写在前面的话

<p>

前面一篇Tinker相关的文章已经介绍了Tinker热修复框架的使用与整个的修复流程，那么这一篇就要开启Tinker的源码解析之路了。

首先简单说一下Tinker的原理，Tinker其实也是类似multidex的dex方式，将目标dex插入到数组最前面，主要是通过对比原dex文件（存在bug）与现dex文件（bug已修复）生成差异包，生成的差异包作为补丁包下发给客户端，客户端做一系列校验之后，将下发的差异包与本应用的dex文件合并成成全量的dex文件，并进行opt优化，当再次启动APP时候则加载优化过的全量dex文件，将dex文件插入到DexPathList 中 dexElements的前面。

所以Tinker其实是两个流程，一个是加载补丁包，另外一个是加载dex文件，两个的加载流程相对较长，这里分开说明，这一篇呢，主要介绍加载补丁包的流程。

补丁包加载流程

<p>

加载补丁包的方法如下

TinkerInstaller.onReceiveUpgradePatch(getApplicationContext(), "FilePath");

往下看发现调用了TinkerInstaller的onReceiveUpgradePatch方法

TinkerInstaller.java

public static void onReceiveUpgradePatch(Context context, String patchLocation) {
    Tinker.with(context).getPatchListener().onPatchReceived(patchLocation);
}

这里调用了PatchListener的onPatchReceived方法

而PatchListener是一个接口，他的具体实现为SamplePatchListener方法，onPatchReceived在SamplePatchListener的父类DefaultPatchListener有实现，我们看下DefaultPatchListener中的onPatchReceived方法
如下

DefaultPatchListener.java

@Override
public int onPatchReceived(String path) {

    int returnCode = patchCheck(path);

    if (returnCode == ShareConstants.ERROR_PATCH_OK) {
        TinkerPatchService.runPatchService(context, path);
    } else {
        Tinker.with(context).getLoadReporter().onLoadPatchListenerReceiveFail(new File(path), returnCode);
    }
    return returnCode;

}

首先这个检测了一下这个插件是否可用，通过SamplePatchListener的patchCheck方法来检测

SamplePatchListener.java

@Override
    public int patchCheck(String path) {
        File patchFile = new File(path);
        TinkerLog.i(TAG, "receive a patch file: %s, file size:%d", path, SharePatchFileUtil.getFileOrDirectorySize(patchFile));
        int returnCode = super.patchCheck(path);

        if (returnCode == ShareConstants.ERROR_PATCH_OK) {
            returnCode = Utils.checkForPatchRecover(NEW_PATCH_RESTRICTION_SPACE_SIZE_MIN, maxMemory);
        }

        if (returnCode == ShareConstants.ERROR_PATCH_OK) {
            String patchMd5 = SharePatchFileUtil.getMD5(patchFile);
            SharedPreferences sp = context.getSharedPreferences(ShareConstants.TINKER_SHARE_PREFERENCE_CONFIG, Context.MODE_MULTI_PROCESS);
            //optional, only disable this patch file with md5
            int fastCrashCount = sp.getInt(patchMd5, 0);
            if (fastCrashCount >= SampleUncaughtExceptionHandler.MAX_CRASH_COUNT) {
                returnCode = Utils.ERROR_PATCH_CRASH_LIMIT;
            } else {
                //for upgrade patch, version must be not the same
                //for repair patch, we won't has the tinker load flag
                Tinker tinker = Tinker.with(context);

                if (tinker.isTinkerLoaded()) {
                    TinkerLoadResult tinkerLoadResult = tinker.getTinkerLoadResultIfPresent();
                    if (tinkerLoadResult != null) {
                        String currentVersion = tinkerLoadResult.currentVersion;
                        if (patchMd5.equals(currentVersion)) {
                            returnCode = Utils.ERROR_PATCH_ALREADY_APPLY;
                        }
                    }
                }
            }
            //check whether retry so many times
            if (returnCode == ShareConstants.ERROR_PATCH_OK) {
                returnCode = UpgradePatchRetry.getInstance(context).onPatchListenerCheck(patchMd5)
                    ? ShareConstants.ERROR_PATCH_OK : Utils.ERROR_PATCH_RETRY_COUNT_LIMIT;
            }
        }
        // Warning, it is just a sample case, you don't need to copy all of these
        // Interception some of the request
        if (returnCode == ShareConstants.ERROR_PATCH_OK) {
            Properties properties = ShareTinkerInternals.fastGetPatchPackageMeta(patchFile);
            if (properties == null) {
                returnCode = Utils.ERROR_PATCH_CONDITION_NOT_SATISFIED;
            } else {
                String platform = properties.getProperty(Utils.PLATFORM);
                TinkerLog.i(TAG, "get platform:" + platform);
                // check patch platform require
                if (platform == null || !platform.equals(BuildInfo.PLATFORM)) {
                    returnCode = Utils.ERROR_PATCH_CONDITION_NOT_SATISFIED;
                }
            }
        }

