| /** |
| * Copyright (C) 2009 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. |
| */ |
| |
| package com.android.internal.util; |
| |
| import android.os.Handler; |
| import android.os.HandlerThread; |
| import android.os.Looper; |
| import android.os.Message; |
| import android.util.Log; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| |
| /** |
| * {@hide} |
| * |
| * A hierarchical state machine is a state machine which processes messages |
| * and can have states arranged hierarchically. A state is a <code>HierarchicalState</code> |
| * object and must implement <code>processMessage</code> and optionally <code>enter/exit/getName</code>. |
| * The enter/exit methods are equivalent to the construction and destruction |
| * in Object Oriented programming and are used to perform initialization and |
| * cleanup of the state respectively. The <code>getName</code> method returns the |
| * name of the state the default implementation returns the class name it may be |
| * desirable to have this return the name of the state instance name instead. |
| * In particular if a particular state class has multiple instances. |
| * |
| * When a state machine is created <code>addState</code> is used to build the |
| * hierarchy and <code>setInitialState</code> is used to identify which of these |
| * is the initial state. After construction the programmer calls <code>start</code> |
| * which initializes the state machine and calls <code>enter</code> for all of the initial |
| * state's hierarchy, starting at its eldest parent. For example given the simple |
| * state machine below after start is called mP1.enter will have been called and |
| * then mS1.enter. |
| <code> |
| mP1 |
| / \ |
| mS2 mS1 ----> initial state |
| </code> |
| * After the state machine is created and started, messages are sent to a state |
| * machine using <code>sendMessage</code> and the messages are created using |
| * <code>obtainMessage</code>. When the state machine receives a message the |
| * current state's <code>processMessage</code> is invoked. In the above example |
| * mS1.processMessage will be invoked first. The state may use <code>transitionTo</code> |
| * to change the current state to a new state |
| * |
| * Each state in the state machine may have a zero or one parent states and if |
| * a child state is unable to handle a message it may have the message processed |
| * by its parent by returning false or NOT_HANDLED. If a message is never processed |
| * <code>unhandledMessage</code> will be invoked to give one last chance for the state machine |
| * to process the message. |
| * |
| * When all processing is completed a state machine may choose to call |
| * <code>transitionToHaltingState</code>. When the current <code>processingMessage</code> |
| * returns the state machine will transfer to an internal <code>HaltingState</code> |
| * and invoke <code>halting</code>. Any message subsequently received by the state |
| * machine will cause <code>haltedProcessMessage</code> to be invoked. |
| * |
| * If it is desirable to completely stop the state machine call <code>quit</code>. This |
| * will exit the current state and its parent and then exit from the controlling thread |
| * and no further messages will be processed. |
| * |
| * In addition to <code>processMessage</code> each <code>HierarchicalState</code> has |
| * an <code>enter</code> method and <code>exit</exit> method which may be overridden. |
| * |
| * Since the states are arranged in a hierarchy transitioning to a new state |
| * causes current states to be exited and new states to be entered. To determine |
| * the list of states to be entered/exited the common parent closest to |
| * the current state is found. We then exit from the current state and its |
| * parent's up to but not including the common parent state and then enter all |
| * of the new states below the common parent down to the destination state. |
| * If there is no common parent all states are exited and then the new states |
| * are entered. |
| * |
| * Two other methods that states can use are <code>deferMessage</code> and |
| * <code>sendMessageAtFrontOfQueue</code>. The <code>sendMessageAtFrontOfQueue</code> sends |
| * a message but places it on the front of the queue rather than the back. The |
| * <code>deferMessage</code> causes the message to be saved on a list until a |
| * transition is made to a new state. At which time all of the deferred messages |
| * will be put on the front of the state machine queue with the oldest message |
| * at the front. These will then be processed by the new current state before |
| * any other messages that are on the queue or might be added later. Both of |
| * these are protected and may only be invoked from within a state machine. |
| * |
| * To illustrate some of these properties we'll use state machine with an 8 |
| * state hierarchy: |
| <code> |
| mP0 |
