8 files changed, 157 insertions, 6 deletions

diff --git a/include/erebos/service.h b/include/erebos/service.h
index cec5ea0..ba06495 100644
--- a/include/erebos/service.h
+++ b/include/erebos/service.h
@@ -32,6 +32,8 @@ public:
 
 	virtual UUID uuid() const = 0;
 	virtual void handle(Context &) = 0;
+
+	virtual void serverStarted(const class Server &);
 };
 
 }
diff --git a/include/erebos/state.h b/include/erebos/state.h
index 543e03c..b1567b0 100644
--- a/include/erebos/state.h
+++ b/include/erebos/state.h
@@ -29,6 +29,9 @@ public:
 	template<class T> LocalState shared(const Storage & st, const T & x)
 	{ return updateShared(T::sharedTypeId, x.store(st)); }
 
+	vector<Ref> sharedRefs() const;
+	LocalState sharedRefAdd(const Ref &) const;
+
 private:
 	vector<Ref> lookupShared(UUID) const;
 	LocalState updateShared(UUID, const vector<Ref> &) const;
@@ -47,7 +50,7 @@ template<class T>
 LocalState LocalState::shared(const vector<Stored<T>> & v) const
 {
 	vector<Ref> refs;
-	for (const auto x : v)
+	for (const auto & x : v)
 		refs.push_back(x.ref());
 	return updateShared(T::sharedTypeId, refs);
 }
diff --git a/include/erebos/storage.h b/include/erebos/storage.h
index 75b8139..7ec73ab 100644
--- a/include/erebos/storage.h
+++ b/include/erebos/storage.h
@@ -507,12 +507,16 @@ class WatchedHead : public Head<T>
 	friend class Head<T>;
 	WatchedHead(const Head<T> & h, int watcherId):
 		Head<T>(h), watcherId(watcherId) {}
+	int watcherId;
+
+public:
 	WatchedHead(WatchedHead<T> && h):
 		Head<T>(h), watcherId(h.watcherId)
 	{ h.watcherId = -1; }
-	int watcherId;
 
-public:
+	WatchedHead<T> & operator=(WatchedHead<T> && h)
+	{ watcherId = h.watcherId; h.watcherId = -1; return *this; }
+
 	WatchedHead<T> & operator=(const Head<T> & h) {
 		if (Head<T>::id() != h.id())
 			throw std::runtime_error("WatchedHead ID mismatch");
diff --git a/include/erebos/sync.h b/include/erebos/sync.h
new file mode 100644
index 0000000..0b9ed9a
--- /dev/null
+++ b/include/erebos/sync.h
@@ -0,0 +1,32 @@
+#pragma once
+
+#include <erebos/service.h>
+#include <erebos/state.h>
+#include <erebos/storage.h>
+
+#include <optional>
+#include <mutex>
+
+namespace erebos {
+
+class SyncService : public Service
+{
+public:
+	SyncService();
+	virtual ~SyncService();
+
+	UUID uuid() const override;
+	void handle(Context &) override;
+
+	void serverStarted(const class Server &) override;
+
+private:
+	void peerWatcher(size_t, const class Peer *);
+	void localStateWatcher(const Head<LocalState> &);
+
+	const class Server * server;
+	std::mutex headMutex;
+	std::optional<WatchedHead<LocalState>> watchedHead;
+};
+
+}
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index d8a076a..61f491f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -13,6 +13,7 @@ add_library(erebos
 	service
 	state
 	storage
+	sync
 	time
 	uuid
 )
diff --git a/src/service.cpp b/src/service.cpp
index c731990..14ff665 100644
--- a/src/service.cpp
+++ b/src/service.cpp
@@ -33,3 +33,7 @@ void Service::Context::local(const LocalState & ls)
 {
 	p->local = p->local.ref().storage().store(ls);
 }
+
+void Service::serverStarted(const class Server &)
+{
+}
diff --git a/src/state.cpp b/src/state.cpp
index 8790dfc..6e39b5e 100644
--- a/src/state.cpp
+++ b/src/state.cpp
@@ -78,13 +78,41 @@ vector<Ref> LocalState::lookupShared(UUID type) const
 	return res;
 }
 
