dexopt的源码跟踪

关于dexopt的预备知识在这里
一般都是从AndroidStudio run出来的apk安装到手机,这里从 adb shell pm install -r xxx.apk 开始看起:
找到android/frameworks/base/cmds/pm/src/com/android/commands/pm/pm.java pm命令的源码
main函数调用了new Pm().run(args);
找到 runInstall()方法
哦刚才的常用参数 “-r” 表示覆盖安装模式 INSTALL_REPLACE_EXISTING
runInstall()方法最终会调用

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mPm.installPackageWithVerification(apkURI, obs, installFlags, installerPackageName,
verificationURI, null, encryptionParams);

而 mPm = IPackageManager.Stub.asInterface(ServiceManager.getService(“package”)); 就是PackageMangerService
PackageMangerService 的main方法:

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public static final IPackageManager main(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
PackageManagerService m = new PackageManagerService(context, installer,
factoryTest, onlyCore);
ServiceManager.addService("package", m);
return m;
}

去看installPackageWithVerification()

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@Override
public void installPackageWithVerification(Uri packageURI, IPackageInstallObserver observer,
int flags, String installerPackageName, Uri verificationURI,
ManifestDigest manifestDigest, ContainerEncryptionParams encryptionParams) {
VerificationParams verificationParams = new VerificationParams(verificationURI, null, null,
VerificationParams.NO_UID, manifestDigest);
installPackageWithVerificationAndEncryption(packageURI, observer, flags,
installerPackageName, verificationParams, encryptionParams);
}

接着看 installPackageWithVerificationAndEncryption()方法

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public void installPackageWithVerificationAndEncryption(Uri packageURI,
IPackageInstallObserver observer, int flags, String installerPackageName,
VerificationParams verificationParams, ContainerEncryptionParams encryptionParams)

在最后的时候:

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final Message msg = mHandler.obtainMessage(INIT_COPY);
msg.obj = new InstallParams(packageURI, observer, filteredFlags, installerPackageName,
verificationParams, encryptionParams, user);
mHandler.sendMessage(msg);

发messge 给handler,找到这个handler的定义

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mHandlerThread.start();
mHandler = new PackageHandler(mHandlerThread.getLooper());
final HandlerThread mHandlerThread = new HandlerThread("PackageManager",
Process.THREAD_PRIORITY_BACKGROUND);
final PackageHandler mHandler;

看来 是个工作线程。
跟进handler的handlemsg() 消息类型会从 INIT_COPY 绕成 MCS_BOUND。总算调用了 params.startCopy()
先看handleStartCopy(). InstallParams 对该方法的实现。 略过各种检查和校验 找到了ret = args.copyApk(mContainerService, true);copy apk文件 到 /data/app 目录下 而且是以一种临时文件的格式。

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final boolean startCopy() {
boolean res;
try {
if (DEBUG_INSTALL) Slog.i(TAG, "startCopy");
if (++mRetries > MAX_RETRIES) {
Slog.w(TAG, "Failed to invoke remote methods on default container service. Giving up");
mHandler.sendEmptyMessage(MCS_GIVE_UP);
handleServiceError();
return false;
} else {
handleStartCopy();
res = true;
}
} catch (RemoteException e) {
if (DEBUG_INSTALL) Slog.i(TAG, "Posting install MCS_RECONNECT");
mHandler.sendEmptyMessage(MCS_RECONNECT);
res = false;
}
handleReturnCode();
return res;
}

然后是handleReturnCode() 主要是:

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private void processPendingInstall(final InstallArgs args, final int currentStatus)

该方法调用

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private void installNewPackageLI(PackageParser.Package pkg,
int parseFlags, int scanMode, UserHandle user,
String installerPackageName, PackageInstalledInfo res)

终于到了 installnewPackage 了

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private void installNewPackageLI(PackageParser.Package pkg,
int parseFlags, int scanMode, UserHandle user,
String installerPackageName, PackageInstalledInfo res)


private PackageParser.Package scanPackageLI(File scanFile,
int parseFlags, int scanMode, long currentTime, UserHandle user)

然后调用了

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// Note that we invoke the following method only if we are about to unpack an application
PackageParser.Package scannedPkg = scanPackageLI(pkg, parseFlags, scanMode
| SCAN_UPDATE_SIGNATURE, currentTime, user);

