MemSharp client for Python

A dependency-free client for MemSharp, an in-memory database for .NET that speaks RESP. Python 3.10+.

pip install ./clients/python

Start a server first: memsharp serve --port 6380.

from memsharp import MemSharpClient, WrongTypeError

with MemSharpClient(port=6380) as db:
    db.set("symbol:BTC", "68350.25")
    db.set("session:9f2", "kang", ex=1800)

    db.zadd("book:BTC:bids", {"bid-1": 68349.75})
    top = db.zrange("book:BTC:bids", 0, 9, desc=True, withscores=True)

    db.xadd("trades", {"sym": "BTC", "qty": "5"}, maxlen=100_000)
    db.ts_add("px", 68_350.25)

    # rows come back keyed by column name
    for row in db.sql("SELECT key, size FROM keys WHERE key LIKE 'order:%'"):
        print(row["key"], row["size"])

    # one round-trip for the whole batch
    db.pipeline([["SET", f"k{i}", str(i)] for i in range(1000)])

Streams and consumer groups

Times are in seconds, as everywhere else in this client (ex=, ttl()).

with MemSharpClient(port=6380) as db:
    db.xgroup_create("jobs", "workers", mkstream=True)      # id defaults to "$": only new entries

    # {key: [(id, fields), ...]}, or None if nothing arrived within block seconds
    batch = db.xreadgroup("workers", "w1", "jobs", count=10, block=5)
    for entry_id, fields in (batch or {}).get("jobs", []):
        ...
        db.xack("jobs", "workers", entry_id)

    db.xpending("jobs", "workers")                 # {"count", "min", "max", "consumers": {name: n}}
    db.xpending_range("jobs", "workers", count=10) # [{"id", "consumer", "idle", "deliveries"}, ...]

    # recover what a crashed consumer left behind
    next_start, claimed, deleted = db.xautoclaim("jobs", "workers", "w2", min_idle=60)
    db.xclaim("jobs", "workers", "w2", 60, "1700000000000-0", justid=True)

    db.xread({"prices": "$"}, block=0)             # plain tail, no group; 0 waits forever

A blocking read lifts the socket timeout for its duration, so block= longer than the client's timeout works. Also: xgroup_destroy, xgroup_createconsumer, xgroup_delconsumer, xgroup_setid, xinfo_groups, xinfo_consumers, xinfo_stream.

Also in 1.1

Tests

They run against a live server rather than a mock, because the only thing worth testing in a protocol client is that its bytes match what the server actually sends back.

memsharp serve --port 6391 --quiet &
python clients/python/test_client.py        # 126 checks

Notes

• No dependencies. RESP is simple enough that a client dragging in a dependency tree costs its users more than it saves them.
• A missing key is distinguishable from an empty one.
• WRONGTYPE gets its own exception type, so you can catch it specifically.
• Pipelining returns errors in place rather than raising, so one failing command does not hide the replies to the others.
• Subscribing takes over the connection. Use a second client for ordinary commands.

Full reference, including every method: docs/en/clients.md · docs/id/clients.md

By Gravicode Studios, led by Kang Fadhil. MIT licensed.