        SampleTinkerReport.onTryApply(returnCode == ShareConstants.ERROR_PATCH_OK);
        return returnCode;
    }

这里对插件是否可用进行了判断，就不进行详细分析了

当插件可用时候returnCode为ERROR_PATCH_OK，当不可用则会log出来失败的errorcode

成功则调用

 TinkerPatchService.runPatchService(context, path);

来启动TinkerPatchService这个IntentService，并且把插件的路径给传递到IntentService

TinkerPatchService通过onHandleIntent来接收传递过来的数据

TinkerPatchService.java

 @Override
    protected void onHandleIntent(Intent intent) {
        final Context context = getApplicationContext();
        Tinker tinker = Tinker.with(context);
        tinker.getPatchReporter().onPatchServiceStart(intent);

        if (intent == null) {
            TinkerLog.e(TAG, "TinkerPatchService received a null intent, ignoring.");
            return;
        }
        String path = getPatchPathExtra(intent);
        if (path == null) {
            TinkerLog.e(TAG, "TinkerPatchService can't get the path extra, ignoring.");
            return;
        }
        File patchFile = new File(path);

        long begin = SystemClock.elapsedRealtime();
        boolean result;
        long cost;
        Throwable e = null;

        increasingPriority();
        PatchResult patchResult = new PatchResult();
        try {
            if (upgradePatchProcessor == null) {
                throw new TinkerRuntimeException("upgradePatchProcessor is null.");
            }
            result = upgradePatchProcessor.tryPatch(context, path, patchResult);
        } catch (Throwable throwable) {
            e = throwable;
            result = false;
            tinker.getPatchReporter().onPatchException(patchFile, e);
        }

        cost = SystemClock.elapsedRealtime() - begin;
        tinker.getPatchReporter().
            onPatchResult(patchFile, result, cost);

        patchResult.isSuccess = result;
        patchResult.rawPatchFilePath = path;
        patchResult.costTime = cost;
        patchResult.e = e;

        AbstractResultService.runResultService(context, patchResult, getPatchResultExtra(intent));

    }

这里首先调用了PatchReporter的onPatchServiceStart方法，而PatchReporter的实现为SamplePatchReporter

SamplePatchReporter.java

   @Override
    public void onPatchServiceStart(Intent intent) {
        super.onPatchServiceStart(intent);
        SampleTinkerReport.onApplyPatchServiceStart();
        UpgradePatchRetry.getInstance(context).onPatchServiceStart(intent);
    }

这里主要看UpgradePatchRetry的onPatchServiceStart方法

UpgradePatchRetry.java

    public void onPatchServiceStart(Intent intent) {
        if (!isRetryEnable) {
            TinkerLog.w(TAG, "onPatchServiceStart retry disabled, just return");
            return;
        }

        if (intent == null) {
            TinkerLog.e(TAG, "onPatchServiceStart intent is null, just return");
            return;
        }

        String path = TinkerPatchService.getPatchPathExtra(intent);

        if (path == null) {
            TinkerLog.w(TAG, "onPatchServiceStart patch path is null, just return");
            return;
        }

        RetryInfo retryInfo;
        File patchFile = new File(path);

