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authorRoman Smrž <roman.smrz@seznam.cz>2021-02-17 22:15:27 +0100
committerRoman Smrž <roman.smrz@seznam.cz>2021-02-19 19:40:58 +0100
commit5dc467310ddebeae8dcb6262f5499f37382711ab (patch)
tree77dc6c6fd0abec84246aaacfbf5a8d471081e2ae /include/erebos
parentd42ed33bb9112d80ae9adc926b7bd818a4d35f8d (diff)
WatchedHead object allowing to stop watching Head
Diffstat (limited to 'include/erebos')
-rw-r--r--include/erebos/storage.h43
1 files changed, 39 insertions, 4 deletions
diff --git a/include/erebos/storage.h b/include/erebos/storage.h
index 07e7a4f..10ced57 100644
--- a/include/erebos/storage.h
+++ b/include/erebos/storage.h
@@ -11,6 +11,7 @@
#include <future>
#include <memory>
#include <optional>
+#include <stdexcept>
#include <string>
#include <variant>
#include <vector>
@@ -99,6 +100,7 @@ public:
protected:
template<typename T> friend class Head;
+ template<typename T> friend class WatchedHead;
Storage(const std::shared_ptr<const Priv> p): PartialStorage(p) {}
@@ -107,7 +109,8 @@ protected:
static UUID storeHead(UUID type, const Ref & ref);
static bool replaceHead(UUID type, UUID id, const Ref & old, const Ref & ref);
static std::optional<Ref> updateHead(UUID type, UUID id, const Ref & old, const std::function<Ref(const Ref &)> &);
- void watchHead(UUID type, UUID id, const std::function<void(const Ref &)>) const;
+ int watchHead(UUID type, UUID id, const std::function<void(const Ref &)>) const;
+ void unwatchHead(UUID type, UUID id, int watchId) const;
};
class Digest
@@ -472,6 +475,8 @@ void filterAncestors(std::vector<Stored<T>> & xs)
}
}
+template<class T> class WatchedHead;
+
template<class T>
class Head
{
@@ -489,13 +494,34 @@ public:
const Ref & ref() const { return mstored.ref(); }
std::optional<Head<T>> update(const std::function<Stored<T>(const Stored<T> &)> &) const;
- void watch(const std::function<void(const Head<T> &)> &) const;
+ WatchedHead<T> watch(const std::function<void(const Head<T> &)> &) const;
private:
UUID mid;
Stored<T> mstored;
};
+template<class T>
+class WatchedHead : public Head<T>
+{
+ friend class Head<T>;
+ WatchedHead(const Head<T> & h, int watcherId):
+ Head<T>(h), watcherId(watcherId) {}
+ WatchedHead(WatchedHead<T> && h):
+ Head<T>(h), watcherId(h.watcherId)
+ { h.watcherId = -1; }
+ int watcherId;
+
+public:
+ WatchedHead<T> & operator=(const Head<T> & h) {
+ if (Head<T>::id() != h.id())
+ throw std::runtime_error("WatchedHead ID mismatch");
+ static_cast<Head<T> &>(*this) = h;
+ return *this;
+ }
+ ~WatchedHead();
+};
+
template<typename T>
std::optional<Head<T>> Storage::head(UUID id) const
{
@@ -545,11 +571,20 @@ std::optional<Head<T>> Head<T>::update(const std::function<Stored<T>(const Store
}
template<typename T>
-void Head<T>::watch(const std::function<void(const Head<T> &)> & watcher) const
+WatchedHead<T> Head<T>::watch(const std::function<void(const Head<T> &)> & watcher) const
{
- stored().ref().storage().watchHead(T::headTypeId, id(), [id = id(), watcher] (const Ref & ref) {
+ int wid = stored().ref().storage().watchHead(T::headTypeId, id(), [id = id(), watcher] (const Ref & ref) {
watcher(Head<T>(id, ref));
});
+ return WatchedHead<T>(*this, wid);
+}
+
+template<class T>
+WatchedHead<T>::~WatchedHead()
+{
+ if (watcherId >= 0)
+ Head<T>::stored().ref().storage().unwatchHead(
+ T::headTypeId, Head<T>::id(), watcherId);
}
}