Merge "Transplant the Logging system from Telecom"
diff --git a/telecomm/java/android/telecom/Log.java b/telecomm/java/android/telecom/Log.java
index a965342..ecda3cd 100644
--- a/telecomm/java/android/telecom/Log.java
+++ b/telecomm/java/android/telecom/Log.java
@@ -18,9 +18,15 @@
 
 import android.net.Uri;
 import android.os.AsyncTask;
+import android.telecom.Logging.EventManager;
+import android.telecom.Logging.Session;
+import android.telecom.Logging.SessionManager;
 import android.telephony.PhoneNumberUtils;
 import android.text.TextUtils;
 
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.util.IndentingPrintWriter;
+
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.util.IllegalFormatException;
@@ -31,24 +37,270 @@
  *
  * @hide
  */
-final public class Log {
+public class Log {
 
-    // Generic tag for all Telecom Framework logging
-    private static final String TAG = "TelecomFramework";
+    private static final long EXTENDED_LOGGING_DURATION_MILLIS = 60000 * 30; // 30 minutes
 
-    public static final boolean FORCE_LOGGING = false; /* STOP SHIP if true */
+    private static final int EVENTS_TO_CACHE = 10;
+    private static final int EVENTS_TO_CACHE_DEBUG = 20;
+
+    // Generic tag for all Telecom logging
+    @VisibleForTesting
+    public static String TAG = "TelecomFramework";
+
+    private static final boolean FORCE_LOGGING = false; /* STOP SHIP if true */
     public static final boolean DEBUG = isLoggable(android.util.Log.DEBUG);
     public static final boolean INFO = isLoggable(android.util.Log.INFO);
     public static final boolean VERBOSE = isLoggable(android.util.Log.VERBOSE);
     public static final boolean WARN = isLoggable(android.util.Log.WARN);
     public static final boolean ERROR = isLoggable(android.util.Log.ERROR);
 
+    // Used to synchronize singleton logging lazy initialization
+    private static final Object sSingletonSync = new Object();
+    private static EventManager sEventManager;
+    private static SessionManager sSessionManager;
+
+    /**
+     * Tracks whether user-activated extended logging is enabled.
+     */
+    private static boolean sIsUserExtendedLoggingEnabled = false;
+
+    /**
+     * The time when user-activated extended logging should be ended.  Used to determine when
+     * extended logging should automatically be disabled.
+     */
+    private static long sUserExtendedLoggingStopTime = 0;
+
+    private Log() {
+    }
+
+    public static void d(String prefix, String format, Object... args) {
+        if (sIsUserExtendedLoggingEnabled) {
+            maybeDisableLogging();
+            android.util.Slog.i(TAG, buildMessage(prefix, format, args));
+        } else if (DEBUG) {
+            android.util.Slog.d(TAG, buildMessage(prefix, format, args));
+        }
+    }
+
+    public static void d(Object objectPrefix, String format, Object... args) {
+        if (sIsUserExtendedLoggingEnabled) {
+            maybeDisableLogging();
+            android.util.Slog.i(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
+        } else if (DEBUG) {
+            android.util.Slog.d(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
+        }
+    }
+
+    public static void i(String prefix, String format, Object... args) {
+        if (INFO) {
+            android.util.Slog.i(TAG, buildMessage(prefix, format, args));
+        }
+    }
+
+    public static void i(Object objectPrefix, String format, Object... args) {
+        if (INFO) {
+            android.util.Slog.i(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
+        }
+    }
+
+    public static void v(String prefix, String format, Object... args) {
+        if (sIsUserExtendedLoggingEnabled) {
+            maybeDisableLogging();
+            android.util.Slog.i(TAG, buildMessage(prefix, format, args));
+        } else if (VERBOSE) {
+            android.util.Slog.v(TAG, buildMessage(prefix, format, args));
+        }
+    }
+
+    public static void v(Object objectPrefix, String format, Object... args) {
+        if (sIsUserExtendedLoggingEnabled) {
+            maybeDisableLogging();
+            android.util.Slog.i(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
+        } else if (VERBOSE) {
+            android.util.Slog.v(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
+        }
+    }
+
+    public static void w(String prefix, String format, Object... args) {
+        if (WARN) {
+            android.util.Slog.w(TAG, buildMessage(prefix, format, args));
+        }
+    }
+
+    public static void w(Object objectPrefix, String format, Object... args) {
+        if (WARN) {
+            android.util.Slog.w(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
+        }
+    }
+
+    public static void e(String prefix, Throwable tr, String format, Object... args) {
+        if (ERROR) {
+            android.util.Slog.e(TAG, buildMessage(prefix, format, args), tr);
+        }
+    }
+
+    public static void e(Object objectPrefix, Throwable tr, String format, Object... args) {
+        if (ERROR) {
+            android.util.Slog.e(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args),
+                    tr);
+        }
+    }
+
+    public static void wtf(String prefix, Throwable tr, String format, Object... args) {
+        android.util.Slog.wtf(TAG, buildMessage(prefix, format, args), tr);
+    }
+
+    public static void wtf(Object objectPrefix, Throwable tr, String format, Object... args) {
+        android.util.Slog.wtf(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args),
+                tr);
+    }
+
+    public static void wtf(String prefix, String format, Object... args) {
+        String msg = buildMessage(prefix, format, args);
+        android.util.Slog.wtf(TAG, msg, new IllegalStateException(msg));
+    }
+
+    public static void wtf(Object objectPrefix, String format, Object... args) {
+        String msg = buildMessage(getPrefixFromObject(objectPrefix), format, args);
+        android.util.Slog.wtf(TAG, msg, new IllegalStateException(msg));
+    }
+
+    /**
+     * The ease of use methods below only act mostly as proxies to the Session and Event Loggers.
+     * They also control the lazy loaders of the singleton instances, which will never be loaded if
+     * the proxy methods aren't used.
+     *
+     * Please see each method's documentation inside of their respective implementations in the
+     * loggers.
+     */
+
+    public static void startSession(String shortMethodName) {
+        getSessionManager().startSession(shortMethodName, null);
+    }
+
+    public static void startSession(String shortMethodName, String callerIdentification) {
+        getSessionManager().startSession(shortMethodName, callerIdentification);
+    }
+
+    public static Session createSubsession() {
+        return getSessionManager().createSubsession();
+    }
+
+    public static void cancelSubsession(Session subsession) {
+        getSessionManager().cancelSubsession(subsession);
+    }
+
+    public static void continueSession(Session subsession, String shortMethodName) {
+        getSessionManager().continueSession(subsession, shortMethodName);
+    }
+
+    public static void endSession() {
+        getSessionManager().endSession();
+    }
+
+    public static String getSessionId() {
+        // If the Session logger has not been initialized, then there have been no sessions logged.
