MICROSECONDS_PER_SECOND
MICROSECONDS_PER_SECOND = 1000000
Microseconds in a second, the unit $microtime is recorded in.
One captured mutation, and the only shape the journal appends.
A value object rather than an array, so a misspelled key is a type error at the call site instead of a silently absent field, and so the fields a restore depends on are checked once, here, rather than again in every writer that reads them.
An op describes a mutation and never carries the value. The value is in the object store under $payloadHash, which keeps a journal row the same size whether the subject is a taxonomy term or a 200 MiB file. $parentHash names the version the mutation was applied to, so a chain can be walked backwards without reading a payload at all.
$sequence orders every op in a window and is assigned by the journal on append, so a caller builds the op and gets its number back through withSequence().
$realm : \Drupal\strata\Journal\Realm
$verb : \Drupal\strata\Journal\Verb
__construct(int $sequence, int $microtime, \Drupal\strata\Journal\Realm $realm, string $subject, \Drupal\strata\Journal\Verb $verb, int|null $actor = null, string|null $requestId = null, string|null $payloadHash = null, string|null $parentHash = null, int $payloadLength = 0, string $label = '', list$fields = []) : mixed
Constructs an op.
| int | $sequence | Position in the window, assigned by the journal on append. Zero or more. |
| int | $microtime | Unix timestamp in microseconds, as |
| \Drupal\strata\Journal\Realm | $realm | The subsystem the subject lives in. |
| string | $subject | What was mutated, addressed the way its realm addresses things: |
| \Drupal\strata\Journal\Verb | $verb | What the mutation did. |
| int|null | $actor | Uid that caused the mutation, or NULL for cron, drush and anything else with no session. |
| string|null | $requestId | Identifier of the request the mutation happened in, so ops that belong to one page submission can be grouped after the fact. NULL when the writer did not record one. |
| string|null | $payloadHash | Digest of the value after the mutation, or NULL when there is no value to store, as for a delete. |
| string|null | $parentHash | Digest of the value before the mutation, or NULL when the subject had no previous version. |
| int | $payloadLength | Length of the value in bytes, so a window can be totalled without reading the store. |
| string | $label | Human-readable description for the UI, such as "Article: Hello world". |
| list |
$fields | Top-level field names the mutation touched. Empty when the writer does not track fields, or when the verb replaces the whole subject. |
When a number is out of range, the subject is empty, a hash is not a valid digest, $fields is not a list of names, or a string the op carries is not valid UTF-8.
timestamp() : float
When the mutation happened, as a float unix timestamp.
Microseconds are stored as an integer so ordering and equality are exact; this is the form for a formatter or a duration, not for a comparison.
Seconds since the epoch, with microsecond resolution.
withSequence(int $sequence) : self
The same op at a different position in the window.
The journal numbers an op on append, and the collapser renumbers nothing: a survivor keeps the sequence of the run it replaces.
| int | $sequence | The new sequence. Zero or more. |
When $sequence is negative.
A copy with the new sequence and every other field unchanged.