+vector<Ref> LocalState::sharedRefs() const
+{
+	vector<Ref> refs;
+	for (const auto & x : p->shared)
+		refs.push_back(x.ref());
+	return refs;
+}
+
+LocalState LocalState::sharedRefAdd(const Ref & ref) const
+{
+	const Storage * st;
+	if (p->shared.size() > 0)
+		st = &p->shared[0].ref().storage();
+	else if (p->identity)
+		st = &p->identity->ref()->storage();
+	else
+		st = &ref.storage();
+
+	LocalState ret;
+	ret.p->identity = p->identity;
+	ret.p->shared = p->shared;
+	ret.p->shared.push_back(SharedState(ref).store(*st));
+	filterAncestors(ret.p->shared);
+	return ret;
+}
+
 LocalState LocalState::updateShared(UUID type, const vector<Ref> & xs) const
 {
 	const Storage * st;
-	if (xs.size() > 0)
-		st = &xs[0].storage();
-	else if (p->shared.size() > 0)
+	if (p->shared.size() > 0)
 		st = &p->shared[0].ref().storage();
+	else if (p->identity)
+		st = &p->identity->ref()->storage();
+	else if (xs.size() > 0)
+		st = &xs[0].storage();
 	else
 		return *this;
 
diff --git a/src/sync.cpp b/src/sync.cpp
new file mode 100644
index 0000000..37f7ca9
--- /dev/null
+++ b/src/sync.cpp
@@ -0,0 +1,77 @@
+#include <erebos/sync.h>
+
+#include <erebos/network.h>
+
+using namespace erebos;
+
+using std::scoped_lock;
+
+static const UUID myUUID("a4f538d0-4e50-4082-8e10-7e3ec2af175d");
+
+SyncService::SyncService() = default;
+SyncService::~SyncService() = default;
+
+UUID SyncService::uuid() const
+{
+	return myUUID;
+}
+
+void SyncService::handle(Context & ctx)
+{
+	auto pid = ctx.peer().identity();
+	if (!pid)
+		return;
+
+	const auto & powner = pid->finalOwner();
+	const auto & owner = ctx.peer().server().identity().finalOwner();
+
+	if (!powner.sameAs(owner))
+		return;
+
+	ctx.local(
+		ctx.local()->sharedRefAdd(ctx.ref())
+	);
+}
+
+void SyncService::serverStarted(const Server & s)
+{
+	server = &s;
+	server->peerList().onUpdate(std::bind(&SyncService::peerWatcher, this,
+				std::placeholders::_1, std::placeholders::_2));
+	watchedHead = server->localHead().watch(std::bind(&SyncService::localStateWatcher, this,
+				std::placeholders::_1));
+}
+
+void SyncService::peerWatcher(size_t, const Peer * peer)
+{
+	if (peer && peer->identity()->finalOwner().sameAs(
+				server->identity().finalOwner())) {
+		scoped_lock lock(headMutex);
+		for (const auto & r : (*watchedHead)->sharedRefs())
+			peer->send(myUUID, r);
+	}
+}
+
+void SyncService::localStateWatcher(const Head<LocalState> & head)
+{
+	scoped_lock lock(headMutex);
+
+	bool same = head->sharedRefs().size() ==
+		(*watchedHead)->sharedRefs().size();
+	if (same) {
+		for (size_t i = 0; i < head->sharedRefs().size(); i++)
+			if (head->sharedRefs()[i].digest() !=
+					(*watchedHead)->sharedRefs()[i].digest()) {
+				same = false;
+				break;
+			}
+	}
+
+	if (!same) {
+		*watchedHead = head;
+		const auto & plist = server->peerList();
+		for (size_t i = 0; i < plist.size(); i++)
+			for (const auto & r : (*watchedHead)->sharedRefs())
+				plist.at(i).send(myUUID, r);
+	}
+}