sde: Implement sequence locker to lock across multiple APIs.

1. Lock prepare() and set() APIs using sequence entry and sequence
   exit lock respectively to prevent the critical section being
   accessed by other threads.
2. Wait for sequence wait lock on HotPlugEvent thread or any other
   binder threads(Eg. dumpsys), before it accesses the critical region.
3. Prevent deadlock during multiple prepare() calls before a set().

Change-Id: I5443675c870ed2967615ec383dd2d59ded30b52b

displayengine/include/utils/locker.h

@@ -1,5 +1,5 @@
 /*
-* Copyright (c) 2014, The Linux Foundation. All rights reserved.
+* Copyright (c) 2014 - 2015, The Linux Foundation. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
@@ -28,7 +28,11 @@
 #include <stdint.h>
 #include <pthread.h>
 
-#define SCOPE_LOCK(locker) Locker::ScopeLock scopeLock(locker)
+#define SCOPE_LOCK(locker) Locker::ScopeLock lock(locker)
+#define SEQUENCE_ENTRY_SCOPE_LOCK(locker) Locker::SequenceEntryScopeLock lock(locker)
+#define SEQUENCE_EXIT_SCOPE_LOCK(locker) Locker::SequenceExitScopeLock lock(locker)
+#define SEQUENCE_WAIT_SCOPE_LOCK(locker) Locker::SequenceWaitScopeLock lock(locker)
+#define SEQUENCE_CANCEL_SCOPE_LOCK(locker) Locker::SequenceCancelScopeLock lock(locker)
 
 namespace sde {
 
@@ -48,7 +52,78 @@ class Locker {
     Locker &locker_;
   };
 
-  Locker() {
+  class SequenceEntryScopeLock {
+   public:
+    explicit SequenceEntryScopeLock(Locker& locker) : locker_(locker) {
+      locker_.Lock();
+      locker_.sequence_wait_ = 1;
+    }
+
+    ~SequenceEntryScopeLock() {
+      locker_.Unlock();
+    }
+
+   private:
+    Locker &locker_;
+  };
+
+  class SequenceExitScopeLock {
+   public:
+    explicit SequenceExitScopeLock(Locker& locker) : locker_(locker) {
+      locker_.Lock();
+      locker_.sequence_wait_ = 0;
+    }
+
+    ~SequenceExitScopeLock() {
+      locker_.Broadcast();
+      locker_.Unlock();
+    }
+
+   private:
+    Locker &locker_;
+  };
+
+  class SequenceWaitScopeLock {
+   public:
+    explicit SequenceWaitScopeLock(Locker& locker) : locker_(locker), error_(false) {
+      locker_.Lock();
+
+      if (locker_.sequence_wait_ == 1) {
+        locker_.Wait();
+        error_ = (locker_.sequence_wait_ == -1);
+      }
+    }
+
+    ~SequenceWaitScopeLock() {
+      locker_.Unlock();
+    }
+
+    bool IsError() {
+      return error_;
+    }
+
+   private:
+    Locker &locker_;
+    bool error_;
+  };
+
+  class SequenceCancelScopeLock {
+   public:
+    explicit SequenceCancelScopeLock(Locker& locker) : locker_(locker) {
+      locker_.Lock();
+      locker_.sequence_wait_ = -1;
+    }
+
+    ~SequenceCancelScopeLock() {
+      locker_.Broadcast();
+      locker_.Unlock();
+    }
+
+   private:
+    Locker &locker_;
+  };
+
+  Locker() : sequence_wait_(0) {
     pthread_mutex_init(&mutex_, 0);
     pthread_cond_init(&condition_, 0);
   }
@@ -63,7 +138,7 @@ class Locker {
   void Signal() { pthread_cond_signal(&condition_); }
   void Broadcast() { pthread_cond_broadcast(&condition_); }
   void Wait() { pthread_cond_wait(&condition_, &mutex_); }
-  int WaitFinite(long int ms) {
+  int WaitFinite(int ms) {
     struct timespec ts;
     struct timeval tv;
     gettimeofday(&tv, NULL);
@@ -77,6 +152,11 @@ class Locker {
  private:
   pthread_mutex_t mutex_;
   pthread_cond_t condition_;
+  int sequence_wait_;   // This flag is set to 1 on sequence entry, 0 on exit, and -1 on cancel.
+                        // Some routines will wait for sequence of function calls to finish
+                        // so that capturing a transitionary snapshot of context is prevented.
+                        // If flag is set to -1, these routines will exit without doing any
+                        // further processing.
 };
 
 }  // namespace sde