commit b6106d5a9db392f7b9ce78fecd49949dd3e3f5a5
author Alex Light <allight@google.com> Wed Oct 18 15:02:15 2017 -0700
committer Alex Light <allight@google.com> Thu Oct 19 09:23:59 2017 -0700
tree 0a3127da47e46ea7c022113ae51067ba41a185e4
parent 24276374dcaf95bfc52be2b8193eb4e337de62e4

Use r/w Mutex to control access to jvmtiEnv event information.

We were previously relying on the mutator_lock_ to provide
synchronization when accessing control information for some jvmti
events. This was not fully thread safe. To fix this problem we
instead use a ReaderWriterMutex to control access to this data.

Refactorings to allow all methods to have appropriate lock annotations
will follow in later CL (see bug).

Performance Impact:
    Tested performance by running main piece of test 993 10 times.
    Printing redirected to /dev/null.
    Total of ~270 breakpoints are executed.

    Before: 2.62 seconds / run
    After:  2.72 seconds / run

Test: ./test.py --host -j50
Test: ./art/tools/run-prebuilt-libjdwp-tests.sh --debug

Bug: 62821960
Bug: 67958496
Bug: 67962439

Change-Id: Ib2935c2e10bc2113e8430b49a9a7b76144e4235e

openjdkjvmti/ti_field.h

diff --git a/openjdkjvmti/ti_field.h b/openjdkjvmti/ti_field.h
index 8a229ed..3cf29f0 100644
--- a/openjdkjvmti/ti_field.h
+++ b/openjdkjvmti/ti_field.h
@@ -35,6 +35,8 @@
 #include "jni.h"
 #include "jvmti.h"
 
+#include "art_jvmti.h"
+
 namespace openjdkjvmti {
 
 class FieldUtil {
@@ -61,10 +63,14 @@
                                      jfieldID field,
                                      jboolean* is_synthetic_ptr);
 
-  static jvmtiError SetFieldModificationWatch(jvmtiEnv* env, jclass klass, jfieldID field);
-  static jvmtiError ClearFieldModificationWatch(jvmtiEnv* env, jclass klass, jfieldID field);
-  static jvmtiError SetFieldAccessWatch(jvmtiEnv* env, jclass klass, jfieldID field);
-  static jvmtiError ClearFieldAccessWatch(jvmtiEnv* env, jclass klass, jfieldID field);
+  static jvmtiError SetFieldModificationWatch(jvmtiEnv* env, jclass klass, jfieldID field)
+      REQUIRES(!ArtJvmTiEnv::event_info_mutex_);
+  static jvmtiError ClearFieldModificationWatch(jvmtiEnv* env, jclass klass, jfieldID field)
+      REQUIRES(!ArtJvmTiEnv::event_info_mutex_);
+  static jvmtiError SetFieldAccessWatch(jvmtiEnv* env, jclass klass, jfieldID field)
+      REQUIRES(!ArtJvmTiEnv::event_info_mutex_);
+  static jvmtiError ClearFieldAccessWatch(jvmtiEnv* env, jclass klass, jfieldID field)
+      REQUIRES(!ArtJvmTiEnv::event_info_mutex_);
 };
 
 }  // namespace openjdkjvmti