From 7aa7649e980ff4b335b41eaea34a9a11820c3e2d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Mon, 8 Aug 2022 22:25:46 +0200
Subject: Generation number of stored objects with caching

---
 src/main.cpp    | 47 +++++++++++++++++++++++++++++++++++++++
 src/storage.cpp | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/storage.h   |  3 +++
 3 files changed, 119 insertions(+)

(limited to 'src')

diff --git a/src/main.cpp b/src/main.cpp
index cb9002e..a3facea 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4,6 +4,8 @@
 #include <erebos/storage.h>
 #include <erebos/sync.h>
 
+#include "storage.h"
+
 #include <arpa/inet.h>
 #include <netinet/in.h>
 #include <sys/socket.h>
@@ -37,6 +39,7 @@ using std::promise;
 using std::scoped_lock;
 using std::string;
 using std::thread;
+using std::to_string;
 using std::unique_ptr;
 using std::vector;
 
@@ -104,6 +107,48 @@ struct Command
 	function<void(const vector<string> &)> action;
 };
 
+void store(const vector<string> & args)
+{
+	auto type = args.at(0);
+
+	vector<uint8_t> inner, data;
+
+	char * line = nullptr;
+	size_t size = 0;
+
+	while (getline(&line, &size, stdin) > 0 && strlen(line) > 1)
+		copy(line, line + strlen(line), std::back_inserter(inner));
+
+	free(line);
+
+	auto inserter = std::back_inserter(data);
+	copy(type.begin(), type.end(), inserter);
+	inserter = ' ';
+
+	auto slen = to_string(inner.size());
+	copy(slen.begin(), slen.end(), inserter);
+	inserter = '\n';
+
+	copy(inner.begin(), inner.end(), inserter);
+
+	auto digest = st.priv().storeBytes(data);
+
+	ostringstream ss;
+	ss << "store-done " << string(digest);
+	printLine(ss.str());
+}
+
+void storedGeneration(const vector<string> & args)
+{
+	auto ref = st.ref(Digest(args.at(0)));
+	if (!ref)
+		throw invalid_argument("ref " + args.at(0) + " not found");
+
+	ostringstream ss;
+	ss << "stored-generation " << string(ref->digest()) << " " << string(ref->generation());
+	printLine(ss.str());
+}
+
 void createIdentity(const vector<string> & args)
 {
 	optional<Identity> identity;
@@ -292,6 +337,8 @@ void attachReject(const vector<string> & params)
 }
 
 vector<Command> commands = {
+	{ "store", store },
+	{ "stored-generation", storedGeneration },
 	{ "create-identity", createIdentity },
 	{ "start-server", startServer },
 	{ "stop-server", stopServer },
diff --git a/src/storage.cpp b/src/storage.cpp
index 05b100a..5784309 100644
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -979,6 +979,56 @@ const Storage & Ref::storage() const
 	return *static_cast<const Storage*>(p->storage.get());
 }
 
+vector<Ref> Ref::previous() const
+{
+	auto rec = (**this).asRecord();
+	if (!rec)
+		return {};
+
+	vector<Ref> res;
+
+	auto sdata = rec->item("SDATA").asRef();
+	if (sdata) {
+		auto drec = sdata.value()->asRecord();
+		if (!drec)
+			return {};
+
+		for (const Record::Item & i : drec->items("SPREV"))
+			if (auto x = i.asRef())
+				res.push_back(*x);
+		return res;
+	}
+
+	for (const Record::Item & i : rec->items("PREV"))
+		if (auto x = i.asRef())
+			res.push_back(*x);
+	return res;
+}
+
+Generation Ref::generation() const
+{
+	scoped_lock lock(p->storage->p->generationCacheLock);
+	return generationLocked();
+}
+
+Generation Ref::generationLocked() const
+{
+	auto it = p->storage->p->generationCache.find(p->digest);
+	if (it != p->storage->p->generationCache.end())
+		return it->second;
+
+	auto prev = previous();
+	vector<Generation> pgen;
+	pgen.reserve(prev.size());
+	for (const auto & r : prev)
+		pgen.push_back(r.generationLocked());
+
+	auto gen = Generation::next(pgen);
+
+	p->storage->p->generationCache.emplace(p->digest, gen);
+	return gen;
+}
+
 
 template<class S>
 RecordT<S>::Item::operator bool() const
@@ -1366,6 +1416,25 @@ optional<Blob> ObjectT<S>::asBlob() const
 template class erebos::ObjectT<Storage>;
 template class erebos::ObjectT<PartialStorage>;
 
+
+Generation::Generation(): Generation(0) {}
+Generation::Generation(size_t g): gen(g) {}
+
+Generation Generation::next(const vector<Generation> & prev)
+{
+	Generation ret;
+	for (const auto g : prev)
+		if (ret.gen <= g.gen)
+			ret.gen = g.gen + 1;
+	return ret;
+}
+
+Generation::operator string() const
+{
+	return to_string(gen);
+}
+
+
 vector<Stored<Object>> erebos::collectStoredObjects(const Stored<Object> & from)
 {
 	unordered_set<Digest> seen;
diff --git a/src/storage.h b/src/storage.h
index 0f7c3bf..ef335b8 100644
--- a/src/storage.h
+++ b/src/storage.h
@@ -164,6 +164,9 @@ struct PartialStorage::Priv
 	optional<Digest> copy(const typename S::Ref &, vector<Digest> *) const;
 	template<class S>
 	optional<Digest> copy(const ObjectT<S> &, vector<Digest> *) const;
+
+	mutable mutex generationCacheLock {};
+	mutable unordered_map<Digest, Generation> generationCache {};
 };
 
 struct PartialRef::Priv
-- 
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