+        // Don't load it now!
+        synchronized (sSingletonSync) {
+            if (sSessionManager != null) {
+                return getSessionManager().getSessionId();
+            } else {
+                return "";
+            }
+        }
+    }
+
+    public static void addEvent(EventManager.Loggable recordEntry, String event) {
+        getEventManager().event(recordEntry, event, null);
+    }
+
+    public static void addEvent(EventManager.Loggable recordEntry, String event, Object data) {
+        getEventManager().event(recordEntry, event, data);
+    }
+
+    public static void addEvent(EventManager.Loggable recordEntry, String event, String format,
+            Object... args) {
+        getEventManager().event(recordEntry, event, format, args);
+    }
+
+    public static void registerEventListener(EventManager.EventListener e) {
+        getEventManager().registerEventListener(e);
+    }
+
+    public static void addRequestResponsePair(EventManager.TimedEventPair p) {
+        getEventManager().addRequestResponsePair(p);
+    }
+
+    public static void dumpEvents(IndentingPrintWriter pw) {
+        // If the Events logger has not been initialized, then there have been no events logged.
+        // Don't load it now!
+        synchronized (sSingletonSync) {
+            if (sEventManager != null) {
+                getEventManager().dumpEvents(pw);
+            } else {
+                pw.println("No Historical Events Logged.");
+            }
+        }
+    }
+
+    /**
+     * Enable or disable extended telecom logging.
+     *
+     * @param isExtendedLoggingEnabled {@code true} if extended logging should be enabled,
+     *          {@code false} if it should be disabled.
+     */
+    public static void setIsExtendedLoggingEnabled(boolean isExtendedLoggingEnabled) {
+        // If the state hasn't changed, bail early.
+        if (sIsUserExtendedLoggingEnabled == isExtendedLoggingEnabled) {
+            return;
+        }
+
+        if (sEventManager != null) {
+            sEventManager.changeEventCacheSize(isExtendedLoggingEnabled ?
+                    EVENTS_TO_CACHE_DEBUG : EVENTS_TO_CACHE);
+        }
+
+        sIsUserExtendedLoggingEnabled = isExtendedLoggingEnabled;
+        if (sIsUserExtendedLoggingEnabled) {
+            sUserExtendedLoggingStopTime = System.currentTimeMillis()
+                    + EXTENDED_LOGGING_DURATION_MILLIS;
+        } else {
+            sUserExtendedLoggingStopTime = 0;
+        }
+    }
+
+    private static EventManager getEventManager() {
+        // Checking for null again outside of synchronization because we only need to synchronize
+        // during the lazy loading of the events logger. We don't need to synchronize elsewhere.
+        if (sEventManager == null) {
+            synchronized (sSingletonSync) {
+                if (sEventManager == null) {
+                    sEventManager = new EventManager(Log::getSessionId);
+                    return sEventManager;
+                }
+            }
+        }
+        return sEventManager;
+    }
+
+    private static SessionManager getSessionManager() {
+        // Checking for null again outside of synchronization because we only need to synchronize
+        // during the lazy loading of the session logger. We don't need to synchronize elsewhere.
+        if (sSessionManager == null) {
+            synchronized (sSingletonSync) {
+                if (sSessionManager == null) {
+                    sSessionManager = new SessionManager();
+                    return sSessionManager;
+                }
+            }
+        }
+        return sSessionManager;
+    }
+
     private static MessageDigest sMessageDigest;
-    private static final Object sMessageDigestLock = new Object();
 
-    private Log() {}
-
-    public static void initMd5Sum() {
+    static void initMd5Sum() {
         new AsyncTask<Void, Void, Void>() {
             @Override
             public Void doInBackground(Void... args) {
@@ -58,96 +310,69 @@
                 } catch (NoSuchAlgorithmException e) {
                     md = null;
                 }
-                synchronized (sMessageDigestLock) {
-                    sMessageDigest = md;
-                }
+                sMessageDigest = md;
                 return null;
             }
         }.execute();
     }
 
+    public static void setTag(String tag) {
+        TAG = tag;
+    }
+
+    /**
+     * If user enabled extended logging is enabled and the time limit has passed, disables the
+     * extended logging.