| / \ |
| mP1 mS0 |
| / \ |
| mS2 mS1 |
| / \ \ |
| mS3 mS4 mS5 ---> initial state |
| </code> |
| * |
| * After starting mS5 the list of active states is mP0, mP1, mS1 and mS5. |
| * So the order of calling processMessage when a message is received is mS5, |
| * mS1, mP1, mP0 assuming each processMessage indicates it can't handle this |
| * message by returning false or NOT_HANDLED. |
| * |
| * Now assume mS5.processMessage receives a message it can handle, and during |
| * the handling determines the machine should change states. It could call |
| * transitionTo(mS4) and return true or HANDLED. Immediately after returning from |
| * processMessage the state machine runtime will find the common parent, |
| * which is mP1. It will then call mS5.exit, mS1.exit, mS2.enter and then |
| * mS4.enter. The new list of active states is mP0, mP1, mS2 and mS4. So |
| * when the next message is received mS4.processMessage will be invoked. |
| * |
| * Now for some concrete examples, here is the canonical HelloWorld as an HSM. |
| * It responds with "Hello World" being printed to the log for every message. |
| <code> |
| class HelloWorld extends HierarchicalStateMachine { |
| Hsm1(String name) { |
| super(name); |
| addState(mState1); |
| setInitialState(mState1); |
| } |
| |
| public static HelloWorld makeHelloWorld() { |
| HelloWorld hw = new HelloWorld("hw"); |
| hw.start(); |
| return hw; |
| } |
| |
| class State1 extends HierarchicalState { |
| @Override public boolean processMessage(Message message) { |
| Log.d(TAG, "Hello World"); |
| return HANDLED; |
| } |
| } |
| State1 mState1 = new State1(); |
| } |
| |
| void testHelloWorld() { |
| HelloWorld hw = makeHelloWorld(); |
| hw.sendMessage(hw.obtainMessage()); |
| } |
| </code> |
| * |
| * A more interesting state machine is one with four states |
| * with two independent parent states. |
| <code> |
| mP1 mP2 |
| / \ |
| mS2 mS1 |
| </code> |
| * |
| * Here is a description of this state machine using pseudo code. |
| * |
| * |
| * state mP1 { |
| * enter { log("mP1.enter"); } |
| * exit { log("mP1.exit"); } |
| * on msg { |
| * CMD_2 { |
| * send(CMD_3); |
| * defer(msg); |
| * transitonTo(mS2); |
| * return HANDLED; |
| * } |
| * return NOT_HANDLED; |
| * } |
| * } |
| * |
| * INITIAL |
| * state mS1 parent mP1 { |
| * enter { log("mS1.enter"); } |
| * exit { log("mS1.exit"); } |
| * on msg { |
| * CMD_1 { |
| * transitionTo(mS1); |
| * return HANDLED; |
| * } |
| * return NOT_HANDLED; |
| * } |
| * } |
| * |
| * state mS2 parent mP1 { |
| * enter { log("mS2.enter"); } |
| * exit { log("mS2.exit"); } |
| * on msg { |
| * CMD_2 { |
| * send(CMD_4); |
| * return HANDLED; |
| * } |
| * CMD_3 { |
| * defer(msg); |
| * transitionTo(mP2); |
| * return HANDLED; |
| * } |
| * return NOT_HANDLED; |
| * } |
| * } |
| * |
| * state mP2 { |
| * enter { |
| * log("mP2.enter"); |
| * send(CMD_5); |
| * } |
| * exit { log("mP2.exit"); } |
| * on msg { |
| * CMD_3, CMD_4 { return HANDLED; } |
| * CMD_5 { |
| * transitionTo(HaltingState); |
| * return HANDLED; |
| * } |
| * return NOT_HANDLED; |
| * } |
| * } |
| * |
| * The implementation is below and also in HierarchicalStateMachineTest: |
| <code> |
| class Hsm1 extends HierarchicalStateMachine { |
| private static final String TAG = "hsm1"; |
| |
| public static final int CMD_1 = 1; |
| public static final int CMD_2 = 2; |
| public static final int CMD_3 = 3; |
| public static final int CMD_4 = 4; |
| public static final int CMD_5 = 5; |
| |
| public static Hsm1 makeHsm1() { |
| Log.d(TAG, "makeHsm1 E"); |
| Hsm1 sm = new Hsm1("hsm1"); |
| sm.start(); |
| Log.d(TAG, "makeHsm1 X"); |
| return sm; |
| } |
| |
| Hsm1(String name) { |
| super(name); |
| Log.d(TAG, "ctor E"); |
| |
| // Add states, use indentation to show hierarchy |
| addState(mP1); |
| addState(mS1, mP1); |
| addState(mS2, mP1); |
| addState(mP2); |
| |
| // Set the initial state |
| setInitialState(mS1); |
| Log.d(TAG, "ctor X"); |
| } |
| |
| class P1 extends HierarchicalState { |
| @Override public void enter() { |
| Log.d(TAG, "mP1.enter"); |
| } |
| @Override public boolean processMessage(Message message) { |
| boolean retVal; |
| Log.d(TAG, "mP1.processMessage what=" + message.what); |
| switch(message.what) { |
| case CMD_2: |
| // CMD_2 will arrive in mS2 before CMD_3 |
| sendMessage(obtainMessage(CMD_3)); |
| deferMessage(message); |
| transitionTo(mS2); |
| retVal = HANDLED; |
| break; |
| default: |
| // Any message we don't understand in this state invokes unhandledMessage |
| retVal = NOT_HANDLED; |
| break; |
| } |
| return retVal; |
| } |
| @Override public void exit() { |
| Log.d(TAG, "mP1.exit"); |
| } |
| } |
| |
| class S1 extends HierarchicalState { |
| @Override public void enter() { |
| Log.d(TAG, "mS1.enter"); |
| } |
| @Override public boolean processMessage(Message message) { |
| Log.d(TAG, "S1.processMessage what=" + message.what); |
| if (message.what == CMD_1) { |
