diff options
Diffstat (limited to 'src/mbgl/actor/mailbox.cpp')
-rw-r--r-- | src/mbgl/actor/mailbox.cpp | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/src/mbgl/actor/mailbox.cpp b/src/mbgl/actor/mailbox.cpp index 5f60629833..947f6f9028 100644 --- a/src/mbgl/actor/mailbox.cpp +++ b/src/mbgl/actor/mailbox.cpp @@ -10,8 +10,23 @@ Mailbox::Mailbox(Scheduler& scheduler_) : scheduler(scheduler_) { } +void Mailbox::close() { + // Block until neither receive() nor push() are in progress. Two mutexes are used because receive() + // must not block send(). Of the two, the receiving mutex must be acquired first, because that is + // the order that an actor will obtain them when it self-sends a message, and consistent lock + // acquisition order prevents deadlocks. + std::lock_guard<std::mutex> receivingLock(receivingMutex); + std::lock_guard<std::mutex> pushingLock(pushingMutex); + + closed = true; +} + void Mailbox::push(std::unique_ptr<Message> message) { - assert(!closing); + std::lock_guard<std::mutex> pushingLock(pushingMutex); + + if (closed) { + return; + } std::lock_guard<std::mutex> queueLock(queueMutex); bool wasEmpty = queue.empty(); @@ -21,16 +36,10 @@ void Mailbox::push(std::unique_ptr<Message> message) { } } -void Mailbox::close() { - // Block until the scheduler is guaranteed not to be executing receive(). - std::lock_guard<std::mutex> closingLock(closingMutex); - closing = true; -} - void Mailbox::receive() { - std::lock_guard<std::mutex> closingLock(closingMutex); + std::lock_guard<std::mutex> receivingLock(receivingMutex); - if (closing) { + if (closed) { return; } |