Parviz MiriyevandGitHub
2212cc8a5f
* shell: expose retention flags on mq.topic.configure
The ConfigureTopicRequest proto already carries a TopicRetention message
({retention_seconds, enabled}), and GetTopicConfigurationResponse / the
admin UI both surface it — but the `mq.topic.configure` shell command
sent Retention: nil unconditionally, leaving CLI and IaC users with no
way to set retention without going through the admin UI. Add three
flags so the shell matches the existing surface:
-retention <duration> Go duration string (e.g. 168h, 30m)
-retentionSeconds <int> raw seconds (mutually exclusive with -retention)
-retentionEnabled bool toggle for retention enforcement
Behavior:
- If none of the retention flags are set, the request omits Retention
(`nil`) — preserving the prior "leave server-side state alone"
semantics for callers that only care about partition count.
- Setting any retention flag populates TopicRetention with both fields
so existing operators keep working when only one is provided.
- -retention and -retentionSeconds together is a hard error (ambiguous);
negative values are rejected.
The new behavior is detected via flag.FlagSet.Visit so default values
of 0 / false are distinguishable from "not provided".
Help text updated with examples for both setting a TTL and disabling
retention on an existing topic. No proto / server changes needed; this
is a CLI-only patch.
* broker, shell: address review for mq.topic.configure retention
Three follow-up fixes for the review comments on the original commit:
1. Server-side: detect retention changes in the early-return path.
Previously ConfigureTopic returned without persisting when
partitionCount + schema were unchanged, even if the request supplied
a different Retention. Now the early-return branch checks both
schema and retention, persists either or both when they differ, and
logs which fields actually changed.
2. Server-side: preserve existing retention when request.Retention is
nil in the fresh-allocation path. Capture the prior resp.Retention
before overwriting `resp = &mq_pb.ConfigureTopicResponse{}`, and
only overwrite the new resp.Retention with `request.Retention` when
the request actually supplies one. Otherwise carry the previous
retention forward, so partition-count changes (or any path that
bypasses the early-return branch) don't accidentally clear retention.
3. CLI: switch the `-retention` / `-retentionSeconds` mutual-exclusion
check from value-based (`!= 0`) to flag.FlagSet.Visit-based, so an
explicit `-retention=0 -retentionSeconds=N` is also rejected.
4. CLI: when any retention flag is set, fetch the current
GetTopicConfiguration and fill in the fields the user didn't
explicitly provide. This means `-retentionEnabled` alone no longer
zeros the existing duration, and `-retention 24h` alone preserves
the existing enabled flag. When the topic doesn't exist yet, the
GetTopicConfiguration error is treated as "no current state" and
we proceed with just the user-supplied values.
Build / vet / gofmt / `go test ./weed/shell/... ./weed/mq/broker/...`
clean.
SeaweedMQ Message Queue on SeaweedFS (WIP, not ready)
What are the use cases it is designed for?
Message queues are like water pipes. Messages flow in the pipes to their destinations.
However, what if a flood comes? Of course, you can increase the number of partitions, add more brokers, restart, and watch the traffic level closely.
Sometimes the flood is expected. For example, backfill some old data in batch, and switch to online messages. You may want to ensure enough brokers to handle the data and reduce them later to cut cost.
SeaweedMQ is designed for use cases that need to:
- Receive and save large number of messages.
- Handle spike traffic automatically.
What is special about SeaweedMQ?
- Separate computation and storage nodes to scale independently.
- Unlimited storage space by adding volume servers.
- Unlimited message brokers to handle incoming messages.
- Offline messages can be operated as normal files.
- Scale up and down with auto split and merge message topics.
- Topics can automatically split into segments when traffic increases, and vice verse.
- Pass messages by reference instead of copying.
- Clients can optionally upload the messages first and just submit the references.
- Drastically reduce the broker load.
- Stateless brokers
- All brokers are equal. One broker is dynamically picked as the leader.
- Add brokers at any time.
- Allow rolling restart brokers or remove brokers at a pace.
Design
How it works?
Brokers are just computation nodes without storage. When a broker starts, it reports itself to masters. Among all the brokers, one of them will be selected as the leader by the masters.
A topic needs to define its partition key on its messages.
Messages for a topic are divided into segments. One segment can cover a range of partitions. A segment can be split into 2 segments, or 2 neighboring segments can be merged back to one segment.
During write time, the client will ask the broker leader for a few brokers to process the segment.
The broker leader will check whether the segment already has assigned the brokers. If not, select a few brokers based on their loads, save the selection into filer, and tell the client.
The client will write the messages for this segment to the selected brokers.
Failover
The broker leader does not contain any state. If it fails, the masters will select a different broker.
For a segment, if any one of the selected brokers is down, the remaining brokers should try to write received messages to the filer, and close the segment to the clients.
Then the clients should start a new segment. The masters should assign other healthy brokers to handle the new segment.
So any brokers can go down without losing data.
Auto Split or Merge
(The idea is learned from Pravega.)
The brokers should report its traffic load to the broker leader periodically.
If any segment has too much load, the broker leader will ask the brokers to tell the client to close current one and create two new segments.
If 2 neighboring segments have the combined load below average load per segment, the broker leader will ask the brokers to tell the client to close this 2 segments and create a new segment.