其中有

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//invoke installer to do the actual installation
int ret = createDataDirsLI(pkgName, pkg.applicationInfo.uid);



if ((scanMode&SCAN_NO_DEX) == 0) {
if (performDexOptLI(pkg, forceDex, (scanMode&SCAN_DEFER_DEX) != 0)
== DEX_OPT_FAILED) {
mLastScanError = PackageManager.INSTALL_FAILED_DEXOPT;
return null;
}
}

先看scanPackageLI

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private int createDataDirsLI(String packageName, int uid) {
int[] users = sUserManager.getUserIds();
int res = mInstaller.install(packageName, uid, uid);
if (res < 0) {
return res;
}
for (int user : users) {
if (user != 0) {
res = mInstaller.createUserData(packageName,
UserHandle.getUid(user, uid), user);
if (res < 0) {
return res;
}
}
}
return res;
}

mInstaller.install() 出现了
再看performDexOptLI()

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private int performDexOptLI(PackageParser.Package pkg, boolean forceDex, boolean defer) {
boolean performed = false;
if ((pkg.applicationInfo.flags&ApplicationInfo.FLAG_HAS_CODE) != 0) {
String path = pkg.mScanPath;
int ret = 0;
try {
if (forceDex || dalvik.system.DexFile.isDexOptNeeded(path)) {
if (!forceDex && defer) {
mDeferredDexOpt.add(pkg);
return DEX_OPT_DEFERRED;
} else {
Log.i(TAG, "Running dexopt on: " + pkg.applicationInfo.packageName);
final int sharedGid = UserHandle.getSharedAppGid(pkg.applicationInfo.uid);
ret = mInstaller.dexopt(path, sharedGid, !isForwardLocked(pkg));
pkg.mDidDexOpt = true;
performed = true;
}
}
} catch (FileNotFoundException e) {
Slog.w(TAG, "Apk not found for dexopt: " + path);
ret = -1;
} catch (IOException e) {
Slog.w(TAG, "IOException reading apk: " + path, e);
ret = -1;
} catch (dalvik.system.StaleDexCacheError e) {
Slog.w(TAG, "StaleDexCacheError when reading apk: " + path, e);
ret = -1;
} catch (Exception e) {
Slog.w(TAG, "Exception when doing dexopt : ", e);
ret = -1;
}
if (ret < 0) {
//error from installer
return DEX_OPT_FAILED;
}
}
return performed ? DEX_OPT_PERFORMED : DEX_OPT_SKIPPED;
}

mInstaller.dexopt() 终于也找出来了
PackageManagerService通过socket访问installd的服务进程,而installd的服务是在init进程里被启动的。继续看
frameworks/base/cmds/installd/installd.c

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int main(const int argc, const char *argv[]) {
char buf[BUFFER_MAX];
struct sockaddr addr;
socklen_t alen;
int lsocket, s, count;
if (initialize_globals() < 0) {
ALOGE("Could not initialize globals; exiting.\n");
exit(1);
}
if (initialize_directories() < 0) {
ALOGE("Could not create directories; exiting.\n");
exit(1);
}
lsocket = android_get_control_socket(SOCKET_PATH);
if (lsocket < 0) {
ALOGE("Failed to get socket from environment: %s\n", strerror(errno));
exit(1);
}
if (listen(lsocket, 5)) {
ALOGE("Listen on socket failed: %s\n", strerror(errno));
exit(1);
}
fcntl(lsocket, F_SETFD, FD_CLOEXEC);
for (;;) {
alen = sizeof(addr);
s = accept(lsocket, &addr, &alen);
if (s < 0) {
ALOGE("Accept failed: %s\n", strerror(errno));
continue;
}
fcntl(s, F_SETFD, FD_CLOEXEC);
ALOGI("new connection\n");
for (;;) {
unsigned short count;
if (readx(s, &count, sizeof(count))) {
ALOGE("failed to read size\n");
break;
}
if ((count < 1) || (count >= BUFFER_MAX)) {
ALOGE("invalid size %d\n", count);
break;
}
if (readx(s, buf, count)) {
ALOGE("failed to read command\n");
break;
}
buf[count] = 0;
if (execute(s, buf)) break;
}
ALOGI("closing connection\n");
close(s);
}
return 0;
}

接收的命令:

