NetdEventListener: add rolling log of connect and dns stats

This patch adds a rolling time order logs of basic statistics of
connect and dns, grouped by network id and including:
 - average error rate
 - average latency
 - max latency
 - total number of operations

The log is segmented in buckets of 5 minutes, and covers the last 4
hours.

Note that only blocking connect() calls latencies are recorded with the
current netd logging infrastructure.

Example of logs:
05:30:00.000: {netId=100, WIFI, dns avg=92ms max=525ms err=00.0% tot=37, connect avg=0ms max=23ms err=00.0% tot=25}
05:35:00.000: {netId=100, WIFI, dns avg=94ms max=537ms err=05.3% tot=57, connect avg=0ms max=0ms err=00.0% tot=69}
05:40:00.000: {netId=100, WIFI, dns avg=220ms max=350ms err=00.0% tot=4, connect avg=0ms max=0ms err=00.0% tot=2}
05:45:00.000: {netId=100, WIFI, dns avg=112ms max=113ms err=00.0% tot=1, connect avg=0ms max=0ms err=00.0% tot=1}
05:50:00.000: {netId=100, WIFI, dns avg=131ms max=269ms err=00.0% tot=2, connect avg=0ms max=0ms err=00.0% tot=1}

Bug: 65700460
Test: runtest frameworks-net
Change-Id: I54e76d18fbaaa92639fb675f93ea90b7615fd6bf
diff --git a/core/java/android/net/metrics/ConnectStats.java b/core/java/android/net/metrics/ConnectStats.java
index 30b2656..2495cab 100644
--- a/core/java/android/net/metrics/ConnectStats.java
+++ b/core/java/android/net/metrics/ConnectStats.java
@@ -20,6 +20,7 @@
 import android.system.OsConstants;
 import android.util.IntArray;
 import android.util.SparseIntArray;
+
 import com.android.internal.util.BitUtils;
 import com.android.internal.util.TokenBucket;
 
@@ -43,6 +44,8 @@
     public final TokenBucket mLatencyTb;
     /** Maximum number of latency values recorded. */
     public final int mMaxLatencyRecords;
+    /** Total count of events */
+    public int eventCount = 0;
     /** Total count of successful connects. */
     public int connectCount = 0;
     /** Total count of successful connects done in blocking mode. */
@@ -57,12 +60,15 @@
         mMaxLatencyRecords = maxLatencyRecords;
     }
 
-    public void addEvent(int errno, int latencyMs, String ipAddr) {
+    boolean addEvent(int errno, int latencyMs, String ipAddr) {
+        eventCount++;
         if (isSuccess(errno)) {
             countConnect(errno, ipAddr);
             countLatency(errno, latencyMs);
+            return true;
         } else {
             countError(errno);
+            return false;
         }
     }
 
@@ -101,7 +107,7 @@
         return (errno == 0) || isNonBlocking(errno);
     }
 
-    private static boolean isNonBlocking(int errno) {
+    static boolean isNonBlocking(int errno) {
         // On non-blocking TCP sockets, connect() immediately returns EINPROGRESS.
         // On non-blocking TCP sockets that are connecting, connect() immediately returns EALREADY.
         return (errno == EINPROGRESS) || (errno == EALREADY);
@@ -117,6 +123,7 @@
         for (int t : BitUtils.unpackBits(transports)) {
             builder.append(NetworkCapabilities.transportNameOf(t)).append(", ");
         }
+        builder.append(String.format("%d events, ", eventCount));
         builder.append(String.format("%d success, ", connectCount));
         builder.append(String.format("%d blocking, ", connectBlockingCount));
         builder.append(String.format("%d IPv6 dst", ipv6ConnectCount));
diff --git a/core/java/android/net/metrics/DnsEvent.java b/core/java/android/net/metrics/DnsEvent.java
index a4970e4..81b098b 100644
--- a/core/java/android/net/metrics/DnsEvent.java
+++ b/core/java/android/net/metrics/DnsEvent.java
@@ -17,11 +17,13 @@
 package android.net.metrics;
 
 import android.net.NetworkCapabilities;
-import java.util.Arrays;
+
 import com.android.internal.util.BitUtils;
 
