tree 07fd076b3ea6f86bfea71e4c6707fd301f108db5
parent 9755c262df1be7f5d5b98d038c8fd3734e974f9d
author Mathieu Chartier <mathieuc@google.com> 1468428815 -0700
committer Mathieu Chartier <mathieuc@google.com> 1469655462 -0700

Use try lock to fix class resolution race

There was some possible deadlocks related to EnsureResolved caused by
acquiring an object lock.

Scenario:
Thread 1 acquires lock on obj1
Thread 1 begins to resolve / initialize class1
Thread 1 blocks since it sees that class1 is already being resolved and
gets preempted before it can acquire the object lock on class1
Thread 2 finishes resolving and initializing class1 and locks class1
Thread 2 blocks attempting to lock obj1
Thread 1 blocks attempting to lock class1
Deadlock

Fixed the deadlock by changing EnsureResolved to use a try lock for the
unresolved case.

Added a test.

Test: Device boot, test-art-host, monitor_test

Bug: 27417671
Change-Id: Ic6e1c3ca6f45490cf8a7bf8e137dee71ac83ff64