bettercommitmessage.diff

commit cb5f051c5ee95e795dedaf3a264062cf75d44b1e
Author: Logan Johnson
Date:   Mon Aug 8 14:41:04 2016 -0400

    don't register Transaction in multiple scopes

    RA-14998

    TransactionBundler used to implement both Bundler and PausesAndResumes.
    In order to correct a lifecycle tangle (obvious from the dual
    implementation), we separated those two concerns and made Transaction
    implement PausesAndResumes instead. That change was made in this PR:

    https://stash.corp.squareup.com/projects/ANDROID/repos/register/pull-requests/10689/overview

    Unfortunately, a side effect of (or possibly, motivation for) having the
    TransactionBundler implement PausesAndResumes is that we vend a
    TransactionBundler instance to each caller. That instance would end up
    getting registered with an Activity scope, which was safe since each
    caller would get a new instance-- even though Activity scopes overlap, a
    single PausesAndResumes instance would only ever be registed with a
    single scope.

    By making the Transaction implement PausesAndResumes, we created a
    problem. Transaction is scoped to the Application, and outlives any
    Activities. Since Activity lifecycles (and thus scopes) overlap, this
    meant we would attempt to register the Transaction in an incoming
    Activity scope (via PauseAndResumeRegistrar) while it was still
    registered in the outgoing Activity's scope. This caused a pretty
    popular crash.

    The fix here is to return to vending a PausesAndResumes object to each
    caller, so that a separate instance is registered with each Activity
    scope, avoiding the dual-registration crash.

    note: The attentive reader will see that it's not actually the
    PausesAndResumes that gets registered with the Scope. It's another
    Scoped object that wraps the PausesAndResumes and delegates its
    equals/hashCode.

diff --git a/register/src/main/java/com/squareup/payment/Transaction.java b/register/src/main/java/com/squareup/payment/Transaction.java
index fd09de4..1121c5e 100644