feat(grpc): add BBR-based adaptive rate limiting middleware for gRPC

[gaius-qi]

Description

This pull request introduces an adaptive rate limiting feature based on a BBR-inspired algorithm for gRPC download and upload servers, and synchronizes workspace dependencies across the project. The most important changes are the addition of the BBRConfig and its integration into server configuration, implementation of the BBR middleware for gRPC, and updates to dependency versions for improved consistency and compatibility.

Adaptive Rate Limiting for gRPC Servers

• Added BBRConfig struct for adaptive rate limiting configuration to dragonfly-client-config/src/dfdaemon.rs, including default values and integration into the Server struct and its Default implementation. This enables dynamic request shedding based on CPU and memory usage. [1] [2] [3]
• Implemented serialization, deserialization, and default logic for BBRConfig in dragonfly-client-util/src/ratelimiter/bbr.rs, along with helper functions for default values. Added debug logging for cooldown periods. [1] [2] [3] [4]

Middleware Integration

• Integrated the BBR rate limiter middleware (BBRLayer) into both download and upload gRPC servers (dragonfly-client/src/grpc/dfdaemon_download.rs and dragonfly-client/src/grpc/dfdaemon_upload.rs), including struct changes and service builder layering. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]

Dependency Synchronization

• Updated workspace package version and dependency versions in Cargo.toml files across the project to ensure consistency, including strict version pinning for several crates (e.g., dragonfly-client, tonic, opentelemetry, tower, console-subscriber, etc.). [1] [2] [3] [4] [5] [6]

Codebase Maintenance

• Minor refactor in dragonfly-client/src/grpc/manager.rs for improved readability and import clarity.

Related Issue

Motivation and Context

Screenshots (if appropriate)

[codecov]

Codecov Report

❌ Patch coverage is 48.52941% with 35 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.87%. Comparing base (b44f9a8) to head (f939e56).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dragonfly-client/src/grpc/middleware.rs	25.80%	23 Missing ⚠️
dragonfly-client/src/bin/dfdaemon/main.rs	0.00%	5 Missing ⚠️
dragonfly-client/src/grpc/dfdaemon_download.rs	0.00%	3 Missing ⚠️
dragonfly-client/src/grpc/dfdaemon_upload.rs	0.00%	3 Missing ⚠️
dragonfly-client-util/src/ratelimiter/bbr.rs	96.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1732      +/-   ##
==========================================
+ Coverage   46.53%   46.87%   +0.33%     
==========================================
  Files          86       87       +1     
  Lines       24749    24811      +62     
==========================================
+ Hits        11517    11629     +112     
+ Misses      13232    13182      -50     

Files with missing lines	Coverage Δ
dragonfly-client-config/src/dfdaemon.rs	89.31% <100.00%> (+0.01%)	⬆️
dragonfly-client/src/grpc/manager.rs	22.07% <ø> (ø)
dragonfly-client/src/grpc/mod.rs	0.00% <ø> (ø)
dragonfly-client-util/src/ratelimiter/bbr.rs	79.80% <96.00%> (+15.38%)	⬆️
dragonfly-client/src/grpc/dfdaemon_download.rs	5.03% <0.00%> (-0.02%)	⬇️
dragonfly-client/src/grpc/dfdaemon_upload.rs	0.00% <0.00%> (ø)
dragonfly-client/src/bin/dfdaemon/main.rs	0.00% <0.00%> (ø)
dragonfly-client/src/grpc/middleware.rs	25.80% <25.80%> (ø)

... and 2 files with indirect coverage changes

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