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// TDReplicatorManager.m
// TouchDB
// Created by Jens Alfke on 2/15/12.
// Copyright (c) 2012 Couchbase, Inc. All rights reserved.
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software distributed under the
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.
#import "TDReplicatorManager.h"
#import "TD_Server.h"
#import <TouchDB/TD_Database.h>
#import "TD_Database+Insertion.h"
#import "TD_Database+Replication.h"
#import "TDPusher.h"
#import "TDPuller.h"
#import "TD_View.h"
#import "TDInternal.h"
#import "TDMisc.h"
#import "MYBlockUtils.h"
#import <UIKit/UIApplication.h>
NSString* const kTDReplicatorDatabaseName = @"_replicator";
@interface TDReplicatorManager ()
- (BOOL) validateRevision: (TD_Revision*)newRev context: (id<TD_ValidationContext>)context;
- (void) processAllDocs;
@implementation TDReplicatorManager
- (id) initWithDatabaseManager: (TD_DatabaseManager*)dbManager {
self = [super init];
if (self) {
_dbManager = dbManager;
_replicatorDB = [dbManager databaseNamed: kTDReplicatorDatabaseName];
if (!_replicatorDB) {
return nil;
_thread = [NSThread currentThread];
return self;
- (void)dealloc {
[self stop];
- (void) start {
[_replicatorDB defineValidation: @"TDReplicatorManager" asBlock:
^BOOL(TD_Revision *newRevision, id<TD_ValidationContext> context) {
return [self validateRevision: newRevision context: context];
[self processAllDocs];
[[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(dbChanged:)
name: TD_DatabaseChangeNotification
object: _replicatorDB];
[[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(someDbDeleted:)
name: TD_DatabaseWillBeDeletedNotification
object: nil];
// Register for foreground/background transition notifications, on iOS:
[[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(appForegrounding:)
name: UIApplicationWillEnterForegroundNotification
object: nil];
- (void) stop {
LogTo(TD_Server, @"STOP %@", self);
[_replicatorDB defineValidation: @"TDReplicatorManager" asBlock: nil];
[[NSNotificationCenter defaultCenter] removeObserver: self];
_replicatorsByDocID = nil;
- (NSString*) docIDForReplicator: (TDReplicator*)repl {
return [[_replicatorsByDocID allKeysForObject: repl] lastObject];
#pragma mark - CRUD:
// Validation function for the _replicator database:
- (BOOL) validateRevision: (TD_Revision*)newRev context: (id<TD_ValidationContext>)context {
// Ignore the change if it's one I'm making myself, or if it's a deletion:
if (_updateInProgress || newRev.deleted)
return YES;
// First make sure the basic properties are valid:
NSDictionary* newProperties =;
LogTo(Sync, @"ReplicatorManager: Validating %@: %@", newRev, newProperties);
if ([_dbManager validateReplicatorProperties: newProperties] >= 300) {
context.errorMessage = @"Invalid replication parameters";
return NO;
// Only certain keys can be changed or removed:
NSSet* deletableProperties = [NSSet setWithObjects: @"_replication_state", nil];
NSSet* mutableProperties = [NSSet setWithObjects: @"filter", @"query_params",
@"heartbeat", @"feed", @"reset", nil];
NSSet* partialMutableProperties = [NSSet setWithObjects:@"target", @"source", nil];
return [context enumerateChanges: ^BOOL(NSString *key, id oldValue, id newValue) {
if (![context currentRevision])
return ![key hasPrefix: @"_"];
// allow change of 'headers' and 'auth' in target and source
if ([partialMutableProperties containsObject:key]) {
NSDictionary *old = $castIf(NSDictionary, oldValue);
NSDictionary *nuu = $castIf(NSDictionary, newValue);
if ([oldValue isKindOfClass:[NSString class]]) {
old = @{@"url": oldValue};
if ([newValue isKindOfClass:[NSString class]]) {
nuu = @{@"url": newValue};
