Files
s3/weed/filer/reader_pattern.go
zooqueen dd74d3e6d6 Replace AGPL MinIO fork with Apache-2.0 SeaweedFS fork; rebrand CLI weed->s3
hanzoai/s3 was an AGPL-3.0 MinIO fork whose network-copyleft blocks embedding
and reselling as a managed service. Replace it wholesale with a fork of
SeaweedFS (github.com/seaweedfs/seaweedfs, Apache-2.0, Go) which ships a
built-in S3 gateway + Filer.

- License: AGPL-3.0 -> Apache-2.0 (upstream LICENSE kept verbatim, incl.
  "Copyright 2025 Chris Lu"); NOTICE added crediting SeaweedFS. No AGPL/BUSL/
  SSPL/GPL or enterprise ("ee") files remain.
- Module: go.mod path set to github.com/hanzoai/s3 with a self-replace
  (replace github.com/seaweedfs/seaweedfs => ./) so the ~1800 internal Go files
  keep their upstream import paths with zero churn. Internal identifiers and
  import paths are intentionally NOT renamed.
- CLI rebrand: the binary is built as `s3` (was `weed`); root usage, per-command
  help/usage/flag strings, shell autocomplete program name, and the product name
  in CLI output now read "Hanzo S3" / `s3`. Users never see `weed`.
  (e.g. `s3 server`, `s3 filer`, `s3 master`, `s3 volume`, `s3 s3`, `s3 mount`.)
- Build: `make` (or `go build -o s3 ./weed`) builds the `s3` binary green;
  `cmd/weed-db` and `cmd/weed-sql` also build; `go vet ./weed/command/` clean.
- README/LLM.md rewritten for Hanzo S3; AGENTS.md/CLAUDE.md symlinks preserved.
- Dropped a 33MB prebuilt Mach-O `stress` binary upstream had committed; `.gitignore`
  updated to ignore the `s3` build output.
2026-06-18 23:41:25 -07:00

67 lines
2.0 KiB
Go

package filer
import (
"sync/atomic"
)
type ReaderPattern struct {
isSequentialCounter int64
readFrontier int64 // highest (offset+size) observed across reads
}
const ModeChangeLimit = 3
// SeqTolerance: a read whose start is within this many bytes of the current read
// frontier still counts as sequential. Using a tolerance window rather than
// strict contiguity absorbs reordered/concurrent readahead (multiple ReadAt can
// be in flight at once) while still rejecting far random jumps.
const SeqTolerance = 8 << 20 // 8 MiB
// For streaming read: only cache the first chunk
// For random read: only fetch the requested range, instead of the whole chunk
func NewReaderPattern() *ReaderPattern {
return &ReaderPattern{
isSequentialCounter: 0,
readFrontier: 0,
}
}
func (rp *ReaderPattern) MonitorReadAt(offset int64, size int) {
// Advance the frontier to max(frontier, offset+size) and capture, in the same
// CAS loop, the pre-image this read is judged against. Reading the frontier
// inside the loop (rather than once up front) keeps `diff` below comparing
// against the freshest value even if a concurrent readahead advances the
// frontier while we loop. Lock-free, consistent with the rest of this type.
end := offset + int64(size)
var frontier int64
for {
frontier = atomic.LoadInt64(&rp.readFrontier)
if end <= frontier || atomic.CompareAndSwapInt64(&rp.readFrontier, frontier, end) {
break
}
}
// near = this read starts within SeqTolerance of where reads had reached.
// Hysteresis (the ±ModeChangeLimit counter) keeps a single outlier read from
// flipping the mode.
diff := offset - frontier
if diff < 0 {
diff = -diff
}
counter := atomic.LoadInt64(&rp.isSequentialCounter)
if diff <= SeqTolerance {
if counter < ModeChangeLimit {
atomic.AddInt64(&rp.isSequentialCounter, 1)
}
} else {
if counter > -ModeChangeLimit {
atomic.AddInt64(&rp.isSequentialCounter, -1)
}
}
}
func (rp *ReaderPattern) IsRandomMode() bool {
return atomic.LoadInt64(&rp.isSequentialCounter) < 0
}