Documentation
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Overview ¶
Package store keeps the last valid snapshot of each source on disk, shared by the sync and API processes and kept across restarts.
File format, version 1 ¶
Each source has one file, <name>.snapshot, where name is the source lowercased with every run of characters other than a-z and 0-9 turned into a single "-" ("AMF listes blanches" is amf-listes-blanches.snapshot). The file holds two parts, both UTF-8 JSON:
- an envelope on the first line, ended by "\n": {"format":"arnakoff-snapshot","version":1,"sha256":"<hex>"}, where sha256 is the hex SHA-256 digest of the body;
- the body, the rest of the file: {"source":"AMF", "fetched_at":"<RFC 3339>","newest":"<RFC 3339>","header":[...], "rows":[[...],...]}; newest is left out when the source dates no entry.
A file whose envelope, digest or body does not check out, or that holds another source, is rejected with ErrCorrupt; one of another version with ErrVersion. A change to the body or envelope bumps the version.
A file is written to a temporary file in the same directory, synced, then renamed over the previous one, and the directory is synced on Unix: a reader sees the previous file or the new one, never part of one.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( ErrCorrupt = errors.New("corrupt snapshot file") ErrVersion = errors.New("unsupported snapshot format version") ErrSourceName = errors.New("source name gives no file name") )
Store errors, checked with errors.Is.
Functions ¶
This section is empty.
Types ¶
type Disk ¶
type Disk struct {
// contains filtered or unexported fields
}
Disk stores one snapshot file per source in a directory. It implements app.SnapshotStore and is safe for concurrent use, also across processes.
Source Files