Bug 1043457 - Add a CrashHandler class to handle uncaught exceptions; r=snorp

mobile/android/base/CrashHandler.java

@@ -0,0 +1,145 @@
+/* -*- Mode: Java; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil; -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+import android.os.Process;
+import android.util.Log;
+
+class CrashHandler implements Thread.UncaughtExceptionHandler {
+
+    private static final String LOGTAG = "GeckoCrashHandler";
+    private static final Thread MAIN_THREAD = Thread.currentThread();
+
+    protected final Thread.UncaughtExceptionHandler systemUncaughtHandler;
+
+    protected boolean crashing;
+
+    /**
+     * Get the root exception from the 'cause' chain of an exception.
+     *
+     * @param exc An exception
+     * @return The root exception
+     */
+    public static Throwable getRootException(Throwable exc) {
+        for (Throwable cause = exc; cause != null; cause = cause.getCause()) {
+            exc = cause;
+        }
+        return exc;
+    }
+
+    /**
+     * Get the standard stack trace string of an exception.
+     *
+     * @param exc An exception
+     * @return The exception stack trace.
+     */
+    public static String getExceptionStackTrace(final Throwable exc) {
+        StringWriter sw = new StringWriter();
+        PrintWriter pw = new PrintWriter(sw);
+        exc.printStackTrace(pw);
+        pw.flush();
+        return sw.toString();
+    }
+
+    /**
+     * Terminate the current process.
+     */
+    public static void terminateProcess() {
+        Process.killProcess(Process.myPid());
+    }
+
+    /**
+     * Create and register a CrashHandler for all threads and thread groups.
+     */
+    public CrashHandler() {
+        systemUncaughtHandler = Thread.getDefaultUncaughtExceptionHandler();
+        Thread.setDefaultUncaughtExceptionHandler(this);
+    }
+
+    /**
+     * Create and register a CrashHandler for a particular thread.
+     *
+     * @param thread A thread to register the CrashHandler
+     */
+    public CrashHandler(final Thread thread) {
+        systemUncaughtHandler = thread.getUncaughtExceptionHandler();
+        thread.setUncaughtExceptionHandler(this);
+    }
+
+    /**
+     * Record an exception stack in logs.
+     *
+     * @param thread The exception thread
+     * @param exc An exception
+     */
+    protected void logException(final Thread thread, final Throwable exc) {
+        try {
+            Log.e(LOGTAG, ">>> REPORTING UNCAUGHT EXCEPTION FROM THREAD "
+                          + thread.getId() + " (\"" + thread.getName() + "\")", exc);
+
+            if (MAIN_THREAD != thread) {
+                Log.e(LOGTAG, "Main thread (" + MAIN_THREAD.getId() + ") stack:");
+                for (StackTraceElement ste : MAIN_THREAD.getStackTrace()) {
+                    Log.e(LOGTAG, "    " + ste.toString());
+                }
+            }
+        } catch (final Throwable e) {
+            // If something throws here, we want to continue to report the exception,
+            // so we catch all exceptions and ignore them.
+        }
+    }
+
+    /**
+     * Report an exception to Socorro.
+     *
+     * @param thread The exception thread
+     * @param exc An exception
+     * @return Whether the exception was successfully reported
+     */
+    protected boolean reportException(final Thread thread, final Throwable exc) {
+        // TODO implement reporting to Socorro without Breakpad.
+    }
+
+    /**
+     * Implements the default behavior for handling uncaught exceptions.
+     *
+     * @param thread The exception thread
+     * @param exc An uncaught exception
+     */
+    @Override
+    public void uncaughtException(Thread thread, Throwable exc) {
+        if (this.crashing) {
+            // Prevent possible infinite recusions.
+            return;
+        }
+
+        if (thread == null) {
+            // Gecko may pass in null for thread to denote the current thread.
+            thread = Thread.currentThread();
+        }
+
+        try {
+            this.crashing = true;
+            exc = getRootException(exc);
+            logException(thread, exc);
+
+            if (reportException(thread, exc)) {
+                // Reporting succeeded; we can terminate our process now.
+                return;
+            }
+
+            if (systemUncaughtHandler != null) {
+                // Follow the chain of uncaught handlers.
+                systemUncaughtHandler.uncaughtException(thread, exc);
+            }
+        } finally {
+            terminateProcess();
+        }
+    }
+}

mobile/android/base/moz.build

@@ -132,6 +132,7 @@ gbjar.sources += [
     'BrowserLocaleManager.java',
     'ContactService.java',
     'ContextGetter.java',
+    'CrashHandler.java',
     'CustomEditText.java',
     'DataReportingNotification.java',
     'db/AbstractPerProfileDatabaseProvider.java',