Merge "Reland "Let InputReader handle its own thread""

Author: TreeHugger Robot

services/inputflinger/InputManager.cpp

@@ -46,7 +46,6 @@ InputManager::~InputManager() {
 }
 
 void InputManager::initialize() {
-    mReaderThread = new InputReaderThread(mReader);
     mDispatcherThread = new InputDispatcherThread(mDispatcher);
 }
 
@@ -57,9 +56,9 @@ status_t InputManager::start() {
         return result;
     }
 
-    result = mReaderThread->run("InputReader", PRIORITY_URGENT_DISPLAY);
+    result = mReader->start();
     if (result) {
-        ALOGE("Could not start InputReader thread due to error %d.", result);
+        ALOGE("Could not start InputReader due to error %d.", result);
 
         mDispatcherThread->requestExit();
         return result;
@@ -69,9 +68,9 @@ status_t InputManager::start() {
 }
 
 status_t InputManager::stop() {
-    status_t result = mReaderThread->requestExitAndWait();
+    status_t result = mReader->stop();
     if (result) {
-        ALOGW("Could not stop InputReader thread due to error %d.", result);
+        ALOGW("Could not stop InputReader due to error %d.", result);
     }
 
     result = mDispatcherThread->requestExitAndWait();

services/inputflinger/InputManager.h

@@ -43,15 +43,15 @@ class InputDispatcherThread;
 /*
  * The input manager is the core of the system event processing.
  *
- * The input manager uses two threads.
+ * The input manager has two components.
  *
- * 1. The InputReaderThread (called "InputReader") reads and preprocesses raw input events,
- *    applies policy, and posts messages to a queue managed by the DispatcherThread.
+ * 1. The InputReader class starts a thread that reads and preprocesses raw input events, applies
+ *    policy, and posts messages to a queue managed by the InputDispatcherThread.
  * 2. The InputDispatcherThread (called "InputDispatcher") thread waits for new events on the
  *    queue and asynchronously dispatches them to applications.
  *
- * By design, the InputReaderThread class and InputDispatcherThread class do not share any
- * internal state.  Moreover, all communication is done one way from the InputReaderThread
+ * By design, the InputReader class and InputDispatcherThread class do not share any
+ * internal state.  Moreover, all communication is done one way from the InputReader
  * into the InputDispatcherThread and never the reverse.  Both classes may interact with the
  * InputDispatchPolicy, however.
  *
@@ -102,7 +102,6 @@ class InputManager : public InputManagerInterface, public BnInputFlinger {
 
 private:
     sp<InputReaderInterface> mReader;
-    sp<InputReaderThread> mReaderThread;
 
     sp<InputClassifierInterface> mClassifier;
 

services/inputflinger/InputReaderBase.cpp

@@ -33,20 +33,6 @@ using android::base::StringPrintf;
 
 namespace android {
 
-// --- InputReaderThread ---
-
-InputReaderThread::InputReaderThread(const sp<InputReaderInterface>& reader) :
-        Thread(/*canCallJava*/ true), mReader(reader) {
-}
-
-InputReaderThread::~InputReaderThread() {
-}
-
-bool InputReaderThread::threadLoop() {
-    mReader->loopOnce();
-    return true;
-}
-
 // --- InputReaderConfiguration ---
 
 std::string InputReaderConfiguration::changesToString(uint32_t changes) {

services/inputflinger/include/InputReaderBase.h

@@ -19,12 +19,12 @@
 
 #include "PointerControllerInterface.h"
 
+#include <input/DisplayViewport.h>
 #include <input/Input.h>
 #include <input/InputDevice.h>
-#include <input/DisplayViewport.h>
 #include <input/VelocityControl.h>
 #include <input/VelocityTracker.h>
-#include <utils/Thread.h>
+#include <utils/Errors.h>
 #include <utils/RefBase.h>
 
 #include <stddef.h>
@@ -44,7 +44,16 @@
 
 namespace android {
 
-/* Processes raw input events and sends cooked event data to an input listener. */
+// --- InputReaderInterface ---
+
+/* The interface for the InputReader shared library.
+ *
+ * Manages one or more threads that process raw input events and sends cooked event data to an
+ * input listener.
+ *
+ * The implementation must guarantee thread safety for this interface. However, since the input
+ * listener is NOT thread safe, all calls to the listener must happen from the same thread.
+ */
 class InputReaderInterface : public virtual RefBase {
 protected:
     InputReaderInterface() { }
@@ -56,18 +65,17 @@ class InputReaderInterface : public virtual RefBase {
      * This method may be called on any thread (usually by the input manager). */
     virtual void dump(std::string& dump) = 0;
 
-    /* Called by the heatbeat to ensures that the reader has not deadlocked. */
+    /* Called by the heartbeat to ensures that the reader has not deadlocked. */
     virtual void monitor() = 0;
 
     /* Returns true if the input device is enabled. */
     virtual bool isInputDeviceEnabled(int32_t deviceId) = 0;
 
-    /* Runs a single iteration of the processing loop.
-     * Nominally reads and processes one incoming message from the EventHub.
-     *
-     * This method should be called on the input reader thread.
-     */
-    virtual void loopOnce() = 0;
+    /* Makes the reader start processing events from the kernel. */
+    virtual status_t start() = 0;
+
+    /* Makes the reader stop processing any more events. */
+    virtual status_t stop() = 0;
 
     /* Gets information about all input devices.
      *
@@ -104,17 +112,7 @@ class InputReaderInterface : public virtual RefBase {
     virtual bool canDispatchToDisplay(int32_t deviceId, int32_t displayId) = 0;
 };
 
