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Removing async code from file writes #94

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merged 6 commits into from
Aug 14, 2024
Merged

Removing async code from file writes #94

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445106c
Removing some async code that was allowing reads to happen in the mid…
MichaelGHSeg Aug 9, 2024
1305177
closing files from read and write
MichaelGHSeg Aug 9, 2024
088d760
Deleting invalid file on read without failing init
MichaelGHSeg Aug 13, 2024
b4ff427
Fixing uninitialized variable
MichaelGHSeg Aug 13, 2024
596dcff
Fixing variable init
MichaelGHSeg Aug 13, 2024
4c7b470
Adding comment about fix
MichaelGHSeg Aug 13, 2024
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41 changes: 22 additions & 19 deletions packages/core/lib/state.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -165,23 +165,34 @@ abstract class PersistedState<T> implements AsyncStateNotifier<T> {
if (_persistance != null) {
_hasUpdated = true;
} else {
_persistance = storageJson
_persistance = storageJson
? _store
.setPersisted(_key, toJson(state))
.whenComplete(_whenPersistenceComplete)
.setPersisted(_key, toJson(state))
.whenComplete(_whenPersistenceComplete)
: null;
}
});
_store.ready.then<void>((_) async {
final rawV = await _store.getPersisted(_key);
Map<String, dynamic>? rawV;
try {
rawV = await _store.getPersisted(_key);
} on FormatException catch (e) {
// Addressing https://github.com/segmentio/analytics_flutter/issues/74
// File corruption should be less likely with removal of async code in writes
// Existing corrupted files are cleaned up here without failing initialization
_store.setPersisted(_key, {});
log("Clean file $_key with format error", kind: LogFilterKind.warning);
final wrappedError = ErrorLoadingStorage(e);
errorHandler(wrappedError);
}
T v;

if (rawV == null) {
final init = await _initialiser();
_persistance = storageJson
_persistance = storageJson
? _store
.setPersisted(_key, toJson(init))
.whenComplete(_whenPersistenceComplete)
.setPersisted(_key, toJson(init))
.whenComplete(_whenPersistenceComplete)
: null;
_notifier.nonNullState = init;
v = init;
Expand All @@ -201,16 +212,9 @@ abstract class PersistedState<T> implements AsyncStateNotifier<T> {
return;
}).catchError((e) {
_error = e;
// Clean file if exist a format error
if(_error.toString().contains("FormatException")) {
_store.setPersisted(_key, {});
log("Clean file $_key with format error",
kind: LogFilterKind.warning);
} else {
final wrappedError = ErrorLoadingStorage(e);
errorHandler(wrappedError);
throw wrappedError;
}
final wrappedError = ErrorLoadingStorage(e);
errorHandler(wrappedError);
throw wrappedError;
});
}

Expand Down Expand Up @@ -552,8 +556,7 @@ class Configuration {
this.debug = false,
this.maxBatchSize,
this.storageJson = true,
this.token
});
this.token});
}

typedef ErrorHandler = void Function(Exception);
Expand Down
20 changes: 12 additions & 8 deletions packages/core/lib/utils/store/io.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -27,22 +27,26 @@ class StoreImpl with Store {
final serialized = json.encode(data);
final buffer = utf8.encode(serialized);

file = await file.lock();
file = await file.setPosition(0);
file = await file.writeFrom(buffer);
file = await file.truncate(buffer.length);
await file.unlock();
file.lockSync(FileLock.blockingExclusive);
file.setPositionSync(0);
file.writeFromSync(buffer);
file.truncateSync(buffer.length);
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Thinking about security out-loud; I wonder if this leaves the file contents in memory or overwrites them with 0s.

file.unlockSync();
file.closeSync();
}

Future<Map<String, dynamic>?> _readFile(String fileKey) async {
RandomAccessFile? file = await _getFile(fileKey);
if (file == null) {
return null;
}
final length = await file.length();
file = await file.setPosition(0);
file = await file.lock(FileLock.blockingShared);
final length = file.lengthSync();
file.setPositionSync(0);
final buffer = Uint8List(length);
await file.readInto(buffer);
file.readIntoSync(buffer);
file.unlockSync();
file.closeSync();
final contentText = utf8.decode(buffer);
if (contentText == "{}") {
return null; // Prefer null to empty map, because we'll want to initialise a valid empty value.
Expand Down
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