NSMutableSet* changedKeys = [NSMutableSet set];
for (NSString *subKey in old.allKeys) {
if (!$equal(old[subKey], nuu[subKey])) {
[changedKeys addObject:subKey];
for (NSString *subKey in nuu.allKeys) {
if (!old[subKey]) {
[changedKeys addObject:subKey];
NSSet* mutableSubProperties = [NSSet setWithObjects:@"headers", @"auth", nil];
[changedKeys minusSet:mutableSubProperties];
return [changedKeys count] == 0;
return [mutableProperties containsObject: key] ||
(newValue == nil && [deletableProperties containsObject: key]);
// PUT a change to a replication document, retrying if there are conflicts:
- (TDStatus) updateDoc: (TD_Revision*)currentRev
withProperties: (NSDictionary*)updates
LogTo(Sync, @"ReplicatorManager: Updating %@ with %@", currentRev, updates);
TDStatus status;
do {
// Create an updated revision by merging in the updates:
NSDictionary* currentProperties =;
NSMutableDictionary* updatedProperties = [currentProperties mutableCopy];
[updatedProperties addEntriesFromDictionary: updates];
[updatedProperties removeObjectForKey: @"reset"]; // reset is one-shot, so take it out now
if ($equal(updatedProperties, currentProperties)) {
status = kTDStatusOK; // this is a no-op change
TD_Revision* updatedRev = [TD_Revision revisionWithProperties: updatedProperties];
// Attempt to PUT the updated revision:
_updateInProgress = YES;
@try {
[_replicatorDB putRevision: updatedRev prevRevisionID: currentRev.revID
allowConflict: NO status: &status];
} @finally {
_updateInProgress = NO;
if (status == kTDStatusConflict) {
// Conflict -- doc has been updated, get the latest revision & try again:
TDStatus status2;
currentRev = [_replicatorDB getDocumentWithID: currentRev.docID
revisionID: nil options: 0
status: &status2];
if (!currentRev)
status = status2;
} while (status == kTDStatusConflict);
if (TDStatusIsError(status))
Warn(@"TDReplicatorManager: Error %d updating _replicator doc %@", status, currentRev);
return status;
- (void) updateDoc: (TD_Revision*)rev forReplicator: (TDReplicator*)repl {
NSString* state;
if (repl.running)
state = @"triggered";
else if (repl.error)
state = @"error";
state = @"completed";
NSMutableDictionary* update = $mdict({@"_replication_id", repl.sessionID});
if (!$equal(state, rev[@"_replication_state"])) {
update[@"_replication_state"] = state;
update[@"_replication_state_time"] = @(time(NULL));
[self updateDoc: rev withProperties: update];
// A replication document has been created, so create the matching TDReplicator:
- (void) processInsertion: (TD_Revision*)rev {
if (_replicatorsByDocID[rev.docID])
LogTo(Sync, @"ReplicatorManager: %@ was created", rev);
NSDictionary* properties =;
TDReplicator* repl = [_dbManager replicatorWithProperties: properties status: NULL];
if (!repl) {
Warn(@"TDReplicatorManager: Can't create replicator for %@", properties);
NSString* replicationID = properties[@"_replication_id"] ?: TDCreateUUID();
repl.sessionID = replicationID;
if (!_replicatorsByDocID)
_replicatorsByDocID = [[NSMutableDictionary alloc] init];
_replicatorsByDocID[rev.docID] = repl;
[[NSNotificationCenter defaultCenter] addObserver: self
selector: @selector(replicatorChanged:)
name: nil
object: repl];
[repl start];
[self updateDoc: rev forReplicator: repl];
// A replication document has been changed:
- (void) processUpdate: (TD_Revision*)rev {
if (!rev[@"_replication_state"]) {
// Client deleted the _replication_state property; restart the replicator:
LogTo(Sync, @"ReplicatorManager: Restarting replicator for %@", rev);
TDReplicator* repl = _replicatorsByDocID[rev.docID];
if (repl) {
[repl.db stopAndForgetReplicator: repl];
[_replicatorsByDocID removeObjectForKey: rev.docID];
[self processInsertion: rev];
