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Commit d2c86ab5 authored by Martijn Coenen's avatar Martijn Coenen
Browse files

Encourage creating Binder tokens with a descriptor. 

Binder tokens (Binder objects without an attached interface) are used
a lot with Android. These tokens don't have an interface descriptor,
which means that proxies (references) to these tokens are impossible
to identify when looking at a heap dump.

To make that easier, introduce a new constructor for Binder that allows
the caller to specify a descriptor.

Bug: 109888955
Test: builds, boots
Change-Id: I18fd00483abc29edf87f84945323a10fe4f6cd42
parent 69a30f68

api/current.txt

+1 −0
Original line number Diff line number Diff line
@@ -32167,6 +32167,7 @@ package android.os { 














  public class Binder implements android.os.IBinder {















    ctor public Binder();













    ctor public Binder(java.lang.String);















    method public void attachInterface(android.os.IInterface, java.lang.String);















    method public static final long clearCallingIdentity();















    method public void dump(java.io.FileDescriptor, java.lang.String[]);

























core/java/android/os/Binder.java



+21
−1




























Original line number
Diff line number
Diff line








@@ -391,9 +391,28 @@ public class Binder implements IBinder {













    public static final native void blockUntilThreadAvailable();































    /**













     * Default constructor initializes the object.













     * Default constructor just initializes the object.













     *













     * If you're creating a Binder token (a Binder object without an attached interface),













     * you should use {@link #Binder(String)} instead.















     */















    public Binder() {













        this(null);













    }



























    /**













     * Constructor for creating a raw Binder object (token) along with a descriptor.













     *













     * The descriptor of binder objects usually specifies the interface they are implementing.













     * In case of binder tokens, no interface is implemented, and the descriptor can be used













     * as a sort of tag to help identify the binder token. This will help identify remote













     * references to these objects more easily when debugging.













     *













     * @param descriptor Used to identify the creator of this token, for example the class name.













     * Instead of creating multiple tokens with the same descriptor, consider adding a suffix to













     * help identify them.













     */













    public Binder(@Nullable String descriptor)  {















        mObject = getNativeBBinderHolder();















        NoImagePreloadHolder.sRegistry.registerNativeAllocation(this, mObject);

























@@ -405,6 +424,7 @@ public class Binder implements IBinder {













                    klass.getCanonicalName());















            }















        }













        mDescriptor = descriptor;















    }































    /**