Add an API android.os.Process.waitForProcessDeath (9f21e892) · Commits · e / os / android_frameworks_base

core/java/android/os/Process.java

+101 −0

Original line number	Diff line number	Diff line
		@@ -20,14 +20,20 @@ import android.annotation.NonNull;
		import android.annotation.Nullable;
		import android.annotation.TestApi;
		import android.compat.annotation.UnsupportedAppUsage;
		import android.system.ErrnoException;
		import android.system.Os;
		import android.system.OsConstants;
		import android.system.StructPollfd;
		import android.util.Pair;
		import android.webkit.WebViewZygote;

		import dalvik.system.VMRuntime;

		import libcore.io.IoUtils;

		import java.io.FileDescriptor;
		import java.util.Map;
		import java.util.concurrent.TimeoutException;

		/**
		* Tools for managing OS processes.
		@@ -487,6 +493,15 @@ public class Process {
		private static long sStartElapsedRealtime;
		private static long sStartUptimeMillis;

		private static final int PIDFD_UNKNOWN = 0;
		private static final int PIDFD_SUPPORTED = 1;
		private static final int PIDFD_UNSUPPORTED = 2;

		/**
		* Whether or not the underlying OS supports pidfd
		*/
		private static int sPidFdSupported = PIDFD_UNKNOWN;

		/**
		* State associated with the zygote process.
		* @hide
		@@ -1189,4 +1204,90 @@ public class Process {
		}

		}

		/**
		* Wait for the death of the given process.
		*
		* @param pid The process ID to be waited on
		* @param timeout The maximum time to wait in milliseconds, or -1 to wait forever
		* @hide
		*/
		public static void waitForProcessDeath(int pid, int timeout)
		throws InterruptedException, TimeoutException {
		FileDescriptor pidfd = null;
		if (sPidFdSupported == PIDFD_UNKNOWN) {
		int fd = -1;
		try {
		fd = nativePidFdOpen(pid, 0);
		sPidFdSupported = PIDFD_SUPPORTED;
		} catch (ErrnoException e) {
		sPidFdSupported = e.errno != OsConstants.ENOSYS
		? PIDFD_SUPPORTED : PIDFD_UNSUPPORTED;
		} finally {
		if (fd >= 0) {
		pidfd = new FileDescriptor();
		pidfd.setInt$(fd);
		}
		}
		}
		boolean fallback = sPidFdSupported == PIDFD_UNSUPPORTED;
		if (!fallback) {
		try {
		if (pidfd == null) {
		int fd = nativePidFdOpen(pid, 0);
		if (fd >= 0) {
		pidfd = new FileDescriptor();
		pidfd.setInt$(fd);
		} else {
		fallback = true;
		}
		}
		if (pidfd != null) {
		StructPollfd[] fds = new StructPollfd[] {
		new StructPollfd()
		};
		fds[0].fd = pidfd;
		fds[0].events = (short) OsConstants.POLLIN;
		fds[0].revents = 0;
		fds[0].userData = null;
		int res = Os.poll(fds, timeout);
		if (res > 0) {
		return;
		} else if (res == 0) {
		throw new TimeoutException();
		} else {
		// We should get an ErrnoException now
		}
		}
		} catch (ErrnoException e) {
		if (e.errno == OsConstants.EINTR) {
		throw new InterruptedException();
		}
		fallback = true;
		} finally {
		if (pidfd != null) {
		IoUtils.closeQuietly(pidfd);
		}
		}
		}
		if (fallback) {
		boolean infinity = timeout < 0;
		long now = System.currentTimeMillis();
		final long end = now + timeout;
		while (infinity \|\| now < end) {
		try {
		Os.kill(pid, 0);
		} catch (ErrnoException e) {
		if (e.errno == OsConstants.ESRCH) {
		return;
		}
		}
		Thread.sleep(1);
		now = System.currentTimeMillis();
		}
		}
		throw new TimeoutException();
		}

		private static native int nativePidFdOpen(int pid, int flags) throws ErrnoException;
		}

core/jni/android_util_Process.cpp

+74 −32

Original line number	Diff line number	Diff line
		@@ -50,11 +50,14 @@
		#include <pwd.h>
		#include <signal.h>
		#include <string.h>
		#include <sys/epoll.h>
		#include <sys/errno.h>
		#include <sys/resource.h>
		#include <sys/stat.h>
		#include <sys/syscall.h>
		#include <sys/sysinfo.h>
		#include <sys/types.h>
		#include <time.h>
		#include <unistd.h>

