Remove unusable key sessions when ProtectionController is stopped wit…

[dsilhavy]

…hout waiting for session.close promise to be resolved. Addresses #4238

[alexhmit]

The problem looks worse than we first thought:

for (let i = 0; i < numSessions; i++) {
                session = sessions[i];
                (function (s) {
                    _closeKeySessionInternal(session)
                    done(s);
                })(session);
  }

The done() calls removeSession which can splice sessions. This can make the next sessions[i] in the for loop to reference the wrong or undefine array item. Basically this code would not work for sessions.length > 1.

[dsilhavy]

@alexhmit can you provide a fix for this?

[alexhmit]

Sorry about the late response. For some reason, I am not getting any notification of this ticket.

We patched temporarily as follow:

            for (let i = numSessions - 1; i >= 0; i--) {
                session = sessions[i];
                (function (s) {
                    _closeKeySessionInternal(session)
                    done(s);
                })(session);
            }

Basically reversing the order of sessions processing so any splicing on sessions won't affect the looping. We did this to minimize the changes to the original code. We are not sure if there are other area of codes afflicted with this problem. But it fixed our regression problems.