Split payload application code into a subdirectory.

This patch splits from the main libupdate_engine code the part that
is strictly used to download and apply a payload into a new static
library, moving the code to subdirectories. The new library is divided
in two subdirectories: common/ and payload_consumer/, and should not
depend on other update_engine files outside those two subdirectories.
The main difference between those two is that the common/ tools are more
generic and not tied to the payload consumer process, but otherwise they
are both compiled together.

There are still dependencies from the new libpayload_consumer library
into the main directory files and DBus generated files. Those will be
addressed in follow up CLs.

Bug: 25197634
Test: FEATURES=test emerge-link update_engine; `mm` on Brillo.

Change-Id: Id8d0204ea573627e6e26ca9ea17b9592ca95bc23

1 files changed, 116 insertions, 0 deletions

diff --git a/common/action_processor.h b/common/action_processor.h
new file mode 100644
index 00000000..d61e12d7
--- /dev/null
+++ b/common/action_processor.h
@@ -0,0 +1,116 @@
+//
+// Copyright (C) 2011 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 UPDATE_ENGINE_COMMON_ACTION_PROCESSOR_H_
+#define UPDATE_ENGINE_COMMON_ACTION_PROCESSOR_H_
+
+#include <deque>
+
+#include <base/macros.h>
+
+#include "update_engine/common/error_code.h"
+
+// The structure of these classes (Action, ActionPipe, ActionProcessor, etc.)
+// is based on the KSAction* classes from the Google Update Engine code at
+// http://code.google.com/p/update-engine/ . The author of this file sends
+// a big thanks to that team for their high quality design, implementation,
+// and documentation.
+
+// See action.h for an overview of this class and other Action* classes.
+
+// An ActionProcessor keeps a queue of Actions and processes them in order.
+
+namespace chromeos_update_engine {
+
+class AbstractAction;
+class ActionProcessorDelegate;
+
+class ActionProcessor {
+ public:
+  ActionProcessor();
+
+  virtual ~ActionProcessor();
+
+  // Starts processing the first Action in the queue. If there's a delegate,
+  // when all processing is complete, ProcessingDone() will be called on the
+  // delegate.
+  virtual void StartProcessing();
+
+  // Aborts processing. If an Action is running, it will have
+  // TerminateProcessing() called on it. The Action that was running
+  // will be lost and must be re-enqueued if this Processor is to use it.
+  void StopProcessing();
+
+  // Returns true iff an Action is currently processing.
+  bool IsRunning() const { return nullptr != current_action_; }
+
+  // Adds another Action to the end of the queue.
+  virtual void EnqueueAction(AbstractAction* action);
+
+  // Sets/gets the current delegate. Set to null to remove a delegate.
+  ActionProcessorDelegate* delegate() const { return delegate_; }
+  void set_delegate(ActionProcessorDelegate *delegate) {
+    delegate_ = delegate;
+  }
+
+  // Returns a pointer to the current Action that's processing.
+  AbstractAction* current_action() const {
+    return current_action_;
+  }
+
+  // Called by an action to notify processor that it's done. Caller passes self.
+  void ActionComplete(AbstractAction* actionptr, ErrorCode code);
+
+ private:
+  // Actions that have not yet begun processing, in the order in which
+  // they'll be processed.
+  std::deque<AbstractAction*> actions_;
+
+  // A pointer to the currently processing Action, if any.
+  AbstractAction* current_action_;
+
+  // A pointer to the delegate, or null if none.
+  ActionProcessorDelegate *delegate_;
+  DISALLOW_COPY_AND_ASSIGN(ActionProcessor);
+};
+
+// A delegate object can be used to be notified of events that happen
+// in an ActionProcessor. An instance of this class can be passed to an
+// ActionProcessor to register itself.
+class ActionProcessorDelegate {
+ public:
+  virtual ~ActionProcessorDelegate() = default;
+
+  // Called when all processing in an ActionProcessor has completed. A pointer
+  // to the ActionProcessor is passed. |code| is set to the exit code of the
+  // last completed action.
+  virtual void ProcessingDone(const ActionProcessor* processor,
+                              ErrorCode code) {}
+
+  // Called when processing has stopped. Does not mean that all Actions have
+  // completed. If/when all Actions complete, ProcessingDone() will be called.
+  virtual void ProcessingStopped(const ActionProcessor* processor) {}
+
+  // Called whenever an action has finished processing, either successfully
+  // or otherwise.
+  virtual void ActionCompleted(ActionProcessor* processor,
+                               AbstractAction* action,
+                               ErrorCode code) {}
+};
+
+}  // namespace chromeos_update_engine
+
+#endif  // UPDATE_ENGINE_COMMON_ACTION_PROCESSOR_H_