| // Transition to ourself to show that enter/exit is called |
| transitionTo(mS1); |
| return HANDLED; |
| } else { |
| // Let parent process all other messages |
| return NOT_HANDLED; |
| } |
| } |
| @Override public void exit() { |
| Log.d(TAG, "mS1.exit"); |
| } |
| } |
| |
| class S2 extends HierarchicalState { |
| @Override public void enter() { |
| Log.d(TAG, "mS2.enter"); |
| } |
| @Override public boolean processMessage(Message message) { |
| boolean retVal; |
| Log.d(TAG, "mS2.processMessage what=" + message.what); |
| switch(message.what) { |
| case(CMD_2): |
| sendMessage(obtainMessage(CMD_4)); |
| retVal = HANDLED; |
| break; |
| case(CMD_3): |
| deferMessage(message); |
| transitionTo(mP2); |
| retVal = HANDLED; |
| break; |
| default: |
| retVal = NOT_HANDLED; |
| break; |
| } |
| return retVal; |
| } |
| @Override public void exit() { |
| Log.d(TAG, "mS2.exit"); |
| } |
| } |
| |
| class P2 extends HierarchicalState { |
| @Override public void enter() { |
| Log.d(TAG, "mP2.enter"); |
| sendMessage(obtainMessage(CMD_5)); |
| } |
| @Override public boolean processMessage(Message message) { |
| Log.d(TAG, "P2.processMessage what=" + message.what); |
| switch(message.what) { |
| case(CMD_3): |
| break; |
| case(CMD_4): |
| break; |
| case(CMD_5): |
| transitionToHaltingState(); |
| break; |
| } |
| return HANDLED; |
| } |
| @Override public void exit() { |
| Log.d(TAG, "mP2.exit"); |
| } |
| } |
| |
| @Override |
| void halting() { |
| Log.d(TAG, "halting"); |
| synchronized (this) { |
| this.notifyAll(); |
| } |
| } |
| |
| P1 mP1 = new P1(); |
| S1 mS1 = new S1(); |
| S2 mS2 = new S2(); |
| P2 mP2 = new P2(); |
| } |
| </code> |
| * |
| * If this is executed by sending two messages CMD_1 and CMD_2 |
| * (Note the synchronize is only needed because we use hsm.wait()) |
| * |
| * Hsm1 hsm = makeHsm1(); |
| * synchronize(hsm) { |
| * hsm.sendMessage(obtainMessage(hsm.CMD_1)); |
| * hsm.sendMessage(obtainMessage(hsm.CMD_2)); |
| * try { |
| * // wait for the messages to be handled |
| * hsm.wait(); |
| * } catch (InterruptedException e) { |
| * Log.e(TAG, "exception while waiting " + e.getMessage()); |
| * } |
| * } |
| * |
| * |
| * The output is: |
| * |
| * D/hsm1 ( 1999): makeHsm1 E |
| * D/hsm1 ( 1999): ctor E |
| * D/hsm1 ( 1999): ctor X |
| * D/hsm1 ( 1999): mP1.enter |
| * D/hsm1 ( 1999): mS1.enter |
| * D/hsm1 ( 1999): makeHsm1 X |
| * D/hsm1 ( 1999): mS1.processMessage what=1 |
| * D/hsm1 ( 1999): mS1.exit |
| * D/hsm1 ( 1999): mS1.enter |
| * D/hsm1 ( 1999): mS1.processMessage what=2 |
| * D/hsm1 ( 1999): mP1.processMessage what=2 |
| * D/hsm1 ( 1999): mS1.exit |
| * D/hsm1 ( 1999): mS2.enter |
| * D/hsm1 ( 1999): mS2.processMessage what=2 |
| * D/hsm1 ( 1999): mS2.processMessage what=3 |
| * D/hsm1 ( 1999): mS2.exit |
| * D/hsm1 ( 1999): mP1.exit |
| * D/hsm1 ( 1999): mP2.enter |
| * D/hsm1 ( 1999): mP2.processMessage what=3 |
| * D/hsm1 ( 1999): mP2.processMessage what=4 |
| * D/hsm1 ( 1999): mP2.processMessage what=5 |
| * D/hsm1 ( 1999): mP2.exit |
| * D/hsm1 ( 1999): halting |
| * |
| */ |
| public class HierarchicalStateMachine { |
| |
| private static final String TAG = "HierarchicalStateMachine"; |
| private String mName; |
| |
| /** Message.what value when quitting */ |
| public static final int HSM_QUIT_CMD = -1; |
| |
| /** Message.what value when initializing */ |
| public static final int HSM_INIT_CMD = -1; |
| |
| /** |
| * Convenience constant that maybe returned by processMessage |
| * to indicate the the message was processed and is not to be |
| * processed by parent states |
| */ |
| public static final boolean HANDLED = true; |
| |
| /** |
| * Convenience constant that maybe returned by processMessage |
| * to indicate the the message was NOT processed and is to be |
| * processed by parent states |
| */ |
| public static final boolean NOT_HANDLED = false; |
| |
| private static class HsmHandler extends Handler { |
| |
| /** The debug flag */ |
| private boolean mDbg = false; |
| |
| /** The quit object */ |
| private static final Object mQuitObj = new Object(); |
| |
| /** The initialization message */ |
| private static final Message mInitMsg = null; |
| |
| /** The current message */ |
| private Message mMsg; |
| |
| /** A list of messages that this state machine has processed */ |
| private ProcessedMessages mProcessedMessages = new ProcessedMessages(); |
| |
| /** true if construction of the state machine has not been completed */ |
| private boolean mIsConstructionCompleted; |
| |
| /** Stack used to manage the current hierarchy of states */ |
| private StateInfo mStateStack[]; |
| |
| /** Top of mStateStack */ |
| private int mStateStackTopIndex = -1; |
| |
| /** A temporary stack used to manage the state stack */ |
| private StateInfo mTempStateStack[]; |
| |
| /** The top of the mTempStateStack */ |
| private int mTempStateStackCount; |
| |
