1 #pragma once
2 
3 #include <mbgl/util/optional.hpp>
4 
5 #include <memory>
6 #include <mutex>
7 #include <queue>
8 
9 namespace mbgl {
10 
11 class Scheduler;
12 class Message;
13 
14 class Mailbox : public std::enable_shared_from_this<Mailbox> {
15 public:
16 
17     // Create a "holding" mailbox, messages to which will remain queued,
18     // unconsumed, until the mailbox is associated with a Scheduler using
19     // start(). This allows a Mailbox object to be created on one thread and
20     // later transferred to a different target thread that may not yet exist.
21     Mailbox();
22 
23     Mailbox(Scheduler&);
24 
25     // Attach the given scheduler to this mailbox and begin processing messages
26     // sent to it. The mailbox must be a "holding" mailbox, as created by the
27     // default constructor Mailbox().
28     void open(Scheduler& scheduler_);
29     void close();
30 
31     bool isOpen() const;
32 
33     void push(std::unique_ptr<Message>);
34     void receive();
35 
36     static void maybeReceive(std::weak_ptr<Mailbox>);
37 
38 private:
39     optional<Scheduler*> scheduler;
40 
41     std::recursive_mutex receivingMutex;
42     std::mutex pushingMutex;
43 
44     bool closed { false };
45 
46     std::mutex queueMutex;
47     std::queue<std::unique_ptr<Message>> queue;
48 };
49 
50 } // namespace mbgl
51