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Add support for sticky and hot-swappable feature flags.
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@greyson-signal
greyson-signal committed Jan 27, 2020
1 parent e7f568e commit 526adce
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Showing 4 changed files with 389 additions and 37 deletions.
1 change: 1 addition & 0 deletions app/src/main/java/org/thoughtcrime/securesms/ApplicationContext.java
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Expand Up @@ -150,6 +150,7 @@ public void onCreate() {
public void onStart(@NonNull LifecycleOwner owner) {
isAppVisible = true;
Log.i(TAG, "App is now visible.");
FeatureFlags.refresh();
ApplicationDependencies.getRecipientCache().warmUp();
executePendingContactSync();
KeyCachingService.onAppForegrounded(this);
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4 changes: 1 addition & 3 deletions app/src/main/java/org/thoughtcrime/securesms/jobs/RemoteConfigRefreshJob.java
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Expand Up @@ -7,10 +7,8 @@
import org.thoughtcrime.securesms.jobmanager.Job;
import org.thoughtcrime.securesms.keyvalue.SignalStore;
import org.thoughtcrime.securesms.util.FeatureFlags;
import org.thoughtcrime.securesms.util.TextSecurePreferences;
import org.whispersystems.signalservice.api.push.exceptions.PushNetworkException;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

Expand Down Expand Up @@ -44,7 +42,7 @@ private RemoteConfigRefreshJob(@NonNull Parameters parameters) {
@Override
protected void onRun() throws Exception {
Map<String, Boolean> config = ApplicationDependencies.getSignalServiceAccountManager().getRemoteConfig();
FeatureFlags.updateDiskCache(config);
FeatureFlags.update(config);
SignalStore.setRemoteConfigLastFetchTime(System.currentTimeMillis());
}

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170 changes: 136 additions & 34 deletions app/src/main/java/org/thoughtcrime/securesms/util/FeatureFlags.java
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Expand Up @@ -3,6 +3,9 @@
import android.text.TextUtils;

import androidx.annotation.NonNull;
import androidx.annotation.VisibleForTesting;

import com.annimon.stream.Stream;

import org.json.JSONException;
import org.json.JSONObject;
Expand All @@ -12,9 +15,12 @@
import org.thoughtcrime.securesms.logging.Log;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.concurrent.TimeUnit;

/**
Expand All @@ -28,6 +34,10 @@
* - If you would like to force a value for testing, place an entry in {@link #FORCED_VALUES}. When
* launching a feature that is planned to be updated via a remote config, do not forget to
* remove the entry!
*
* Other interesting things you can do:
* - Make a flag {@link #HOT_SWAPPABLE}
* - Make a flag {@link #STICKY}
*/
public final class FeatureFlags {

Expand Down Expand Up @@ -56,73 +66,143 @@ public final class FeatureFlags {
put(STORAGE_SERVICE, false);
}};

private static final Map<String, Boolean> REMOTE_VALUES = new HashMap<>();
/**
* By default, flags are only updated once at app start. This is to ensure that values don't
* change within an app session, simplifying logic. However, given that this can delay how often
* a flag is updated, you can put a flag in here to mark it as 'hot swappable'. Flags in this set
* will be updated arbitrarily at runtime. This will make values more responsive, but also places
* more burden on the reader to ensure that the app experience remains consistent.
*/
private static final Set<String> HOT_SWAPPABLE = new TreeSet<String>() {{
}};

/**
* Flags in this set will stay true forever once they receive a true value from a remote config.
*/
private static final Set<String> STICKY = new HashSet<String>() {{
}};

private static final Map<String, Boolean> REMOTE_VALUES = new TreeMap<>();

private FeatureFlags() {}

public static void init() {
scheduleFetchIfNecessary();
public static synchronized void init() {
REMOTE_VALUES.putAll(parseStoredConfig());
Log.i(TAG, "init() " + REMOTE_VALUES.toString());
}

public static void updateDiskCache(@NonNull Map<String, Boolean> config) {
try {
JSONObject filtered = new JSONObject();

for (Map.Entry<String, Boolean> entry : config.entrySet()) {
if (entry.getKey().startsWith(PREFIX)) {
filtered.put(entry.getKey(), (boolean) entry.getValue());
}
}
public static synchronized void refresh() {
long timeSinceLastFetch = System.currentTimeMillis() - SignalStore.getRemoteConfigLastFetchTime();

SignalStore.setRemoteConfig(filtered.toString());
} catch (JSONException e) {
throw new AssertionError(e);
if (timeSinceLastFetch > FETCH_INTERVAL) {
Log.i(TAG, "Scheduling remote config refresh.");
ApplicationDependencies.getJobManager().add(new RemoteConfigRefreshJob());
} else {
Log.i(TAG, "Skipping remote config refresh. Refreshed " + timeSinceLastFetch + " ms ago.");
}
}

public static synchronized void update(@NonNull Map<String, Boolean> config) {
Map<String, Boolean> memory = REMOTE_VALUES;
Map<String, Boolean> disk = parseStoredConfig();
UpdateResult result = updateInternal(config, memory, disk, HOT_SWAPPABLE, STICKY);

