AdRoll/mero

Mero is a Memcached client library that supports multiple clusters with automatic AWS ElastiCache discovery and per-cluster configuration. It implements a binary protocol with support for pipelined operations and Compare-And-Swap (CAS) mechanics. The system is built using rebar3 and includes comprehensive test coverage for cluster lifecycle and protocol handling.

Mero now supports configuring multiple memcached clusters with independent settings (such as timeouts and connection limits) rather than a single global configuration. It includes automatic discovery of AWS ElastiCache cluster topologies via the config endpoint, allowing the client to dynamically detect and manage cluster membership changes. The configuration system also introduces a heartbeat mechanism to monitor and reload cluster definitions without requiring a restart.

src · high confidence

The include/mero.hrl header now defines new binary protocol command codes for pipelined operations (MEMCACHE\_INCREMENTQ, SETQ, ADDQ, DELETEQ) and a comprehensive set of error codes (e.g., VALUE\_TOO\_LARGE, NON\_NUMERIC\_INCR, OOM). It also introduces a mero\_item record with a cas field to support Compare-And-Swap (CAS) operations and updates the logging macro structure.

include · high confidence

The project has migrated its build system from a custom Makefile to rebar3, introducing a standardized workflow for compilation, testing, and linting. This change brings several developer-facing improvements: dependency management is now handled via a rebar.lock file with pinned versions (e.g., dynamic\_compile 1.0.0); code quality is enforced through integrated dialyzer, xref, and elvis linting rules; and the build process now supports OTP 25+ (as indicated by minimum\_otp\_vsn) and includes coverage reporting. Additionally, new configuration files (.gitignore, CONTRIBUTING.md, elvis.config) and a CHANGELOG entry clarify contribution guidelines and project structure.

(repo-wide) · high confidence

The placeholder file in the ebin directory has been removed, likely as part of the migration from Makefile to rebar3 which handles the compilation output directory differently.

ebin · medium confidence

Added new Common Test suites to verify cluster configuration processing (\mero\_conf\_monitor\_SUITE\, \mero\_conf\_SUITE\), binary and text protocol worker response parsing (\mero\_wrk\_tcp\_binary\_SUITE\, \mero\_wrk\_tcp\_txt\_SUITE\), and cluster availability/restart logic (\mero\_cluster\_SUITE\). The existing \mero\_SUITE\ was refactored to group tests by protocol and include multi-key operations (\madd\, \mset\, \mcas\), while \mero\_test\_localhost\_SUITE\ was removed in favor of the new structured suites.

test · high confidence

Written by watchdog.canine.dev from the codebase's own history, inside the signed delivery this page is composed from.

• CAI 69 → 65 (-3.7)
• Rubric changed (rubric-2026.09.12 → rubric-2026.09.18) — scores are not directly comparable.

• Code Health 94 → 94 (+0.0)
• Architecture 100 → 100 (+0.0)
• Maturity 49 → 49 (+0.0)
• Readiness 78 → 63 (-14.7)
• Security 97 → 99 (+1.5)

• Coverage not measured — no coverage collector is wired up
• Documentation: no installation or build instructions (README.md)
• Documentation: no usage examples (README.md)
• Off-boarding risk: anonymized user #1

• Off-boarding risk: anonymized user #1

Written by watchdog.canine.dev from the codebase's own history, inside the signed delivery this page is composed from.

AdRoll/mero was measured the same way every project in this corpus was: the same rubric, at a pinned commit, with the result published in full. Point a surveyor at a repository you know and see whether you agree with it.