Server watching local state head

4 files changed, 176 insertions, 9 deletions

diff --git a/src/network.cpp b/src/network.cpp
index 4b79dcb..bd64e07 100644
--- a/src/network.cpp
+++ b/src/network.cpp
@@ -21,8 +21,8 @@ using std::unique_lock;
 
 using namespace erebos;
 
-Server::Server(const Identity & self, vector<unique_ptr<Service>> && svcs):
-	p(new Priv(self, std::move(svcs)))
+Server::Server(const Head<LocalState> & head, vector<unique_ptr<Service>> && svcs):
+	p(new Priv(head, *head->identity(), std::move(svcs)))
 {
 }
 
@@ -139,7 +139,9 @@ void PeerList::onUpdate(function<void(size_t, const Peer *)> w)
 }
 
 
-Server::Priv::Priv(const Identity & self, vector<unique_ptr<Service>> && svcs):
+Server::Priv::Priv(const Head<LocalState> & local, const Identity & self,
+		vector<unique_ptr<Service>> && svcs):
+	localHead(local),
 	self(self),
 	services(std::move(svcs))
 {
@@ -176,6 +178,8 @@ Server::Priv::Priv(const Identity & self, vector<unique_ptr<Service>> && svcs):
 
 	threadListen = thread([this] { doListen(); });
 	threadAnnounce = thread([this] { doAnnounce(); });
+
+	local.watch(std::bind(&Priv::handleLocalHeadChange, this, std::placeholders::_1));
 }
 
 Server::Priv::~Priv()
@@ -447,6 +451,23 @@ void Server::Priv::handlePacket(Server::Peer & peer, const TransportHeader & hea
 	}
 }
 
+void Server::Priv::handleLocalHeadChange(const Head<LocalState> & head)
+{
+	scoped_lock lock(dataMutex);
+	if (auto id = head->identity()) {
+		if (id->ref()->digest() != self.ref()->digest()) {
+			self = *id;
+
+			TransportHeader header({
+				{ TransportHeader::Type::AnnounceSelf, *self.ref() }
+			});
+
+			for (const auto & peer : peers)
+				peer->send(header, { **self.ref() });
+		}
+	}
+}
+
 void Server::Peer::send(const TransportHeader & header, const vector<Object> & objs) const
 {
 	vector<uint8_t> data, part, out;
diff --git a/src/network.h b/src/network.h
index 9b146a9..c02dbc3 100644
--- a/src/network.h
+++ b/src/network.h
@@ -136,7 +136,8 @@ struct WaitingRef
 
 struct Server::Priv
 {
-	Priv(const Identity & self, vector<unique_ptr<Service>> && svcs);
+	Priv(const Head<LocalState> & local, const Identity & self,
+			vector<unique_ptr<Service>> && svcs);
 	~Priv();
 	void doListen();
 	void doAnnounce();
@@ -144,6 +145,8 @@ struct Server::Priv
 	Peer & getPeer(const sockaddr_in & paddr);
 	void handlePacket(Peer &, const TransportHeader &, ReplyBuilder &);
 
+	void handleLocalHeadChange(const Head<LocalState> &);
+
 	constexpr static uint16_t discoveryPort { 29665 };
 	constexpr static chrono::seconds announceInterval { 60 };
 
@@ -151,6 +154,7 @@ struct Server::Priv
 	condition_variable announceCondvar;
 	bool finish = false;
 
+	Head<LocalState> localHead;
 	Identity self;
 	vector<unique_ptr<Service>> services;
 
diff --git a/src/storage.cpp b/src/storage.cpp
index 45caadb..4f48c67 100644
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -9,7 +9,10 @@
 #include <stdexcept>
 #include <thread>
 
+#include <poll.h>
 #include <stdio.h>
+#include <sys/eventfd.h>
+#include <sys/inotify.h>
 
 #include <blake2.h>
 #include <zlib.h>
@@ -28,8 +31,10 @@ using std::monostate;
 using std::nullopt;
 using std::ofstream;
 using std::runtime_error;
+using std::scoped_lock;
 using std::shared_ptr;
 using std::string;
+using std::system_error;
 using std::to_string;
 
 FilesystemStorage::FilesystemStorage(const fs::path & path):
@@ -45,6 +50,24 @@ FilesystemStorage::FilesystemStorage(const fs::path & path):
 		fs::create_directory(path/"heads");
 }
 
+FilesystemStorage::~FilesystemStorage()
+{
+	if (inotifyWakeup >= 0) {
+		uint64_t x = 1;
+		write(inotifyWakeup, &x, sizeof(x));
+	}
+
+	if (watcherThread.joinable())
+		watcherThread.join();
+
+	if (inotify >= 0)
+		close(inotify);
+
+	if (inotifyWakeup >= 0)
+		close(inotifyWakeup);
+
+}
+
 bool FilesystemStorage::contains(const Digest & digest) const
 {
 	return fs::exists(objectPath(digest));
@@ -237,6 +260,29 @@ bool FilesystemStorage::replaceHead(UUID type, UUID id, const Digest & old, cons
 	return true;
 }
 