+import java.util.Arrays;
+
 /**
- * A DNS event recorded by NetdEventListenerService.
+ * A batch of DNS events recorded by NetdEventListenerService for a specific network.
  * {@hide}
  */
 final public class DnsEvent {
@@ -38,6 +40,8 @@
     // the eventTypes, returnCodes, and latenciesMs arrays have the same length and the i-th event
     // is spread across the three array at position i.
     public int eventCount;
+    // The number of successful DNS queries recorded.
+    public int successCount;
     // The types of DNS queries as defined in INetdEventListener.
     public byte[] eventTypes;
     // Current getaddrinfo codes go from 1 to EAI_MAX = 15. gethostbyname returns errno, but there
@@ -54,10 +58,11 @@
         latenciesMs = new int[initialCapacity];
     }
 
-    public void addResult(byte eventType, byte returnCode, int latencyMs) {
+    boolean addResult(byte eventType, byte returnCode, int latencyMs) {
+        boolean isSuccess = (returnCode == 0);
         if (eventCount >= SIZE_LIMIT) {
             // TODO: implement better rate limiting that does not biases metrics.
-            return;
+            return isSuccess;
         }
         if (eventCount == eventTypes.length) {
             resize((int) (1.4 * eventCount));
@@ -66,6 +71,10 @@
         returnCodes[eventCount] = returnCode;
         latenciesMs[eventCount] = latencyMs;
         eventCount++;
+        if (isSuccess) {
+            successCount++;
+        }
+        return isSuccess;
     }
 