// A replication document has been deleted:
- (void) processDeletion: (TD_Revision*)rev ofReplicator: (TDReplicator*)repl {
LogTo(Sync, @"ReplicatorManager: %@ was deleted", rev);
[_replicatorsByDocID removeObjectForKey: rev.docID];
[repl stop];
#pragma mark - NOTIFICATIONS:
- (void) processRevision: (TD_Revision*)rev {
if (rev.generation == 1)
[self processInsertion: rev];
[self processUpdate: rev];
// Create TDReplications for all documents at startup:
- (void) processAllDocs {
if (!_replicatorDB.exists)
[_replicatorDB open];
LogTo(Sync, @"ReplicatorManager scanning existing _replicator docs...");
TDQueryOptions options = kDefaultTDQueryOptions;
options.includeDocs = YES;
NSArray* allDocs = [_replicatorDB getAllDocs: &options][@"rows"];
for (NSDictionary* row in allDocs) {
NSDictionary* docProps = row[@"doc"];
NSString* state = docProps[@"_replication_state"];
if (state==nil || $equal(state, @"triggered") ||
[docProps[@"continuous"] boolValue]) {
[self processInsertion: [TD_Revision revisionWithProperties: docProps]];
LogTo(Sync, @"ReplicatorManager done scanning.");
- (void) appForegrounding: (NSNotification*)n {
// Danger: This is called on the main thread!
MYOnThread(_thread, ^{
LogTo(Sync, @"App activated -- restarting all replications");
[self processAllDocs];
// Notified that a _replicator database document has been created/updated/deleted:
- (void) dbChanged: (NSNotification*)n {
if (_updateInProgress)
TD_Revision* rev = (n.userInfo)[@"rev"];
LogTo(SyncVerbose, @"ReplicatorManager: %@ %@",, rev);
NSString* docID = rev.docID;
if ([docID hasPrefix: @"_"])
if (rev.deleted) {
TDReplicator* repl = _replicatorsByDocID[docID];
if (repl)
[self processDeletion: rev ofReplicator: repl];
} else {
if ([_replicatorDB loadRevisionBody: rev options: 0])
[self processRevision: rev];
Warn(@"Unable to load body of %@", rev);
// Notified that a TDReplicator has changed status or stopped:
- (void) replicatorChanged: (NSNotification*)n {
TDReplicator* repl = n.object;
LogTo(SyncVerbose, @"ReplicatorManager: %@ %@",, repl);
NSString* docID = [self docIDForReplicator: repl];
if (!docID)
return; // If it's not a persistent replicator
TD_Revision* rev = [_replicatorDB getDocumentWithID: docID revisionID: nil];
[self updateDoc: rev forReplicator: repl];
if ($equal(, TDReplicatorStoppedNotification)) {
// Replicator has stopped:
[[NSNotificationCenter defaultCenter] removeObserver: self name: nil object: repl];
[_replicatorsByDocID removeObjectForKey: docID];
// Notified that some database is being deleted; delete any associated replication document:
- (void) someDbDeleted: (NSNotification*)n {
if (!_replicatorDB.exists)
TD_Database* db = n.object;
if ([_dbManager.allOpenDatabases indexOfObjectIdenticalTo: db] == NSNotFound)
NSString* dbName =;
TDQueryOptions options = kDefaultTDQueryOptions;
options.includeDocs = YES;
NSArray* allDocs = [_replicatorDB getAllDocs: &options][@"rows"];
for (NSDictionary* row in allDocs) {
NSDictionary* docProps = row[@"doc"];
NSString* source = $castIf(NSString, docProps[@"source"]);
NSString* target = $castIf(NSString, docProps[@"target"]);
if ([source isEqualToString: dbName] || [target isEqualToString: dbName]) {
// Replication doc involves this database -- delete it:
LogTo(Sync, @"ReplicatorManager deleting replication %@", docProps);
TD_Revision* delRev = [[TD_Revision alloc] initWithDocID: docProps[@"_id"]
revID: nil deleted: YES];
TDStatus status;
if (![_replicatorDB putRevision: delRev
prevRevisionID: docProps[@"_rev"]
allowConflict: NO status: &status]) {
Warn(@"TDReplicatorManager: Couldn't delete replication doc %@", docProps);
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