+     */
+    private static void maybeDisableLogging() {
+        if (!sIsUserExtendedLoggingEnabled) {
+            return;
+        }
+
+        if (sUserExtendedLoggingStopTime < System.currentTimeMillis()) {
+            sUserExtendedLoggingStopTime = 0;
+            sIsUserExtendedLoggingEnabled = false;
+        }
+    }
+
     public static boolean isLoggable(int level) {
         return FORCE_LOGGING || android.util.Log.isLoggable(TAG, level);
     }
 
-    public static void d(String prefix, String format, Object... args) {
-        if (DEBUG) {
-            android.util.Log.d(TAG, buildMessage(prefix, format, args));
+    public static String piiHandle(Object pii) {
+        if (pii == null || VERBOSE) {
+            return String.valueOf(pii);
         }
-    }
 
-    public static void d(Object objectPrefix, String format, Object... args) {
-        if (DEBUG) {
-            android.util.Log.d(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
+        StringBuilder sb = new StringBuilder();
+        if (pii instanceof Uri) {
+            Uri uri = (Uri) pii;
+            String scheme = uri.getScheme();
+
+            if (!TextUtils.isEmpty(scheme)) {
+                sb.append(scheme).append(":");
+            }
+
+            String textToObfuscate = uri.getSchemeSpecificPart();
+            if (PhoneAccount.SCHEME_TEL.equals(scheme)) {
+                for (int i = 0; i < textToObfuscate.length(); i++) {
+                    char c = textToObfuscate.charAt(i);
+                    sb.append(PhoneNumberUtils.isDialable(c) ? "*" : c);
+                }
+            } else if (PhoneAccount.SCHEME_SIP.equals(scheme)) {
+                for (int i = 0; i < textToObfuscate.length(); i++) {
+                    char c = textToObfuscate.charAt(i);
+                    if (c != '@' && c != '.') {
+                        c = '*';
+                    }
+                    sb.append(c);
+                }
+            } else {
+                sb.append(pii(pii));
+            }
         }
-    }
 
-    public static void i(String prefix, String format, Object... args) {
-        if (INFO) {
-            android.util.Log.i(TAG, buildMessage(prefix, format, args));
-        }
-    }
-
-    public static void i(Object objectPrefix, String format, Object... args) {
-        if (INFO) {
-            android.util.Log.i(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
-        }
-    }
-
-    public static void v(String prefix, String format, Object... args) {
-        if (VERBOSE) {
-            android.util.Log.v(TAG, buildMessage(prefix, format, args));
-        }
-    }
-
-    public static void v(Object objectPrefix, String format, Object... args) {
-        if (VERBOSE) {
-            android.util.Log.v(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
-        }
-    }
-
-    public static void w(String prefix, String format, Object... args) {
-        if (WARN) {
-            android.util.Log.w(TAG, buildMessage(prefix, format, args));
-        }
-    }
-
-    public static void w(Object objectPrefix, String format, Object... args) {
-        if (WARN) {
-            android.util.Log.w(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args));
-        }
-    }
-
-    public static void e(String prefix, Throwable tr, String format, Object... args) {
-        if (ERROR) {
-            android.util.Log.e(TAG, buildMessage(prefix, format, args), tr);
-        }
-    }
-
-    public static void e(Object objectPrefix, Throwable tr, String format, Object... args) {
-        if (ERROR) {
-            android.util.Log.e(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args),
-                    tr);
-        }
-    }
-
-    public static void wtf(String prefix, Throwable tr, String format, Object... args) {
-        android.util.Log.wtf(TAG, buildMessage(prefix, format, args), tr);
-    }
-
-    public static void wtf(Object objectPrefix, Throwable tr, String format, Object... args) {
-        android.util.Log.wtf(TAG, buildMessage(getPrefixFromObject(objectPrefix), format, args),
-                tr);
-    }
-
-    public static void wtf(String prefix, String format, Object... args) {
-        String msg = buildMessage(prefix, format, args);
-        android.util.Log.wtf(TAG, msg, new IllegalStateException(msg));
-    }
-
-    public static void wtf(Object objectPrefix, String format, Object... args) {
-        String msg = buildMessage(getPrefixFromObject(objectPrefix), format, args);
-        android.util.Log.wtf(TAG, msg, new IllegalStateException(msg));
+        return sb.toString();
     }
 
     /**
@@ -158,47 +383,18 @@
     public static String pii(Object pii) {
         if (pii == null || VERBOSE) {
             return String.valueOf(pii);
-        } if (pii instanceof Uri) {
-            return piiUri((Uri) pii);
         }
         return "[" + secureHash(String.valueOf(pii).getBytes()) + "]";
     }
 
-    private static String piiUri(Uri handle) {
-        StringBuilder sb = new StringBuilder();
-        String scheme = handle.getScheme();
-        if (!TextUtils.isEmpty(scheme)) {
-            sb.append(scheme).append(":");
-        }
-        String value = handle.getSchemeSpecificPart();
-        if (!TextUtils.isEmpty(value)) {
-            for (int i = 0; i < value.length(); i++) {
-                char c = value.charAt(i);
-                if (PhoneNumberUtils.isStartsPostDial(c)) {
-                    sb.append(c);
-                } else if (PhoneNumberUtils.isDialable(c)) {
-                    sb.append("*");
-                } else if (('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z')) {
-                    sb.append("*");
-                } else {
-                    sb.append(c);
-                }
-            }
-        }
-        return sb.toString();
-
-    }
-
     private static String secureHash(byte[] input) {
-        synchronized (sMessageDigestLock) {
-            if (sMessageDigest != null) {
-                sMessageDigest.reset();
-                sMessageDigest.update(input);
-                byte[] result = sMessageDigest.digest();
-                return encodeHex(result);
-            } else {
-                return "Uninitialized SHA1";
-            }
+        if (sMessageDigest != null) {
+            sMessageDigest.reset();
+            sMessageDigest.update(input);
+            byte[] result = sMessageDigest.digest();
+            return encodeHex(result);
+        } else {
+            return "Uninitialized SHA1";
         }
     }
 
@@ -221,15 +417,19 @@
     }
 
     private static String buildMessage(String prefix, String format, Object... args) {
+        // Incorporate thread ID and calling method into prefix
+        String sessionName = getSessionId();
+        String sessionPostfix = TextUtils.isEmpty(sessionName) ? "" : ": " + sessionName;
+
         String msg;
         try {
             msg = (args == null || args.length == 0) ? format
                     : String.format(Locale.US, format, args);
         } catch (IllegalFormatException ife) {
-            wtf("Log", ife, "IllegalFormatException: formatString='%s' numArgs=%d", format,
+            e("Log", ife, "IllegalFormatException: formatString='%s' numArgs=%d", format,
                     args.length);
             msg = format + " (An error occurred while formatting the message.)";
         }
-        return String.format(Locale.US, "%s: %s", prefix, msg);
+        return String.format(Locale.US, "%s: %s%s", prefix, msg, sessionPostfix);
     }
 }
diff --git a/telecomm/java/android/telecom/Logging/EventManager.java b/telecomm/java/android/telecom/Logging/EventManager.java
new file mode 100644
index 0000000..8e7a393
--- /dev/null
+++ b/telecomm/java/android/telecom/Logging/EventManager.java
@@ -0,0 +1,365 @@
+/*
+ * Copyright (C) 2016 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.telecom.Logging;
+
+import android.annotation.NonNull;
+import android.telecom.Log;
+import android.text.TextUtils;
+
+import com.android.internal.util.IndentingPrintWriter;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.IllegalFormatException;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingQueue;
+
+/**
+ * A utility class that provides the ability to define Events that a subsystem deems important, and
+ * then relate those events to other events so that information can be extracted. For example, a
+ * START and FINISH event can be defined and when a START and then FINISH occurs in a sequence, the
+ * time it took to complete that sequence can be saved to be retrieved later.
+ * @hide
+ */
+
+public class EventManager {
+
+    public static final String TAG = "Logging.Events";
+    public static final int DEFAULT_EVENTS_TO_CACHE = 10;  // Arbitrarily chosen.
+
+    public interface Loggable {
+        /**
+         * @return a unique String ID that will allow the Event to be recognized later in the logs.