| /** State used when state machine is halted */ |
| private HaltingState mHaltingState = new HaltingState(); |
| |
| /** State used when state machine is quitting */ |
| private QuittingState mQuittingState = new QuittingState(); |
| |
| /** Reference to the HierarchicalStateMachine */ |
| private HierarchicalStateMachine mHsm; |
| |
| /** |
| * Information about a state. |
| * Used to maintain the hierarchy. |
| */ |
| private class StateInfo { |
| /** The state */ |
| HierarchicalState state; |
| |
| /** The parent of this state, null if there is no parent */ |
| StateInfo parentStateInfo; |
| |
| /** True when the state has been entered and on the stack */ |
| boolean active; |
| |
| /** |
| * Convert StateInfo to string |
| */ |
| @Override |
| public String toString() { |
| return "state=" + state.getName() + ",active=" + active |
| + ",parent=" + ((parentStateInfo == null) ? |
| "null" : parentStateInfo.state.getName()); |
| } |
| } |
| |
| /** The map of all of the states in the state machine */ |
| private HashMap<HierarchicalState, StateInfo> mStateInfo = |
| new HashMap<HierarchicalState, StateInfo>(); |
| |
| /** The initial state that will process the first message */ |
| private HierarchicalState mInitialState; |
| |
| /** The destination state when transitionTo has been invoked */ |
| private HierarchicalState mDestState; |
| |
| /** The list of deferred messages */ |
| private ArrayList<Message> mDeferredMessages = new ArrayList<Message>(); |
| |
| /** |
| * State entered when transitionToHaltingState is called. |
| */ |
| private class HaltingState extends HierarchicalState { |
| @Override |
| public boolean processMessage(Message msg) { |
| mHsm.haltedProcessMessage(msg); |
| return true; |
| } |
| } |
| |
| /** |
| * State entered when a valid quit message is handled. |
| */ |
| private class QuittingState extends HierarchicalState { |
| @Override |
| public boolean processMessage(Message msg) { |
| return NOT_HANDLED; |
| } |
| } |
| |
| /** |
| * Handle messages sent to the state machine by calling |
| * the current state's processMessage. It also handles |
| * the enter/exit calls and placing any deferred messages |
| * back onto the queue when transitioning to a new state. |
| */ |
| @Override |
| public final void handleMessage(Message msg) { |
| if (mDbg) Log.d(TAG, "handleMessage: E msg.what=" + msg.what); |
| |
| /** Save the current message */ |
| mMsg = msg; |
| |
| /** |
| * Check that construction was completed |
| */ |
| if (!mIsConstructionCompleted) { |
| Log.e(TAG, "The start method not called, ignore msg: " + msg); |
| return; |
| } |
| |
| /** |
| * Process the message abiding by the hierarchical semantics |
| * and perform any requested transitions. |
| */ |
| processMsg(msg); |
| performTransitions(); |
| |
| if (mDbg) Log.d(TAG, "handleMessage: X"); |
| } |
| |
| /** |
| * Do any transitions |
| */ |
| private void performTransitions() { |
| /** |
| * If transitionTo has been called, exit and then enter |
| * the appropriate states. We loop on this to allow |
| * enter and exit methods to use transitionTo. |
| */ |
| HierarchicalState destState = null; |
| while (mDestState != null) { |
| if (mDbg) Log.d(TAG, "handleMessage: new destination call exit"); |
| |
| /** |
| * Save mDestState locally and set to null |
| * to know if enter/exit use transitionTo. |
| */ |
| destState = mDestState; |
| mDestState = null; |
| |
| /** |
| * Determine the states to exit and enter and return the |
| * common ancestor state of the enter/exit states. Then |
| * invoke the exit methods then the enter methods. |
| */ |
| StateInfo commonStateInfo = setupTempStateStackWithStatesToEnter(destState); |
| invokeExitMethods(commonStateInfo); |
| int stateStackEnteringIndex = moveTempStateStackToStateStack(); |
| invokeEnterMethods(stateStackEnteringIndex); |
| |
| |
| /** |
| * Since we have transitioned to a new state we need to have |
| * any deferred messages moved to the front of the message queue |
| * so they will be processed before any other messages in the |
| * message queue. |
| */ |
| moveDeferredMessageAtFrontOfQueue(); |
| } |
| |
| /** |
| * After processing all transitions check and |
| * see if the last transition was to quit or halt. |
| */ |
| if (destState != null) { |
| if (destState == mQuittingState) { |
| /** |
| * We are quitting so ignore all messages. |
| */ |
| mHsm.quitting(); |
| if (mHsm.mHsmThread != null) { |
| // If we made the thread then quit looper |
| getLooper().quit(); |
| } |
| } else if (destState == mHaltingState) { |
| /** |
| * Call halting() if we've transitioned to the halting |
| * state. All subsequent messages will be processed in |
| * in the halting state which invokes haltedProcessMessage(msg); |
| */ |
| mHsm.halting(); |
| } |
| } |
| } |
| |
| /** |
| * Complete the construction of the state machine. |
| */ |
| private final void completeConstruction() { |
