Implement XNACK - #4734
Implement XNACK#4734nickiaq wants to merge 2 commits into
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This command makes it possible to release stream message(s) for immediate
reclaim.
XNACK <key> <group> <SILENT | FAIL | FATAL> IDS <numids> <id…>
[RETRYCOUNT <count>] [FORCE]
For one or more entries in the consumer group's PEL, set the delivery time
to 0. This allows XCLAIM/XAUTOCLAIM to immediately claim it. The mode
option (SILENT, FAIL, FATAL) allows control over the delivery count of the
message as follows:
- SILENT: decrements the count, returning it to the value before claim (min 0)
- FAIL: does nothing, allowing count to tick up with each claim
- FATAL: sets count to LLONG_MAX
This PR also clamps each path that increases the delivery count so that it
cannot overflow LLONG_MAX, which is the largest RESP integer for
replication/aof. (XCLAIM, XAUTOCLAIM, and XREADGROUP)
The trailing options are intended for internal use only, enabling
AOF/replication of each message NACK'd specifying the exact delivery count.
For the FORCE option specifically, it introduces a blank consumer name that
is used whenever creating a PEL entry that didn't exist before. This isn't
necessary in XCLAIM because it comes with a consumer name. However, there
is none here, thus the blank consumer.
This internal consumer is necessary to ensure that state converges. It is
excluded in several places (`XINFO CONSUMERS`, `XGROUP DELCONSUMER`,
`XINFO GROUPS`, `XINFO STREAM ... FULL`), but not all places (ex. XPENDING
with extended output).
Return value of the command is the number of messages successfully NACK'd.
This commit also includes test coverage for 1) each mode & option, 2)
the additions to other commands (ignoring blank consumer & incr clamp
to LLONG_MAX), and 3) replication/aof using RETRYCOUNT/FORCE.
Signed-off-by: Nick Iaquinto <git+valkey@iaquinto.io>
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Included review availability: Your plan provides up to 10 included reviews per hour; 8 remain after this review. 📝 WalkthroughWalkthroughXNACK adds a stream command that releases PEL entries for immediate reclaim. It supports delivery-count modes, retry-count overrides, and FORCE-created dummy consumers. The change also updates replication, AOF restoration, delivery-count clamping, IDS parsing, and consumer metadata. ChangesXNACK stream command
Priority: ➖ Normal Estimated code review effort: 4 (Complex) | ~45 minutes Sequence Diagram(s)sequenceDiagram
participant Client
participant xnackCommand
participant StreamPEL
participant Replica
Client->>xnackCommand: XNACK key group mode IDS ids
xnackCommand->>StreamPEL: Update PEL delivery state
xnackCommand->>Replica: Propagate per-ID XNACK commands
Replica->>StreamPEL: Restore replicated PEL state
Possibly related PRs
Suggested reviewers: Merge Risk: 🟡 Moderate · up to A client can create an empty-named consumer whose pending entries become hidden from consumer metadata and cannot be removed through DELCONSUMER, so this should be fixed before merging. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
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Actionable comments posted: 3
- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
In `@src/commands/xnack.json`:
- Line 3: Update the XNACK command’s summary and reply_schema description to
describe releasing entries for immediate reclaim rather than removing them from
the PEL; make the wording consistent with entries remaining in the PEL, and
apply the change in the XNACK definition alongside the existing summary and
reply_schema fields.
In `@src/t_stream.c`:
- Around line 3352-3357: Introduce an explicit FORCE-sentinel representation for
stream consumers, distinct from legitimate empty-name consumers, and propagate
it through stream creation, RDB loading, AOF rewrite/replay, and consumer
copying. Update count, XINFO, and DELCONSUMER filtering/deletion to check the
sentinel state rather than consumer-name length, while preserving existing
empty-name consumers and their persistence behavior.
In `@tests/unit/type/stream-cgroups.tcl`:
- Around line 1972-1973: Update the XPENDING assertion in the stream
consumer-group replication test to request all pending entries instead of one.
Using the existing pend result, assert that both entries are returned and verify
IDs 1-0 and 2-0 each have delivery count 1.
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src/commands.defsrc/commands/xnack.jsonsrc/server.csrc/server.hsrc/t_stream.ctests/unit/type/stream-cgroups.tcltests/unit/type/stream.tcl
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| argv[8] = createStringObjectFromLongLong(nack->delivery_count); | ||
| argv[9] = shared.force; | ||
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| alsoPropagate(c->db->id, argv, 10, PROPAGATE_AOF | PROPAGATE_REPL, c->slot); |
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This sends the new XNACK command to every replica unconditionally. A pre-9.2 replica does not know this command, so applying the stream fails (and panics when propagation-error-behavior is panic/panic-on-replicas). The neighboring XACKDEL/XDELEX path explicitly emits only older primitives for the same compatibility boundary (src/t_stream.c:1634-1655), and the cross-version suite verifies that behavior. Encode the effect with commands understood by pre-9.2 replicas, or add an explicit compatibility gate/fallback and a current-primary → pre-9.2-replica test.
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This is unfortunately unavoidable. XNACK cannot be replicated in pre-9.2 commands. See discussion here
Signed-off-by: Nick Iaquinto <git+valkey@iaquinto.io>
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## unstable #4734 +/- ##
============================================
- Coverage 80.83% 80.65% -0.18%
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Files 192 192
Lines 100853 100960 +107
============================================
- Hits 81523 81433 -90
- Misses 19330 19527 +197
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1 participant
This command makes it possible to release stream message(s) for immediate reclaim.
For one or more entries in the consumer group's PEL, set the delivery time to 0. This allows
XCLAIM/XAUTOCLAIMto immediately claim it. The mode option (SILENT,FAIL,FATAL) allows control over the delivery count of the message as follows:SILENT: decrements the count, returning it to the value before claim (min 0)FAIL: does nothing, allowing count to tick up with each claimFATAL: sets count toLLONG_MAXThis PR also clamps each path that increases the delivery count so that it cannot overflow
LLONG_MAX, which is the largest RESP integer for replication/aof. (XCLAIM,XAUTOCLAIM, andXREADGROUP)The trailing options are intended for internal use only, enabling AOF/replication of each message NACK'd specifying the exact delivery count.
For the
FORCEoption specifically, it introduces a blank consumer name that is used whenever creating a PEL entry that didn't exist before. This isn’t necessary inXCLAIMbecause it comes with a consumer name. However, there is none here, thus the blank consumer.This internal consumer is necessary to ensure that state converges. It is excluded in several places (
XINFO CONSUMERS,XGROUP DELCONSUMER,XINFO GROUPS,XINFO STREAM ... FULL), but not all places (ex.XPENDINGwith extended output).Return value of the command is the number of messages successfully NACK'd. Any messages that did not exist or were not in the groups PEL (except with
FORCE) are excluded from the count that’s returned.This commit also includes test coverage for 1) each mode & option, 2) the additions to other commands (ignoring blank consumer & delivery count incr clamp to LLONG_MAX), and 3) replication/aof using
RETRYCOUNT/FORCE.Closes #4561