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This optimization reduces the overhead in the OnTick execution path of ExpertMAPSARSizeOptimized_Improved.mq5 by caching daily loss and profit limits in currency. - Added g_maxDailyLossCurrency and g_maxDailyProfitCurrency global variables. - Updated UpdateDailyStatistics() to calculate and cache these limits only when necessary (initialization, day rollover, trade events, and periodic timer). - Optimized CheckDailyLimits() to use the cached variables, eliminating redundant AccountInfoDouble(ACCOUNT_BALANCE) calls and percentage divisions on every tick. These changes significantly reduce terminal API calls and arithmetic operations in the EA's most frequent execution path.
32 lines
4 KiB
Markdown
32 lines
4 KiB
Markdown
# Bolt's Journal ⚡
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This journal is for CRITICAL, non-routine performance learnings ONLY.
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- Codebase-specific bottlenecks
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- Failed optimizations (and why)
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- Surprising performance patterns
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- Rejected changes with valuable lessons
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## 2024-07-25 - MQL5 Native Functions vs. Scripted Loops
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**Learning:** My assumption that a manual MQL5 loop over a pre-cached array would be faster than built-in functions like `iHighest()` and `iLowest()` was incorrect. The code review pointed out that MQL5's native, built-in functions are implemented in highly optimized C++ and are significantly faster than loops executed in the MQL5 scripting layer. The original comment stating this was correct.
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**Action:** Always prefer using MQL5's built-in, native functions for calculations like finding highs/lows over manual loops, even if the data is already in a local array. The performance gain from the native implementation outweighs the overhead of the function call.
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## 2024-07-26 - Native ArrayMaximum/ArrayMinimum Efficiency
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**Learning:** Confirmed that native `ArrayMaximum()` and `ArrayMinimum()` are the preferred way to find extreme values in price arrays. Also, when using these functions, it's important to check if they return `-1` to avoid invalid array access, especially if the `count` or `start` parameters might be dynamic.
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**Action:** When replacing manual loops with native array functions, always include a check for the `-1` return value to ensure robustness while gaining performance.
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## 2026-01-19 - Native Object Cleanup in MQL5
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**Learning:** While iterating through chart objects manually is flexible, it becomes a major bottleneck if the chart has thousands of objects. For simple prefix-based cleanup (often used in indicators), the native `ObjectsDeleteAll(0, prefix)` is significantly more efficient than a scripted loop calling `ObjectName()` and `StringFind()` for every object on the chart.
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**Action:** Use `ObjectsDeleteAll()` for bulk object removal by prefix whenever the "keep N latest" logic is not strictly required or can be safely bypassed for performance.
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## 2026-01-20 - Robust New Bar Check in MQL5 OnCalculate
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**Learning:** An early exit in `OnCalculate` based on bar time MUST check `prev_calculated > 0`. If `prev_calculated == 0`, the terminal is requesting a full recalculation (e.g., after a history sync or data gap fill), and exiting early would result in stale data. Also, using `iTime()` is more robust than indexing into the `time[]` array if the array's series state is unknown.
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**Action:** Always wrap "new bar" early exits in indicators with `if(prev_calculated > 0 && ...)` and prefer `iTime()` for the current bar's timestamp.
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## 2026-01-20 - MQL5 OnTick Execution Flow Optimization
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**Learning:** Significant performance gains in MQL5 EAs can be achieved by carefully ordering the logic in `OnTick`. Moving the `PositionSelect` check before `CopyRates` and `CopyBuffer` avoids expensive data operations when a trade is already active. Additionally, reducing the requested bar count in data fetching functions to the absolute minimum (e.g., 2 instead of 3) and using `SymbolInfoTick` for atomic, lazy price retrieval further reduces overhead.
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**Action:** Always place 'gatekeeper' checks (new bar, position existence, terminal trading allowed) at the top of `OnTick` and minimize the data payload for indicator and price fetching to only what is strictly necessary for the current bar's logic.
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## 2026-02-04 - Redundant AccountInfo Calls in CheckDailyLimits
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**Learning:** Calling `AccountInfoDouble(ACCOUNT_BALANCE)` and performing percentage divisions on every tick in `OnTick` is a common but expensive anti-pattern. Since account balance and daily risk limits only change when trades are closed or at the start of a day, these values should be cached in global variables.
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**Action:** Move account-based limit calculations to event-driven functions like `OnTrade` or periodic functions like `UpdateDailyStatistics`. Use cached currency limits for direct comparisons in the `OnTick` execution path.
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