 => 'lookup_server_connector'
-    9 => 'provisioning_api'
-    10 => 'twofactor_backupcodes'
-    11 => 'workflowengine'
+    3 => 'dav'
+    4 => 'federatedfilesharing'
+    5 => 'lookup_server_connector'
+    6 => 'provisioning_api'
+    7 => 'twofactor_backupcodes'
+    8 => 'workflowengine'
 )
/drone/src/github.com/nextcloud/server/tests/lib/AppTest.php:487