| if (mDbg) Log.d(TAG, "completeConstruction: E"); |
| |
| /** |
| * Determine the maximum depth of the state hierarchy |
| * so we can allocate the state stacks. |
| */ |
| int maxDepth = 0; |
| for (StateInfo si : mStateInfo.values()) { |
| int depth = 0; |
| for (StateInfo i = si; i != null; depth++) { |
| i = i.parentStateInfo; |
| } |
| if (maxDepth < depth) { |
| maxDepth = depth; |
| } |
| } |
| if (mDbg) Log.d(TAG, "completeConstruction: maxDepth=" + maxDepth); |
| |
| mStateStack = new StateInfo[maxDepth]; |
| mTempStateStack = new StateInfo[maxDepth]; |
| setupInitialStateStack(); |
| |
| /** |
| * Construction is complete call all enter methods |
| * starting at the first entry. |
| */ |
| mIsConstructionCompleted = true; |
| mMsg = obtainMessage(HSM_INIT_CMD); |
| invokeEnterMethods(0); |
| |
| /** |
| * Perform any transitions requested by the enter methods |
| */ |
| performTransitions(); |
| |
| if (mDbg) Log.d(TAG, "completeConstruction: X"); |
| } |
| |
| /** |
| * Process the message. If the current state doesn't handle |
| * it, call the states parent and so on. If it is never handled then |
| * call the state machines unhandledMessage method. |
| */ |
| private final void processMsg(Message msg) { |
| StateInfo curStateInfo = mStateStack[mStateStackTopIndex]; |
| if (mDbg) { |
| Log.d(TAG, "processMsg: " + curStateInfo.state.getName()); |
| } |
| while (!curStateInfo.state.processMessage(msg)) { |
| /** |
| * Not processed |
| */ |
| curStateInfo = curStateInfo.parentStateInfo; |
| if (curStateInfo == null) { |
| /** |
| * No parents left so it's not handled |
| */ |
| mHsm.unhandledMessage(msg); |
| if (isQuit(msg)) { |
| transitionTo(mQuittingState); |
| } |
| break; |
| } |
| if (mDbg) { |
| Log.d(TAG, "processMsg: " + curStateInfo.state.getName()); |
| } |
| } |
| |
| /** |
| * Record that we processed the message |
| */ |
| if (curStateInfo != null) { |
| HierarchicalState orgState = mStateStack[mStateStackTopIndex].state; |
| mProcessedMessages.add(msg, curStateInfo.state, orgState); |
| } else { |
| mProcessedMessages.add(msg, null, null); |
| } |
| } |
| |
| /** |
| * Call the exit method for each state from the top of stack |
| * up to the common ancestor state. |
| */ |
| private final void invokeExitMethods(StateInfo commonStateInfo) { |
| while ((mStateStackTopIndex >= 0) && |
| (mStateStack[mStateStackTopIndex] != commonStateInfo)) { |
| HierarchicalState curState = mStateStack[mStateStackTopIndex].state; |
| if (mDbg) Log.d(TAG, "invokeExitMethods: " + curState.getName()); |
| curState.exit(); |
| mStateStack[mStateStackTopIndex].active = false; |
| mStateStackTopIndex -= 1; |
| } |
| } |
| |
| /** |
| * Invoke the enter method starting at the entering index to top of state stack |
| */ |
| private final void invokeEnterMethods(int stateStackEnteringIndex) { |
| for (int i = stateStackEnteringIndex; i <= mStateStackTopIndex; i++) { |
| if (mDbg) Log.d(TAG, "invokeEnterMethods: " + mStateStack[i].state.getName()); |
| mStateStack[i].state.enter(); |
| mStateStack[i].active = true; |
| } |
| } |
| |
| /** |
| * Move the deferred message to the front of the message queue. |
| */ |
| private final void moveDeferredMessageAtFrontOfQueue() { |
| /** |
| * The oldest messages on the deferred list must be at |
| * the front of the queue so start at the back, which |
| * as the most resent message and end with the oldest |
| * messages at the front of the queue. |
| */ |
| for (int i = mDeferredMessages.size() - 1; i >= 0; i-- ) { |
| Message curMsg = mDeferredMessages.get(i); |
| if (mDbg) Log.d(TAG, "moveDeferredMessageAtFrontOfQueue; what=" + curMsg.what); |
| sendMessageAtFrontOfQueue(curMsg); |
| } |
| mDeferredMessages.clear(); |
| } |
| |
| /** |
| * Move the contents of the temporary stack to the state stack |
| * reversing the order of the items on the temporary stack as |
| * they are moved. |
| * |
| * @return index into mStateState where entering needs to start |
| */ |
| private final int moveTempStateStackToStateStack() { |
| int startingIndex = mStateStackTopIndex + 1; |
| int i = mTempStateStackCount - 1; |
| int j = startingIndex; |
| while (i >= 0) { |
| if (mDbg) Log.d(TAG, "moveTempStackToStateStack: i=" + i + ",j=" + j); |
| mStateStack[j] = mTempStateStack[i]; |
| j += 1; |
| i -= 1; |
| } |
| |
| mStateStackTopIndex = j - 1; |
| if (mDbg) { |
| Log.d(TAG, "moveTempStackToStateStack: X mStateStackTop=" |
| + mStateStackTopIndex + ",startingIndex=" + startingIndex |
| + ",Top=" + mStateStack[mStateStackTopIndex].state.getName()); |
| } |
| return startingIndex; |
| } |
| |
| /** |
| * Setup the mTempStateStack with the states we are going to enter. |
| * |
| * This is found by searching up the destState's ancestors for a |
| * state that is already active i.e. StateInfo.active == true. |
| * The destStae and all of its inactive parents will be on the |
| * TempStateStack as the list of states to enter. |
