Optimize UserHandle.of()
There will be more calls to *ForUser() APIs over time by mainline modules.
Let's avoid creating new objects in common cases.
Bug: 142134660
Fix: 140429319
Test: atest cts/tests/app/src/android/app/cts/UserHandleTest.java
Change-Id: Ie71850bd08a8d9831232ddb40807ae49e3a56841
diff --git a/api/test-current.txt b/api/test-current.txt
index 9396515..ce2c49a 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -2033,10 +2033,18 @@
public final class UserHandle implements android.os.Parcelable {
method public static int getAppId(int);
method public int getIdentifier();
+ method public static int getUid(int, int);
+ method public static int getUserId(int);
method public static boolean isApp(int);
+ method public static int myUserId();
+ method public static android.os.UserHandle of(int);
field @NonNull public static final android.os.UserHandle ALL;
field @NonNull public static final android.os.UserHandle CURRENT;
+ field public static final int MIN_SECONDARY_USER_ID = 10; // 0xa
field @NonNull public static final android.os.UserHandle SYSTEM;
+ field public static final int USER_ALL = -1; // 0xffffffff
+ field public static final int USER_NULL = -10000; // 0xffffd8f0
+ field public static final int USER_SYSTEM = 0; // 0x0
}
public class UserManager {
diff --git a/core/java/android/os/UserHandle.java b/core/java/android/os/UserHandle.java
index 0754dc7..3558fcd 100644
--- a/core/java/android/os/UserHandle.java
+++ b/core/java/android/os/UserHandle.java
@@ -39,6 +39,7 @@
/** @hide A user id to indicate all users on the device */
@UnsupportedAppUsage
+ @TestApi
public static final @UserIdInt int USER_ALL = -1;
/** @hide A user handle to indicate all users on the device */
@@ -69,8 +70,11 @@
/** @hide An undefined user id */
@UnsupportedAppUsage
+ @TestApi
public static final @UserIdInt int USER_NULL = -10000;
+ private static final @NonNull UserHandle NULL = new UserHandle(USER_NULL);
+
/**
* @hide A user id constant to indicate the "owner" user of the device
* @deprecated Consider using either {@link UserHandle#USER_SYSTEM} constant or
@@ -91,6 +95,7 @@
/** @hide A user id constant to indicate the "system" user of the device */
@UnsupportedAppUsage
+ @TestApi
public static final @UserIdInt int USER_SYSTEM = 0;
/** @hide A user serial constant to indicate the "system" user of the device */
@@ -110,6 +115,27 @@
public static final boolean MU_ENABLED = true;
/** @hide */
+ @TestApi
+ public static final int MIN_SECONDARY_USER_ID = 10;
+
+ /**
+ * Arbitrary user handle cache size. We use the cache even when {@link #MU_ENABLED} is false
+ * anyway, so we can always assume in CTS that UserHandle.of(10) returns a cached instance
+ * even on non-multiuser devices.
+ */
+ private static final int NUM_CACHED_USERS = 4;
+
+ private static final UserHandle[] CACHED_USER_INFOS = new UserHandle[NUM_CACHED_USERS];
+
+ static {
+ // Not lazily initializing the cache, so that we can share them across processes.
+ // (We'll create them in zygote.)
+ for (int i = 0; i < CACHED_USER_INFOS.length; i++) {
+ CACHED_USER_INFOS[i] = new UserHandle(MIN_SECONDARY_USER_ID + i);
+ }
+ }
+
+ /** @hide */
@UnsupportedAppUsage
public static final int ERR_GID = -1;
/** @hide */
@@ -209,6 +235,7 @@
* @hide
*/
@UnsupportedAppUsage
+ @TestApi
public static @UserIdInt int getUserId(int uid) {
if (MU_ENABLED) {
return uid / PER_USER_RANGE;
@@ -229,9 +256,31 @@
}
/** @hide */
+ @TestApi
@SystemApi
public static UserHandle of(@UserIdInt int userId) {
- return userId == USER_SYSTEM ? SYSTEM : new UserHandle(userId);
+ if (userId == USER_SYSTEM) {
+ return SYSTEM; // Most common.
+ }
+ // These are sequential; so use a switch. Maybe they'll be optimized to a table lookup.
+ switch (userId) {
+ case USER_ALL:
+ return ALL;
+
+ case USER_CURRENT:
+ return CURRENT;
+
+ case USER_CURRENT_OR_SELF:
+ return CURRENT_OR_SELF;
+ }
+ if (userId >= MIN_SECONDARY_USER_ID
+ && userId < (MIN_SECONDARY_USER_ID + CACHED_USER_INFOS.length)) {
+ return CACHED_USER_INFOS[userId - MIN_SECONDARY_USER_ID];
+ }
+ if (userId == USER_NULL) { // Not common.
+ return NULL;
+ }
+ return new UserHandle(userId);
}
/**
@@ -239,6 +288,7 @@
* @hide
*/
@UnsupportedAppUsage
+ @TestApi
public static int getUid(@UserIdInt int userId, @AppIdInt int appId) {
if (MU_ENABLED) {
return userId * PER_USER_RANGE + (appId % PER_USER_RANGE);
@@ -404,6 +454,7 @@
* @hide
*/
@SystemApi
+ @TestApi
public static @UserIdInt int myUserId() {
return getUserId(Process.myUid());
}
@@ -513,7 +564,9 @@
public static final @android.annotation.NonNull Parcelable.Creator<UserHandle> CREATOR
= new Parcelable.Creator<UserHandle>() {
public UserHandle createFromParcel(Parcel in) {
- return new UserHandle(in);
+ // Try to avoid allocation; use of() here. Keep this and the constructor below
+ // in sync.
+ return UserHandle.of(in.readInt());
}
public UserHandle[] newArray(int size) {
@@ -532,6 +585,6 @@
* positioned at the location in the buffer where it was written.
*/
public UserHandle(Parcel in) {
- mHandle = in.readInt();
+ mHandle = in.readInt(); // Keep this and createFromParcel() in sync.
}
}
diff --git a/services/core/java/com/android/server/pm/UserManagerService.java b/services/core/java/com/android/server/pm/UserManagerService.java
index 8431fa3..95baa01 100644
--- a/services/core/java/com/android/server/pm/UserManagerService.java
+++ b/services/core/java/com/android/server/pm/UserManagerService.java
@@ -209,7 +209,8 @@
| UserInfo.FLAG_DEMO;
@VisibleForTesting
- static final int MIN_USER_ID = 10;
+ static final int MIN_USER_ID = UserHandle.MIN_SECONDARY_USER_ID;
+
// We need to keep process uid within Integer.MAX_VALUE.
@VisibleForTesting
static final int MAX_USER_ID = Integer.MAX_VALUE / UserHandle.PER_USER_RANGE;