Add MemcacheSocket class and response types with CI tests

[bisho]

Motivation / Description

This pull request introduces a high-performance Rust-based MemcacheSocket class that provides low-level socket operations for memcache protocol communication. The implementation focuses on performance optimization through zero-copy operations, efficient buffer management, and GIL-free I/O operations.

This replaced the python-implementation in meta-memcahce-py extension and provides 20% faster gets and 40% faster set/deletes (less CPU) on multithreaded tests:

Latency per-request is not that measurable, as typical memcache latency will be dominated by the network, but it significantly reduces CPU usage, allocations and GIL lock time.

Before/after with 10 threads doing operations on a loop against a local memcache.

=== Starting benchmark ===
 - server: 127.0.0.1:11211
 - consistent_sharding: OFF
 - concurrency: 10 threads
 - per phase: 0.30M requests (3 runs x 10,000 ops x 10 threads)
 - key space: 200 keys

-SET total: 0.30M in 6.72s => 44,638 RPS / 22.40 us/req
-GET total: 0.30M in 6.79s => 44,214 RPS / 22.62 us/req
-DELETE total: 0.30M in 6.75s => 44,415 RPS / 22.51 us/req
+SET total: 0.30M in 4.02s => 74,598 RPS / 13.41 us/req
+GET total: 0.30M in 5.45s => 55,047 RPS / 18.17 us/req
+DELETE total: 0.30M in 3.94s => 76,060 RPS / 13.15 us/req

Changes introduced

• Added MemcacheSocket class with methods for sending commands (sendall), receiving responses (get_response), and reading value data (get_value)
• Implemented response type classes (Value, Success, Miss, NotStored, Conflict) to represent different memcache server responses
• Added NOOP command handling to support pipelined operations and response synchronization
• Introduced server version constants (SERVER_VERSION_AWS_1_6_6, SERVER_VERSION_STABLE) for compatibility with different memcache server implementations
• Added libc dependency for direct system call access to socket operations
• Implemented zero-copy value reading for small values that fit within the internal buffer
• Added support for non-blocking sockets with timeout handling via poll()
• Created comprehensive test suite covering socket operations, response parsing, buffer management, and error handling scenarios
• Added CI jobs for both Rust tests and Python integration tests using uv and maturin
• Bumped package version from 0.1.7 to 2.0.0 to reflect the major API additions

[bisho]

• Raw cmd for special usages #17
• multi-get #16
• Move key encoding to socket api #15
• Add meta command methods to MemcacheSocket #14
• Add MemcacheSocket class and response types with CI tests #13 👈 (View in Graphite)
• Bump version to 0.1.7 and add Python 3.13t support #12
• Refactor parse_header to return structured type and update to Rust 2024 #11
• Bump version to 0.1.6 and optimize performance #9
• Update to PyO3 Bound API #10
• main

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[antoniobg]

Overall this is a really impressive change — the performance gains are substantial and the code is well-structured. I found a few issues worth addressing before merging, mostly around socket/OS-level edge cases.

[bisho]

Merge activity

• Mar 24, 4:58 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Mar 24, 5:07 PM UTC: Graphite rebased this pull request as part of a merge.
• Mar 24, 5:07 PM UTC: @bisho merged this pull request with Graphite.