Pass self to lock methods.
This avoids frequent recomputation of
Thread::Current/pthread_getspecific.
Also add a futex based reader/writer mutex that is disabled.
Change-Id: I118fdb99ef1d1c4bfda6446ba3a0d8b6ab31eaee
diff --git a/src/locks.h b/src/locks.h
new file mode 100644
index 0000000..c5821d8
--- /dev/null
+++ b/src/locks.h
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_SRC_LOCKS_H_
+#define ART_SRC_LOCKS_H_
+
+#include <ostream>
+
+#include "macros.h"
+
+namespace art {
+
+class LOCKABLE Mutex;
+class LOCKABLE ReaderWriterMutex;
+
+// LockLevel is used to impose a lock hierarchy [1] where acquisition of a Mutex at a higher or
+// equal level to a lock a thread holds is invalid. The lock hierarchy achieves a cycle free
+// partial ordering and thereby cause deadlock situations to fail checks.
+//
+// [1] http://www.drdobbs.com/parallel/use-lock-hierarchies-to-avoid-deadlock/204801163
+enum LockLevel {
+ kLoggingLock = 0,
+ kUnexpectedSignalLock = 1,
+ kThreadSuspendCountLock = 2,
+ kAbortLock = 3,
+ kDefaultMutexLevel = 4,
+ kJdwpSerialLock = 5,
+ kAllocSpaceLock = 6,
+ kLoadLibraryLock = 7,
+ kClassLinkerClassesLock = 8,
+ kThreadListLock = 9,
+ kHeapBitmapLock = 10,
+ kMonitorLock = 11,
+ kMutatorLock = 12,
+ kZygoteCreationLock = 13,
+ kMaxMutexLevel = kMutatorLock,
+};
+std::ostream& operator<<(std::ostream& os, const LockLevel& rhs);
+
+// Global mutexes corresponding to the levels above.
+class Locks {
+ public:
+ static void Init();
+
+ // The mutator_lock_ is used to allow mutators to execute in a shared (reader) mode or to block
+ // mutators by having an exclusive (writer) owner. In normal execution each mutator thread holds
+ // a share on the mutator_lock_. The garbage collector may also execute with shared access but
+ // at times requires exclusive access to the heap (not to be confused with the heap meta-data
+ // guarded by the heap_lock_ below). When the garbage collector requires exclusive access it asks
+ // the mutators to suspend themselves which also involves usage of the thread_suspend_count_lock_
+ // to cover weaknesses in using ReaderWriterMutexes with ConditionVariables. We use a condition
+ // variable to wait upon in the suspension logic as releasing and then re-acquiring a share on
+ // the mutator lock doesn't necessarily allow the exclusive user (e.g the garbage collector)
+ // chance to acquire the lock.
+ //
+ // Thread suspension:
+ // Shared users | Exclusive user
+ // (holding mutator lock and in kRunnable state) | .. running ..
+ // .. running .. | Request thread suspension by:
+ // .. running .. | - acquiring thread_suspend_count_lock_
+ // .. running .. | - incrementing Thread::suspend_count_ on
+ // .. running .. | all mutator threads
+ // .. running .. | - releasing thread_suspend_count_lock_
+ // .. running .. | Block trying to acquire exclusive mutator lock
+ // Poll Thread::suspend_count_ and enter full | .. blocked ..
+ // suspend code. | .. blocked ..
+ // Change state to kSuspended | .. blocked ..
+ // x: Release share on mutator_lock_ | Carry out exclusive access
+ // Acquire thread_suspend_count_lock_ | .. exclusive ..
+ // while Thread::suspend_count_ > 0 | .. exclusive ..
+ // - wait on Thread::resume_cond_ | .. exclusive ..
+ // (releases thread_suspend_count_lock_) | .. exclusive ..
+ // .. waiting .. | Release mutator_lock_
+ // .. waiting .. | Request thread resumption by:
+ // .. waiting .. | - acquiring thread_suspend_count_lock_
+ // .. waiting .. | - decrementing Thread::suspend_count_ on
+ // .. waiting .. | all mutator threads
+ // .. waiting .. | - notifying on Thread::resume_cond_
+ // - re-acquire thread_suspend_count_lock_ | - releasing thread_suspend_count_lock_
+ // Release thread_suspend_count_lock_ | .. running ..
+ // Acquire share on mutator_lock_ | .. running ..
+ // - This could block but the thread still | .. running ..
+ // has a state of kSuspended and so this | .. running ..
+ // isn't an issue. | .. running ..
+ // Acquire thread_suspend_count_lock_ | .. running ..
+ // - we poll here as we're transitioning into | .. running ..
+ // kRunnable and an individual thread suspend | .. running ..
+ // request (e.g for debugging) won't try | .. running ..
+ // to acquire the mutator lock (which would | .. running ..
+ // block as we hold the mutator lock). This | .. running ..
+ // poll ensures that if the suspender thought | .. running ..
+ // we were suspended by incrementing our | .. running ..
+ // Thread::suspend_count_ and then reading | .. running ..
+ // our state we go back to waiting on | .. running ..
+ // Thread::resume_cond_. | .. running ..
+ // can_go_runnable = Thread::suspend_count_ == 0 | .. running ..
+ // Release thread_suspend_count_lock_ | .. running ..
+ // if can_go_runnable | .. running ..
+ // Change state to kRunnable | .. running ..
+ // else | .. running ..
+ // Goto x | .. running ..
+ // .. running .. | .. running ..
+ static ReaderWriterMutex* mutator_lock_;
+
+ // Allow reader-writer mutual exclusion on the mark and live bitmaps of the heap.
+ static ReaderWriterMutex* heap_bitmap_lock_ ACQUIRED_AFTER(mutator_lock_);
+
+ // The thread_list_lock_ guards ThreadList::list_. It is also commonly held to stop threads
+ // attaching and detaching.
+ static Mutex* thread_list_lock_ ACQUIRED_AFTER(heap_bitmap_lock_);
+
+ // Guards lists of classes within the class linker.
+ static Mutex* classlinker_classes_lock_ ACQUIRED_AFTER(thread_list_lock_);
+
+ // When declaring any Mutex add DEFAULT_MUTEX_ACQUIRED_AFTER to use annotalysis to check the code
+ // doesn't try to hold a higher level Mutex.
+ #define DEFAULT_MUTEX_ACQUIRED_AFTER ACQUIRED_AFTER(classlinker_classes_lock_)
+
+ // Have an exclusive aborting thread.
+ static Mutex* abort_lock_ ACQUIRED_AFTER(classlinker_classes_lock_);
+
+ // Allow mutual exclusion when manipulating Thread::suspend_count_.
+ // TODO: Does the trade-off of a per-thread lock make sense?
+ static Mutex* thread_suspend_count_lock_ ACQUIRED_AFTER(abort_lock_);
+
+ // One unexpected signal at a time lock.
+ static Mutex* unexpected_signal_lock_ ACQUIRED_AFTER(thread_suspend_count_lock_);
+
+ // Have an exclusive logging thread.
+ static Mutex* logging_lock_ ACQUIRED_AFTER(unexpected_signal_lock_);
+};
+
+} // namespace art
+
+#endif // ART_SRC_LOCKS_H_