KMC 京都マイクロコンピュータ株式会社

  /**
     * Performs Zygote process initialization. Loads and initializes
     * commonly used classes.
     *
     * Most classes only cause a few hundred bytes to be allocated, but
     * a few will allocate a dozen Kbytes (in one case, 500+K).
     */
    private static void preloadClasses() {
        final VMRuntime runtime = VMRuntime.getRuntime();

        InputStream is = ZygoteInit.class.getClassLoader().getResourceAsStream(
                PRELOADED_CLASSES);
        if (is == null) {
            Log.e(TAG, "Couldn't find " + PRELOADED_CLASSES + ".");
        } else {
            Log.i(TAG, "Preloading classes...");
            long startTime = SystemClock.uptimeMillis();

            // Drop root perms while running static initializers.
            setEffectiveGroup(UNPRIVILEGED_GID);
            setEffectiveUser(UNPRIVILEGED_UID);

            // Alter the target heap utilization.  With explicit GCs this
            // is not likely to have any effect.
            float defaultUtilization = runtime.getTargetHeapUtilization();
            runtime.setTargetHeapUtilization(0.8f);

            // Start with a clean slate.
            runtime.gcSoftReferences();
            runtime.runFinalizationSync();
            Debug.startAllocCounting();

            try {
                BufferedReader br
                    = new BufferedReader(new InputStreamReader(is), 256);

                int count = 0;
                String line;
                String missingClasses = null;
                while ((line = br.readLine()) != null) {
                    // Skip comments and blank lines.
                    line = line.trim();
                    if (line.startsWith("#") || line.equals("")) {
                        continue;
                    }

                    try {
                        if (Config.LOGV) {
                            Log.v(TAG, "Preloading " + line + "...");
                        }
                        Class.forName(line);
                        if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) {
                            if (Config.LOGV) {
                                Log.v(TAG,
                                    " GC at " + Debug.getGlobalAllocSize());
                            }
                            runtime.gcSoftReferences();
                            runtime.runFinalizationSync();
                            Debug.resetGlobalAllocSize();
                        }
                        count++;
                    } catch (ClassNotFoundException e) {
                        Log.e(TAG, "Class not found for preloading: " + line);
                        if (missingClasses == null) {
                            missingClasses = line;
                        } else {
                            missingClasses += " " + line;
                        }
                    } catch (Throwable t) {
                        Log.e(TAG, "Error preloading " + line + ".", t);
                        if (t instanceof Error) {
                            throw (Error) t;
                        }
                        if (t instanceof RuntimeException) {
                            throw (RuntimeException) t;
                        }
                        throw new RuntimeException(t);
                    }
                }

                if (THROW_ON_MISSING_PRELOAD &&
                    missingClasses != null) {
                    throw new IllegalStateException(
                            "Missing class(es) for preloading, update preloaded-classes ["
                            + missingClasses + "]");
                }

                Log.i(TAG, "...preloaded " + count + " classes in "
                        + (SystemClock.uptimeMillis()-startTime) + "ms.");
            } catch (IOException e) {
                Log.e(TAG, "Error reading " + PRELOADED_CLASSES + ".", e);
            } finally {
                // Restore default.
                runtime.setTargetHeapUtilization(defaultUtilization);

                Debug.stopAllocCounting();

                // Bring back root. We'll need it later.
                setEffectiveUser(ROOT_UID);
                setEffectiveGroup(ROOT_GID);
            }
        }
    }