		#define GUARD_THREAD_PRIORITY 0
		@@ -1271,6 +1274,39 @@ void android_os_Process_removeAllProcessGroups(JNIEnv* env, jobject clazz)
		return removeAllProcessGroups();
		}

		static void throwErrnoException(JNIEnv* env, const char* functionName, int error) {
		ScopedLocalRef<jstring> detailMessage(env, env->NewStringUTF(functionName));
		if (detailMessage.get() == NULL) {
		// Not really much we can do here. We're probably dead in the water,
		// but let's try to stumble on...
		env->ExceptionClear();
		}
		static jclass errnoExceptionClass =
		MakeGlobalRefOrDie(env, FindClassOrDie(env, "android/system/ErrnoException"));

		static jmethodID errnoExceptionCtor =
		GetMethodIDOrDie(env, errnoExceptionClass, "<init>", "(Ljava/lang/String;I)V");

		jobject exception =
		env->NewObject(errnoExceptionClass, errnoExceptionCtor, detailMessage.get(), error);
		env->Throw(reinterpret_cast<jthrowable>(exception));
		}

		// Wrapper function to the syscall pidfd_open, which creates a file
		// descriptor that refers to the process whose PID is specified in pid.
		static inline int sys_pidfd_open(pid_t pid, unsigned int flags) {
		return syscall(__NR_pidfd_open, pid, flags);
		}

		static jboolean android_os_Process_nativePidFdOpen(JNIEnv* env, jobject, jint pid, jint flags) {
		int fd = sys_pidfd_open(pid, flags);
		if (fd < 0) {
		throwErrnoException(env, "nativePidFdOpen", errno);
		return -1;
		}
		return fd;
		}

		static const JNINativeMethod methods[] = {
		{"getUidForName", "(Ljava/lang/String;)I", (void*)android_os_Process_getUidForName},
		{"getGidForName", "(Ljava/lang/String;)I", (void*)android_os_Process_getGidForName},
		@@ -1293,17 +1329,23 @@ static const JNINativeMethod methods[] = {
		{"sendSignalQuiet", "(II)V", (void*)android_os_Process_sendSignalQuiet},
		{"getFreeMemory", "()J", (void*)android_os_Process_getFreeMemory},
		{"getTotalMemory", "()J", (void*)android_os_Process_getTotalMemory},
		{"readProcLines", "(Ljava/lang/String;[Ljava/lang/String;[J)V", (void*)android_os_Process_readProcLines},
		{"readProcLines", "(Ljava/lang/String;[Ljava/lang/String;[J)V",
		(void*)android_os_Process_readProcLines},
		{"getPids", "(Ljava/lang/String;[I)[I", (void*)android_os_Process_getPids},
		{"readProcFile", "(Ljava/lang/String;[I[Ljava/lang/String;[J[F)Z", (void*)android_os_Process_readProcFile},
		{"parseProcLine", "([BII[I[Ljava/lang/String;[J[F)Z", (void*)android_os_Process_parseProcLine},
		{"readProcFile", "(Ljava/lang/String;[I[Ljava/lang/String;[J[F)Z",
		(void*)android_os_Process_readProcFile},
		{"parseProcLine", "([BII[I[Ljava/lang/String;[J[F)Z",
		(void*)android_os_Process_parseProcLine},
		{"getElapsedCpuTime", "()J", (void*)android_os_Process_getElapsedCpuTime},
		{"getPss", "(I)J", (void*)android_os_Process_getPss},
		{"getRss", "(I)[J", (void*)android_os_Process_getRss},
		{"getPidsForCommands", "([Ljava/lang/String;)[I", (void*)android_os_Process_getPidsForCommands},
		//{"setApplicationObject", "(Landroid/os/IBinder;)V", (void*)android_os_Process_setApplicationObject},
		{"getPidsForCommands", "([Ljava/lang/String;)[I",
		(void*)android_os_Process_getPidsForCommands},
		//{"setApplicationObject", "(Landroid/os/IBinder;)V",
		//(void*)android_os_Process_setApplicationObject},
		{"killProcessGroup", "(II)I", (void*)android_os_Process_killProcessGroup},
		{"removeAllProcessGroups", "()V", (void*)android_os_Process_removeAllProcessGroups},
		{"nativePidFdOpen", "(II)I", (void*)android_os_Process_nativePidFdOpen},
		};

