WifiScoreReport - separate scoring classes

Move various wifi connected-link scoring algorithms in WifiScoreReport
into separate classes.

This commit introduces the abstract base class.

Bug: 62622378
Test: Compiles
Change-Id: Ie8362f6d521c072a960dacfb0a62d68ab5e05ae1

1 files changed, 108 insertions, 0 deletions

diff --git a/service/java/com/android/server/wifi/ConnectedScore.java b/service/java/com/android/server/wifi/ConnectedScore.java
new file mode 100644
index 000000000..5c7ffa8e4
--- /dev/null
+++ b/service/java/com/android/server/wifi/ConnectedScore.java
@@ -0,0 +1,108 @@
+/*
+ * 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.server.wifi;
+
+import android.net.NetworkAgent;
+import android.net.wifi.WifiInfo;
+
+/**
+ * Base class for connection scoring
+ */
+public abstract class ConnectedScore {
+
+    /** Maximum NetworkAgent score that should be generated by wifi */
+    public static final int WIFI_MAX_SCORE = NetworkAgent.WIFI_BASE_SCORE;
+
+    /** Score at which wifi is considered poor enough to give up ant try something else */
+    public static final int WIFI_TRANSITION_SCORE = NetworkAgent.WIFI_BASE_SCORE - 10;
+
+    public static final int WIFI_MIN_SCORE = 0;
+
+    final Clock mClock;
+
+    /** This is a typical STD for the connected RSSI for a phone sitting still */
+    public double mDefaultRssiStandardDeviation = 2.0;
+
+    /**
+     *
+     * @param clock is the time source for getMillis()
+     */
+    public ConnectedScore(Clock clock) {
+        mClock = clock;
+    }
+
+    /**
+     * Returns the current time in milliseconds
+     *
+     * This time is to be passed into the update methods.
+     * The scoring methods generally don't need a particular epoch, depending
+     * only on deltas. So a different time source may be used, as long as it is consistent.
+     *
+     * Note that when there are long intervals between updates, it is unlikely to matter much
+     * how large the interval is, so a time source that does not update while the processor is
+     * asleep could be just fine.
+     *
+     * @return millisecond-resolution time.
+     */
+    public long getMillis() {
+        return mClock.getWallClockMillis();
+    }
+
+    /**
+     * Updates scoring state using RSSI alone
+     *
+     * @param rssi signal strength (dB).
+     * @param millis millisecond-resolution time.
+     */
+    public void updateUsingRssi(int rssi, long millis) {
+        updateUsingRssi(rssi, millis, mDefaultRssiStandardDeviation);
+    }
+
+    /**
+     * Updates scoring state using RSSI and noise estimate
+     *
+     * This is useful if an RSSI comes from another source (e.g. scan results) and the
+     * expected noise varies by source.
+     *
+     * @param rssi signal strength (dB).
+     * @param millis millisecond-resolution time.
+     * @param standardDeviation of the RSSI.
+     */
+    public abstract void updateUsingRssi(int rssi, long millis, double standardDeviation);
+
+    /**
+     * Updates the score using relevant parts of WifiInfo
+     *
+     * @param wifiInfo object holding relevant values.
+     * @param millis millisecond-resolution time.
+     */
+    public void updateUsingWifiInfo(WifiInfo wifiInfo, long millis) {
+        updateUsingRssi(wifiInfo.getRssi(), millis);
+    }
+
+    /**
+     * Generates a score based on the current state
+     *
+     * @return network score - on NetworkAgent scale.
+     */
+    public abstract int generateScore();
+
+    /**
+     * Clears out state associated with the connection
+     */
+    public abstract void reset();
+}