diff --git a/briar-android/src/net/sf/briar/android/AndroidModule.java b/briar-android/src/net/sf/briar/android/AndroidModule.java
index 83ec34737014019708dcf2a0e0dcbeea57c9a106..3be4882c8c32bd8d34e16a88f40b25a3bf543fdf 100644
--- a/briar-android/src/net/sf/briar/android/AndroidModule.java
+++ b/briar-android/src/net/sf/briar/android/AndroidModule.java
@@ -1,7 +1,11 @@
package net.sf.briar.android;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
import net.sf.briar.api.android.AndroidExecutor;
import net.sf.briar.api.android.BundleEncrypter;
+import net.sf.briar.api.android.DatabaseUiExecutor;
import net.sf.briar.api.android.ReferenceManager;
import com.google.inject.AbstractModule;
@@ -16,5 +20,8 @@ public class AndroidModule extends AbstractModule {
Singleton.class);
bind(ReferenceManager.class).to(ReferenceManagerImpl.class).in(
Singleton.class);
+ // Use a single thread so DB accesses from the UI don't overlap
+ bind(Executor.class).annotatedWith(DatabaseUiExecutor.class).toInstance(
+ Executors.newSingleThreadExecutor());
}
}
diff --git a/briar-android/src/net/sf/briar/android/groups/GroupActivity.java b/briar-android/src/net/sf/briar/android/groups/GroupActivity.java
index 59dbbca49f00d1830e647e4ce396b2f82b518971..deff171b85a52ce829bbc2effb32f5732001cc69 100644
--- a/briar-android/src/net/sf/briar/android/groups/GroupActivity.java
+++ b/briar-android/src/net/sf/briar/android/groups/GroupActivity.java
@@ -6,6 +6,7 @@ import static java.util.logging.Level.INFO;
import static java.util.logging.Level.WARNING;
import java.util.Collection;
+import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.logging.Logger;
@@ -16,8 +17,8 @@ import net.sf.briar.android.BriarService;
import net.sf.briar.android.BriarService.BriarServiceConnection;
import net.sf.briar.android.widgets.CommonLayoutParams;
import net.sf.briar.android.widgets.HorizontalBorder;
+import net.sf.briar.api.android.DatabaseUiExecutor;
import net.sf.briar.api.db.DatabaseComponent;
-import net.sf.briar.api.db.DatabaseExecutor;
import net.sf.briar.api.db.DbException;
import net.sf.briar.api.db.GroupMessageHeader;
import net.sf.briar.api.db.NoSuchSubscriptionException;
@@ -56,7 +57,7 @@ OnClickListener, OnItemClickListener {
// Fields that are accessed from DB threads must be volatile
@Inject private volatile DatabaseComponent db;
- @Inject @DatabaseExecutor private volatile Executor dbExecutor;
+ @Inject @DatabaseUiExecutor private volatile Executor dbUiExecutor;
private volatile GroupId groupId = null;
@Override
@@ -107,7 +108,7 @@ OnClickListener, OnItemClickListener {
}
private void loadHeaders() {
- dbExecutor.execute(new Runnable() {
+ dbUiExecutor.execute(new Runnable() {
public void run() {
try {
// Wait for the service to be bound and started
@@ -119,8 +120,10 @@ OnClickListener, OnItemClickListener {
long duration = System.currentTimeMillis() - now;
if(LOG.isLoggable(INFO))
LOG.info("Load took " + duration + " ms");
- // Display the headers in the UI
- displayHeaders(headers);
+ // Wait for the headers to be displayed in the UI
+ CountDownLatch latch = new CountDownLatch(1);
+ displayHeaders(latch, headers);
+ latch.await();
} catch(NoSuchSubscriptionException e) {
if(LOG.isLoggable(INFO)) LOG.info("Subscription removed");
finishOnUiThread();
@@ -129,20 +132,25 @@ OnClickListener, OnItemClickListener {
LOG.log(WARNING, e.toString(), e);
} catch(InterruptedException e) {
if(LOG.isLoggable(INFO))
- LOG.info("Interrupted while waiting for service");
+ LOG.info("Interrupted while loading headers");
Thread.currentThread().interrupt();
}
}
});
}
- private void displayHeaders(final Collection<GroupMessageHeader> headers) {