+void FilesystemStorage::watchHead(UUID type, const function<void(UUID id, const Digest &)> & watcher)
+{
+	scoped_lock lock(watcherLock);
+	watchers.emplace(type, watcher);
+
+	if (inotify < 0) {
+		inotify = inotify_init();
+		if (inotify < 0)
+			throw system_error(errno, std::generic_category());
+
+		inotifyWakeup = eventfd(0, 0);
+		if (inotifyWakeup < 0)
+			throw system_error(errno, std::generic_category());
+
+		watcherThread = std::thread(&FilesystemStorage::inotifyWatch, this);
+	}
+
+	int fd = inotify_add_watch(inotify, headPath(type).c_str(), IN_MOVED_TO);
+	if (fd < 0)
+		throw system_error(errno, std::generic_category());
+	watchMap[fd] = type;
+}
+
 optional<vector<uint8_t>> FilesystemStorage::loadKey(const Digest & pubref) const
 {
 	fs::path path = keyPath(pubref);
@@ -259,6 +305,55 @@ void FilesystemStorage::storeKey(const Digest & pubref, const vector<uint8_t> &
 	file.write((const char *) key.data(), key.size());
 }
 
+void FilesystemStorage::inotifyWatch()
+{
+	char buf[4096]
+		__attribute__ ((aligned(__alignof__(struct inotify_event))));
+	const struct inotify_event * event;
+
+	array pfds {
+		pollfd { inotify, POLLIN, 0 },
+		pollfd { inotifyWakeup, POLLIN, 0 },
+	};
+
+	while (true) {
+		int ret = poll(pfds.data(), pfds.size(), -1);
+		if (ret < 0)
+			throw system_error(errno, std::generic_category());
+
+		if (!(pfds[0].revents & POLLIN))
+			break;
+
+		ssize_t len = read(inotify, buf, sizeof buf);
+		if (len < 0) {
+			if (errno == EAGAIN)
+				continue;
+
+			throw system_error(errno, std::generic_category());
+		}
+
+		if (len == 0)
+			break;
+
+		for (char * ptr = buf; ptr < buf + len;
+				ptr += sizeof(struct inotify_event) + event->len) {
+			event = (const struct inotify_event *) ptr;
+
+			if (event->mask & IN_MOVED_TO) {
+				UUID type = watchMap[event->wd];
+				if (auto mbid = UUID::fromString(event->name)) {
+					if (auto mbref = headRef(type, *mbid)) {
+						scoped_lock lock(watcherLock);
+						auto range = watchers.equal_range(type);
+						for (auto it = range.first; it != range.second; it++)
+							it->second(*mbid, *mbref);
+					}
+				}
+			}
+		}
+	}
+}
+
 fs::path FilesystemStorage::objectPath(const Digest & digest) const
 {
 	string name(digest);
@@ -267,12 +362,16 @@ fs::path FilesystemStorage::objectPath(const Digest & digest) const
 		fs::path(name.begin() + 2, name.end());
 }
 
+fs::path FilesystemStorage::headPath(UUID type) const
+{
+	string stype(type);
+	return root/"heads"/fs::path(stype.begin(), stype.end());
+}
+
 fs::path FilesystemStorage::headPath(UUID type, UUID id) const
 {
-	string stype(type), sid(id);
-	return root/"heads"/
-		fs::path(stype.begin(), stype.end())/
-		fs::path(sid.begin(), sid.end());
+	string sid(id);
+	return headPath(type) / fs::path(sid.begin(), sid.end());
 }
 
 fs::path FilesystemStorage::keyPath(const Digest & digest) const
@@ -367,6 +466,12 @@ bool MemoryStorage::replaceHead(UUID type, UUID id, const Digest & old, const Di
 	return false;
 }
 
+void MemoryStorage::watchHead(UUID type, const function<void(UUID id, const Digest &)> & watcher)
+{
+	scoped_lock lock(watcherLock);
+	watchers.emplace(type, watcher);
+}
+
 optional<vector<uint8_t>> MemoryStorage::loadKey(const Digest & digest) const
 {
 	auto it = keys.find(digest);
@@ -436,6 +541,12 @@ bool ChainStorage::replaceHead(UUID type, UUID id, const Digest & old, const Dig
 	return storage->replaceHead(type, id, old, dgst);
 }
 
+void ChainStorage::watchHead(UUID type, const function<void(UUID id, const Digest &)> & watcher)
+{
+	parent->watchHead(type, watcher);
+	storage->watchHead(type, watcher);
+}
+
 optional<vector<uint8_t>> ChainStorage::loadKey(const Digest & digest) const
 {
 	if (auto res = storage->loadKey(digest))
@@ -669,6 +780,15 @@ optional<Ref> Storage::updateHead(UUID type, UUID id, const Ref & old, const std
 		return nullopt;
 }
 
