Delay deleting the blob after the last lease is released.

Bug: 159485704
Test: atest --test-mapping apex/blobstore
Change-Id: Iab153ae00107ee35705d7c17a3e51e7308e2e823

2 files changed, 40 insertions, 3 deletions

diff --git a/apex/blobstore/service/java/com/android/server/blob/BlobStoreConfig.java b/apex/blobstore/service/java/com/android/server/blob/BlobStoreConfig.java
index d780d5dab14d..265479f7c533 100644
--- a/apex/blobstore/service/java/com/android/server/blob/BlobStoreConfig.java
+++ b/apex/blobstore/service/java/com/android/server/blob/BlobStoreConfig.java
@@ -131,6 +131,16 @@ class BlobStoreConfig {
         public static boolean USE_REVOCABLE_FD_FOR_READS =
                 DEFAULT_USE_REVOCABLE_FD_FOR_READS;
 
+        /**
+         * Denotes how long before a blob is deleted, once the last lease on it is released.
+         */
+        public static final String KEY_DELETE_ON_LAST_LEASE_DELAY_MS =
+                "delete_on_last_lease_delay_ms";
+        public static final long DEFAULT_DELETE_ON_LAST_LEASE_DELAY_MS =
+                TimeUnit.HOURS.toMillis(6);
+        public static long DELETE_ON_LAST_LEASE_DELAY_MS =
+                DEFAULT_DELETE_ON_LAST_LEASE_DELAY_MS;
+
         static void refresh(Properties properties) {
             if (!NAMESPACE_BLOBSTORE.equals(properties.getNamespace())) {
                 return;
@@ -164,6 +174,10 @@ class BlobStoreConfig {
                         USE_REVOCABLE_FD_FOR_READS = properties.getBoolean(key,
                                 DEFAULT_USE_REVOCABLE_FD_FOR_READS);
                         break;
+                    case KEY_DELETE_ON_LAST_LEASE_DELAY_MS:
+                        DELETE_ON_LAST_LEASE_DELAY_MS = properties.getLong(key,
+                                DEFAULT_DELETE_ON_LAST_LEASE_DELAY_MS);
+                        break;
                     default:
                         Slog.wtf(TAG, "Unknown key in device config properties: " + key);
                 }
@@ -193,6 +207,9 @@ class BlobStoreConfig {
                     TimeUtils.formatDuration(DEFAULT_COMMIT_COOL_OFF_DURATION_MS)));
             fout.println(String.format(dumpFormat, KEY_USE_REVOCABLE_FD_FOR_READS,
                     USE_REVOCABLE_FD_FOR_READS, DEFAULT_USE_REVOCABLE_FD_FOR_READS));
+            fout.println(String.format(dumpFormat, KEY_DELETE_ON_LAST_LEASE_DELAY_MS,
+                    TimeUtils.formatDuration(DELETE_ON_LAST_LEASE_DELAY_MS),
+                    TimeUtils.formatDuration(DEFAULT_DELETE_ON_LAST_LEASE_DELAY_MS)));
         }
     }
 
@@ -264,6 +281,13 @@ class BlobStoreConfig {
         return DeviceConfigProperties.USE_REVOCABLE_FD_FOR_READS;
     }
 
+    /**
+     * Returns the duration to wait before a blob is deleted, once the last lease on it is released.
+     */
+    public static long getDeletionOnLastLeaseDelayMs() {
+        return DeviceConfigProperties.DELETE_ON_LAST_LEASE_DELAY_MS;
+    }
+
     @Nullable
     public static File prepareBlobFile(long sessionId) {
         final File blobsDir = prepareBlobsDir();
diff --git a/apex/blobstore/service/java/com/android/server/blob/BlobStoreManagerService.java b/apex/blobstore/service/java/com/android/server/blob/BlobStoreManagerService.java
index 78eab0b0a21e..a90536fee904 100644
--- a/apex/blobstore/service/java/com/android/server/blob/BlobStoreManagerService.java
+++ b/apex/blobstore/service/java/com/android/server/blob/BlobStoreManagerService.java
@@ -34,6 +34,7 @@ import static com.android.server.blob.BlobStoreConfig.LOGV;
 import static com.android.server.blob.BlobStoreConfig.TAG;
 import static com.android.server.blob.BlobStoreConfig.XML_VERSION_CURRENT;
 import static com.android.server.blob.BlobStoreConfig.getAdjustedCommitTimeMs;
+import static com.android.server.blob.BlobStoreConfig.getDeletionOnLastLeaseDelayMs;
 import static com.android.server.blob.BlobStoreSession.STATE_ABANDONED;
 import static com.android.server.blob.BlobStoreSession.STATE_COMMITTED;
 import static com.android.server.blob.BlobStoreSession.STATE_VERIFIED_INVALID;
@@ -488,9 +489,21 @@ public class BlobStoreManagerService extends SystemService {
                 Slog.v(TAG, "Released lease on " + blobHandle
                         + "; callingUid=" + callingUid + ", callingPackage=" + callingPackage);
             }
-            if (blobMetadata.shouldBeDeleted(true /* respectLeaseWaitTime */)) {
-                deleteBlobLocked(blobMetadata);
-                userBlobs.remove(blobHandle);
+            if (!blobMetadata.hasLeases()) {
+                mHandler.postDelayed(() -> {
+                    synchronized (mBlobsLock) {
+                        // Check if blobMetadata object is still valid. If it is not, then
+                        // it means that it was already deleted and nothing else to do here.
+                        if (!Objects.equals(userBlobs.get(blobHandle), blobMetadata)) {
+                            return;
+                        }
+                        if (blobMetadata.shouldBeDeleted(true /* respectLeaseWaitTime */)) {
+                            deleteBlobLocked(blobMetadata);
+                            userBlobs.remove(blobHandle);
+                        }
+                        writeBlobsInfoAsync();
+                    }
+                }, getDeletionOnLastLeaseDelayMs());
             }
             writeBlobsInfoAsync();
         }