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[bluetooth_proxy] Optimize memory usage with fixed-size array and const string references - #10015

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jesserockz merged 2 commits into
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bluetooth_connection_churn_array
Aug 5, 2025
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[bluetooth_proxy] Optimize memory usage with fixed-size array and const string references#10015
jesserockz merged 2 commits into
devfrom
bluetooth_connection_churn_array

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@bdraco
@bdraco bdraco commented Aug 2, 2025 •
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What does this implement/fix?

This PR optimizes the bluetooth_proxy component to reduce both flash and RAM usage:

  1. Optimize string handling in logging: Changed address_str() method in BLEClientBase to return a const reference instead of by value, eliminating unnecessary string copies during frequent logging operations.

  2. Replace dynamic vector with fixed array: Converted the connections_ vector to a fixed-size std::array since all connection objects are created at compile time and the count never changes. This eliminates:

    • 12 bytes of RAM on 32-bit systems (vector's internal pointer, size, and capacity members)
    • Dynamic memory allocation for the vector's buffer
    • Heap fragmentation
    • Code for dynamic memory management

These optimizations result in:

  • 576 bytes of flash savings
  • 12+ bytes of RAM savings (12 bytes for vector overhead plus heap allocation overhead)

Types of changes

  • Bugfix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • Code quality improvements to existing code or addition of tests
  • Other

Related issue or feature (if applicable):

Pull request in esphome-docs with documentation (if applicable):

  • N/A (no user-visible changes)

Test Environment

  • ESP32
  • ESP32 IDF
  • ESP8266
  • RP2040
  • BK72xx
  • RTL87xx
  • nRF52840

Example entry for config.yaml:

# No configuration changes required - internal optimization only
bluetooth_proxy:
  active: true

Checklist:

  • The code change is tested and works locally.
  • Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

@github-actions
github-actions Bot commented Aug 2, 2025 •
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To use the changes from this PR as an external component, add the following to your ESPHome configuration YAML file:

external_components:
  - source: github://pr#10015
    components: [bluetooth_proxy, esp32_ble_client]
    refresh: 1h

(Added by the PR bot)

@codecov-commenter
codecov-commenter commented Aug 2, 2025 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.19%. Comparing base (4f58e1c) to head (a8f4b5c).

Additional details and impacted files 
@@           Coverage Diff           @@
##              dev   #10015   +/-   ##
=======================================
  Coverage   60.19%   60.19%           
=======================================
  Files          51       51           
  Lines       10305    10305           
  Branches     1368     1368           
=======================================
  Hits         6203     6203           
  Misses       3745     3745           
  Partials      357      357

☔ View full re 8000 port in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:
  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

@bdraco
bdraco force-pushed the bluetooth_connection_churn_array branch from 68ab351 to 20959c2 Compare August 2, 2025 06:32
@bdraco
bdraco marked this pull request as ready for review August 2, 2025 06:32
Copilot AI review requested due to automatic review settings August 2, 2025 06:33
@bdraco
bdraco requested a review from jesserockz as a code owner August 2, 2025 06:33
@github-actions
github-actions Bot commented Aug 2, 2025
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👋 Hi there! I've automatically requested reviews from codeowners based on the files changed in this PR.

@jesserockz - You've been requested to review this PR as codeowner(s) of 3 file(s) that were modified. Thanks for your time! 🙏

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@bdraco
bdraco requested a review from Copilot August 2, 2025 07:28
Copilot AI reviewed Aug 2, 2025
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Pull Request Overview

This PR optimizes memory usage in the bluetooth_proxy component by implementing two key changes to reduce both flash and RAM consumption. The optimization converts dynamic memory structures to more efficient alternatives while maintaining the same functionality.

  • Changed address_str() method to return const string reference instead of by value to eliminate unnecessary string copies
  • Replaced dynamic std::vector with fixed-size std::array for connection storage since the connection count is determined at compile time

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File Description
esphome/components/esp32_ble_client/ble_client_base.h Modified address_str() to return const reference for optimized string handling
esphome/components/bluetooth_proxy/bluetooth_proxy.h Replaced std::vector with std::array and added connection counter for fixed-size storage
esphome/components/bluetooth_proxy/bluetooth_proxy.cpp Updated connection iteration logic to use array indexing with connection counter

Comment thread esphome/components/bluetooth_proxy/bluetooth_proxy.h
@jesserockz
jesserockz merged commit 93b2844 into dev Aug 5, 2025
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@jesserockz
jesserockz deleted the bluetooth_connection_churn_array branch August 5, 2025 01:13
@github-actions github-actions Bot locked and limited conversation to collaborators Aug 7, 2025
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@jesserockz jesserockz jesserockz approved these changes

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