+ private void displayHeaders(final CountDownLatch latch,
+ final Collection<GroupMessageHeader> headers) {
runOnUiThread(new Runnable() {
public void run() {
- adapter.clear();
- for(GroupMessageHeader h : headers) adapter.add(h);
- adapter.sort(AscendingHeaderComparator.INSTANCE);
- selectFirstUnread();
+ try {
+ adapter.clear();
+ for(GroupMessageHeader h : headers) adapter.add(h);
+ adapter.sort(AscendingHeaderComparator.INSTANCE);
+ selectFirstUnread();
+ } finally {
+ latch.countDown();
+ }
}
});
}
@@ -184,11 +192,9 @@ OnClickListener, OnItemClickListener {
unbindService(serviceConnection);
}
- // FIXME: Load operations may overlap, resulting in an inconsistent view
public void eventOccurred(DatabaseEvent e) {
if(e instanceof GroupMessageAddedEvent) {
- GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
- if(g.getMessage().getGroup().getId().equals(groupId)) {
+ if(((GroupMessageAddedEvent) e).getGroupId().equals(groupId)) {
if(LOG.isLoggable(INFO)) LOG.info("Message added, reloading");
loadHeaders();
}
diff --git a/briar-android/src/net/sf/briar/android/groups/GroupListActivity.java b/briar-android/src/net/sf/briar/android/groups/GroupListActivity.java
index 6921e582fe5cebbbe66d1709b7b11d494ee9c7c8..f1885f61021b77860ade106310b6b5266c5e91c8 100644
--- a/briar-android/src/net/sf/briar/android/groups/GroupListActivity.java
+++ b/briar-android/src/net/sf/briar/android/groups/GroupListActivity.java
@@ -16,6 +16,7 @@ import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;
+import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.logging.Logger;
@@ -26,6 +27,7 @@ import net.sf.briar.android.BriarService.BriarServiceConnection;
import net.sf.briar.android.widgets.CommonLayoutParams;
import net.sf.briar.android.widgets.HorizontalBorder;
import net.sf.briar.api.ContactId;
+import net.sf.briar.api.android.DatabaseUiExecutor;
import net.sf.briar.api.crypto.CryptoComponent;
import net.sf.briar.api.db.DatabaseComponent;
import net.sf.briar.api.db.DatabaseExecutor;
@@ -70,6 +72,7 @@ implements OnClickListener, DatabaseListener {
@Inject private volatile CryptoComponent crypto;
@Inject private volatile DatabaseComponent db;
@Inject @DatabaseExecutor private volatile Executor dbExecutor;
+ @Inject @DatabaseUiExecutor private volatile Executor dbUiExecutor;
@Inject private volatile AuthorFactory authorFactory;
@Inject private volatile GroupFactory groupFactory;
@Inject private volatile MessageFactory messageFactory;
@@ -220,58 +223,68 @@ implements OnClickListener, DatabaseListener {
}
private void loadHeaders() {
- dbExecutor.execute(new Runnable() {
+ dbUiExecutor.execute(new Runnable() {
public void run() {
try {
// Wait for the service to be bound and started
serviceConnection.waitForStartup();
// Load the subscribed groups from the DB
+ Collection<CountDownLatch> latches =
+ new ArrayList<CountDownLatch>();
+ long now = System.currentTimeMillis();
for(Group g : db.getSubscriptions()) {
// Filter out restricted groups
if(g.getPublicKey() != null) continue;
try {
- long now = System.currentTimeMillis();
// Load the headers from the database
Collection<GroupMessageHeader> headers =
db.getMessageHeaders(g.getId());
- long duration = System.currentTimeMillis() - now;
- if(LOG.isLoggable(INFO))
- LOG.info("Full load took " + duration + " ms");
// Display the headers in the UI
- displayHeaders(g, headers);
+ CountDownLatch latch = new CountDownLatch(1);
+ displayHeaders(latch, g, headers);
+ latches.add(latch);
} catch(NoSuchSubscriptionException e) {
if(LOG.isLoggable(INFO))
LOG.info("Subscription removed");
}
}
