feat contrib: add futures subscription from contrib

<https://nda.ya.ru/t/nesU8Ssd7StzZd>
commit_hash:3b5733332bec71a4f2f26e6e878afb23dde01fe7

1 files changed, 65 insertions, 0 deletions

diff --git a/library/cpp/threading/future/subscription/subscription.cpp b/library/cpp/threading/future/subscription/subscription.cpp
new file mode 100644
index 00000000000..e3cb3052c8d
--- /dev/null
+++ b/library/cpp/threading/future/subscription/subscription.cpp
@@ -0,0 +1,65 @@
+#include "subscription.h"
+
+namespace NThreading {
+
+bool operator==(TSubscriptionId const& l, TSubscriptionId const& r) noexcept {
+    return l.StateId() == r.StateId() && l.SubId() == r.SubId();
+}
+
+bool operator!=(TSubscriptionId const& l, TSubscriptionId const& r) noexcept {
+    return !(l == r);
+}
+
+void TSubscriptionManager::TSubscription::operator()() {
+    Callback();
+}
+
+TSubscriptionManagerPtr TSubscriptionManager::NewInstance() {
+    return new TSubscriptionManager();
+}
+
+TSubscriptionManagerPtr TSubscriptionManager::Default() {
+    static auto instance = NewInstance();
+    return instance;
+}
+
+void TSubscriptionManager::Unsubscribe(TSubscriptionId id) {
+    with_lock(Lock) {
+        UnsubscribeImpl(id);
+    }
+}
+
+void TSubscriptionManager::Unsubscribe(TVector<TSubscriptionId> const& ids) {
+    with_lock(Lock) {
+        UnsubscribeImpl(ids);
+    }
+}
+
+void TSubscriptionManager::OnCallback(TFutureStateId stateId) noexcept {
+    THashMap<ui64, TSubscription> subscriptions;
+    with_lock(Lock) {
+        auto const it = Subscriptions.find(stateId);
+        Y_ABORT_UNLESS(it != Subscriptions.end(), "The callback has been triggered more than once");
+        subscriptions.swap(it->second);
+        Subscriptions.erase(it);
+    }
+    for (auto& [_, subscription] : subscriptions) {
+        subscription();
+    }
+}
+
+void TSubscriptionManager::UnsubscribeImpl(TSubscriptionId id) {
+    auto const it = Subscriptions.find(id.StateId());
+    if (it == std::end(Subscriptions)) {
+        return;
+    }
+    it->second.erase(id.SubId());
+}
+
+void TSubscriptionManager::UnsubscribeImpl(TVector<TSubscriptionId> const& ids) {
+    for (auto const& id : ids) {
+        UnsubscribeImpl(id);
+    }
+}
+
+}