     public void resize(int newLength) {
@@ -80,6 +89,8 @@
         for (int t : BitUtils.unpackBits(transports)) {
             builder.append(NetworkCapabilities.transportNameOf(t)).append(", ");
         }
-        return builder.append(eventCount).append(" events)").toString();
+        builder.append(String.format("%d events, ", eventCount));
+        builder.append(String.format("%d success)", successCount));
+        return builder.toString();
     }
 }
diff --git a/core/java/android/net/metrics/NetworkMetrics.java b/core/java/android/net/metrics/NetworkMetrics.java
new file mode 100644
index 0000000..2b662a0
--- /dev/null
+++ b/core/java/android/net/metrics/NetworkMetrics.java
@@ -0,0 +1,168 @@
+/*
+ * 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 android.net.metrics;
+
+import android.net.NetworkCapabilities;
+
+import com.android.internal.util.BitUtils;
+import com.android.internal.util.TokenBucket;
+
+import java.util.StringJoiner;
+
+/**
+ * A class accumulating network metrics received from Netd regarding dns queries and
+ * connect() calls on a given network.
+ *
+ * This class also accumulates running sums of dns and connect latency stats and
+ * error counts for bug report logging.
+ *
+ * @hide
+ */
+public class NetworkMetrics {
+
+    private static final int INITIAL_DNS_BATCH_SIZE = 100;
+    private static final int CONNECT_LATENCY_MAXIMUM_RECORDS = 20000;
+
+    // The network id of the Android Network.
+    public final int netId;
+    // The transport types bitmap of the Android Network, as defined in NetworkCapabilities.java.
+    public final long transports;
+    // Accumulated metrics for connect events.
+    public final ConnectStats connectMetrics;
+    // Accumulated metrics for dns events.
+    public final DnsEvent dnsMetrics;
+    // Running sums of latencies and error counts for connect and dns events.
+    public final Summary summary;
+    // Running sums of the most recent latencies and error counts for connect and dns events.
+    // Starts null until some events are accumulated.
+    // Allows to collect periodic snapshot of the running summaries for a given network.
+    public Summary pendingSummary;
+
+    public NetworkMetrics(int netId, long transports, TokenBucket tb) {
+        this.netId = netId;
+        this.transports = transports;
+        this.connectMetrics =
+                new ConnectStats(netId, transports, tb, CONNECT_LATENCY_MAXIMUM_RECORDS);
+        this.dnsMetrics = new DnsEvent(netId, transports, INITIAL_DNS_BATCH_SIZE);
+        this.summary = new Summary(netId, transports);
+    }
+
+    /**
+     * Get currently pending Summary statistics, if any, for this NetworkMetrics, merge them
+     * into the long running Summary statistics of this NetworkMetrics, and also clear them.
+     */
+    public Summary getPendingStats() {
+        Summary s = pendingSummary;
+        pendingSummary = null;
+        if (s != null) {
+            summary.merge(s);
+        }
+        return s;
+    }
+
+    /** Accumulate a dns query result reported by netd. */
+    public void addDnsResult(int eventType, int returnCode, int latencyMs) {
+        if (pendingSummary == null) {
+            pendingSummary = new Summary(netId, transports);
+        }
+        boolean isSuccess = dnsMetrics.addResult((byte) eventType, (byte) returnCode, latencyMs);
+        pendingSummary.dnsLatencies.count(latencyMs);
+        pendingSummary.dnsErrorRate.count(isSuccess ? 0 : 1);
+    }
+
+    /** Accumulate a connect query result reported by netd. */
+    public void addConnectResult(int error, int latencyMs, String ipAddr) {
+        if (pendingSummary == null) {
+            pendingSummary = new Summary(netId, transports);
+        }
+        boolean isSuccess = connectMetrics.addEvent(error, latencyMs, ipAddr);
+        pendingSummary.connectErrorRate.count(isSuccess ? 0 : 1);
+        if (ConnectStats.isNonBlocking(error)) {
+            pendingSummary.connectLatencies.count(latencyMs);
+        }
+    }
+
+    /** Represents running sums for dns and connect average error counts and average latencies. */
+    public static class Summary {
+
+        public final int netId;
+        public final long transports;
+        // DNS latencies measured in milliseconds.
+        public final Metrics dnsLatencies = new Metrics();
+        // DNS error rate measured in percentage points.
+        public final Metrics dnsErrorRate = new Metrics();
+        // Blocking connect latencies measured in milliseconds.
+        public final Metrics connectLatencies = new Metrics();
+        // Blocking and non blocking connect error rate measured in percentage points.
+        public final Metrics connectErrorRate = new Metrics();
+
+        public Summary(int netId, long transports) {
+            this.netId = netId;
+            this.transports = transports;
+        }
+
+        void merge(Summary that) {
+            dnsLatencies.merge(that.dnsLatencies);
+            dnsErrorRate.merge(that.dnsErrorRate);
+            connectLatencies.merge(that.connectLatencies);
+            connectErrorRate.merge(that.connectErrorRate);
+        }
+
+        @Override
+        public String toString() {
+            StringJoiner j = new StringJoiner(", ", "{", "}");
+            j.add("netId=" + netId);
+            for (int t : BitUtils.unpackBits(transports)) {
+                j.add(NetworkCapabilities.transportNameOf(t));
+            }
+            j.add(String.format("dns avg=%dms max=%dms err=%.1f%% tot=%d",
+                    (int) dnsLatencies.average(), (int) dnsLatencies.max,
+                    100 * dnsErrorRate.average(), dnsErrorRate.count));
+            j.add(String.format("connect avg=%dms max=%dms err=%.1f%% tot=%d",
+                    (int) connectLatencies.average(), (int) connectLatencies.max,
+                    100 * connectErrorRate.average(), connectErrorRate.count));
+            return j.toString();
+        }
+    }
+
+    /** Tracks a running sum and returns the average of a metric. */
+    static class Metrics {
+        public double sum;
+        public double max = Double.MIN_VALUE;
+        public int count;
+
+        void merge(Metrics that) {
+            this.count += that.count;
+            this.sum += that.sum;
+            this.max = Math.max(this.max, that.max);
+        }
+
+        void count(double value) {
+            count++;
+            sum += value;
+            max = Math.max(max, value);
+        }
+
+        double average() {
+            double a = sum / (double) count;
+            if (Double.isNaN(a)) {
+                a = 0;
+            }
+            return a;
+        }
+    }
+}