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Fix handling of sqlite transactions #136

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Merged
merged 5 commits into from
Nov 22, 2018
Merged

Fix handling of sqlite transactions #136

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8ead372
Move as much work as possible out of the sqlite txn
rsgowman Nov 21, 2018
4a9dcd1
Use sqlite transaction listeners (rather than doing so manually)
rsgowman Nov 21, 2018
496e614
Dont implement SQLiteTransactionListener within SQLiteLruReferenceDel…
rsgowman Nov 21, 2018
2931f24
Create adapter to reduce duplication
rsgowman Nov 21, 2018
b2146b9
Remove adapter in favour of an extra private member...
rsgowman Nov 21, 2018
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17 changes: 16 additions & 1 deletion ...restore/src/main/java/com/google/firebase/firestore/local/SQLiteLruReferenceDelegate.java
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Original file line number Diff line number Diff line change
Expand Up @@ -16,14 +16,16 @@

import static com.google.firebase.firestore.util.Assert.hardAssert;

import android.database.sqlite.SQLiteTransactionListener;
import android.util.SparseArray;
import com.google.firebase.firestore.core.ListenSequence;
import com.google.firebase.firestore.model.DocumentKey;
import com.google.firebase.firestore.model.ResourcePath;
import com.google.firebase.firestore.util.Consumer;

/** Provides LRU functionality for SQLite persistence. */
class SQLiteLruReferenceDelegate implements ReferenceDelegate, LruDelegate {
class SQLiteLruReferenceDelegate
implements ReferenceDelegate, LruDelegate, SQLiteTransactionListener {
private final SQLitePersistence persistence;
private ListenSequence listenSequence;
private long currentSequenceNumber;
Expand All @@ -40,6 +42,19 @@ void start(long highestSequenceNumber) {
listenSequence = new ListenSequence(highestSequenceNumber);
}

@Override
public void onBegin() {
onTransactionStarted();
}

@Override
public void onCommit() {
onTransactionCommitted();
}

@Override
public void onRollback() {}

@Override
public void onTransactionStarted() {
hardAssert(
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17 changes: 7 additions & 10 deletions firebase-firestore/src/main/java/com/google/firebase/firestore/local/SQLitePersistence.java
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Expand Up @@ -143,35 +143,32 @@ RemoteDocumentCache getRemoteDocumentCache() {

@Override
void runTransaction(String action, Runnable operation) {
Logger.debug(TAG, "Starting transaction: %s", action);
db.beginTransactionWithListener(referenceDelegate);
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Since ReferenceDelegate has public onTransactionStarted() / onTransactionCommitted() methods as part of its interface contract, I think it might be cleaner to leave SQLiteLruReferenceDelegate alone, and have an anonymous implementation of SQLiteTransactionListener here that calls the existing methods on the referenceDelegate.

I know this will result in some duplication here since we start transactions in two places, but I think it keeps the contract cleaner. WDYT?

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Good point, though by moving it in here, it clutters the transaction logic, making it more difficult to audit. See 496e614

However, we can create an adapter to (a) reduce the duplication and (b) move the clutter out from the transaction methods. See 2931f24

wdyt?

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This probably isn't worth churning on too much, but having an "Adapter" class introduces some conceptual complexity. I'd actually just have the listener be a private class member initialized via an anonymous class:

// Create a SQLiteTransactionListener that delegates to our referenceDelegate.
private final SQLiteTransactionListener transactionListener = 
  new SQLiteTransactionListener() {
          @Override
          public void onBegin() {
            referenceDelegate.onTransactionStarted();
          }
           @Override
          public void onCommit() {
            referenceDelegate.onTransactionCommitted();
          }
           @Override
          public void onRollback() {}
        });

...

db.beginTransactionWithListener(transactionListener);

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WDYT? I'm fine with you just submitting as-is too. :-)

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Yeah, that makes more sense; done.

try {
Logger.debug(TAG, "Starting transaction: %s", action);
referenceDelegate.onTransactionStarted();
db.beginTransaction();
operation.run();

// Note that an exception in operation.run() will prevent this code from running.
db.setTransactionSuccessful();
} finally {
db.endTransaction();
referenceDelegate.onTransactionCommitted();
}
}

@Override
<T> T runTransaction(String action, Supplier<T> operation) {
Logger.debug(TAG, "Starting transaction: %s", action);
T value = null;
db.beginTransactionWithListener(referenceDelegate);
try {
Logger.debug(TAG, "Starting transaction: %s", action);
referenceDelegate.onTransactionStarted();
db.beginTransaction();
T value = operation.get();
value = operation.get();

// Note that an exception in operation.run() will prevent this code from running.
db.setTransactionSuccessful();
return value;
} finally {
db.endTransaction();
referenceDelegate.onTransactionCommitted();
}
return value;
}

/**
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