| * |
| * @return StateInfo of the common ancestor for the destState and |
| * current state or null if there is no common parent. |
| */ |
| private final StateInfo setupTempStateStackWithStatesToEnter(HierarchicalState destState) { |
| /** |
| * Search up the parent list of the destination state for an active |
| * state. Use a do while() loop as the destState must always be entered |
| * even if it is active. This can happen if we are exiting/entering |
| * the current state. |
| */ |
| mTempStateStackCount = 0; |
| StateInfo curStateInfo = mStateInfo.get(destState); |
| do { |
| mTempStateStack[mTempStateStackCount++] = curStateInfo; |
| curStateInfo = curStateInfo.parentStateInfo; |
| } while ((curStateInfo != null) && !curStateInfo.active); |
| |
| if (mDbg) { |
| Log.d(TAG, "setupTempStateStackWithStatesToEnter: X mTempStateStackCount=" |
| + mTempStateStackCount + ",curStateInfo: " + curStateInfo); |
| } |
| return curStateInfo; |
| } |
| |
| /** |
| * Initialize StateStack to mInitialState. |
| */ |
| private final void setupInitialStateStack() { |
| if (mDbg) { |
| Log.d(TAG, "setupInitialStateStack: E mInitialState=" |
| + mInitialState.getName()); |
| } |
| |
| StateInfo curStateInfo = mStateInfo.get(mInitialState); |
| for (mTempStateStackCount = 0; curStateInfo != null; mTempStateStackCount++) { |
| mTempStateStack[mTempStateStackCount] = curStateInfo; |
| curStateInfo = curStateInfo.parentStateInfo; |
| } |
| |
| // Empty the StateStack |
| mStateStackTopIndex = -1; |
| |
| moveTempStateStackToStateStack(); |
| } |
| |
| /** |
| * @return current message |
| */ |
| private final Message getCurrentMessage() { |
| return mMsg; |
| } |
| |
| /** |
| * @return current state |
| */ |
| private final HierarchicalState getCurrentState() { |
| return mStateStack[mStateStackTopIndex].state; |
| } |
| |
| /** |
| * Add a new state to the state machine. Bottom up addition |
| * of states is allowed but the same state may only exist |
| * in one hierarchy. |
| * |
| * @param state the state to add |
| * @param parent the parent of state |
| * @return stateInfo for this state |
| */ |
| private final StateInfo addState(HierarchicalState state, HierarchicalState parent) { |
| if (mDbg) { |
| Log.d(TAG, "addStateInternal: E state=" + state.getName() |
| + ",parent=" + ((parent == null) ? "" : parent.getName())); |
| } |
| StateInfo parentStateInfo = null; |
| if (parent != null) { |
| parentStateInfo = mStateInfo.get(parent); |
| if (parentStateInfo == null) { |
| // Recursively add our parent as it's not been added yet. |
| parentStateInfo = addState(parent, null); |
| } |
| } |
| StateInfo stateInfo = mStateInfo.get(state); |
| if (stateInfo == null) { |
| stateInfo = new StateInfo(); |
| mStateInfo.put(state, stateInfo); |
| } |
| |
| // Validate that we aren't adding the same state in two different hierarchies. |
| if ((stateInfo.parentStateInfo != null) && |
| (stateInfo.parentStateInfo != parentStateInfo)) { |
| throw new RuntimeException("state already added"); |
| } |
| stateInfo.state = state; |
| stateInfo.parentStateInfo = parentStateInfo; |
| stateInfo.active = false; |
| if (mDbg) Log.d(TAG, "addStateInternal: X stateInfo: " + stateInfo); |
| return stateInfo; |
| } |
| |
| /** |
| * Constructor |
| * |
| * @param looper for dispatching messages |
| * @param hsm the hierarchical state machine |
| */ |
| private HsmHandler(Looper looper, HierarchicalStateMachine hsm) { |
| super(looper); |
| mHsm = hsm; |
| |
| addState(mHaltingState, null); |
| addState(mQuittingState, null); |
| } |
| |
| /** @see HierarchicalStateMachine#setInitialState(HierarchicalState) */ |
| private final void setInitialState(HierarchicalState initialState) { |
| if (mDbg) Log.d(TAG, "setInitialState: initialState" + initialState.getName()); |
| mInitialState = initialState; |
| } |
| |
| /** @see HierarchicalStateMachine#transitionTo(HierarchicalState) */ |
| private final void transitionTo(HierarchicalState destState) { |
| if (mDbg) Log.d(TAG, "StateMachine.transitionTo EX destState" + destState.getName()); |
| mDestState = destState; |
| } |
| |
| /** @see HierarchicalStateMachine#deferMessage(Message) */ |
| private final void deferMessage(Message msg) { |
| if (mDbg) Log.d(TAG, "deferMessage: msg=" + msg.what); |
| |
| /* Copy the "msg" to "newMsg" as "msg" will be recycled */ |
| Message newMsg = obtainMessage(); |
| newMsg.copyFrom(msg); |
| |
| mDeferredMessages.add(newMsg); |
| } |
| |
| /** @see HierarchicalStateMachine#deferMessage(Message) */ |
| private final void quit() { |
| if (mDbg) Log.d(TAG, "quit:"); |
| sendMessage(obtainMessage(HSM_QUIT_CMD, mQuitObj)); |
| } |
| |
| /** @see HierarchicalStateMachine#isQuit(Message) */ |
| private final boolean isQuit(Message msg) { |
| return (msg.what == HSM_QUIT_CMD) && (msg.obj == mQuitObj); |
| } |
| |
| /** @see HierarchicalStateMachine#isDbg() */ |
