tree fdb546e13488a07e92dc8b40a036779fe0199682
parent bcb32310ce68faee2e33e0b887db8a2f760dd67e
author Aaron Vaage <vaage@google.com> 1717561022 -0700
committer Aaron Vaage <vaage@google.com> 1717688994 -0700

Trace Redaction - Implement thread merge strategy

To implement thread merging, there are only a few interfaces that
need to be implemented. These are the same interfaces that other
redactions are based one.

A simple example of this is the thread sched modification interface.
The thread merging implementation replaces the pid value with the cpu
pid value.

It is through these simple strategies that thread merging can be
implemented while requiring very little (to no) risk.

As implemented, there are some some small issues:

  1. The process tree contains removed threads and processes. The
     names have been removed, but the pids and tids are present.

  2. The process tree does not contain the new per-cpu threads.

  3. In some cases, threads split and one gets orphaned. In case,
     a thread which started at time X and ended at time Y gets
     split into two threads, one starting at time X and never
     ends, and another that always existed and never ends.

Bug: 339504266
Bug: 336807771
Change-Id: Icec4b7625c2decc8466b15aecd53b626f86644e3