+         */
+        String getId();
+
+        /**
+         * @return Formatted information about the state that will be printed out later in the logs.
+         */
+        String getDescription();
+    }
+
+    private final Map<Loggable, EventRecord> mCallEventRecordMap = new HashMap<>();
+    private LinkedBlockingQueue<EventRecord> mEventRecords =
+            new LinkedBlockingQueue<>(DEFAULT_EVENTS_TO_CACHE);
+
+    private List<EventListener> mEventListeners = new ArrayList<>();
+
+    public interface EventListener {
+        /**
+         * Notifies the implementation of this method that a new event record has been added.
+         * @param eventRecord Reference to the recently added EventRecord
+         */
+        void eventRecordAdded(EventRecord eventRecord);
+    }
+
+    private SessionManager.ISessionIdQueryHandler mSessionIdHandler;
+    /**
+     * Maps from request events to a list of possible response events. Used to track
+     * end-to-end timing for critical user-facing operations in Telecom.
+     */
+    public final Map<String, List<TimedEventPair>> requestResponsePairs = new HashMap<>();
+
+    private static final Object mSync = new Object();
+
+    /**
+     * Stores the various events.
+     * Also stores all request-response pairs amongst the events.
+     */
+    public static class TimedEventPair {
+        private static final long DEFAULT_TIMEOUT = 3000L;
+
+        String mRequest;
+        String mResponse;
+        String mName;
+        long mTimeoutMillis = DEFAULT_TIMEOUT;
+
+        public TimedEventPair(String request, String response, String name) {
+            this.mRequest = request;
+            this.mResponse = response;
+            this.mName = name;
+        }
+
+        public TimedEventPair(String request, String response, String name, long timeoutMillis) {
+            this.mRequest = request;
+            this.mResponse = response;
+            this.mName = name;
+            this.mTimeoutMillis = timeoutMillis;
+        }
+    }
+
+    public void addRequestResponsePair(TimedEventPair p) {
+        if (requestResponsePairs.containsKey(p.mRequest)) {
+            requestResponsePairs.get(p.mRequest).add(p);
+        } else {
+            ArrayList<TimedEventPair> responses = new ArrayList<>();
+            responses.add(p);
+            requestResponsePairs.put(p.mRequest, responses);
+        }
+    }
+
+    public static class Event {
+        public String eventId;
+        public String sessionId;
+        public long time;
+        public Object data;
+
+        public Event(String eventId, String sessionId, long time, Object data) {
+            this.eventId = eventId;
+            this.sessionId = sessionId;
+            this.time = time;
+            this.data = data;
+        }
+    }
+
+    public class EventRecord {
+        public class EventTiming extends TimedEvent<String> {
+            public String name;
+            public long time;
+
+            public EventTiming(String name, long time) {
+                this.name = name;
+                this.time = time;
+            }
+
+            public String getKey() {
+                return name;
+            }
+
+            public long getTime() {
+                return time;
+            }
+        }
+
+        private class PendingResponse {
+            String requestEventId;
+            long requestEventTimeMillis;
+            long timeoutMillis;
+            String name;
+
+            public PendingResponse(String requestEventId, long requestEventTimeMillis,
+                    long timeoutMillis, String name) {
+                this.requestEventId = requestEventId;
+                this.requestEventTimeMillis = requestEventTimeMillis;
+                this.timeoutMillis = timeoutMillis;
+                this.name = name;
+            }
+        }
+
+        private final DateFormat sDateFormat = new SimpleDateFormat("HH:mm:ss.SSS");
+        private final List<Event> mEvents = new LinkedList<>();
+        private final Loggable mRecordEntry;
+
+        public EventRecord(Loggable recordEntry) {
+            mRecordEntry = recordEntry;
+        }
+
+        public Loggable getRecordEntry() {
+            return mRecordEntry;
+        }
+
+        public void addEvent(String event, String sessionId, Object data) {
+            mEvents.add(new Event(event, sessionId, System.currentTimeMillis(), data));
+            Log.i("Event", "RecordEntry %s: %s, %s", mRecordEntry.getId(), event, data);
+        }
+
+        public List<Event> getEvents() {
+            return mEvents;
+        }
+
+        public List<EventTiming> extractEventTimings() {
+            if (mEvents == null) {
+                return Collections.emptyList();
+            }
+
+            LinkedList<EventTiming> result = new LinkedList<>();
+            Map<String, PendingResponse> pendingResponses = new HashMap<>();
+            for (Event event : mEvents) {
+                if (requestResponsePairs.containsKey(event.eventId)) {
+                    // This event expects a response, so add that expected response to the maps
+                    // of pending events.
+                    for (EventManager.TimedEventPair p : requestResponsePairs.get(event.eventId)) {
+                        pendingResponses.put(p.mResponse, new PendingResponse(event.eventId,
+                                event.time, p.mTimeoutMillis, p.mName));
+                    }
+                }
+
+                PendingResponse pendingResponse = pendingResponses.remove(event.eventId);
+                if (pendingResponse != null) {
+                    long elapsedTime = event.time - pendingResponse.requestEventTimeMillis;
+                    if (elapsedTime < pendingResponse.timeoutMillis) {
+                        result.add(new EventTiming(pendingResponse.name, elapsedTime));
+                    }
+                }
+            }
+
+            return result;
+        }
+
+        public void dump(IndentingPrintWriter pw) {
+            pw.print(mRecordEntry.getDescription());
+
+            pw.increaseIndent();
+            for (Event event : mEvents) {
+                pw.print(sDateFormat.format(new Date(event.time)));
+                pw.print(" - ");
+                pw.print(event.eventId);
+                if (event.data != null) {
+                    pw.print(" (");
+                    Object data = event.data;
+
+                    if (data instanceof Loggable) {
+                        // If the data is another Loggable, then change the data to the
+                        // Entry's Event ID instead.
