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Commit f4c64ad3 authored by Janis Danisevskis's avatar Janis Danisevskis
Browse files

Keystore 2.0 SPI: Add back-off hint to BackendBusyException. 

BackendBusyException now returns a back-off hint that API users can use
to implement their retry loop.

Bug: 174761871
Test: N/A
Change-Id: I95662a5a5432965de365017eae43c502eb5bfc06
parent 5d496eb9

core/api/current.txt

+4 −3
Original line number Diff line number Diff line
@@ -36183,9 +36183,10 @@ package android.security.identity { 
package android.security.keystore {















  public class BackendBusyException extends java.security.ProviderException {













    ctor public BackendBusyException();













    ctor public BackendBusyException(@NonNull String);













    ctor public BackendBusyException(@NonNull String, @NonNull Throwable);













    ctor public BackendBusyException(long);













    ctor public BackendBusyException(long, @NonNull String);













    ctor public BackendBusyException(long, @NonNull String, @NonNull Throwable);













    method public long getBackOffHintMillis();















  }





























  public class KeyExpiredException extends java.security.InvalidKeyException {

























keystore/java/android/security/KeyStoreSecurityLevel.java



+4
−3




























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Diff line








@@ -96,20 +96,21 @@ public class KeyStoreSecurityLevel {













            } catch (ServiceSpecificException e) {















                switch (e.errorCode) {















                    case ResponseCode.BACKEND_BUSY: {













                        long backOffHint = (long) (Math.random() * 80 + 20);















                        if (CompatChanges.isChangeEnabled(















                                KeyStore2.KEYSTORE_OPERATION_CREATION_MAY_FAIL)) {















                            // Starting with Android S we inform the caller about the















                            // backend being busy.













                            throw new BackendBusyException();













                            throw new BackendBusyException(backOffHint);















                        } else {















                            // Before Android S operation creation must always succeed. So we















                            // just have to retry. We do so with a randomized back-off between













                            // 50 and 250ms.













                            // 20 and 100ms.















                            // It is a little awkward that we cannot break out of this loop















                            // by interrupting this thread. But that is the expected behavior.















                            // There is some comfort in the fact that interrupting a thread















                            // also does not unblock a thread waiting for a binder transaction.













                            interruptedPreservingSleep((long) (Math.random() * 200 + 50));













                            interruptedPreservingSleep(backOffHint);















                        }















                        break;















                    }

































keystore/java/android/security/keystore/BackendBusyException.java



+33
−4




























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@@ -16,37 +16,66 @@





























package android.security.keystore;





























import android.annotation.DurationMillisLong;















import android.annotation.NonNull;































import java.security.ProviderException;































/**















 * Indicates a transient error that prevented a key operation from being created.













 * Callers should try again with a back-off period of 10-30 milliseconds.













 * Callers should try again with a back-off period of {@link #getBackOffHintMillis()}













 * milliseconds.















 */















public class BackendBusyException extends ProviderException {





























    private final long mBackOffHintMillis;





























    /**















     * Constructs a new {@code BackendBusyException} without detail message and cause.













     *















     */













    public BackendBusyException() {













    public BackendBusyException(@DurationMillisLong long backOffHintMillis) {















        super("The keystore backend has no operation slots available. Retry later.");













        if (backOffHintMillis < 0) {













            throw new IllegalArgumentException("Back-off hint cannot be negative.");













        }













        mBackOffHintMillis = backOffHintMillis;















    }































    /**















     * Constructs a new {@code BackendBusyException} with the provided detail message and















     * no cause.















     */













    public BackendBusyException(@NonNull String message) {













    public BackendBusyException(@DurationMillisLong long backOffHintMillis,













            @NonNull String message) {















        super(message);













        if (backOffHintMillis < 0) {













            throw new IllegalArgumentException("Back-off hint cannot be negative.");













        }













        mBackOffHintMillis = backOffHintMillis;















    }































    /**















     * Constructs a new {@code BackendBusyException} with the provided detail message and















     * cause.















     */













    public BackendBusyException(@NonNull String message, @NonNull Throwable cause) {













    public BackendBusyException(@DurationMillisLong long backOffHintMillis,













            @NonNull String message, @NonNull Throwable cause) {















        super(message, cause);













        if (backOffHintMillis < 0) {













            throw new IllegalArgumentException("Back-off hint cannot be negative.");













        }













        mBackOffHintMillis = backOffHintMillis;















    }





























    /**













     * When retrying to start a Keystore operation after receiving this exception, this can be













     * used to determine how long to wait before retrying. It is not guaranteed that the operation













     * will succeeds after this time. Multiple retries may be necessary if the system is congested.













     *













     * @return Number of milliseconds to back off before retrying.













     */













    public @DurationMillisLong long getBackOffHintMillis() {













        return mBackOffHintMillis;













    }















}