Documentation
¶
Overview ¶
Package cachestore defines the in-DC chunk store interface and shared types. Concrete drivers live under cachestore/<driver>/.
Commit safety rests on the content-addressed chunk layout: a chunk's ETag is part of its storage path (see designs/orca/design.md s5), so the only way two concurrent fills target the same key is when they are writing byte-identical content. PutChunk commits with a stat-then-put step (HeadObject; if present, skip the upload and report the existing object as the winner). SelfTest is run at boot to verify the backend provides read-after-write visibility, which the stat-then-put step depends on.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( ErrNotFound = errors.New("cachestore: not found") ErrTransient = errors.New("cachestore: transient") ErrAuth = errors.New("cachestore: auth") // ErrCommitLost reports that another replica already committed this // chunk: the commit's stat-then-put step found the object already // present and skipped the upload. The chunk is in the cachestore; // the caller treats the existing object as the truth. Because the // ETag is part of the chunk path, the existing object is // byte-identical to what this replica would have written. ErrCommitLost = errors.New("cachestore: commit lost (chunk already present)") )
Sentinel errors. Wrap with %w so callers use errors.Is.
Functions ¶
This section is empty.
Types ¶
type CacheStore ¶
type CacheStore interface {
GetChunk(ctx context.Context, k chunk.Key, off, n int64) (io.ReadCloser, error)
PutChunk(ctx context.Context, k chunk.Key, size int64, r io.Reader) error
Stat(ctx context.Context, k chunk.Key) (Info, error)
// Delete removes a committed chunk. No production code calls this
// today: routine space reclamation is handled outside Orca by the
// cachestore bucket's age-based lifecycle policy (passive
// eviction; see designs/orca/design.md s11.1). It is kept on the
// interface for the deferred, opt-in active-eviction loop that
// would delete cold chunks itself (see s13 "Active eviction
// loop").
Delete(ctx context.Context, k chunk.Key) error
SelfTest(ctx context.Context) error
}
CacheStore is where chunk bytes physically live. Source of truth for chunk presence; backed by an in-DC S3-like store in production and a self-hosted S3-compatible store in dev.
type Info ¶
type Info struct {
Size int64
// Committed is when the chunk was written to the cachestore (the
// stored object's last-modified time). Nothing reads it today; it
// is filled in as the age signal that the deferred active-eviction
// loop would use to find cold chunks (see designs/orca/design.md
// s11.1 and s13 "Active eviction loop"). It pairs with Delete.
Committed time.Time
}
Info is the result of a successful Stat.
Source Files
Directories