| private final boolean isDbg() { |
| return mDbg; |
| } |
| |
| /** @see HierarchicalStateMachine#setDbg(boolean) */ |
| private final void setDbg(boolean dbg) { |
| mDbg = dbg; |
| } |
| |
| /** @see HierarchicalStateMachine#setProcessedMessagesSize(int) */ |
| private final void setProcessedMessagesSize(int maxSize) { |
| mProcessedMessages.setSize(maxSize); |
| } |
| |
| /** @see HierarchicalStateMachine#getProcessedMessagesSize() */ |
| private final int getProcessedMessagesSize() { |
| return mProcessedMessages.size(); |
| } |
| |
| /** @see HierarchicalStateMachine#getProcessedMessagesCount() */ |
| private final int getProcessedMessagesCount() { |
| return mProcessedMessages.count(); |
| } |
| |
| /** @see HierarchicalStateMachine#getProcessedMessage(int) */ |
| private final ProcessedMessages.Info getProcessedMessage(int index) { |
| return mProcessedMessages.get(index); |
| } |
| |
| } |
| |
| private HsmHandler mHsmHandler; |
| private HandlerThread mHsmThread; |
| |
| /** |
| * Initialize. |
| * |
| * @param looper for this state machine |
| * @param name of the state machine |
| */ |
| private void initStateMachine(String name, Looper looper) { |
| mName = name; |
| mHsmHandler = new HsmHandler(looper, this); |
| } |
| |
| /** |
| * Constructor creates an HSM with its own thread. |
| * |
| * @param name of the state machine |
| */ |
| protected HierarchicalStateMachine(String name) { |
| mHsmThread = new HandlerThread(name); |
| mHsmThread.start(); |
| Looper looper = mHsmThread.getLooper(); |
| |
| initStateMachine(name, looper); |
| } |
| |
| /** |
| * Constructor creates an HSMStateMachine using the looper. |
| * |
| * @param name of the state machine |
| */ |
| protected HierarchicalStateMachine(String name, Looper looper) { |
| initStateMachine(name, looper); |
| } |
| |
| /** |
| * Add a new state to the state machine |
| * @param state the state to add |
| * @param parent the parent of state |
| */ |
| protected final void addState(HierarchicalState state, HierarchicalState parent) { |
| mHsmHandler.addState(state, parent); |
| } |
| |
| /** |
| * @return current message |
| */ |
| protected final Message getCurrentMessage() { |
| return mHsmHandler.getCurrentMessage(); |
| } |
| |
| /** |
| * @return current state |
| */ |
| protected final HierarchicalState getCurrentState() { |
| return mHsmHandler.getCurrentState(); |
| } |
| |
| /** |
| * Add a new state to the state machine, parent will be null |
| * @param state to add |
| */ |
| protected final void addState(HierarchicalState state) { |
| mHsmHandler.addState(state, null); |
| } |
| |
| /** |
| * Set the initial state. This must be invoked before |
| * and messages are sent to the state machine. |
| * |
| * @param initialState is the state which will receive the first message. |
| */ |
| protected final void setInitialState(HierarchicalState initialState) { |
| mHsmHandler.setInitialState(initialState); |
| } |
| |
| /** |
| * transition to destination state. Upon returning |
| * from processMessage the current state's exit will |
| * be executed and upon the next message arriving |
| * destState.enter will be invoked. |
| * |
| * @param destState will be the state that receives the next message. |
| */ |
| protected final void transitionTo(HierarchicalState destState) { |
| mHsmHandler.transitionTo(destState); |
| } |
| |
| /** |
| * transition to halt state. Upon returning |
| * from processMessage we will exit all current |
| * states, execute the halting() method and then |
| * all subsequent messages haltedProcessMesage |
| * will be called. |
| */ |
| protected final void transitionToHaltingState() { |
| mHsmHandler.transitionTo(mHsmHandler.mHaltingState); |
| } |
| |
| /** |
| * Defer this message until next state transition. |
| * Upon transitioning all deferred messages will be |
| * placed on the queue and reprocessed in the original |
| * order. (i.e. The next state the oldest messages will |
| * be processed first) |
| * |
| * @param msg is deferred until the next transition. |
| */ |
| protected final void deferMessage(Message msg) { |
| mHsmHandler.deferMessage(msg); |
| } |
| |
| |
| /** |
| * Called when message wasn't handled |
| * |
| * @param msg that couldn't be handled. |
| */ |
| protected void unhandledMessage(Message msg) { |
| if (false) { |
| Log.e(TAG, mName + " - unhandledMessage: msg.what=" + msg.what); |
| } |
| } |
| |
| /** |
| * Called for any message that is received after |
| * transitionToHalting is called. |
| */ |
| protected void haltedProcessMessage(Message msg) { |
| } |
| |
| /** |
| * Called after the message that called transitionToHalting |
| * is called and should be overridden by StateMachine's that |
| * call transitionToHalting. |
| */ |
| protected void halting() { |
| } |
| |
| /** |
| * Called after the quitting message was NOT handled and |
| * just before the quit actually occurs. |
| */ |
| protected void quitting() { |