+ long duration = System.currentTimeMillis() - now;
+ if(LOG.isLoggable(INFO))
+ LOG.info("Full load took " + duration + " ms");
+ // Wait for the headers to be displayed in the UI
+ for(CountDownLatch latch : latches) latch.await();
} catch(DbException e) {
if(LOG.isLoggable(WARNING))
LOG.log(WARNING, e.toString(), e);
} catch(InterruptedException e) {
if(LOG.isLoggable(INFO))
- LOG.info("Interrupted while waiting for service");
+ LOG.info("Interrupted while loading headers");
Thread.currentThread().interrupt();
}
}
});
}
- private void displayHeaders(final Group g,
+ private void displayHeaders(final CountDownLatch latch, final Group g,
final Collection<GroupMessageHeader> headers) {
runOnUiThread(new Runnable() {
public void run() {
- // Remove the old item, if any
- GroupListItem item = findGroup(g.getId());
- if(item != null) adapter.remove(item);
- // Add a new item if there are any headers to display
- if(!headers.isEmpty()) {
- List<GroupMessageHeader> headerList =
- new ArrayList<GroupMessageHeader>(headers);
- adapter.add(new GroupListItem(g, headerList));
- adapter.sort(GroupComparator.INSTANCE);
+ try {
+ // Remove the old item, if any
+ GroupListItem item = findGroup(g.getId());
+ if(item != null) adapter.remove(item);
+ // Add a new item if there are any headers to display
+ if(!headers.isEmpty()) {
+ List<GroupMessageHeader> headerList =
+ new ArrayList<GroupMessageHeader>(headers);
+ adapter.add(new GroupListItem(g, headerList));
+ adapter.sort(GroupComparator.INSTANCE);
+ }
+ selectFirstUnread();
+ } finally {
+ latch.countDown();
}
- selectFirstUnread();
- }
+ }
});
}
@@ -312,23 +325,22 @@ implements OnClickListener, DatabaseListener {
startActivity(new Intent(this, WriteGroupMessageActivity.class));
}
- // FIXME: Load operations may overlap, resulting in an inconsistent view
public void eventOccurred(DatabaseEvent e) {
if(e instanceof GroupMessageAddedEvent) {
if(LOG.isLoggable(INFO)) LOG.info("Message added, reloading");
- GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
- loadHeaders(g.getMessage().getGroup().getId());
+ loadHeaders(((GroupMessageAddedEvent) e).getGroupId());
} else if(e instanceof MessageExpiredEvent) {
if(LOG.isLoggable(INFO)) LOG.info("Message expired, reloading");
loadHeaders(); // FIXME: Don't reload everything
} else if(e instanceof SubscriptionRemovedEvent) {
- if(LOG.isLoggable(INFO)) LOG.info("Removing group");
- removeGroup(((SubscriptionRemovedEvent) e).getGroupId());
+ // Reload the group, expecting NoSuchSubscriptionException
+ if(LOG.isLoggable(INFO)) LOG.info("Group removed, reloading");
+ loadHeaders(((SubscriptionRemovedEvent) e).getGroupId());
}
}
private void loadHeaders(final GroupId g) {
- dbExecutor.execute(new Runnable() {
+ dbUiExecutor.execute(new Runnable() {
public void run() {
try {
serviceConnection.waitForStartup();
@@ -339,15 +351,18 @@ implements OnClickListener, DatabaseListener {
long duration = System.currentTimeMillis() - now;
if(LOG.isLoggable(INFO))
LOG.info("Partial load took " + duration + " ms");
- displayHeaders(group, headers);
+ CountDownLatch latch = new CountDownLatch(1);
+ displayHeaders(latch, group, headers);
+ latch.await();
} catch(NoSuchSubscriptionException e) {
if(LOG.isLoggable(INFO)) LOG.info("Subscription removed");
+ removeGroup(g);
} catch(DbException e) {
if(LOG.isLoggable(WARNING))
LOG.log(WARNING, e.toString(), e);
} catch(InterruptedException e) {
if(LOG.isLoggable(INFO))
- LOG.info("Interrupted while waiting for service");
+ LOG.info("Interrupted while loading headers");
Thread.currentThread().interrupt();
}
}