-/* Reads raw events from the event hub and processes them, endlessly. */
-class InputReaderThread : public Thread {
-public:
-    explicit InputReaderThread(const sp<InputReaderInterface>& reader);
-    virtual ~InputReaderThread();
-
-private:
-    sp<InputReaderInterface> mReader;
-
-    virtual bool threadLoop();
-};
+// --- InputReaderConfiguration ---
 
 /*
  * Input reader configuration.
@@ -285,6 +283,8 @@ struct InputReaderConfiguration {
     std::vector<DisplayViewport> mDisplays;
 };
 
+// --- TouchAffineTransformation ---
+
 struct TouchAffineTransformation {
     float x_scale;
     float x_ymix;
@@ -307,6 +307,8 @@ struct TouchAffineTransformation {
     void applyTo(float& x, float& y) const;
 };
 
+// --- InputReaderPolicyInterface ---
+
 /*
  * Input reader policy interface.
  *
@@ -316,8 +318,8 @@ struct TouchAffineTransformation {
  * The actual implementation is partially supported by callbacks into the DVM
  * via JNI.  This interface is also mocked in the unit tests.
  *
- * These methods must NOT re-enter the input reader since they may be called while
- * holding the input reader lock.
+ * These methods will NOT re-enter the input reader interface, so they may be called from
+ * any method in the input reader interface.
  */
 class InputReaderPolicyInterface : public virtual RefBase {
 protected:

services/inputflinger/reader/InputReader.cpp

@@ -38,16 +38,38 @@
 #include <unistd.h>
 
 #include <log/log.h>
+#include <utils/Errors.h>
 
 #include <android-base/stringprintf.h>
 #include <input/Keyboard.h>
 #include <input/VirtualKeyMap.h>
-
+#include <utils/Thread.h>
 
 using android::base::StringPrintf;
 
 namespace android {
 
+// --- InputReader::InputReaderThread ---
+
+/* Thread that reads raw events from the event hub and processes them, endlessly. */
+class InputReader::InputReaderThread : public Thread {
+public:
+    explicit InputReaderThread(InputReader* reader)
+          : Thread(/* canCallJava */ true), mReader(reader) {}
+
+    ~InputReaderThread() {}
+
+private:
+    InputReader* mReader;
+
+    bool threadLoop() override {
+        mReader->loopOnce();
+        return true;
+    }
+};
+
+// --- InputReader ---
+
 InputReader::InputReader(std::shared_ptr<EventHubInterface> eventHub,
                          const sp<InputReaderPolicyInterface>& policy,
                          const sp<InputListenerInterface>& listener)
@@ -61,6 +83,7 @@ InputReader::InputReader(std::shared_ptr<EventHubInterface> eventHub,
         mNextTimeout(LLONG_MAX),
         mConfigurationChangesToRefresh(0) {
     mQueuedListener = new QueuedInputListener(listener);
+    mThread = new InputReaderThread(this);
 
     { // acquire lock
         AutoMutex _l(mLock);
@@ -76,6 +99,28 @@ InputReader::~InputReader() {
     }
 }
 
+status_t InputReader::start() {
+    if (mThread->isRunning()) {
+        return ALREADY_EXISTS;
+    }
+    return mThread->run("InputReader", PRIORITY_URGENT_DISPLAY);
+}
+
+status_t InputReader::stop() {
+    if (!mThread->isRunning()) {
+        return OK;
+    }
+    if (gettid() == mThread->getTid()) {
+        ALOGE("InputReader can only be stopped from outside of the InputReaderThread!");
+        return INVALID_OPERATION;
+    }
+    // Directly calling requestExitAndWait() causes the thread to not exit
+    // if mEventHub is waiting for a long timeout.
+    mThread->requestExit();
+    mEventHub->wake();
+    return mThread->requestExitAndWait();
+}
+
 void InputReader::loopOnce() {
     int32_t oldGeneration;
     int32_t timeoutMillis;

services/inputflinger/reader/include/InputReader.h

@@ -38,12 +38,12 @@ struct StylusState;
  * that it sends to the input listener.  Some functions of the input reader, such as early
  * event filtering in low power states, are controlled by a separate policy object.
  *
- * The InputReader owns a collection of InputMappers.  Most of the work it does happens
- * on the input reader thread but the InputReader can receive queries from other system
+ * The InputReader owns a collection of InputMappers. InputReader starts its own thread, where
+ * most of the work happens, but the InputReader can receive queries from other system
  * components running on arbitrary threads.  To keep things manageable, the InputReader
  * uses a single Mutex to guard its state.  The Mutex may be held while calling into the
  * EventHub or the InputReaderPolicy but it is never held while calling into the
- * InputListener.
+ * InputListener. All calls to InputListener must happen from InputReader's thread.
  */
 class InputReader : public InputReaderInterface {
 public:
@@ -55,7 +55,8 @@ class InputReader : public InputReaderInterface {
     virtual void dump(std::string& dump) override;
     virtual void monitor() override;
 
-    virtual void loopOnce() override;
+    virtual status_t start() override;
+    virtual status_t stop() override;
 
     virtual void getInputDevices(std::vector<InputDeviceInfo>& outInputDevices) override;
 
@@ -86,6 +87,10 @@ class InputReader : public InputReaderInterface {
                                             const InputDeviceIdentifier& identifier,
                                             uint32_t classes);
 
+    // With each iteration of the loop, InputReader reads and processes one incoming message from
+    // the EventHub.
+    void loopOnce();
+
     class ContextImpl : public InputReaderContext {
         InputReader* mReader;
 
@@ -111,6 +116,9 @@ class InputReader : public InputReaderInterface {
     friend class ContextImpl;
 
 private:
+    class InputReaderThread;
+    sp<InputReaderThread> mThread;
+
     Mutex mLock;
 
     Condition mReaderIsAliveCondition;