+                        EventRecord record = mCallEventRecordMap.get(data);
+                        if (record != null) {
+                            data = "RecordEntry " + record.mRecordEntry.getId();
+                        }
+                    }
+
+                    pw.print(data);
+                    pw.print(")");
+                }
+                if (!TextUtils.isEmpty(event.sessionId)) {
+                    pw.print(":");
+                    pw.print(event.sessionId);
+                }
+                pw.println();
+            }
+
+            pw.println("Timings (average for this call, milliseconds):");
+            pw.increaseIndent();
+            Map<String, Double> avgEventTimings = EventTiming.averageTimings(extractEventTimings());
+            List<String> eventNames = new ArrayList<>(avgEventTimings.keySet());
+            Collections.sort(eventNames);
+            for (String eventName : eventNames) {
+                pw.printf("%s: %.2f\n", eventName, avgEventTimings.get(eventName));
+            }
+            pw.decreaseIndent();
+            pw.decreaseIndent();
+        }
+    }
+
+    public EventManager(@NonNull SessionManager.ISessionIdQueryHandler l) {
+        mSessionIdHandler = l;
+    }
+
+    public void event(Loggable recordEntry, String event, Object data) {
+        String currentSessionID = mSessionIdHandler.getSessionId();
+
+        if (recordEntry == null) {
+            Log.i(TAG, "Non-call EVENT: %s, %s", event, data);
+            return;
+        }
+        synchronized (mEventRecords) {
+            if (!mCallEventRecordMap.containsKey(recordEntry)) {
+                EventRecord newRecord = new EventRecord(recordEntry);
+                addEventRecord(newRecord);
+            }
+
+            EventRecord record = mCallEventRecordMap.get(recordEntry);
+            record.addEvent(event, currentSessionID, data);
+        }
+    }
+
+    public void event(Loggable recordEntry, String event, String format, Object... args) {
+        String msg;
+        try {
+            msg = (args == null || args.length == 0) ? format
+                    : String.format(Locale.US, format, args);
+        } catch (IllegalFormatException ife) {
+            Log.e("Log", ife, "IllegalFormatException: formatString='%s' numArgs=%d", format,
+                    args.length);
+            msg = format + " (An error occurred while formatting the message.)";
+        }
+
+        event(recordEntry, event, msg);
+    }
+
+    public void dumpEvents(IndentingPrintWriter pw) {
+        pw.println("Historical Events:");
+        pw.increaseIndent();
+        for (EventRecord eventRecord : mEventRecords) {
+            eventRecord.dump(pw);
+        }
+        pw.decreaseIndent();
+    }
+
+    public void changeEventCacheSize(int newSize) {
+
+        // Resize the event queue.
+        LinkedBlockingQueue<EventRecord> oldEventLog = mEventRecords;
+        mEventRecords = new LinkedBlockingQueue<>(newSize);
+        mCallEventRecordMap.clear();
+
+        oldEventLog.forEach((newRecord -> {
+            Loggable recordEntry = newRecord.getRecordEntry();
+            // Copy the existing queue into the new one.
+            // First remove the oldest entry if no new ones exist.
+            if (mEventRecords.remainingCapacity() == 0) {
+                EventRecord record = mEventRecords.poll();
+                if (record != null) {
+                    mCallEventRecordMap.remove(record.getRecordEntry());
+                }
+            }
+
+            // Now add a new entry
+            mEventRecords.add(newRecord);
+            mCallEventRecordMap.put(recordEntry, newRecord);
+
+            // Don't worry about notifying mEventListeners, since we are just resizing the records.
+        }));
+    }
+
+    public void registerEventListener(EventListener e) {
+        if (e != null) {
+            synchronized (mSync) {
+                mEventListeners.add(e);
+            }
+        }
+    }
+
+    private void addEventRecord(EventRecord newRecord) {
+        Loggable recordEntry = newRecord.getRecordEntry();
+
+        // First remove the oldest entry if no new ones exist.
+        if (mEventRecords.remainingCapacity() == 0) {
+            EventRecord record = mEventRecords.poll();
+            if (record != null) {
+                mCallEventRecordMap.remove(record.getRecordEntry());
+            }
+        }
+
+        // Now add a new entry
+        mEventRecords.add(newRecord);
+        mCallEventRecordMap.put(recordEntry, newRecord);
+
+        // TODO: Add Implementation of this in Telecom for Analytics
+        synchronized (mSync) {
+            for (EventListener l : mEventListeners) {
+                l.eventRecordAdded(newRecord);
+            }
+        }
+    }
+}
diff --git a/telecomm/java/android/telecom/Logging/Session.java b/telecomm/java/android/telecom/Logging/Session.java
new file mode 100644
index 0000000..14f4a0f
--- /dev/null
+++ b/telecomm/java/android/telecom/Logging/Session.java
@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) 2016 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.telecom.Logging;
+
+import android.annotation.NonNull;
+
+import java.util.ArrayList;
+
+/**
+ * The session that stores information about a thread's point of entry into the Telecom code that
+ * persists until the thread exits Telecom.
+ * @hide
+ */
+public class Session {
+
+    public static final String START_SESSION = "START_SESSION";
+    public static final String CREATE_SUBSESSION = "CREATE_SUBSESSION";
+    public static final String CONTINUE_SUBSESSION = "CONTINUE_SUBSESSION";
+    public static final String END_SUBSESSION = "END_SUBSESSION";
+    public static final String END_SESSION = "END_SESSION";
+
+    public static final int UNDEFINED = -1;
+
+    private String mSessionId;
+    private String mShortMethodName;
+    private long mExecutionStartTimeMs;
+    private long mExecutionEndTimeMs = UNDEFINED;
+    private Session mParentSession;
+    private ArrayList<Session> mChildSessions;
+    private boolean mIsCompleted = false;
+    private int mChildCounter = 0;
+    // True if this is a subsession that has been started from the same thread as the parent
+    // session. This can happen if Log.startSession(...) is called multiple times on the same
+    // thread in the case of one Telecom entry point method calling another entry point method.
+    // In this case, we can just make this subsession "invisible," but still keep track of it so
+    // that the Log.endSession() calls match up.
+    private boolean mIsStartedFromActiveSession = false;
+    // Optionally provided info about the method/class/component that started the session in order
+    // to make Logging easier. This info will be provided in parentheses along with the session.
