don't purge the results from buffer

[januszmk]

I tried upgrading graphqlite lib in my project and I was hit by this issue: #729

I am making pr that removes purging from the buffer, but if there is different way to fix the issue, please let me know

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.81%. Comparing base (53f9d49) to head (c3f7884).
⚠️ Report is 118 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #752      +/-   ##
============================================
- Coverage     95.72%   94.81%   -0.91%     
- Complexity     1773     1838      +65     
============================================
  Files           154      175      +21     
  Lines          4586     4998     +412     
============================================
+ Hits           4390     4739     +349     
- Misses          196      259      +63     

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[oojacoboo]

@oprypkhantc was there a reason to purge results from the prefetch buffer? I'm inclined to merge this, but would like to hear your reasoning for adding.

[autaut03]

@oojacoboo Wasn't me who added that. git blame reports #702 as the source. I guess the purging is done because the result for that entity should already exist, so logically there's no reason to store anything other than the result itself.

But I don't know how it's actually implemented, so don't quote me on that. @sudevva you remember any details?

[sudevva]

I guess the main reason is that the buffer will never be cleared in other case. I need to check why I added this

[autaut03]

We should get a new context (along with the whole prefetch buffer) on each new request, so it will get cleared, just a bit later. It should result in higher memory usage before the response is generated, right?

[sudevva]

purgeResult can be safely removed, most likely
And if we're targeting php>=8 WeakMap can be used as a replacement for SplObjectStorage