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feat: Document the RosterStateManager better

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This commit is contained in:
PapaTutuWawa 2023-01-07 18:11:41 +01:00
parent 995f2e0248
commit 2581bbe203
2 changed files with 108 additions and 66 deletions
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74
packages/moxxmpp/lib/src/roster/state.dart
View File

@ -1,6 +1,7 @@
import 'package:meta/meta.dart';
import 'package:moxxmpp/src/events.dart';
import 'package:moxxmpp/src/roster/roster.dart';
import 'package:synchronized/synchronized.dart';
class _RosterProcessTriple {
const _RosterProcessTriple(this.removed, this.modified, this.added);
@ -15,33 +16,65 @@ class RosterCacheLoadResult {
final List<XmppRosterItem> roster;
}
/// This class manages the roster state in order to correctly process and persist
/// roster pushes and facilitate roster versioning requests.
abstract class BaseRosterStateManager {
List<XmppRosterItem>? currentRoster;
String? currentVersion;
/// The cached version of the roster. If null, then it has not been loaded yet.
List<XmppRosterItem>? _currentRoster;
/// The cached version of the roster version.
String? _currentVersion;
/// A critical section locking both _currentRoster and _currentVersion.
final Lock _lock = Lock();
/// Overrideable function
/// Loads the old cached version of the roster and optionally that roster version
/// from persistent storage into a RosterCacheLoadResult object.
Future<RosterCacheLoadResult> loadRosterCache();
/// Overrideable function
/// Commits the roster data to persistent storage.
///
/// [version] is the roster version string. If none was provided, then this value
/// is null.
///
/// [removed] is a (possibly empty) list of bare JIDs that are removed from the
/// roster.
///
/// [modified] is a (possibly empty) list of XmppRosterItems that are modified. Correlation with
/// the cache is done using its jid attribute.
///
/// [added] is a (possibly empty) list of XmppRosterItems that are added by the
/// roster push or roster fetch request.
Future<void> commitRoster(String? version, List<String> removed, List<XmppRosterItem> modified, List<XmppRosterItem> added);
/// Load and cache or return the cached roster version.
Future<String?> getRosterVersion() async {
return _lock.synchronized(() async {
await _loadRosterCache();
return currentVersion;
return _currentVersion;
});
}
/// Loads the cached roster data into memory, if that has not already happened.
/// NOTE: Must be called from within the _lock critical section.
Future<void> _loadRosterCache() async {
if (currentRoster == null) {
if (_currentRoster == null) {
final result = await loadRosterCache();
currentRoster = result.roster;
currentVersion = result.version;
_currentRoster = result.roster;
_currentVersion = result.version;
}
}
/// Processes only single XmppRosterItem [item].
/// NOTE: Requires to be called from within the _lock critical section.
_RosterProcessTriple _handleRosterItem(XmppRosterItem item) {
if (item.subscription == 'remove') {
// The item has been removed
currentRoster!.removeWhere((i) => i.jid == item.jid);
_currentRoster!.removeWhere((i) => i.jid == item.jid);
return _RosterProcessTriple(
item.jid,
null,
@ -49,10 +82,10 @@ abstract class BaseRosterStateManager {
);
}
final index = currentRoster!.indexWhere((i) => i.jid == item.jid);
final index = _currentRoster!.indexWhere((i) => i.jid == item.jid);
if (index == -1) {
// The item does not exist
currentRoster!.add(item);
_currentRoster!.add(item);
return _RosterProcessTriple(
null,
null,
@ -60,7 +93,7 @@ abstract class BaseRosterStateManager {
);
} else {
// The item is updated
currentRoster![index] = item;
_currentRoster![index] = item;
return _RosterProcessTriple(
null,
item,
@ -69,44 +102,49 @@ abstract class BaseRosterStateManager {
}
}
/// Handles a roster push from the RosterManager.
Future<void> handleRosterPush(RosterPushEvent event) async {
await _lock.synchronized(() async {
await _loadRosterCache();
currentVersion = event.ver;
_currentVersion = event.ver;
final result = _handleRosterItem(event.item);
if (result.removed != null) {
return commitRoster(
currentVersion,
_currentVersion,
[result.removed!],
[],
[],
);
} else if (result.modified != null) {
return commitRoster(
currentVersion,
_currentVersion,
[],
[result.modified!],
[],
);
} else if (result.added != null) {
return commitRoster(
currentVersion,
_currentVersion,
[],
[],
[result.added!],
);
}
});
}
/// Handles the result from a roster fetch.
Future<void> handleRosterFetch(RosterRequestResult result) async {
await _lock.synchronized(() async {
final removed = List<String>.empty(growable: true);
final modified = List<XmppRosterItem>.empty(growable: true);
final added = List<XmppRosterItem>.empty(growable: true);
await _loadRosterCache();
currentVersion = result.ver;
_currentVersion = result.ver;
for (final item in result.items) {
final result = _handleRosterItem(item);
@ -116,12 +154,16 @@ abstract class BaseRosterStateManager {
}
await commitRoster(
currentVersion,
_currentVersion,
removed,
modified,
added,
);
});
}
@visibleForTesting
List<XmppRosterItem> getRosterItems() => _currentRoster!;
}
@visibleForTesting

