Merge "Adds ERROR state to ImsConfig"

am: 6391598412

Change-Id: I612aae570b12b1106f515d32bd8caa3843a3953e

telephony/java/com/android/ims/ImsConfig.java

@@ -524,6 +524,7 @@ public class ImsConfig {
     * Defines IMS feature value.
     */
     public static class FeatureValueConstants {
+        public static final int ERROR = -1;
         public static final int OFF = 0;
         public static final int ON = 1;
     }

telephony/java/com/android/internal/telephony/ExponentialBackoff.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2017 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.telephony;
+
+import android.annotation.NonNull;
+import android.os.Handler;
+import android.os.Looper;
+
+/** The implementation of exponential backoff with jitter applied. */
+public class ExponentialBackoff {
+    private int mRetryCounter;
+    private long mStartDelayMs;
+    private long mMaximumDelayMs;
+    private long mCurrentDelayMs;
+    private int mMultiplier;
+    private Runnable mRunnable;
+    private Handler mHandler;
+
+    public ExponentialBackoff(
+            long initialDelayMs,
+            long maximumDelayMs,
+            int multiplier,
+            @NonNull Looper looper,
+            @NonNull Runnable runnable) {
+        this(initialDelayMs, maximumDelayMs, multiplier, new Handler(looper), runnable);
+    }
+
+    public ExponentialBackoff(
+            long initialDelayMs,
+            long maximumDelayMs,
+            int multiplier,
+            @NonNull Handler handler,
+            @NonNull Runnable runnable) {
+        mRetryCounter = 0;
+        mStartDelayMs = initialDelayMs;
+        mMaximumDelayMs = maximumDelayMs;
+        mMultiplier = multiplier;
+        mHandler = handler;
+        mRunnable = runnable;
+    }
+
+    /** Starts the backoff, the runnable will be executed after {@link #mStartDelayMs}. */
+    public void start() {
+        mRetryCounter = 0;
+        mCurrentDelayMs = mStartDelayMs;
+        mHandler.removeCallbacks(mRunnable);
+        mHandler.postDelayed(mRunnable, mCurrentDelayMs);
+    }
+
+    /** Stops the backoff, all pending messages will be removed from the message queue. */
+    public void stop() {
+        mRetryCounter = 0;
+        mHandler.removeCallbacks(mRunnable);
+    }
+
+    /** Should call when the retry action has failed and we want to retry after a longer delay. */
+    public void notifyFailed() {
+        mRetryCounter++;
+        long temp = Math.min(
+                mMaximumDelayMs, (long) (mStartDelayMs * Math.pow(mMultiplier, mRetryCounter)));
+        mCurrentDelayMs = (long) (((1 + Math.random()) / 2) * temp);
+        mHandler.removeCallbacks(mRunnable);
+        mHandler.postDelayed(mRunnable, mCurrentDelayMs);
+    }
+
+    /** Returns the delay for the most recently posted message. */
+    public long getCurrentDelay() {
+        return mCurrentDelayMs;
+    }
+}