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relaxed move idempotency requirements #90

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Merged
mcrnic merged 1 commit into from
Jan 12, 2026
Merged

relaxed move idempotency requirements #90

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12 changes: 11 additions & 1 deletion go/client/metadatareq.go
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Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,17 @@ func (c *Client) metadataRequest(
if resp.err != nil {
var isTernError bool
ternError, isTernError = resp.err.(msgs.TernError)
if isTernError && attempts > 0 {
shouldCheckIdempotency := attempts > 0
if (shid >=0) {
if reqBody.(msgs.ShardRequest).ShardRequestKind() == msgs.SAME_DIRECTORY_RENAME {
shouldCheckIdempotency = true
}
} else {
if reqBody.(msgs.CDCRequest).CDCRequestKind() == msgs.RENAME_FILE || reqBody.(msgs.CDCRequest).CDCRequestKind() == msgs.RENAME_DIRECTORY {
shouldCheckIdempotency = true
}
}
if isTernError && shouldCheckIdempotency {
if shid >= 0 {
ternError = c.checkRepeatedShardRequestError(log, reqBody.(msgs.ShardRequest), respBody.(msgs.ShardResponse), ternError)
} else {
Expand Down
13 changes: 13 additions & 0 deletions go/client/shardreq.go
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Expand Up @@ -67,6 +67,19 @@ func (c *Client) checkNewEdgeAfterRename(
logger.Info("got mismatched current target (%v), giving up and returning original error", lookupResp.TargetId)
return false
}
nowNs := msgs.Now()
var delta msgs.TernTime
if nowNs > lookupResp.CreationTime {
delta = nowNs - lookupResp.CreationTime
} else {
delta = lookupResp.CreationTime - nowNs
}
const edgeRenameMaxFuzzNs = msgs.TernTime(60 * 1000 * 1000 * 1000) // 60 seconds
if delta > edgeRenameMaxFuzzNs {
logger.Info("got creation time %v too far from now %v (delta %v), giving up and returning original error", lookupResp.CreationTime, nowNs, delta)
return false
}

*creationTime = lookupResp.CreationTime
return true
}
Expand Down
15 changes: 12 additions & 3 deletions kmod/metadata.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ int ternfs_mtu = TERNFS_DEFAULT_MTU;
int ternfs_default_mtu = TERNFS_DEFAULT_MTU;
int ternfs_max_mtu = TERNFS_MAX_MTU;

#define TERNFS_RENAME_NEW_EDGE_CREATION_TIME_FUZZ_NS (60ULL * 1000 * 1000 * 1000) // 60 seconds

static DEFINE_PER_CPU(u64, next_request_id);

static inline u64 alloc_request_id(void) {
Expand Down Expand Up @@ -356,6 +358,13 @@ static bool check_new_edge_after_rename(
consume_skb(skb);
if (ctx.err != 0) { return false; }
if (resp_target.x != target) { return false; }

u64 now_ns = ktime_get_real_ns();
u64 delta = now_ns > resp_creation_time.x ? now_ns - resp_creation_time.x : resp_creation_time.x - now_ns;
if (delta > TERNFS_RENAME_NEW_EDGE_CREATION_TIME_FUZZ_NS) {
return false;
}

*creation_time = resp_creation_time.x;
}

Expand Down Expand Up @@ -483,7 +492,7 @@ int ternfs_shard_rename(
ternfs_same_directory_rename_resp_get_end(&ctx, resp_new_creation_time, end);
ternfs_same_directory_rename_resp_get_finish(&ctx, end);
bool recovered = false;
if (attempts > 1 && ctx.err == TERNFS_ERR_EDGE_NOT_FOUND) {
if (ctx.err == TERNFS_ERR_EDGE_NOT_FOUND) {
ternfs_debug("got edge not found, performing followup checks");
// See commentary in shardreq.go
if (
Expand Down Expand Up @@ -1239,7 +1248,7 @@ int ternfs_cdc_rename_directory(
ternfs_rename_directory_resp_get_end(&ctx, resp_new_creation_time, end);
ternfs_rename_directory_resp_get_finish(&ctx, end);
bool recovered = false;
if (attempts > 1 && ctx.err == TERNFS_ERR_EDGE_NOT_FOUND) {
if (ctx.err == TERNFS_ERR_EDGE_NOT_FOUND) {
ternfs_debug("got edge not found, performing followup checks");
// See commentary in shardreq.go
if (
Expand Down Expand Up @@ -1290,7 +1299,7 @@ int ternfs_cdc_rename_file(
ternfs_rename_file_resp_get_end(&ctx, resp_new_creation_time, end);
ternfs_rename_file_resp_get_finish(&ctx, end);
bool recovered = false;
if (attempts > 1 && ctx.err == TERNFS_ERR_EDGE_NOT_FOUND) {
if (ctx.err == TERNFS_ERR_EDGE_NOT_FOUND) {
ternfs_debug("got edge not found, performing followup checks");
// See commentary in shardreq.go
if (
Expand Down