Use memory chunks for monitors on LP64

Monitor IDs in lock words are only 30b. On a 32b system that works
fine, as memory is usually aligned enough that shifting works out.
On 64b systems, the virtual memory space is too large for that.
This adds memory chunks into which we allocate the monitors so that
we have base_addr + offset and can use the offset as the monitor ID.
To allow for relatively compact but growable storage, we use a list
of chunks.

Added a global lock for the monitor pool.

Change-Id: I0e290c4914a2556e0b2eef9902422d7c4dcf536d

1 files changed, 9 insertions, 1 deletions

diff --git a/runtime/monitor.h b/runtime/monitor.h
index d7552a3..0d0ad0b 100644
--- a/runtime/monitor.h
+++ b/runtime/monitor.h
@@ -124,7 +124,9 @@ class Monitor {
 
  private:
   explicit Monitor(Thread* self, Thread* owner, mirror::Object* obj, int32_t hash_code)
-      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+        SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+  explicit Monitor(Thread* self, Thread* owner, mirror::Object* obj, int32_t hash_code,
+                   MonitorId id) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Install the monitor into its object, may fail if another thread installs a different monitor
   // first.
@@ -212,8 +214,14 @@ class Monitor {
   // The denser encoded version of this monitor as stored in the lock word.
   MonitorId monitor_id_;
 
+#ifdef __LP64__
+  // Free list for monitor pool.
+  Monitor* next_free_ GUARDED_BY(Locks::allocated_monitor_ids_lock_);
+#endif
+
   friend class MonitorInfo;
   friend class MonitorList;
+  friend class MonitorPool;
   friend class mirror::Object;
   DISALLOW_COPY_AND_ASSIGN(Monitor);
 };