SignalStore.setRemoteConfig(mapToJson(result.getDisk()).toString());
REMOTE_VALUES.clear();
REMOTE_VALUES.putAll(result.getMemory());

Log.i(TAG, "[Memory] Before: " + memory.toString());
Log.i(TAG, "[Memory] After : " + result.getMemory().toString());
Log.i(TAG, "[Disk] Before: " + disk.toString());
Log.i(TAG, "[Disk] After : " + result.getDisk().toString());
}

/** UUID-related stuff that shouldn't be activated until the user-facing launch. */
public static boolean uuids() {
public static synchronized boolean uuids() {
return getValue(UUIDS, false);
}

/** Favoring profile names when displaying contacts. */
public static boolean profileDisplay() {
public static synchronized boolean profileDisplay() {
return getValue(PROFILE_DISPLAY, false);
}

/** MessageRequest stuff */
public static boolean messageRequests() {
public static synchronized boolean messageRequests() {
return getValue(MESSAGE_REQUESTS, false);
}

/** Creating usernames, sending messages by username. Requires {@link #uuids()}. */
public static boolean usernames() {
public static synchronized boolean usernames() {
boolean value = getValue(USERNAMES, false);
if (value && !uuids()) throw new MissingFlagRequirementError();
return value;
}

/** Storage service. */
public static boolean storageService() {
public static synchronized boolean storageService() {
return getValue(STORAGE_SERVICE, false);
}

/** Send support for reactions. */
public static boolean reactionSending() {
public static synchronized boolean reactionSending() {
return getValue(REACTION_SENDING, false);
}

/** Only for rendering debug info. */
public static @NonNull Map<String, Boolean> getRemoteValues() {
public static synchronized @NonNull Map<String, Boolean> getRemoteValues() {
return new TreeMap<>(REMOTE_VALUES);
}

/** Only for rendering debug info. */
public static @NonNull Map<String, Boolean> getForcedValues() {
public static synchronized @NonNull Map<String, Boolean> getForcedValues() {
return new TreeMap<>(FORCED_VALUES);
}

@VisibleForTesting
static @NonNull UpdateResult updateInternal(@NonNull Map<String, Boolean> remote,
@NonNull Map<String, Boolean> localMemory,
@NonNull Map<String, Boolean> localDisk,
@NonNull Set<String> hotSwap,
@NonNull Set<String> sticky)
{
Map<String, Boolean> newMemory = new TreeMap<>(localMemory);
Map<String, Boolean> newDisk = new TreeMap<>(localDisk);

Set<String> allKeys = new HashSet<>();
allKeys.addAll(remote.keySet());
allKeys.addAll(localDisk.keySet());
allKeys.addAll(localMemory.keySet());

Stream.of(allKeys)
.filter(k -> k.startsWith(PREFIX))
.forEach(key -> {
Boolean remoteValue = remote.get(key);
Boolean diskValue = localDisk.get(key);
Boolean newValue = remoteValue;

if (sticky.contains(key)) {
newValue = diskValue == Boolean.TRUE ? Boolean.TRUE : newValue;
}

if (newValue != null) {
newDisk.put(key, newValue);
} else {
newDisk.remove(key);
}

if (hotSwap.contains(key)) {
if (newValue != null) {
newMemory.put(key, newValue);
} else {
newMemory.remove(key);
}
}
});

return new UpdateResult(newMemory, newDisk);
}

private static @NonNull String generateKey(@NonNull String key) {
return PREFIX + key;
}
Expand All @@ -141,17 +221,6 @@ private static boolean getValue(@NonNull String key, boolean defaultValue) {
return defaultValue;
}

private static void scheduleFetchIfNecessary() {
long timeSinceLastFetch = System.currentTimeMillis() - SignalStore.getRemoteConfigLastFetchTime();

if (timeSinceLastFetch > FETCH_INTERVAL) {
Log.i(TAG, "Scheduling remote config refresh.");
ApplicationDependencies.getJobManager().add(new RemoteConfigRefreshJob());
} else {
Log.i(TAG, "Skipping remote config refresh. Refreshed " + timeSinceLastFetch + " ms ago.");
}
}

private static Map<String, Boolean> parseStoredConfig() {
Map<String, Boolean> parsed = new HashMap<>();
String stored = SignalStore.getRemoteConfig();
Expand All @@ -177,6 +246,39 @@ private static Map<String, Boolean> parseStoredConfig() {
return parsed;
}

private static JSONObject mapToJson(@NonNull Map<String, Boolean> map) {
try {
JSONObject json = new JSONObject();

for (Map.Entry<String, Boolean> entry : map.entrySet()) {
json.put(entry.getKey(), (boolean) entry.getValue());
}

return json;
} catch (JSONException e) {
throw new AssertionError(e);
}
}

private static final class MissingFlagRequirementError extends Error {
}

@VisibleForTesting
static final class UpdateResult {
private final Map<String, Boolean> memory;
private final Map<String, Boolean> disk;

UpdateResult(@NonNull Map<String, Boolean> memory, @NonNull Map<String, Boolean> disk) {
this.memory = memory;
this.disk = disk;
}

public @NonNull Map<String, Boolean> getMemory() {
return memory;
}

public @NonNull Map<String, Boolean> getDisk() {
return disk;
}
}
}

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