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struct cmdinfo {
const char *name;
unsigned numargs;
int (*func)(char **arg, char reply[REPLY_MAX]);
};
struct cmdinfo cmds[] = {
{ "ping", 0, do_ping },
{ "install", 3, do_install },
{ "dexopt", 3, do_dexopt },
{ "movedex", 2, do_move_dex },
{ "rmdex", 1, do_rm_dex },
{ "remove", 2, do_remove },
{ "rename", 2, do_rename },
{ "freecache", 1, do_free_cache },
{ "rmcache", 1, do_rm_cache },
{ "protect", 2, do_protect },
{ "getsize", 4, do_get_size },
{ "rmuserdata", 2, do_rm_user_data },
{ "movefiles", 0, do_movefiles },
{ "linklib", 2, do_linklib },
{ "unlinklib", 1, do_unlinklib },
{ "mkuserdata", 3, do_mk_user_data },
{ "rmuser", 1, do_rm_user },
{ "cloneuserdata", 3, do_clone_user_data },
};

比如

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static int do_install(char **arg, char reply[REPLY_MAX])
{
return install(arg[0], atoi(arg[1]), atoi(arg[2])); /* pkgname, uid, gid */
}
static int do_dexopt(char **arg, char reply[REPLY_MAX])
{
/* apk_path, uid, is_public */
return dexopt(arg[0], atoi(arg[1]), atoi(arg[2]));
}

frameworks/base/cmds/installd/commands.c

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int install(const char *pkgname, uid_t uid, gid_t gid)
{
char pkgdir[PKG_PATH_MAX];
char libdir[PKG_PATH_MAX];
if ((uid < AID_SYSTEM) || (gid < AID_SYSTEM)) {
ALOGE("invalid uid/gid: %d %d\n", uid, gid);
return -1;
}
if (create_pkg_path(pkgdir, pkgname, PKG_DIR_POSTFIX, 0)) {
ALOGE("cannot create package path\n");
return -1;
}
if (create_pkg_path(libdir, pkgname, PKG_LIB_POSTFIX, 0)) {
ALOGE("cannot create package lib path\n");
return -1;
}
if (mkdir(pkgdir, 0751) < 0) {
ALOGE("cannot create dir '%s': %s\n", pkgdir, strerror(errno));
return -errno;
}
if (chmod(pkgdir, 0751) < 0) {
ALOGE("cannot chmod dir '%s': %s\n", pkgdir, strerror(errno));
unlink(pkgdir);
return -errno;
}
if (chown(pkgdir, uid, gid) < 0) {
ALOGE("cannot chown dir '%s': %s\n", pkgdir, strerror(errno));
unlink(pkgdir);
return -errno;
}
if (mkdir(libdir, 0755) < 0) {
ALOGE("cannot create dir '%s': %s\n", libdir, strerror(errno));
unlink(pkgdir);
return -errno;
}
if (chmod(libdir, 0755) < 0) {
ALOGE("cannot chmod dir '%s': %s\n", libdir, strerror(errno));
unlink(libdir);
unlink(pkgdir);
return -errno;
}
if (chown(libdir, AID_SYSTEM, AID_SYSTEM) < 0) {
ALOGE("cannot chown dir '%s': %s\n", libdir, strerror(errno));
unlink(libdir);
unlink(pkgdir);
return -errno;
}2
return 0;
}

adb pm -r install xxx.apk 的流程跟踪结束。

再来看看MultiDex.install()的流程:

android.support.multidex.MultiDex.V14#install()
android.support.multidex.MultiDex.V14#makeDexElements();
通过反射调用了DexPathList 的makeDexElements()
该方法就是调用dex = loadDexFile(file, optimizedDirectory);
看看 loadDexFile

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/**
* Constructs a {@code DexFile} instance, as appropriate depending
* on whether {@code optimizedDirectory} is {@code null}.
*/
private static DexFile loadDexFile(File file, File optimizedDirectory)
throws IOException {
if (optimizedDirectory == null) {
return new DexFile(file);
} else {
String optimizedPath = optimizedPathFor(file, optimizedDirectory);
return DexFile.loadDex(file.getPath(), optimizedPath, 0);
}
}

第一次load dex文件的时候 是 optimizedDirectory 空的 。
进入 return new DexFile(file); 的分支。

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/*
* Open a DEX file. The value returned is a magic VM cookie. On
* failure, an IOException is thrown.
*/
native private static int openDexFile(String sourceName, String outputName,
int flags) throws IOException;

进入native层代码openDexFile()

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static void Dalvik_dalvik_system_DexFile_openDexFile(const u4* args,
JValue* pResult)