+    private String mOwnerInfo;
+
+    public Session(String sessionId, String shortMethodName, long startTimeMs, long threadID,
+            boolean isStartedFromActiveSession, String ownerInfo) {
+        setSessionId(sessionId);
+        setShortMethodName(shortMethodName);
+        mExecutionStartTimeMs = startTimeMs;
+        mParentSession = null;
+        mChildSessions = new ArrayList<>(5);
+        mIsStartedFromActiveSession = isStartedFromActiveSession;
+        mOwnerInfo = ownerInfo;
+    }
+
+    public void setSessionId(@NonNull String sessionId) {
+        if (sessionId == null) {
+            mSessionId = "?";
+        }
+        mSessionId = sessionId;
+    }
+
+    public String getShortMethodName() {
+        return mShortMethodName;
+    }
+
+    public void setShortMethodName(String shortMethodName) {
+        if (shortMethodName == null) {
+            shortMethodName = "";
+        }
+        mShortMethodName = shortMethodName;
+    }
+
+    public void setParentSession(Session parentSession) {
+        mParentSession = parentSession;
+    }
+
+    public void addChild(Session childSession) {
+        if (childSession != null) {
+            mChildSessions.add(childSession);
+        }
+    }
+
+    public void removeChild(Session child) {
+        if (child != null) {
+            mChildSessions.remove(child);
+        }
+    }
+
+    public long getExecutionStartTimeMilliseconds() {
+        return mExecutionStartTimeMs;
+    }
+
+    public void setExecutionStartTimeMs(long startTimeMs) {
+        mExecutionStartTimeMs = startTimeMs;
+    }
+
+    public Session getParentSession() {
+        return mParentSession;
+    }
+
+    public ArrayList<Session> getChildSessions() {
+        return mChildSessions;
+    }
+
+    public boolean isSessionCompleted() {
+        return mIsCompleted;
+    }
+
+    public boolean isStartedFromActiveSession() {
+        return mIsStartedFromActiveSession;
+    }
+
+    // Mark this session complete. This will be deleted by Log when all subsessions are complete
+    // as well.
+    public void markSessionCompleted(long executionEndTimeMs) {
+        mExecutionEndTimeMs = executionEndTimeMs;
+        mIsCompleted = true;
+    }
+
+    public long getLocalExecutionTime() {
+        if (mExecutionEndTimeMs == UNDEFINED) {
+            return UNDEFINED;
+        }
+        return mExecutionEndTimeMs - mExecutionStartTimeMs;
+    }
+
+    public synchronized String getNextChildId() {
+        return String.valueOf(mChildCounter++);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof Session)) {
+            return false;
+        }
+        if (obj == this) {
+            return true;
+        }
+        Session otherSession = (Session) obj;
+        return (mSessionId.equals(otherSession.mSessionId)) &&
+                (mShortMethodName.equals(otherSession.mShortMethodName)) &&
+                mExecutionStartTimeMs == otherSession.mExecutionStartTimeMs &&
+                mParentSession == otherSession.mParentSession &&
+                mChildSessions.equals(otherSession.mChildSessions) &&
+                mIsCompleted == otherSession.mIsCompleted &&
+                mExecutionEndTimeMs == otherSession.mExecutionEndTimeMs &&
+                mChildCounter == otherSession.mChildCounter &&
+                mIsStartedFromActiveSession == otherSession.mIsStartedFromActiveSession &&
+                mOwnerInfo == otherSession.mOwnerInfo;
+    }
+
+    // Builds full session id recursively
+    private String getFullSessionId() {
+        // Cache mParentSession locally to prevent a concurrency problem where
+        // Log.endParentSessions() is called while a logging statement is running (Log.i, for
+        // example) and setting mParentSession to null in a different thread after the null check
+        // occurred.
+        Session parentSession = mParentSession;
+        if (parentSession == null) {
+            return mSessionId;
+        } else {
+            return parentSession.getFullSessionId() + "_" + mSessionId;
+        }
+    }
+
+    // Print out the full Session tree from any subsession node
+    public String printFullSessionTree() {
+        // Get to the top of the tree
+        Session topNode = this;
+        while (topNode.getParentSession() != null) {
+            topNode = topNode.getParentSession();
+        }
+        return topNode.printSessionTree();
+    }
+
+    // Recursively move down session tree using DFS, but print out each node when it is reached.
+    public String printSessionTree() {
+        StringBuilder sb = new StringBuilder();
+        printSessionTree(0, sb);
+        return sb.toString();
+    }
+
+    private void printSessionTree(int tabI, StringBuilder sb) {
+        sb.append(toString());
+        for (Session child : mChildSessions) {
+            sb.append("\n");
+            for (int i = 0; i <= tabI; i++) {
+                sb.append("\t");
+            }
+            child.printSessionTree(tabI + 1, sb);
+        }
+    }
+
+    @Override
+    public String toString() {
+        if (mParentSession != null && mIsStartedFromActiveSession) {
+            // Log.startSession was called from within another active session. Use the parent's
+            // Id instead of the child to reduce confusion.
+            return mParentSession.toString();
+        } else {
+            StringBuilder methodName = new StringBuilder();
+            methodName.append(mShortMethodName);
+            if (mOwnerInfo != null && !mOwnerInfo.isEmpty()) {
+                methodName.append("(InCall package: ");
+                methodName.append(mOwnerInfo);
+                methodName.append(")");
+            }
+            return methodName.toString() + "@" + getFullSessionId();
+        }
+    }
+}
diff --git a/telecomm/java/android/telecom/Logging/SessionManager.java b/telecomm/java/android/telecom/Logging/SessionManager.java
new file mode 100644
index 0000000..a4e8977
--- /dev/null
+++ b/telecomm/java/android/telecom/Logging/SessionManager.java
@@ -0,0 +1,344 @@
+/*
+ * Copyright (C) 2016 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.telecom.Logging;
+
+import android.content.Context;
+import android.os.Handler;
+import android.os.Looper;
+import android.provider.Settings;
+import android.util.Base64;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * TODO: Create better Sessions Documentation
+ * @hide
+ */
+
+public class SessionManager {
+
+    // Currently using 3 letters, So don't exceed 64^3
+    private static final long SESSION_ID_ROLLOVER_THRESHOLD = 262144;
+
+    // This parameter can be overridden in Telecom's Timeouts class.
+    public static final long DEFAULT_SESSION_TIMEOUT_MS = 30000L; // 30 seconds
+
+    private static String LOGGING_TAG = "Logging";
+
+    private static final String TIMEOUTS_PREFIX = "telecom.";
+
+    // Synchronized in all method calls
+    private int sCodeEntryCounter = 0;
+    private Context mContext;
+
+    @VisibleForTesting
+    public ConcurrentHashMap<Integer, Session> sSessionMapper = new ConcurrentHashMap<>(100);
+    @VisibleForTesting
+    public Handler sSessionCleanupHandler = new Handler(Looper.getMainLooper());
+    @VisibleForTesting
+    public java.lang.Runnable sCleanStaleSessions = () ->
+            cleanupStaleSessions(getSessionCleanupTimeoutMs());
+
+    // Overridden in LogTest to skip query to ContentProvider
+    private interface ISessionCleanupTimeoutMs {
+        long get();
+    }
+
+    @VisibleForTesting
+    public ISessionCleanupTimeoutMs sSessionCleanupTimeoutMs = () -> {
+        // mContext may be null in some cases, such as testing. For these cases, use the
+        // default value.