        String patchMd5 = SharePatchFileUtil.getMD5(patchFile);
        if (patchMd5 == null) {
            TinkerLog.w(TAG, "onPatchServiceStart patch md5 is null, just return");
            return;
        }

        if (retryInfoFile.exists()) {
            retryInfo = RetryInfo.readRetryProperty(retryInfoFile);
            if (retryInfo.md5 == null || retryInfo.times == null || !patchMd5.equals(retryInfo.md5)) {
                copyToTempFile(patchFile);
                retryInfo.md5 = patchMd5;
                retryInfo.times = "1";
            } else {
                int nowTimes = Integer.parseInt(retryInfo.times);
                if (nowTimes >= RETRY_MAX_COUNT) {
                    SharePatchFileUtil.safeDeleteFile(tempPatchFile);
                    TinkerLog.w(TAG, "onPatchServiceStart retry more than max count, delete retry info file!");
                    return;
                } else {
                    retryInfo.times = String.valueOf(nowTimes + 1);
                }
            }

        } else {
            copyToTempFile(patchFile);
            retryInfo = new RetryInfo(patchMd5, "1");
        }

        RetryInfo.writeRetryProperty(retryInfoFile, retryInfo);
    }

这里主要也做了一些验证，并且把文件复制一份到/data/data/tinker.sample.android/tinker_temp/路径下，然后把相关信息写入到配置文件中

在回到TinkerPatchService的onHandleIntent方法

主要看

result = upgradePatchProcessor.tryPatch(context, path, patchResult);

这个方法的实现在UpgradePatch中

UpgradePatch.java

    @Override
    public boolean tryPatch(Context context, String tempPatchPath, PatchResult patchResult) {
        Tinker manager = Tinker.with(context);

        final File patchFile = new File(tempPatchPath);

        if (!manager.isTinkerEnabled() || !ShareTinkerInternals.isTinkerEnableWithSharedPreferences(context)) {
            TinkerLog.e(TAG, "UpgradePatch tryPatch:patch is disabled, just return");
            return false;
        }

        if (!patchFile.isFile() || !patchFile.exists()) {
            TinkerLog.e(TAG, "UpgradePatch tryPatch:patch file is not found, just return");
            return false;
        }
        //check the signature, we should create a new checker
        ShareSecurityCheck signatureCheck = new ShareSecurityCheck(context);

        int returnCode = ShareTinkerInternals.checkTinkerPackage(context, manager.getTinkerFlags(), patchFile, signatureCheck);
        if (returnCode != ShareConstants.ERROR_PACKAGE_CHECK_OK) {
            TinkerLog.e(TAG, "UpgradePatch tryPatch:onPatchPackageCheckFail");
            manager.getPatchReporter().onPatchPackageCheckFail(patchFile, returnCode);
            return false;
        }

        //it is a new patch, so we should not find a exist
        SharePatchInfo oldInfo = manager.getTinkerLoadResultIfPresent().patchInfo;
        String patchMd5 = SharePatchFileUtil.getMD5(patchFile);

        if (patchMd5 == null) {
            TinkerLog.e(TAG, "UpgradePatch tryPatch:patch md5 is null, just return");
            return false;
        }

        //use md5 as version
        patchResult.patchVersion = patchMd5;

        SharePatchInfo newInfo;

        //already have patch
        if (oldInfo != null) {
            if (oldInfo.oldVersion == null || oldInfo.newVersion == null) {
                TinkerLog.e(TAG, "UpgradePatch tryPatch:onPatchInfoCorrupted");
                manager.getPatchReporter().onPatchInfoCorrupted(patchFile, oldInfo.oldVersion, oldInfo.newVersion);
                return false;
            }

            if (oldInfo.oldVersion.equals(patchMd5) || oldInfo.newVersion.equals(patchMd5)) {
                TinkerLog.e(TAG, "UpgradePatch tryPatch:onPatchVersionCheckFail");
                manager.getPatchReporter().onPatchVersionCheckFail(patchFile, oldInfo, patchMd5);
                return false;
            }
            newInfo = new SharePatchInfo(oldInfo.oldVersion, patchMd5, Build.FINGERPRINT);
        } else {
            newInfo = new SharePatchInfo("", patchMd5, Build.FINGERPRINT);
        }

        //check ok, we can real recover a new patch
        final String patchDirectory = manager.getPatchDirectory().getAbsolutePath();

        TinkerLog.i(TAG, "UpgradePatch tryPatch:patchMd5:%s", patchMd5);

        final String patchName = SharePatchFileUtil.getPatchVersionDirectory(patchMd5);

        final String patchVersionDirectory = patchDirectory + "/" + patchName;

