Keeps track of the number of connected clients #447
Conversation
in the GridConnect TCP hub.
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Perhaps this can be extended slightly further to actively reject new clients when the current client count is over a certain limit? |
I don't need that feature. Do you? |
Possibly, the esp32 heap quickly reduces (and may crash) when both CAN and TCP/IP GC Hub are enabled and more than a couple clients are connected. I've considered dropping Hub support on the esp32 entirely for this reason and have already disabled it on the esp32s2 (slightly lower heap to start with). If the GC connections were sharing the payload it may not be as much of an issue though. |
Did you debug why this crashes? Or under which condition?
Did you try setting SO_SNDBUF to a low value (e.g. 2 kbytes)? |
Not fully yet, I'll be delving into it before taking any action to disable.
I'll need to do some testing with that, the default is 5744 bytes (4x MSS). |
| create_gc_port_for_can_hub(canHub_, fd, nullptr, use_select); | ||
| { | ||
| AtomicHolder h(this); | ||
| numClients_++; |
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Not sure if modern compilers are smart enough to substitute a pre-increment if they can, but a pre-increment should be less instruction cycles.
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The recommendation to use pre-increment instead of post-increment comes from Scott Meyers' Effective C++ book, and specifically applies to class types that define the pre- and post-increment operator. The most typical place where we encounter such classes are STL iterators. The recommendation was true until about GCC 2.95, beyond which however GCC figured out how to optimize away the copies even from iterators if the implementation available for inlining. It also means that this recommendation has never been true for primitive types.
| AtomicHolder h(this); | ||
| if (numClients_) | ||
| { | ||
| numClients_--; |
I will defer the client count limiting, because it really has to be a feature of the SocketListener instead. When we have limiting we must make sure not to call the accept() after the connection limit has been reached. So the accept thread needs to be paused and resumed, which needs API changes there. |
Keeps track of the number of connected clients in the GridConnect TCP hub. Conversation is in #447. * Adds an accessor to fetch the number of connected stations. * fix whitespace * Keeps track of the number of connected clients in the GridConnect TCP hub. * fix whitespace * Fix typo
in the GridConnect TCP hub.