mzimbres | 1 year ago | on: BSD kqueue is a mountain of technical debt (2021)
mzimbres's comments
mzimbres | 1 year ago | on: Async await: the worst thing to happen to programming?
This depends on what are your expectation. IO operations must suspend to wait for data read and writes, therefore it is not possible to avoid Async/Await. In other cases you might have multiple tasks depending on a specific IO operation, for example, one connection to a database that is used by multiple HTTP sessions, here it is also not possible to avoid Async/Await because those sessions are bound to an IO operation.
The real problem however comes when tasks that can complete synchrously are implemented with an asynchronous interface, for example
message = Await websocket.read(socket, buffer, ...)
This is a poor design because a socket read can pull multiple messages from the kernel buffers into user space and there should be a way to consumed them without Await. Many libraries however don't for watch this problem and that results in the everything is async madness.mzimbres | 1 year ago | on: Async await: the worst thing to happen to programming?
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mzimbres | 2 years ago | on: How to think about async/await in Rust
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mzimbres | 3 years ago | on: Build Your Own Redis with C/C++
- Be asynchronous and based on Boost.Asio.
- Perform automatic command pipelining [1]. All C++ libraries I looked at the time would open new connections for that, which results in unacceptable performance losses.
- Parse Redis responses directly in their final data structures avoiding extra copies. This is useful for example to store json strings in Redis and read them back efficiently.
With time I built more performance features
- Full duplex communication.
- Support for RESP3 and server pushes on the same connection that is being used for request/response.
- Event demultiplexing: It can server thousands of requests (e.g. websocket sessions) on a single connection to Redis with back pressure. This is important to keep the number of connections to Redis low and avoid latency introduced by countermeasures like [3].
This client was proposed and accepted in Boost (but not yet integrated), interested readers can find links to the review here [2].
[1] https://redis.io/docs/manual/pipelining/
mzimbres | 3 years ago | on: Building a Cloud Database from Scratch: Why We Moved from C++ to Rust (2022)
* unreadable coding style: This is not a C++ problem. * memory leak: Memory leak is an old C++ problem, since C++11 there is no reason for not using smart pointers.
The only point that could be attributed to C++ is the segfaults perhaps, due to its lack of safety. But your other two points made me skeptical about Rust bringing you much benefit. I am specially concerned about throwing away months worth of code. Rewriting everything from scratch is what newbies love to do and will most likely get you in the same mess you were in. Try to learn with the error of others [1]. And btw, the problem is usually who writes the code and not which language is used.
[1] https://www.joelonsoftware.com/2000/04/06/things-you-should-...
mzimbres | 4 years ago | on: “Modern” C++ Lamentations (2018)
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mzimbres | 4 years ago | on: Why can’t I go faster than the speed of light?
I don't think so. You can't even implement a full-duplex protocol properly with sync IO since reading and writing can't happen at the same time on the same thread. Splitting them to different threads also won't help since accessing shared state requires synchronization with e.g. mutex that kills again simultaneous reading and writing.