diff --git a/briar-android/src/net/sf/briar/android/messages/ConversationActivity.java b/briar-android/src/net/sf/briar/android/messages/ConversationActivity.java
index 635eee594085948d4c528f387579759677672e77..5e2cbacc1d14adeb5f25e68d41ba36ad692a220a 100644
--- a/briar-android/src/net/sf/briar/android/messages/ConversationActivity.java
+++ b/briar-android/src/net/sf/briar/android/messages/ConversationActivity.java
@@ -6,6 +6,7 @@ import static java.util.logging.Level.INFO;
import static java.util.logging.Level.WARNING;
import java.util.Collection;
+import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.logging.Logger;
@@ -17,8 +18,8 @@ import net.sf.briar.android.BriarService.BriarServiceConnection;
import net.sf.briar.android.widgets.CommonLayoutParams;
import net.sf.briar.android.widgets.HorizontalBorder;
import net.sf.briar.api.ContactId;
+import net.sf.briar.api.android.DatabaseUiExecutor;
import net.sf.briar.api.db.DatabaseComponent;
-import net.sf.briar.api.db.DatabaseExecutor;
import net.sf.briar.api.db.DbException;
import net.sf.briar.api.db.NoSuchContactException;
import net.sf.briar.api.db.PrivateMessageHeader;
@@ -54,7 +55,7 @@ implements DatabaseListener, OnClickListener, OnItemClickListener {
// Fields that are accessed from DB threads must be volatile
@Inject private volatile DatabaseComponent db;
- @Inject @DatabaseExecutor private volatile Executor dbExecutor;
+ @Inject @DatabaseUiExecutor private volatile Executor dbUiExecutor;
private volatile ContactId contactId = null;
@Override
@@ -105,7 +106,7 @@ implements DatabaseListener, OnClickListener, OnItemClickListener {
}
private void loadHeaders() {
- dbExecutor.execute(new Runnable() {
+ dbUiExecutor.execute(new Runnable() {
public void run() {
try {
// Wait for the service to be bound and started
@@ -117,8 +118,10 @@ implements DatabaseListener, OnClickListener, OnItemClickListener {
long duration = System.currentTimeMillis() - now;
if(LOG.isLoggable(INFO))
LOG.info("Load took " + duration + " ms");
- // Display the headers in the UI
- displayHeaders(headers);
+ // Wait for the headers to be displayed in the UI
+ CountDownLatch latch = new CountDownLatch(1);
+ displayHeaders(latch, headers);
+ latch.await();
} catch(NoSuchContactException e) {
if(LOG.isLoggable(INFO)) LOG.info("Contact removed");
finishOnUiThread();
@@ -127,21 +130,25 @@ implements DatabaseListener, OnClickListener, OnItemClickListener {
LOG.log(WARNING, e.toString(), e);
} catch(InterruptedException e) {
if(LOG.isLoggable(INFO))
- LOG.info("Interrupted while waiting for service");
+ LOG.info("Interrupted while loading headers");
Thread.currentThread().interrupt();
}
}
});
}
- private void displayHeaders(
+ private void displayHeaders(final CountDownLatch latch,
final Collection<PrivateMessageHeader> headers) {
runOnUiThread(new Runnable() {
public void run() {
- adapter.clear();
- for(PrivateMessageHeader h : headers) adapter.add(h);
- adapter.sort(AscendingHeaderComparator.INSTANCE);
- selectFirstUnread();
+ try {
+ adapter.clear();
+ for(PrivateMessageHeader h : headers) adapter.add(h);
+ adapter.sort(AscendingHeaderComparator.INSTANCE);
+ selectFirstUnread();
+ } finally {
+ latch.countDown();
+ }
}
});
}
@@ -176,14 +183,13 @@ implements DatabaseListener, OnClickListener, OnItemClickListener {
super.onPause();
db.removeListener(this);
}
-
+
@Override
public void onDestroy() {
super.onDestroy();
unbindService(serviceConnection);
}
- // FIXME: Load operations may overlap, resulting in an inconsistent view
public void eventOccurred(DatabaseEvent e) {
if(e instanceof ContactRemovedEvent) {
ContactRemovedEvent c = (ContactRemovedEvent) e;
