聊聊Exception的前世今生

service zygote /system/bin/app_process64 -Xzygote /system/bin --zygote --start-system-server 

int main(int argc, char* const argv[])
{
    // Parse runtime arguments.  Stop at first unrecognized option.
    bool zygote = false;
    bool startSystemServer = false;
    bool application = false;
    String8 niceName;
    String8 className;

    ++i;  // Skip unused "parent dir" argument.
    while (i < argc) {
        const char* arg = argv[i++];
        if (strcmp(arg, "--zygote") == 0) {
            zygote = true;
            niceName = ZYGOTE_NICE_NAME;
        } else if (strcmp(arg, "--start-system-server") == 0) {
            startSystemServer = true;
        } else if (strcmp(arg, "--application") == 0) {
            application = true;
        } else if (strncmp(arg, "--nice-name=", 12) == 0) {
            niceName.setTo(arg + 12);
        } else if (strncmp(arg, "--", 2) != 0) {
            className.setTo(arg);
            break;
        } else {
            --i;
            break;
        }
    }

    Vector<String8> args;
    if (!className.isEmpty()) {
//......
    } else {
        // We're in zygote mode.
        maybeCreateDalvikCache();

        if (startSystemServer) {
            args.add(String8("start-system-server"));
        }
//......
    }
//......
    if (zygote) {
        runtime.start("com.android.internal.os.ZygoteInit", args, zygote);
    } else if (className) {
        runtime.start("com.android.internal.os.RuntimeInit", args, zygote);
    } else {
        fprintf(stderr, "Error: no class name or --zygote supplied.\n");
        app_usage();
        LOG_ALWAYS_FATAL("app_process: no class name or --zygote supplied.");
    }
}

if (zygote) {
        runtime.start("com.android.internal.os.ZygoteInit", args, zygote);
    } else if (className) {
        runtime.start("com.android.internal.os.RuntimeInit", args, zygote);
    } 

static final void enableDdms() {
        // Register handlers for DDM messages.
        android.ddm.DdmRegister.registerHandlers();
    }

public static void registerHandlers() {
        if (false)
            Log.v("ddm", "Registering DDM message handlers");
        DdmHandleHello.register();
        DdmHandleThread.register();
        DdmHandleHeap.register();
        DdmHandleNativeHeap.register();
        DdmHandleProfiling.register();
        DdmHandleExit.register();
        DdmHandleViewDebug.register();

        DdmServer.registrationComplete();
    }

public static void registrationComplete() {
        // sync on mHandlerMap because it's convenient and makes a kind of
        // sense
        synchronized (mHandlerMap) {
            mRegistrationComplete = true;
            mHandlerMap.notifyAll();
        }
    }

LoggingHandler loggingHandler = new LoggingHandler();
RuntimeHooks.setUncaughtExceptionPreHandler(loggingHandler);
Thread.setDefaultUncaughtExceptionHandler(new KillApplicationHandler(loggingHandler));

public interface UncaughtExceptionHandler {
        void uncaughtException(Thread t, Throwable e);
    }

public final void dispatchUncaughtException(Throwable e) {
        // BEGIN Android-added: uncaughtExceptionPreHandler for use by platform.
        Thread.UncaughtExceptionHandler initialUeh =
                Thread.getUncaughtExceptionPreHandler();
        if (initialUeh != null) {
            try {
                initialUeh.uncaughtException(this, e);
            } catch (RuntimeException | Error ignored) {
                // Throwables thrown by the initial handler are ignored
            }
        }
        // END Android-added: uncaughtExceptionPreHandler for use by platform.
        getUncaughtExceptionHandler().uncaughtException(this, e);
    }

initialUeh.uncaughtException(this, e);
getUncaughtExceptionHandler().uncaughtException(this, e);

private static class FinalizerWatchdogDaemon extends Daemon {
        private static final FinalizerWatchdogDaemon INSTANCE = new FinalizerWatchdogDaemon();

        private boolean needToWork = true;  // Only accessed in synchronized methods.

        FinalizerWatchdogDaemon() {
            super("FinalizerWatchdogDaemon");
        }

        @Override public void runInternal() {
            while (isRunning()) {
                if (!sleepUntilNeeded()) {
                    // We have been interrupted, need to see if this daemon has been stopped.
                    continue;
                }
                final Object finalizing = waitForFinalization();
                if (finalizing != null && !VMRuntime.getRuntime().isDebuggerActive()) {
                    finalizerTimedOut(finalizing);
                    break;
                }
            }
        }
}

private static void finalizerTimedOut(Object object) {
            // The current object has exceeded the finalization deadline; abort!
            String message = object.getClass().getName() + ".finalize() timed out after "
                    + (MAX_FINALIZE_NANOS / NANOS_PER_SECOND) + " seconds";
            Exception syntheticException = new TimeoutException(message);
            // We use the stack from where finalize() was running to show where it was stuck.
            syntheticException.setStackTrace(FinalizerDaemon.INSTANCE.getStackTrace());

            // Send SIGQUIT to get native stack traces.
            try {
                Os.kill(Os.getpid(), OsConstants.SIGQUIT);
                // Sleep a few seconds to let the stack traces print.
                Thread.sleep(5000);
            } catch (Exception e) {
                System.logE("failed to send SIGQUIT", e);
            } catch (OutOfMemoryError ignored) {
                // May occur while trying to allocate the exception.
            }
            if (Thread.getUncaughtExceptionPreHandler() == null &&
                    Thread.getDefaultUncaughtExceptionHandler() == null) {
                System.logE(message, syntheticException);
                System.exit(2);
            }
            Thread.currentThread().dispatchUncaughtException(syntheticException);
        }
    }

public void uncaughtException(Thread t, Throwable e) {
            try {
                ensureLogging(t, e);
                if (mCrashing) return;
                mCrashing = true;
                if (ActivityThread.currentActivityThread() != null) {
                    ActivityThread.currentActivityThread().stopProfiling();
                }
                ActivityManager.getService().handleApplicationCrash(
                        mApplicationObject, new ApplicationErrorReport.ParcelableCrashInfo(e));
            } catch (Throwable t2) {
                if (t2 instanceof DeadObjectException) {
                    // System process is dead; ignore
                } else {
                    try {
                        Clog_e(TAG, "Error reporting crash", t2);
                    } catch (Throwable t3) {
                        // Even Clog_e() fails!  Oh well.
                    }
                }
            } finally {
                // Try everything to make sure this process goes away.
                Process.killProcess(Process.myPid());
                System.exit(10);
            }
        }