22
packages/moxxmpp/test/roster_state_test.dart
View File

@ -15,11 +15,11 @@ void main() {
);
expect(
rs.currentRoster!.indexWhere((item) => item.jid == 'testuser@server.example') != -1,
rs.getRosterItems().indexWhere((item) => item.jid == 'testuser@server.example') != -1,
true,
);
expect(rs.loadCount, 1);
expect(rs.currentRoster!.length, 1);
expect(rs.getRosterItems().length, 1);
// Receive another roster push
await rs.handleRosterPush(
@ -32,11 +32,11 @@ void main() {
);
expect(
rs.currentRoster!.indexWhere((item) => item.jid == 'testuser2@server2.example') != -1,
rs.getRosterItems().indexWhere((item) => item.jid == 'testuser2@server2.example') != -1,
true,
);
expect(rs.loadCount, 1);
expect(rs.currentRoster!.length, 2);
expect(rs.getRosterItems().length, 2);
// Remove one of the items
await rs.handleRosterPush(
@ -49,15 +49,15 @@ void main() {
);
expect(
rs.currentRoster!.indexWhere((item) => item.jid == 'testuser2@server2.example') == -1,
rs.getRosterItems().indexWhere((item) => item.jid == 'testuser2@server2.example') == -1,
true,
);
expect(
rs.currentRoster!.indexWhere((item) => item.jid == 'testuser@server.example') != 1,
rs.getRosterItems().indexWhere((item) => item.jid == 'testuser@server.example') != 1,
true,
);
expect(rs.loadCount, 1);
expect(rs.currentRoster!.length, 1);
expect(rs.getRosterItems().length, 1);
});
test('Test a roster fetch', () async {
@ -85,9 +85,9 @@ void main() {
);
expect(rs.loadCount, 1);
expect(rs.currentRoster!.length, 3);
expect(rs.currentRoster!.indexWhere((item) => item.jid == 'testuser@server.example') != -1, true);
expect(rs.currentRoster!.indexWhere((item) => item.jid == 'testuser2@server2.example') != -1, true);
expect(rs.currentRoster!.indexWhere((item) => item.jid == 'testuser3@server3.example') != -1, true);
expect(rs.getRosterItems().length, 3);
expect(rs.getRosterItems().indexWhere((item) => item.jid == 'testuser@server.example') != -1, true);
expect(rs.getRosterItems().indexWhere((item) => item.jid == 'testuser2@server2.example') != -1, true);
expect(rs.getRosterItems().indexWhere((item) => item.jid == 'testuser3@server3.example') != -1, true);
});
}