diff --git a/briar-android/src/net/sf/briar/android/messages/ConversationListActivity.java b/briar-android/src/net/sf/briar/android/messages/ConversationListActivity.java
index a6f829e990d1dc990e27647b8c646d0cd5e12578..2078a521c526909089af404195678a16ae79455c 100644
--- a/briar-android/src/net/sf/briar/android/messages/ConversationListActivity.java
+++ b/briar-android/src/net/sf/briar/android/messages/ConversationListActivity.java
@@ -11,6 +11,7 @@ import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;
+import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.logging.Logger;
@@ -22,6 +23,7 @@ import net.sf.briar.android.widgets.CommonLayoutParams;
import net.sf.briar.android.widgets.HorizontalBorder;
import net.sf.briar.api.Contact;
import net.sf.briar.api.ContactId;
+import net.sf.briar.api.android.DatabaseUiExecutor;
import net.sf.briar.api.db.DatabaseComponent;
import net.sf.briar.api.db.DatabaseExecutor;
import net.sf.briar.api.db.DbException;
@@ -59,6 +61,7 @@ implements OnClickListener, DatabaseListener {
// Fields that are accessed from DB threads must be volatile
@Inject private volatile DatabaseComponent db;
@Inject @DatabaseExecutor private volatile Executor dbExecutor;
+ @Inject @DatabaseUiExecutor private volatile Executor dbUiExecutor;
@Inject private volatile MessageFactory messageFactory;
@Override
@@ -164,55 +167,65 @@ implements OnClickListener, DatabaseListener {
}
private void loadHeaders() {
- dbExecutor.execute(new Runnable() {
+ dbUiExecutor.execute(new Runnable() {
public void run() {
try {
// Wait for the service to be bound and started
serviceConnection.waitForStartup();
// Load the contact list from the database
+ Collection<CountDownLatch> latches =
+ new ArrayList<CountDownLatch>();
+ long now = System.currentTimeMillis();
for(Contact c : db.getContacts()) {
try {
// Load the headers from the database
- long now = System.currentTimeMillis();
Collection<PrivateMessageHeader> headers =
db.getPrivateMessageHeaders(c.getId());
- long duration = System.currentTimeMillis() - now;
- if(LOG.isLoggable(INFO))
- LOG.info("Full load took " + duration + " ms");
// Display the headers in the UI
- displayHeaders(c, headers);
+ CountDownLatch latch = new CountDownLatch(1);
+ displayHeaders(latch, c, headers);
+ latches.add(latch);
} catch(NoSuchContactException e) {
if(LOG.isLoggable(INFO))
LOG.info("Contact removed");
}
}
+ long duration = System.currentTimeMillis() - now;
+ if(LOG.isLoggable(INFO))
+ LOG.info("Full load took " + duration + " ms");
+ // Wait for the headers to be displayed in the UI
+ for(CountDownLatch latch : latches) latch.await();
} catch(DbException e) {
if(LOG.isLoggable(WARNING))
LOG.log(WARNING, e.toString(), e);
} catch(InterruptedException e) {
if(LOG.isLoggable(INFO))
- LOG.info("Interrupted while waiting for service");
+ LOG.info("Interrupted while loading headers");
Thread.currentThread().interrupt();
}
}
});
}
- private void displayHeaders(final Contact c,
+ private void displayHeaders(final CountDownLatch latch, final Contact c,
final Collection<PrivateMessageHeader> headers) {
runOnUiThread(new Runnable() {
public void run() {
- // Remove the old item, if any
- ConversationListItem item = findConversation(c.getId());
- if(item != null) adapter.remove(item);
- // Add a new item if there are any headers to display
- if(!headers.isEmpty()) {
- List<PrivateMessageHeader> headerList =
- new ArrayList<PrivateMessageHeader>(headers);
- adapter.add(new ConversationListItem(c, headerList));
- adapter.sort(ConversationComparator.INSTANCE);
+ try {
+ // Remove the old item, if any
+ ConversationListItem item = findConversation(c.getId());