+        if (mContext == null) {
+            return DEFAULT_SESSION_TIMEOUT_MS;
+        }
+        return getCleanupTimeout(mContext);
+    };
+
+    // Usage is synchronized on this class.
+    private List<ISessionListener> mSessionListeners = new ArrayList<>();
+
+    public interface ISessionListener {
+        /**
+         * This method is run when a full Session has completed.
+         * @param sessionName The name of the Session that has completed.
+         * @param timeMs The time it took to complete in ms.
+         */
+        void sessionComplete(String sessionName, long timeMs);
+    }
+
+    public interface ISessionIdQueryHandler {
+        String getSessionId();
+    }
+
+    public void setContext(Context context) {
+        mContext = context;
+    }
+
+    public SessionManager() {
+    }
+
+    private long getSessionCleanupTimeoutMs() {
+        return sSessionCleanupTimeoutMs.get();
+    }
+
+    private synchronized void resetStaleSessionTimer() {
+        sSessionCleanupHandler.removeCallbacksAndMessages(null);
+        // Will be null in Log Testing
+        if (sCleanStaleSessions != null) {
+            sSessionCleanupHandler.postDelayed(sCleanStaleSessions, getSessionCleanupTimeoutMs());
+        }
+    }
+
+    /**
+     * Call at an entry point to the Telecom code to track the session. This code must be
+     * accompanied by a Log.endSession().
+     */
+    public synchronized void startSession(String shortMethodName,
+            String callerIdentification) {
+        resetStaleSessionTimer();
+        int threadId = getCallingThreadId();
+        Session activeSession = sSessionMapper.get(threadId);
+        // We have called startSession within an active session that has not ended... Register this
+        // session as a subsession.
+        if (activeSession != null) {
+            Session childSession = createSubsession(true);
+            continueSession(childSession, shortMethodName);
+            return;
+        }
+        Session newSession = new Session(getNextSessionID(), shortMethodName,
+                System.currentTimeMillis(), threadId, false, callerIdentification);
+        sSessionMapper.put(threadId, newSession);
+
+        android.telecom.Log.v(LOGGING_TAG, Session.START_SESSION);
+    }
+
+
+    /**
+     * Notifies the logging system that a subsession will be run at a later point and
+     * allocates the resources. Returns a session object that must be used in
+     * Log.continueSession(...) to start the subsession.
+     */
+    public Session createSubsession() {
+        return createSubsession(false);
+    }
+
+    private synchronized Session createSubsession(boolean isStartedFromActiveSession) {
+        int threadId = getCallingThreadId();
+        Session threadSession = sSessionMapper.get(threadId);
+        if (threadSession == null) {
+            android.telecom.Log.d(LOGGING_TAG, "Log.createSubsession was called with no session " +
+                    "active.");
+            return null;
+        }
+        // Start execution time of the session will be overwritten in continueSession(...).
+        Session newSubsession = new Session(threadSession.getNextChildId(),
+                threadSession.getShortMethodName(), System.currentTimeMillis(), threadId,
+                isStartedFromActiveSession, null);
+        threadSession.addChild(newSubsession);
+        newSubsession.setParentSession(threadSession);
+
+        if (!isStartedFromActiveSession) {
+            android.telecom.Log.v(LOGGING_TAG, Session.CREATE_SUBSESSION + " " +
+                    newSubsession.toString());
+        } else {
+            android.telecom.Log.v(LOGGING_TAG, Session.CREATE_SUBSESSION +
+                    " (Invisible subsession)");
+        }
+        return newSubsession;
+    }
+
+    /**
+     * Cancels a subsession that had Log.createSubsession() called on it, but will never have
+     * Log.continueSession(...) called on it due to an error. Allows the subsession to be cleaned
+     * gracefully instead of being removed by the sSessionCleanupHandler forcefully later.
+     */
+    public synchronized void cancelSubsession(Session subsession) {
+        if (subsession == null) {
+            return;
+        }
+
+        subsession.markSessionCompleted(0);
+        endParentSessions(subsession);
+    }
+
+    /**
+     * Starts the subsession that was created in Log.CreateSubsession. The Log.endSession() method
+     * must be called at the end of this method. The full session will complete when all
+     * subsessions are completed.
+     */
+    public synchronized void continueSession(Session subsession, String shortMethodName) {
+        if (subsession == null) {
+            return;
+        }
+        resetStaleSessionTimer();
+        String callingMethodName = subsession.getShortMethodName();
+        subsession.setShortMethodName(callingMethodName + "->" + shortMethodName);
+        subsession.setExecutionStartTimeMs(System.currentTimeMillis());
+        Session parentSession = subsession.getParentSession();
+        if (parentSession == null) {
+            android.telecom.Log.d(LOGGING_TAG, "Log.continueSession was called with no session " +
+                    "active for method %s.", shortMethodName);
+            return;
+        }
+
+        sSessionMapper.put(getCallingThreadId(), subsession);
+        if (!subsession.isStartedFromActiveSession()) {
+            android.telecom.Log.v(LOGGING_TAG, Session.CONTINUE_SUBSESSION);
+        } else {
+            android.telecom.Log.v(LOGGING_TAG, Session.CONTINUE_SUBSESSION +
+                    " (Invisible Subsession) with Method " + shortMethodName);
+        }
+    }
+
+    /**
+     * Ends the current session/subsession. Must be called after a Log.startSession(...) and
+     * Log.continueSession(...) call.
