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Ensure blobs from old sessions are deleted before creating new ones.

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There was a race condition where if you created a blob super-early in
the application lifecycle, you could create it *before* we deleted the
blobs from the previous session, leading you to lose the blob you just
created immediately.

In an effort to protect our cold start time, I just made a little
initialization flow where read/write calls to BlobProvider will block
until it's deleted blobs from the old session.
This commit is contained in:
Greyson Parrelli
2021-02-24 16:04:58 -05:00
committed by GitHub
parent da56c2790f
commit 32ac6e3429
2 changed files with 49 additions and 11 deletions
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56
app/src/main/java/org/thoughtcrime/securesms/providers/BlobProvider.java
View File

@@ -6,6 +6,7 @@ import android.content.UriMatcher;
import android.media.MediaDataSource;
import android.net.Uri;
import androidx.annotation.AnyThread;
import androidx.annotation.IntRange;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
@@ -21,6 +22,7 @@ import org.thoughtcrime.securesms.crypto.AttachmentSecretProvider;
import org.thoughtcrime.securesms.crypto.ModernDecryptingPartInputStream;
import org.thoughtcrime.securesms.crypto.ModernEncryptingPartOutputStream;
import org.thoughtcrime.securesms.util.IOFunction;
import org.thoughtcrime.securesms.util.Util;
import org.thoughtcrime.securesms.video.ByteArrayMediaDataSource;
import org.thoughtcrime.securesms.video.EncryptedMediaDataSource;
@@ -64,6 +66,8 @@ public class BlobProvider {
private final Map<Uri, byte[]> memoryBlobs = new HashMap<>();
private volatile boolean initialized = false;
public static BlobProvider getInstance() {
return INSTANCE;
@@ -88,6 +92,7 @@ public class BlobProvider {
* @throws IOException If the stream fails to open or the spec of the URI doesn't match.
*/
public synchronized @NonNull InputStream getStream(@NonNull Context context, @NonNull Uri uri) throws IOException {
waitUntilInitialized();
return getStream(context, uri, 0L);
}
@@ -96,6 +101,7 @@ public class BlobProvider {
* @throws IOException If the stream fails to open or the spec of the URI doesn't match.
*/
public synchronized @NonNull InputStream getStream(@NonNull Context context, @NonNull Uri uri, long position) throws IOException {
waitUntilInitialized();
return getBlobRepresentation(context,
uri,
bytes -> {
@@ -112,6 +118,7 @@ public class BlobProvider {
@RequiresApi(23)
public synchronized @NonNull MediaDataSource getMediaDataSource(@NonNull Context context, @NonNull Uri uri) throws IOException {
waitUntilInitialized();
return getBlobRepresentation(context,
uri,
ByteArrayMediaDataSource::new,
@@ -158,6 +165,8 @@ public class BlobProvider {
* Delete the content with the specified URI.
*/
public synchronized void delete(@NonNull Context context, @NonNull Uri uri) {
waitUntilInitialized();
if (!isAuthority(uri)) {
Log.d(TAG, "Can't delete. Not the authority for uri: " + uri);
return;
@@ -187,17 +196,30 @@ public class BlobProvider {
}
/**
* Indicates a new app session has started, allowing old single-session blobs to be deleted.
* Allows the class to be initialized. Part of this initialization is deleting any leftover
* single-session blobs from the previous session. However, this class defers that work to a
* background thread, so callers don't have to worry about it.
*/
public synchronized void onSessionStart(@NonNull Context context) {
File directory = getOrCreateDirectory(context, SINGLE_SESSION_DIRECTORY);
for (File file : directory.listFiles()) {
if (file.delete()) {
Log.d(TAG, "Deleted single-session file: " + file.getName());
@AnyThread
public synchronized void initialize(@NonNull Context context) {
SignalExecutors.BOUNDED.execute(() -> {
File directory = getOrCreateDirectory(context, SINGLE_SESSION_DIRECTORY);
File[] files = directory.listFiles();
if (files != null) {
for (File file : files) {
if (file.delete()) {
Log.d(TAG, "Deleted single-session file: " + file.getName());
} else {
Log.w(TAG, "Failed to delete single-session file! " + file.getName());
}
}
} else {
Log.w(TAG, "Failed to delete single-session file! " + file.getName());
Log.w(TAG, "Null directory listing!");
}
}
initialized = true;
});
}
public static @Nullable String getMimeType(@NonNull Uri uri) {
@@ -249,7 +271,10 @@ public class BlobProvider {
{
CountDownLatch latch = new CountDownLatch(1);
AtomicReference<IOException> exception = new AtomicReference<>(null);
Uri uri = writeBlobSpecToDiskAsync(context, blobSpec, latch::countDown, exception::set);
Uri uri = writeBlobSpecToDiskAsync(context, blobSpec, latch::countDown, e -> {
exception.set(e);
latch.countDown();
});
try {
latch.await();
@@ -285,6 +310,7 @@ public class BlobProvider {
successListener.onSuccess();
}
} catch (IOException e) {
Log.w(TAG, "Error during write!", e);
if (errorListener != null) {
errorListener.onError(e);
}
@@ -401,6 +427,18 @@ public class BlobProvider {
}
}
private synchronized void waitUntilInitialized() {
if (!initialized) {
Log.i(TAG, "Waiting for initialization...");
synchronized (this) {
while (!initialized) {
Util.wait(this, 0);
}
Log.i(TAG, "Initialization complete.");
}
}
}
public class MemoryBlobBuilder extends BlobBuilder {
private byte[] data;