| } |
| |
| /** |
| * @return the name |
| */ |
| public final String getName() { |
| return mName; |
| } |
| |
| /** |
| * Set size of messages to maintain and clears all current messages. |
| * |
| * @param maxSize number of messages to maintain at anyone time. |
| */ |
| public final void setProcessedMessagesSize(int maxSize) { |
| mHsmHandler.setProcessedMessagesSize(maxSize); |
| } |
| |
| /** |
| * @return number of messages processed |
| */ |
| public final int getProcessedMessagesSize() { |
| return mHsmHandler.getProcessedMessagesSize(); |
| } |
| |
| /** |
| * @return the total number of messages processed |
| */ |
| public final int getProcessedMessagesCount() { |
| return mHsmHandler.getProcessedMessagesCount(); |
| } |
| |
| /** |
| * @return a processed message |
| */ |
| public final ProcessedMessages.Info getProcessedMessage(int index) { |
| return mHsmHandler.getProcessedMessage(index); |
| } |
| |
| /** |
| * @return Handler |
| */ |
| public final Handler getHandler() { |
| return mHsmHandler; |
| } |
| |
| /** |
| * Get a message and set Message.target = this. |
| * |
| * @return message |
| */ |
| public final Message obtainMessage() |
| { |
| return Message.obtain(mHsmHandler); |
| } |
| |
| /** |
| * Get a message and set Message.target = this and what |
| * |
| * @param what is the assigned to Message.what. |
| * @return message |
| */ |
| public final Message obtainMessage(int what) { |
| return Message.obtain(mHsmHandler, what); |
| } |
| |
| /** |
| * Get a message and set Message.target = this, |
| * what and obj. |
| * |
| * @param what is the assigned to Message.what. |
| * @param obj is assigned to Message.obj. |
| * @return message |
| */ |
| public final Message obtainMessage(int what, Object obj) |
| { |
| return Message.obtain(mHsmHandler, what, obj); |
| } |
| |
| /** |
| * Enqueue a message to this state machine. |
| */ |
| public final void sendMessage(int what) { |
| mHsmHandler.sendMessage(obtainMessage(what)); |
| } |
| |
| /** |
| * Enqueue a message to this state machine. |
| */ |
| public final void sendMessage(int what, Object obj) { |
| mHsmHandler.sendMessage(obtainMessage(what,obj)); |
| } |
| |
| /** |
| * Enqueue a message to this state machine. |
| */ |
| public final void sendMessage(Message msg) { |
| mHsmHandler.sendMessage(msg); |
| } |
| |
| /** |
| * Enqueue a message to this state machine after a delay. |
| */ |
| public final void sendMessageDelayed(int what, long delayMillis) { |
| mHsmHandler.sendMessageDelayed(obtainMessage(what), delayMillis); |
| } |
| |
| /** |
| * Enqueue a message to this state machine after a delay. |
| */ |
| public final void sendMessageDelayed(int what, Object obj, long delayMillis) { |
| mHsmHandler.sendMessageDelayed(obtainMessage(what, obj), delayMillis); |
| } |
| |
| /** |
| * Enqueue a message to this state machine after a delay. |
| */ |
| public final void sendMessageDelayed(Message msg, long delayMillis) { |
| mHsmHandler.sendMessageDelayed(msg, delayMillis); |
| } |
| |
| /** |
| * Enqueue a message to the front of the queue for this state machine. |
| * Protected, may only be called by instances of HierarchicalStateMachine. |
| */ |
| protected final void sendMessageAtFrontOfQueue(int what, Object obj) { |
| mHsmHandler.sendMessageAtFrontOfQueue(obtainMessage(what, obj)); |
| } |
| |
| /** |
| * Enqueue a message to the front of the queue for this state machine. |
| * Protected, may only be called by instances of HierarchicalStateMachine. |
| */ |
| protected final void sendMessageAtFrontOfQueue(int what) { |
| mHsmHandler.sendMessageAtFrontOfQueue(obtainMessage(what)); |
| } |
| |
| /** |
| * Enqueue a message to the front of the queue for this state machine. |
| * Protected, may only be called by instances of HierarchicalStateMachine. |
| */ |
| protected final void sendMessageAtFrontOfQueue(Message msg) { |
| mHsmHandler.sendMessageAtFrontOfQueue(msg); |
| } |
| |
| /** |
| * Conditionally quit the looper and stop execution. |
| * |
| * This sends the HSM_QUIT_MSG to the state machine and |
| * if not handled by any state's processMessage then the |
| * state machine will be stopped and no further messages |
| * will be processed. |
| */ |
| public final void quit() { |
| mHsmHandler.quit(); |
| } |
| |
| /** |
| * @return ture if msg is quit |
| */ |
| protected final boolean isQuit(Message msg) { |
| return mHsmHandler.isQuit(msg); |
| } |
| |
| /** |
| * @return if debugging is enabled |
| */ |
| public boolean isDbg() { |
| return mHsmHandler.isDbg(); |
| } |
| |
| /** |
| * Set debug enable/disabled. |
| * |
| * @param dbg is true to enable debugging. |
| */ |
| public void setDbg(boolean dbg) { |
| mHsmHandler.setDbg(dbg); |
| } |
| |
| /** |
| * Start the state machine. |
| */ |
| public void start() { |
| /** Send the complete construction message */ |
| mHsmHandler.completeConstruction(); |
| } |
| } |