该方法比较长 主要是调用了dvmJarFileOpen()方法,在 android/dalvik/vm/JarFile.cpp

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/*
* Open a Jar file. It's okay if it's just a Zip archive without all of
* the Jar trimmings, but we do insist on finding "classes.dex" inside
* or an appropriately-named ".odex" file alongside.
*
* If "isBootstrap" is not set, the optimizer/verifier regards this DEX as
* being part of a different class loader.
*/
int dvmJarFileOpen(const char* fileName, const char* odexOutputName,
JarFile** ppJarFile, bool isBootstrap)
{
/*
* TODO: This function has been duplicated and modified to become
* dvmRawDexFileOpen() in RawDexFile.c. This should be refactored.
*/
ZipArchive archive;
DvmDex* pDvmDex = NULL;
char* cachedName = NULL;
bool archiveOpen = false;
bool locked = false;
int fd = -1;
int result = -1;
/* Even if we're not going to look at the archive, we need to
* open it so we can stuff it into ppJarFile.
*/
if (dexZipOpenArchive(fileName, &archive) != 0)
goto bail;
archiveOpen = true;
/* If we fork/exec into dexopt, don't let it inherit the archive's fd.
*/
dvmSetCloseOnExec(dexZipGetArchiveFd(&archive));
/* First, look for a ".odex" alongside the jar file. It will
* have the same name/path except for the extension.
*/
fd = openAlternateSuffix(fileName, "odex", O_RDONLY, &cachedName);
if (fd >= 0) {
ALOGV("Using alternate file (odex) for %s ...", fileName);
if (!dvmCheckOptHeaderAndDependencies(fd, false, 0, 0, true, true)) {
ALOGE("%s odex has stale dependencies", fileName);
free(cachedName);
cachedName = NULL;
close(fd);
fd = -1;
goto tryArchive;
} else {
ALOGV("%s odex has good dependencies", fileName);
//TODO: make sure that the .odex actually corresponds
// to the classes.dex inside the archive (if present).
// For typical use there will be no classes.dex.
}
} else {
ZipEntry entry;
tryArchive:
/*
* Pre-created .odex absent or stale. Look inside the jar for a
* "classes.dex".
*/
entry = dexZipFindEntry(&archive, kDexInJarName);
if (entry != NULL) {
bool newFile = false;
/*
* We've found the one we want. See if there's an up-to-date copy
* in the cache.
*
* On return, "fd" will be seeked just past the "opt" header.
*
* If a stale .odex file is present and classes.dex exists in
* the archive, this will *not* return an fd pointing to the
* .odex file; the fd will point into dalvik-cache like any
* other jar.
*/
if (odexOutputName == NULL) {
cachedName = dexOptGenerateCacheFileName(fileName,
kDexInJarName);
if (cachedName == NULL)
goto bail;
} else {
cachedName = strdup(odexOutputName);
}
ALOGV("dvmJarFileOpen: Checking cache for %s (%s)",
fileName, cachedName);
fd = dvmOpenCachedDexFile(fileName, cachedName,
dexGetZipEntryModTime(&archive, entry),
dexGetZipEntryCrc32(&archive, entry),
isBootstrap, &newFile, /*createIfMissing=*/true);
if (fd < 0) {
ALOGI("Unable to open or create cache for %s (%s)",
fileName, cachedName);
goto bail;
}
locked = true;
/*
* If fd points to a new file (because there was no cached version,
* or the cached version was stale), generate the optimized DEX.
* The file descriptor returned is still locked, and is positioned
* just past the optimization header.
*/
if (newFile) {
u8 startWhen, extractWhen, endWhen;
bool result;
off_t dexOffset;
dexOffset = lseek(fd, 0, SEEK_CUR);
result = (dexOffset > 0);
if (result) {
startWhen = dvmGetRelativeTimeUsec();
result = dexZipExtractEntryToFile(&archive, entry, fd) == 0;
extractWhen = dvmGetRelativeTimeUsec();
}
if (result) {
result = dvmOptimizeDexFile(fd, dexOffset,
dexGetZipEntryUncompLen(&archive, entry),
fileName,
dexGetZipEntryModTime(&archive, entry),
dexGetZipEntryCrc32(&archive, entry),
isBootstrap);
}
if (!result) {
ALOGE("Unable to extract+optimize DEX from '%s'",
fileName);
goto bail;
}
endWhen = dvmGetRelativeTimeUsec();
ALOGD("DEX prep '%s': unzip in %dms, rewrite %dms",
fileName,
(int) (extractWhen - startWhen) / 1000,
(int) (endWhen - extractWhen) / 1000);
}
} else {
ALOGI("Zip is good, but no %s inside, and no valid .odex "
"file in the same directory", kDexInJarName);
goto bail;
}
}
/*
* Map the cached version. This immediately rewinds the fd, so it
* doesn't have to be seeked anywhere in particular.
*/
if (dvmDexFileOpenFromFd(fd, &pDvmDex) != 0) {
ALOGI("Unable to map %s in %s", kDexInJarName, fileName);
goto bail;
}
if (locked) {
/* unlock the fd */
if (!dvmUnlockCachedDexFile(fd)) {
/* uh oh -- this process needs to exit or we'll wedge the system */
ALOGE("Unable to unlock DEX file");
goto bail;
}
locked = false;
}
ALOGV("Successfully opened '%s' in '%s'", kDexInJarName, fileName);
*ppJarFile = (JarFile*) calloc(1, sizeof(JarFile));
(*ppJarFile)->archive = archive;
(*ppJarFile)->cacheFileName = cachedName;
(*ppJarFile)->pDvmDex = pDvmDex;
cachedName = NULL; // don't free it below
result = 0;
bail:
/* clean up, closing the open file */
if (archiveOpen && result != 0)
dexZipCloseArchive(&archive);
free(cachedName);
if (fd >= 0) {
if (locked)
(void) dvmUnlockCachedDexFile(fd);
close(fd);
}
return result;
}

