From 2abd6593c8b047d3fd579aa6cc0058bbebe266f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Sun, 17 Jan 2021 21:59:46 +0100
Subject: Server watching local state head

---
 src/storage.h | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

(limited to 'src/storage.h')

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;
-- 
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