From 409ef553fa30d9aae8c906108711866edb58d7fa Mon Sep 17 00:00:00 2001
From: Petr Pokorny <petr-pokorny@hotmail.com>
Date: Mon, 22 Feb 2021 16:00:37 +0100
Subject: [PATCH] MGLSDKMetricsManager.h imported by accident. Added
 observable.hpp header.

---
 platform/ios/platform/ios/src/Mapbox.h |  1 -
 src/mbgl/util/observable.hpp           | 67 ++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 src/mbgl/util/observable.hpp

diff --git a/platform/ios/platform/ios/src/Mapbox.h b/platform/ios/platform/ios/src/Mapbox.h
index 88e0486a8..333190cf6 100644
--- a/platform/ios/platform/ios/src/Mapbox.h
+++ b/platform/ios/platform/ios/src/Mapbox.h
@@ -56,7 +56,6 @@ FOUNDATION_EXPORT MGL_EXPORT const unsigned char MapboxVersionString[];
 #import "MGLRasterDEMSource.h"
 #import "MGLRasterStyleLayer.h"
 #import "MGLRasterTileSource.h"
-#import "MGLSDKMetricsManager.h"
 #import "MGLShape.h"
 #import "MGLShapeCollection.h"
 #import "MGLShapeOfflineRegion.h"
diff --git a/src/mbgl/util/observable.hpp b/src/mbgl/util/observable.hpp
new file mode 100644
index 000000000..15af10003
--- /dev/null
+++ b/src/mbgl/util/observable.hpp
@@ -0,0 +1,67 @@
+#pragma once
+
+#include <map>
+#include <mapbox/compatibility/value.hpp>
+#include <mbgl/actor/scheduler.hpp>
+#include <mbgl/util/chrono.hpp>
+#include <memory>
+#include <mutex>
+#include <string>
+#include <vector>
+
+namespace mbgl {
+
+class Observer;
+
+struct ObservableEvent {
+    explicit ObservableEvent(std::string type);
+    std::string type;
+    TimePoint begin;
+    TimePoint end;
+    mapbox::base::Value data;
+};
+
+class Observer {
+public:
+    virtual ~Observer() = default;
+
+    // Notifies Observer about an event
+    virtual void notify(const ObservableEvent&) = 0;
+
+    // Id of an observer, must be unique.
+    // Default implementation uses `this` address of an instance.
+    virtual std::size_t id() const;
+};
+
+// Observable class implements basic Publish&Subscribe functionality
+class Observable {
+public:
+    Observable();
+    virtual ~Observable();
+
+    // Subscribes `Observer` to recieve notifications of the event types provided in `eventTypes`
+    // `Observer::id()` would be used as an `id` for subscription.
+    virtual void subscribe(const std::shared_ptr<Observer>&, const std::vector<std::string>& eventTypes);
+
+    // Unsubscribes perviosly subscribed `Observer` with an `id`, that is provided by `Observer::id()`
+    // Whenever an empty list of events is provided, observer would be unsubscribed from all events.
+    virtual void unsubscribeWithId(std::size_t id, const std::vector<std::string>& eventTypes);
+
+    // Must return true if `Observable` supports an `eventType`.
+    virtual bool supportsEventType(const std::string& eventType) const;
+
+    // Shorthand for virtual method accepting `Observer` id.
+    void unsubscribe(const std::shared_ptr<Observer>&, const std::vector<std::string>& eventTypes);
+    void unsubscribe(const std::shared_ptr<Observer>&);
+
+protected:
+    void dispatchEvent(const ObservableEvent&);
+    bool hasSubscribers() const;
+
+private:
+    struct Subscriber;
+    std::map<std::size_t, std::unique_ptr<Subscriber>> subscribers;
+    mutable std::mutex mutex;
+};
+
+} // namespace mbgl