其中 , 执行了dvmOpenCachedDexFile()后 newFile 为true 。 会执行

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result = dvmOptimizeDexFile(fd, dexOffset,
dexGetZipEntryUncompLen(&archive, entry),
fileName,
dexGetZipEntryModTime(&archive, entry),
dexGetZipEntryCrc32(&archive, entry),
isBootstrap);

这里调用了 /dalvik/vm/RawDexFile.cpp 中的 dvmOptimizeDexFile()方法

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/*
* Given a descriptor for a file with DEX data in it, produce an
* optimized version.
*
* The file pointed to by "fd" is expected to be a locked shared resource
* (or private); we make no efforts to enforce multi-process correctness
* here.
*
* "fileName" is only used for debug output. "modWhen" and "crc" are stored
* in the dependency set.
*
* The "isBootstrap" flag determines how the optimizer and verifier handle
* package-scope access checks. When optimizing, we only load the bootstrap
* class DEX files and the target DEX, so the flag determines whether the
* target DEX classes are given a (synthetic) non-NULL classLoader pointer.
* This only really matters if the target DEX contains classes that claim to
* be in the same package as bootstrap classes.
*
* The optimizer will need to load every class in the target DEX file.
* This is generally undesirable, so we start a subprocess to do the
* work and wait for it to complete.
*
* Returns "true" on success. All data will have been written to "fd".
*/
bool dvmOptimizeDexFile(int fd, off_t dexOffset, long dexLength,
const char* fileName, u4 modWhen, u4 crc, bool isBootstrap)
{
const char* lastPart = strrchr(fileName, '/');
if (lastPart != NULL)
lastPart++;
else
lastPart = fileName;
ALOGD("DexOpt: --- BEGIN '%s' (bootstrap=%d) ---", lastPart, isBootstrap);
pid_t pid;
/*
* This could happen if something in our bootclasspath, which we thought
* was all optimized, got rejected.
*/
if (gDvm.optimizing) {
ALOGW("Rejecting recursive optimization attempt on '%s'", fileName);
return false;
}
pid = fork();
if (pid == 0) {
static const int kUseValgrind = 0;
static const char* kDexOptBin = "/bin/dexopt";
static const char* kValgrinder = "/usr/bin/valgrind";
static const int kFixedArgCount = 10;
static const int kValgrindArgCount = 5;
static const int kMaxIntLen = 12; // '-'+10dig+'\0' -OR- 0x+8dig
int bcpSize = dvmGetBootPathSize();
int argc = kFixedArgCount + bcpSize
+ (kValgrindArgCount * kUseValgrind);
const char* argv[argc+1]; // last entry is NULL
char values [argc][kMaxIntLen];
char* execFile;
const char* androidRoot;
int flags;
/* change process groups, so we don't clash with ProcessManager */
setpgid(0, 0);
/* full path to optimizer */
androidRoot = getenv("ANDROID_ROOT");
if (androidRoot == NULL) {
ALOGW("ANDROID_ROOT not set, defaulting to /system");
androidRoot = "/system";
}
execFile = (char*)alloca(strlen(androidRoot) + strlen(kDexOptBin) + 1);
strcpy(execFile, androidRoot);
strcat(execFile, kDexOptBin);