+     */
+    public synchronized void endSession() {
+        int threadId = getCallingThreadId();
+        Session completedSession = sSessionMapper.get(threadId);
+        if (completedSession == null) {
+            android.telecom.Log.w(LOGGING_TAG, "Log.endSession was called with no session active.");
+            return;
+        }
+
+        completedSession.markSessionCompleted(System.currentTimeMillis());
+        if (!completedSession.isStartedFromActiveSession()) {
+            android.telecom.Log.v(LOGGING_TAG, Session.END_SUBSESSION + " (dur: " +
+                    completedSession.getLocalExecutionTime() + " mS)");
+        } else {
+            android.telecom.Log.v(LOGGING_TAG, Session.END_SUBSESSION +
+                    " (Invisible Subsession) (dur: " + completedSession.getLocalExecutionTime() +
+                    " ms)");
+        }
+        // Remove after completed so that reference still exists for logging the end events
+        Session parentSession = completedSession.getParentSession();
+        sSessionMapper.remove(threadId);
+        endParentSessions(completedSession);
+        // If this subsession was started from a parent session using Log.startSession, return the
+        // ThreadID back to the parent after completion.
+        if (parentSession != null && !parentSession.isSessionCompleted() &&
+                completedSession.isStartedFromActiveSession()) {
+            sSessionMapper.put(threadId, parentSession);
+        }
+    }
+
+    // Recursively deletes all complete parent sessions of the current subsession if it is a leaf.
+    private void endParentSessions(Session subsession) {
+        // Session is not completed or not currently a leaf, so we can not remove because a child is
+        // still running
+        if (!subsession.isSessionCompleted() || subsession.getChildSessions().size() != 0) {
+            return;
+        }
+
+        Session parentSession = subsession.getParentSession();
+        if (parentSession != null) {
+            subsession.setParentSession(null);
+            parentSession.removeChild(subsession);
+            endParentSessions(parentSession);
+        } else {
+            // All of the subsessions have been completed and it is time to report on the full
+            // running time of the session.
+            long fullSessionTimeMs =
+                    System.currentTimeMillis() - subsession.getExecutionStartTimeMilliseconds();
+            android.telecom.Log.v(LOGGING_TAG, Session.END_SESSION + " (dur: " + fullSessionTimeMs
+                    + " ms): " + subsession.toString());
+            // TODO: Add analytics hook
+            for (ISessionListener l : mSessionListeners) {
+                l.sessionComplete(subsession.getShortMethodName(), fullSessionTimeMs);
+            }
+        }
+    }
+
+    public String getSessionId() {
+        Session currentSession = sSessionMapper.get(getCallingThreadId());
+        return currentSession != null ? currentSession.toString() : "";
+    }
+
+    public synchronized void registerSessionListener(ISessionListener l) {
+        if (l != null) {
+            mSessionListeners.add(l);
+        }
+    }
+
+    private synchronized String getNextSessionID() {
+        Integer nextId = sCodeEntryCounter++;
+        if (nextId >= SESSION_ID_ROLLOVER_THRESHOLD) {
+            restartSessionCounter();
+            nextId = sCodeEntryCounter++;
+        }
+        return getBase64Encoding(nextId);
+    }
+
+    @VisibleForTesting
+    public synchronized void restartSessionCounter() {
+        sCodeEntryCounter = 0;
+    }
+
+    @VisibleForTesting
+    public String getBase64Encoding(int number) {
+        byte[] idByteArray = ByteBuffer.allocate(4).putInt(number).array();
+        idByteArray = Arrays.copyOfRange(idByteArray, 2, 4);
+        return Base64.encodeToString(idByteArray, Base64.NO_WRAP | Base64.NO_PADDING);
+    }
+
+    public int getCallingThreadId() {
+        return android.os.Process.myTid();
+    }
+
+    @VisibleForTesting
+    private synchronized void cleanupStaleSessions(long timeoutMs) {
+        String logMessage = "Stale Sessions Cleaned:\n";
+        boolean isSessionsStale = false;
+        long currentTimeMs = System.currentTimeMillis();
+        // Remove references that are in the Session Mapper (causing GC to occur) on
+        // sessions that are lasting longer than LOGGING_SESSION_TIMEOUT_MS.
+        // If this occurs, then there is most likely a Session active that never had
+        // Log.endSession called on it.
+        for (Iterator<ConcurrentHashMap.Entry<Integer, Session>> it =
+             sSessionMapper.entrySet().iterator(); it.hasNext(); ) {
+            ConcurrentHashMap.Entry<Integer, Session> entry = it.next();
+            Session session = entry.getValue();
+            if (currentTimeMs - session.getExecutionStartTimeMilliseconds() > timeoutMs) {
+                it.remove();
+                logMessage += session.printFullSessionTree() + "\n";
+                isSessionsStale = true;
+            }
+        }
+        if (isSessionsStale) {
+            android.telecom.Log.w(LOGGING_TAG, logMessage);
+        } else {
+            android.telecom.Log.v(LOGGING_TAG, "No stale logging sessions needed to be cleaned...");
+        }
+    }
+
+    /**
+     * Returns the amount of time after a Logging session has been started that Telecom is set to
+     * perform a sweep to check and make sure that the session is still not incomplete (stale).
+     */
+    private long getCleanupTimeout(Context context) {
+        return Settings.Secure.getLong(context.getContentResolver(), TIMEOUTS_PREFIX +
+                "stale_session_cleanup_timeout_millis", DEFAULT_SESSION_TIMEOUT_MS);
+    }
+}
diff --git a/telecomm/java/android/telecom/Logging/TimedEvent.java b/telecomm/java/android/telecom/Logging/TimedEvent.java
new file mode 100644
index 0000000..6785e92
--- /dev/null
+++ b/telecomm/java/android/telecom/Logging/TimedEvent.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2016 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.telecom.Logging;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * @hide
+ */
+public abstract class TimedEvent<T> {
+    public abstract long getTime();
+    public abstract T getKey();
+
+    public static <T> Map<T, Double> averageTimings(Collection<? extends TimedEvent<T>> events) {
+        HashMap<T, Integer> counts = new HashMap<>();
+        HashMap<T, Double> result = new HashMap<>();
+
+        for (TimedEvent<T> entry : events) {
+            if (counts.containsKey(entry.getKey())) {
+                counts.put(entry.getKey(), counts.get(entry.getKey()) + 1);
+                result.put(entry.getKey(), result.get(entry.getKey()) + entry.getTime());
+            } else {
+                counts.put(entry.getKey(), 1);
+                result.put(entry.getKey(), (double) entry.getTime());
+            }
+        }
+
+        for (Map.Entry<T, Double> entry : result.entrySet()) {
+            result.put(entry.getKey(), entry.getValue() / counts.get(entry.getKey()));
+        }
+
+        return result;
+    }
+}