        TinkerLog.i(TAG, "UpgradePatch tryPatch:patchVersionDirectory:%s", patchVersionDirectory);

        //it is a new patch, we first delete if there is any files
        //don't delete dir for faster retry
//        SharePatchFileUtil.deleteDir(patchVersionDirectory);

        //copy file
        File destPatchFile = new File(patchVersionDirectory + "/" + SharePatchFileUtil.getPatchVersionFile(patchMd5));
        try {
            SharePatchFileUtil.copyFileUsingStream(patchFile, destPatchFile);
            TinkerLog.w(TAG, "UpgradePatch after %s size:%d, %s size:%d", patchFile.getAbsolutePath(), patchFile.length(),
                destPatchFile.getAbsolutePath(), destPatchFile.length());
        } catch (IOException e) {
//            e.printStackTrace();
            TinkerLog.e(TAG, "UpgradePatch tryPatch:copy patch file fail from %s to %s", patchFile.getPath(), destPatchFile.getPath());
            manager.getPatchReporter().onPatchTypeExtractFail(patchFile, destPatchFile, patchFile.getName(), ShareConstants.TYPE_PATCH_FILE);
            return false;
        }

        //we use destPatchFile instead of patchFile, because patchFile may be deleted during the patch process
        if (!DexDiffPatchInternal.tryRecoverDexFiles(manager, signatureCheck, context, patchVersionDirectory, destPatchFile)) {
            TinkerLog.e(TAG, "UpgradePatch tryPatch:new patch recover, try patch dex failed");
            return false;
        }

        if (!BsDiffPatchInternal.tryRecoverLibraryFiles(manager, signatureCheck, context, patchVersionDirectory, destPatchFile)) {
            TinkerLog.e(TAG, "UpgradePatch tryPatch:new patch recover, try patch library failed");
            return false;
        }

        if (!ResDiffPatchInternal.tryRecoverResourceFiles(manager, signatureCheck, context, patchVersionDirectory, destPatchFile)) {
            TinkerLog.e(TAG, "UpgradePatch tryPatch:new patch recover, try patch resource failed");
            return false;
        }

        final File patchInfoFile = manager.getPatchInfoFile();

        if (!SharePatchInfo.rewritePatchInfoFileWithLock(patchInfoFile, newInfo, SharePatchFileUtil.getPatchInfoLockFile(patchDirectory))) {
            TinkerLog.e(TAG, "UpgradePatch tryPatch:new patch recover, rewrite patch info failed");
            manager.getPatchReporter().onPatchInfoCorrupted(patchFile, newInfo.oldVersion, newInfo.newVersion);
            return false;
        }


        TinkerLog.w(TAG, "UpgradePatch tryPatch: done, it is ok");
        return true;
    }

}

这里首先初始化相关数据与相关验证，再将补丁文件拷贝到目标目录中

SharePatchFileUtil.copyFileUsingStream(patchFile, destPatchFile);

路径为/data/data/tinker.sample.android/tinker/patch-xxxxxx/patch-xxxxxx.apk

接下来就是调用DexDiffPatchInternal，BsDiffPatchInternal，ResDiffPatchInternal这些类的方法进行dexDiff差分的计算相关

至于相关差分的计算，由于比较复杂，我暂时还没有深入去看，暂时埋个坑在这里，等后面找时间去填上这个坑

在回到TinkerPatchService的onHandleIntent方法

后面调用了PatchReporter的onPatchResult，这个方法主要删除了上面拷贝在/data/data/tinker.sample.android/tinker_temp/的文件

接下来启动了AbstractResultService，并把插件的路径传递过去了

AbstractResultService的实现在SampleResultService类里面，SampleResultService的onPatchResult删除了原始的插件文件。

到这里插件加载分析就基本结束了

写在后面的话

<p>

插件加载分析结束了，但是却没有去分析dexDiff差分的计算，而这个dexDiff差分计算则是区分的Tinker与其他相同方案的热修复库，dexDiff是基于 Dex 的文件结构来下手，将产生变化的结构提取出来，产生的补丁非常小，而且在 diff 的过程中也处理了一些会造成补丁包很大的场景，所以等后面有时间将这一块补上，下一篇文章则是对dex文件加载进行源码分析了，peace~~~