/*
* Create arg vector.
*/
int curArg = 0;
if (kUseValgrind) {
/* probably shouldn't ship the hard-coded path */
argv[curArg++] = (char*)kValgrinder;
argv[curArg++] = "--tool=memcheck";
argv[curArg++] = "--leak-check=yes"; // check for leaks too
argv[curArg++] = "--leak-resolution=med"; // increase from 2 to 4
argv[curArg++] = "--num-callers=16"; // default is 12
assert(curArg == kValgrindArgCount);
}
argv[curArg++] = execFile;
argv[curArg++] = "--dex";
sprintf(values[2], "%d", DALVIK_VM_BUILD);
argv[curArg++] = values[2];
sprintf(values[3], "%d", fd);
argv[curArg++] = values[3];
sprintf(values[4], "%d", (int) dexOffset);
argv[curArg++] = values[4];
sprintf(values[5], "%d", (int) dexLength);
argv[curArg++] = values[5];
argv[curArg++] = (char*)fileName;
sprintf(values[7], "%d", (int) modWhen);
argv[curArg++] = values[7];
sprintf(values[8], "%d", (int) crc);
argv[curArg++] = values[8];
flags = 0;
if (gDvm.dexOptMode != OPTIMIZE_MODE_NONE) {
flags |= DEXOPT_OPT_ENABLED;
if (gDvm.dexOptMode == OPTIMIZE_MODE_ALL)
flags |= DEXOPT_OPT_ALL;
}
if (gDvm.classVerifyMode != VERIFY_MODE_NONE) {
flags |= DEXOPT_VERIFY_ENABLED;
if (gDvm.classVerifyMode == VERIFY_MODE_ALL)
flags |= DEXOPT_VERIFY_ALL;
}
if (isBootstrap)
flags |= DEXOPT_IS_BOOTSTRAP;
if (gDvm.generateRegisterMaps)
flags |= DEXOPT_GEN_REGISTER_MAPS;
sprintf(values[9], "%d", flags);
argv[curArg++] = values[9];
assert(((!kUseValgrind && curArg == kFixedArgCount) ||
((kUseValgrind && curArg == kFixedArgCount+kValgrindArgCount))));
ClassPathEntry* cpe;
for (cpe = gDvm.bootClassPath; cpe->ptr != NULL; cpe++) {
argv[curArg++] = cpe->fileName;
}
assert(curArg == argc);
argv[curArg] = NULL;
if (kUseValgrind)
execv(kValgrinder, const_cast<char**>(argv));
else
execv(execFile, const_cast<char**>(argv));
ALOGE("execv '%s'%s failed: %s", execFile,
kUseValgrind ? " [valgrind]" : "", strerror(errno));
exit(1);
} else {
ALOGV("DexOpt: waiting for verify+opt, pid=%d", (int) pid);
int status;
pid_t gotPid;
/*
* Wait for the optimization process to finish. We go into VMWAIT
* mode here so GC suspension won't have to wait for us.
*/
ThreadStatus oldStatus = dvmChangeStatus(NULL, THREAD_VMWAIT);
while (true) {
gotPid = waitpid(pid, &status, 0);
if (gotPid == -1 && errno == EINTR) {
ALOGD("waitpid interrupted, retrying");
} else {
break;
}
}
dvmChangeStatus(NULL, oldStatus);
if (gotPid != pid) {
ALOGE("waitpid failed: wanted %d, got %d: %s",
(int) pid, (int) gotPid, strerror(errno));
return false;
}
if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
ALOGD("DexOpt: --- END '%s' (success) ---", lastPart);
return true;
} else {
ALOGW("DexOpt: --- END '%s' --- status=0x%04x, process failed",
lastPart, status);
return false;
}
}
}

终于找到 ALOGD(“DexOpt: — BEGIN ‘%s’ (bootstrap=%d) —“, lastPart, isBootstrap); 这句日志的出处了!

该方法的注释写的也比较详细了,其中pid=fork(); 表明dexopt确实开启了新的进程来完成,而且当前进程是使用while循环等待这个子进程返回结果的。

那么之前关于dexopt的所有疑惑都解开了。