+void Storage::watchHead(UUID type, UUID wid, const std::function<void(const Ref &)> watcher) const
+{
+	p->backend->watchHead(type, [this, wid, watcher] (UUID id, const Digest & dgst) {
+		if (id == wid)
+			if (auto r = ref(dgst))
+				watcher(*r);
+	});
+}
+
 
 Digest::Digest(const string & str)
 {
diff --git a/src/storage.h b/src/storage.h
index 18ac1ad..b8d769c 100644
--- a/src/storage.h
+++ b/src/storage.h
@@ -2,16 +2,21 @@
 
 #include "erebos/storage.h"
 
+#include <functional>
+#include <mutex>
 #include <unordered_map>
 #include <unordered_set>
 
 namespace fs = std::filesystem;
 
+using std::function;
+using std::mutex;
 using std::optional;
 using std::shared_future;
 using std::shared_ptr;
 using std::unique_ptr;
 using std::unordered_map;
+using std::unordered_multimap;
 using std::unordered_set;
 using std::tuple;
 using std::variant;
@@ -34,6 +39,7 @@ public:
 	virtual vector<tuple<UUID, Digest>> headRefs(UUID type) const = 0;
 	virtual UUID storeHead(UUID type, const Digest & dgst) = 0;
 	virtual bool replaceHead(UUID type, UUID id, const Digest & old, const Digest & dgst) = 0;
+	virtual void watchHead(UUID type, const function<void(UUID id, const Digest &)> &) = 0;
 
 	virtual optional<vector<uint8_t>> loadKey(const Digest &) const = 0;
 	virtual void storeKey(const Digest &, const vector<uint8_t> &) = 0;
@@ -43,7 +49,7 @@ class FilesystemStorage : public StorageBackend
 {
 public:
 	FilesystemStorage(const fs::path &);
-	virtual ~FilesystemStorage() = default;
+	virtual ~FilesystemStorage();
 
 	virtual bool contains(const Digest &) const override;
 
@@ -54,20 +60,31 @@ public:
 	virtual vector<tuple<UUID, Digest>> headRefs(UUID type) const override;
 	virtual UUID storeHead(UUID type, const Digest & dgst) override;
 	virtual bool replaceHead(UUID type, UUID id, const Digest & old, const Digest & dgst) override;
+	virtual void watchHead(UUID type, const function<void(UUID id, const Digest &)> &) override;
 
 	virtual optional<vector<uint8_t>> loadKey(const Digest &) const override;
 	virtual void storeKey(const Digest &, const vector<uint8_t> &) override;
 
 private:
+	void inotifyWatch();
+
 	static constexpr size_t CHUNK = 16384;
 
 	fs::path objectPath(const Digest &) const;
+	fs::path headPath(UUID id) const;
 	fs::path headPath(UUID id, UUID type) const;
 	fs::path keyPath(const Digest &) const;
 
 	FILE * openLockFile(const fs::path & path) const;
 
 	fs::path root;
+
+	mutex watcherLock;
+	std::thread watcherThread;
+	int inotify = -1;
+	int inotifyWakeup = -1;
+	unordered_multimap<UUID, function<void(UUID id, const Digest &)>> watchers;
+	unordered_map<int, UUID> watchMap;
 };
 
 class MemoryStorage : public StorageBackend
@@ -85,6 +102,7 @@ public:
 	virtual vector<tuple<UUID, Digest>> headRefs(UUID type) const override;
 	virtual UUID storeHead(UUID type, const Digest & dgst) override;
 	virtual bool replaceHead(UUID type, UUID id, const Digest & old, const Digest & dgst) override;
+	virtual void watchHead(UUID type, const function<void(UUID id, const Digest &)> &) override;
 
 	virtual optional<vector<uint8_t>> loadKey(const Digest &) const override;
 	virtual void storeKey(const Digest &, const vector<uint8_t> &) override;
@@ -93,6 +111,9 @@ private:
 	unordered_map<Digest, vector<uint8_t>> storage;
 	unordered_map<UUID, vector<tuple<UUID, Digest>>> heads;
 	unordered_map<Digest, vector<uint8_t>> keys;
+
+	mutex watcherLock;
+	unordered_multimap<UUID, function<void(UUID id, const Digest &)>> watchers;
 };
 
 class ChainStorage : public StorageBackend
@@ -113,6 +134,7 @@ public:
 	virtual vector<tuple<UUID, Digest>> headRefs(UUID type) const override;
 	virtual UUID storeHead(UUID type, const Digest & dgst) override;
 	virtual bool replaceHead(UUID type, UUID id, const Digest & old, const Digest & dgst) override;
+	virtual void watchHead(UUID type, const function<void(UUID id, const Digest &)> &) override;
 
 	virtual optional<vector<uint8_t>> loadKey(const Digest &) const override;
 	virtual void storeKey(const Digest &, const vector<uint8_t> &) override;