+ if(item != null) adapter.remove(item);
+ // Add a new item if there are any headers to display
+ if(!headers.isEmpty()) {
+ List<PrivateMessageHeader> headerList =
+ new ArrayList<PrivateMessageHeader>(headers);
+ adapter.add(new ConversationListItem(c, headerList));
+ adapter.sort(ConversationComparator.INSTANCE);
+ }
+ selectFirstUnread();
+ } finally {
+ latch.countDown();
}
- selectFirstUnread();
}
});
}
@@ -243,7 +256,7 @@ implements OnClickListener, DatabaseListener {
super.onPause();
db.removeListener(this);
}
-
+
@Override
public void onDestroy() {
super.onDestroy();
@@ -254,11 +267,11 @@ implements OnClickListener, DatabaseListener {
startActivity(new Intent(this, WritePrivateMessageActivity.class));
}
- // FIXME: Load operations may overlap, resulting in an inconsistent view
public void eventOccurred(DatabaseEvent e) {
if(e instanceof ContactRemovedEvent) {
- if(LOG.isLoggable(INFO)) LOG.info("Removing conversation");
- removeConversation(((ContactRemovedEvent) e).getContactId());
+ // Reload the conversation, expecting NoSuchContactException
+ if(LOG.isLoggable(INFO)) LOG.info("Contact removed, reloading");
+ loadHeaders(((ContactRemovedEvent) e).getContactId());
} else if(e instanceof MessageExpiredEvent) {
if(LOG.isLoggable(INFO)) LOG.info("Message expired, reloading");
loadHeaders(); // FIXME: Don't reload everything
@@ -268,20 +281,8 @@ implements OnClickListener, DatabaseListener {
}
}
- private void removeConversation(final ContactId c) {
- runOnUiThread(new Runnable() {
- public void run() {
- ConversationListItem item = findConversation(c);
- if(item != null) {
- adapter.remove(item);
- selectFirstUnread();
- }
- }
- });
- }
-
private void loadHeaders(final ContactId c) {
- dbExecutor.execute(new Runnable() {
+ dbUiExecutor.execute(new Runnable() {
public void run() {
try {
serviceConnection.waitForStartup();
@@ -292,21 +293,36 @@ implements OnClickListener, DatabaseListener {
long duration = System.currentTimeMillis() - now;
if(LOG.isLoggable(INFO))
LOG.info("Partial load took " + duration + " ms");
- displayHeaders(contact, headers);
+ CountDownLatch latch = new CountDownLatch(1);
+ displayHeaders(latch, contact, headers);
+ latch.await();
} catch(NoSuchContactException e) {
if(LOG.isLoggable(INFO)) LOG.info("Contact removed");
+ removeConversation(c);
} catch(DbException e) {
if(LOG.isLoggable(WARNING))
LOG.log(WARNING, e.toString(), e);
} catch(InterruptedException e) {
if(LOG.isLoggable(INFO))
- LOG.info("Interrupted while waiting for service");
+ LOG.info("Interrupted while loading headers");
Thread.currentThread().interrupt();
}
}
});
}
+ private void removeConversation(final ContactId c) {
+ runOnUiThread(new Runnable() {
+ public void run() {
+ ConversationListItem item = findConversation(c);
+ if(item != null) {
+ adapter.remove(item);
+ selectFirstUnread();
+ }
+ }
+ });
+ }
+
private static class ConversationComparator
implements Comparator<ConversationListItem> {
diff --git a/briar-api/src/net/sf/briar/api/android/DatabaseUiExecutor.java b/briar-api/src/net/sf/briar/api/android/DatabaseUiExecutor.java
new file mode 100644
index 0000000000000000000000000000000000000000..1a28396e41d141867b045d3446667efe4d914d02
--- /dev/null
+++ b/briar-api/src/net/sf/briar/api/android/DatabaseUiExecutor.java
@@ -0,0 +1,18 @@
+package net.sf.briar.api.android;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import com.google.inject.BindingAnnotation;
+
+/**
+ * Annotation for injecting the executor for accessing the database from the UI.
+ */
+@BindingAnnotation
+@Target({ FIELD, PARAMETER })
+@Retention(RUNTIME)
+public @interface DatabaseUiExecutor {}