		int register_android_os_Process(JNIEnv* env)

services/core/java/com/android/server/am/ProcessList.java

+4 −44

Original line number	Diff line number	Diff line
		@@ -91,9 +91,7 @@ import android.os.UserHandle;
		import android.os.storage.StorageManager;
		import android.os.storage.StorageManagerInternal;
		import android.provider.DeviceConfig;
		import android.system.ErrnoException;
		import android.system.Os;
		import android.system.OsConstants;
		import android.text.TextUtils;
		import android.util.ArrayMap;
		import android.util.EventLog;
		@@ -327,12 +325,7 @@ public final class ProcessList {
		/**
		* How long between a process kill and we actually receive its death recipient
		*/
		private static final long PROC_KILL_TIMEOUT = 2000; // 2 seconds;

		/**
		* How long between polls to check if the given process is dead or not.
		*/
		private static final long PROC_DEATH_POLL_INTERVAL = 100;
		private static final int PROC_KILL_TIMEOUT = 2000; // 2 seconds;

		ActivityManagerService mService = null;

		@@ -2168,28 +2161,6 @@ public final class ProcessList {
		return success ? app : null;
		}

		/**
		* A lite version of checking if a process is alive or not, by using kill(2) with signal 0.
		*
		* <p>
		* Note that, zombie processes are stil "alive" in this case, use the {@link
		* ActivityManagerService#isProcessAliveLocked} if zombie processes need to be excluded.
		* </p>
		*/
		@GuardedBy("mService")
		private boolean isProcessAliveLiteLocked(ProcessRecord app) {
		// If somehow the pid is invalid, let's think it's dead.
		if (app.pid <= 0) {
		return false;
		}
		try {
		Os.kill(app.pid, 0);
		} catch (ErrnoException e) {
		return e.errno != OsConstants.ESRCH;
		}
		return true;
		}

		/**
		* Kill (if asked to) and wait for the given process died if necessary
		* @param app - The process record to kill
		@@ -2214,20 +2185,9 @@ public final class ProcessList {

		// wait for the death
		if (wait) {
		boolean isAlive = true;
		// ideally we should use pidfd_open(2) but it's available on kernel 5.3 or later

		final long timeout = SystemClock.uptimeMillis() + PROC_KILL_TIMEOUT;
		isAlive = isProcessAliveLiteLocked(app);
		while (timeout > SystemClock.uptimeMillis() && isAlive) {
		try {
		Thread.sleep(PROC_DEATH_POLL_INTERVAL);
		} catch (InterruptedException e) {
		}
		isAlive = isProcessAliveLiteLocked(app);
		}

		if (isAlive) {
		Process.waitForProcessDeath(app.pid, PROC_KILL_TIMEOUT);
		} catch (Exception e) {
		// Maybe the process goes into zombie, use an expensive API to check again.
		if (mService.isProcessAliveLocked(app)) {
		Slog.w(TAG, String.format(formatString,