Fix issues with CustomerSession listeners #856
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**Motivation** The previous implementation of `CustomerSession` listeners had a reference to a single `CustomerRetrievalListener` and `SourceRetrievalListener`. After a listener is called, it would be nulled out. This logic was buggy because it resulted in possible race conditions in which two calls are both in flight, and the first call that completes nulls out the listener for the second. **Summary** The solution to this issue is to associate an `operationId` (i.e. UUID) with each listener. This avoids the race condition and ambiguity about which listener is being referenced. Additionally, the listeners were being held with a strong reference, which could lead to memory leaks if the listener held a reference to an Activity. **Testing** Manually verified with samplestore and example apps.
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mshafrir-stripe
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aphexcx
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Apr 9, 2019
| @@ -327,19 +354,23 @@ long getCustomerCacheTime() { | |||
| private void addCustomerSource( | |||
| @NonNull final Context context, | |||
| @NonNull final CustomerEphemeralKey key, | |||
| @Nullable final String operationId, | |||
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Makes sense to me to stick this argument on the end to match the API of the other functions
| @@ -81,8 +84,10 @@ | |||
| @Nullable private Customer mCustomer; | |||
| private long mCustomerCacheTime; | |||
| @Nullable private Context mContext; | |||
| @Nullable private CustomerRetrievalListener mCustomerRetrievalListener; | |||
| @Nullable private SourceRetrievalListener mSourceRetrievalListener; | |||
| @NonNull private final Map<String, WeakReference<CustomerRetrievalListener>> | |||
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Is there really a need for weakreferences here? I'm concerned it would bring back that issue of listeners getting garbage collected, and I don't see these leaking any contexts
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These listeners can have references to Activity contexts (see PaymentMethodsActivity), so they should be WeakReferences to avoid memory leaks. We'll monitor new reports of GC issues.
jemerick-stripe
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Apr 9, 2019
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Motivation
The previous implementation of
CustomerSessionlistenershad a reference to a single
CustomerRetrievalListenerandSourceRetrievalListener. After a listener is called, itwould be nulled out.
This logic was buggy because it resulted in possible race
conditions in which two calls are both in flight, and the
first call that completes nulls out the listener for the
second.
Summary
The solution to this issue is to associate an
operationId(i.e. UUID) with each listener. This avoids the race condition
and ambiguity about which listener is being referenced.
Additionally, the listeners were being held with a strong
reference, which could lead to memory leaks if the listener
held a reference to an Activity.
Testing
Manually verified with samplestore and example apps.