feat: Improve the RTC process of Read/Write model

[chenbt-hz]

about: #2542
改动：在读请求放入队列前，先进行判断是否在cache中读取

[chejinge]

我有个疑问，如果这个命令应该在cache中读取 但是命不中，还是得放入队列吧，只有命中了才不用放入队列
判断命中不命中就相当于查询了一次cache了

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

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I have a question. If this command should be read from the cache but misses, it still has to be put into the queue. Only if it hits, there is no need to put it into the queue.
Determining whether the hit is a hit or not is equivalent to querying the cache once.

[chejinge]

读命令并且没有命中，不去读DB直接返回时为什么

[chenbt-hz]

没有命中就回走正常逻辑，把命令扔队列里

[chejinge]

这里需要判断cache的状态

[AlexStocks]

@CodiumAI-Agent /review

[CodiumAI-Agent]

PR Review 🔍

⏱️ Estimated effort to review [1-5]	4, because the PR involves significant changes across multiple files including core functionality and command behavior modifications. The changes impact the command execution flow, particularly in how commands are processed for cache reads and the conditions under which commands are queued. Understanding and verifying these changes requires a deep understanding of the existing architecture and the implications of the new flags and command behaviors.
🧪 Relevant tests	No
⚡ Possible issues	Thread Safety: The BatchReadCmdInCache function modifies shared state such as resp_num and resp_array without apparent synchronization mechanisms in a multi-threaded context, which might lead to race conditions.
	Error Handling: In the BatchReadCmdInCache function, if AuthRequired() returns true and the command does not pass the authentication check, it sets an error response but does not clean up or reset the state, potentially leading to incorrect behavior or leaks in subsequent operations.
🔒 Security concerns	No

Code feedback:

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relevant file	src/pika_client_conn.cc
suggestion	Consider adding thread safety mechanisms, such as mutexes, to protect the shared state modifications in the BatchReadCmdInCache function. This is important to prevent data races and ensure the integrity of shared data across multiple threads. [important]
relevant line	resp_num.store(static_cast(argvs.size()));

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relevant file	src/pika_client_conn.cc
suggestion	Implement proper cleanup and state reset in the BatchReadCmdInCache function when an authentication error occurs. This could prevent potential memory leaks or undefined behaviors in subsequent operations. [important]
relevant line	c_ptr->res().SetRes(CmdRes::kErrOther, "NOAUTH Authentication required.");

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relevant file	src/pika_client_conn.cc
suggestion	Optimize the command lookup in BatchReadCmdInCache by reducing redundant lookups for the same command, which could improve performance by minimizing map access operations. [medium]
relevant line	std::shared_ptr c_ptr = g_pika_cmd_table_manager->GetCmd(argv[0]);

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relevant file	src/pika_command.cc
suggestion	Refactor the DoReadCommandInCache method to separate concerns more clearly, possibly by splitting the method into smaller, more focused methods. This can improve readability and maintainability of the code. [medium]
relevant line	bool Cmd::DoReadCommandInCache(const HintKeys& hint_keys) {

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[AlexStocks]

@CodiumAI-Agent /improve

[CodiumAI-Agent]

PR Code Suggestions ✨

Category	Suggestion	Score
Possible issue	Ensure command processing only continues if the batch read operation was successful Consider checking the return value of BatchReadCmdInCache before proceeding with scheduling the client pool. This ensures that the command processing only continues if the batch read operation was successful. src/pika_client_conn.cc [282-288] if (BatchReadCmdInCache(argvs)){ + g_pika_server->ScheduleClientPool(&DoBackgroundTask, arg, is_slow_cmd); return; } -g_pika_server->ScheduleClientPool(&DoBackgroundTask, arg, is_slow_cmd); Suggestion importance[1-10]: 9 Why: This suggestion ensures that the command processing only continues if the batch read operation was successful, which is crucial for the correct functioning of the code. It addresses a potential issue where the client pool might be scheduled even if the batch read operation failed.	9
Thread safety	Ensure thread safety and correct handling by using fetch_sub for atomic decrement Replace the manual decrement of resp_num with a more robust method that ensures thread safety and correct handling under various conditions. src/pika_client_conn.cc [354-355] *resp_ptr = std::move(c_ptr->res().message()); -resp_num--; +resp_num.fetch_sub(1, std::memory_order_relaxed); Suggestion importance[1-10]: 8 Why: This suggestion enhances thread safety by using fetch_sub for atomic decrement of resp_num. It ensures correct handling under various conditions, which is important for concurrent environments.	8
Performance	Improve memory allocation efficiency by reserving capacity for resp_array outside the loop Avoid using std::make_sharedstd::string() repeatedly inside a loop. Instead, reserve the necessary capacity for resp_array outside the loop to improve memory allocation efficiency. src/pika_client_conn.cc [327-329] +resp_array.reserve(argvs.size()); for (const auto& argv : argvs) { std::shared_ptr<std::string> resp_ptr = std::make_shared<std::string>(); resp_array.push_back(resp_ptr); ... } Suggestion importance[1-10]: 7 Why: This suggestion improves memory allocation efficiency by reserving capacity for resp_array outside the loop. It is a minor optimization but can enhance performance, especially with large input sizes.	7
Maintainability	Improve code readability and maintainability by separating locking logic into a dedicated method Refactor the DoReadCommandInCache method to separate concerns of locking and cache reading. This improves readability and maintainability. src/pika_command.cc [920-927] -if (!IsSuspend()) { - db_->DBLockShared(); +ManageLock(); +... +void Cmd::ManageLock() { + if (!IsSuspend()) { + db_->DBLockShared(); + DEFER { + db_->DBUnlockShared(); + }; + } } -DEFER { - if (!IsSuspend()) { - db_->DBUnlockShared(); - } -}; -... Suggestion importance[1-10]: 6 Why: This suggestion improves code readability and maintainability by separating the locking logic into a dedicated method. While it does not change the functionality, it makes the code easier to understand and maintain.	6