| ANVIL(8) | System Manager's Manual | ANVIL(8) |
In the following text, ident specifies a (service, client) combination. The exact syntax of that information is application-dependent; the anvil(8) server does not care.
request=connect
ident=string
The anvil(8) server answers with the number of simultaneous connections and the number of connections per unit time for the (service, client) combination specified with ident:
status=0
count=number
rate=number
To register a disconnect event send the following request to the anvil(8) server:
request=disconnect
ident=string
The anvil(8) server replies with:
status=0
request=message
ident=string
The anvil(8) server answers with the number of message delivery requests per unit time for the (service, client) combination specified with ident:
status=0
rate=number
request=recipient
ident=string
The anvil(8) server answers with the number of recipient addresses per unit time for the (service, client) combination specified with ident:
status=0
rate=number
To register a request for a new (i.e. not cached) TLS session send the following request to the anvil(8) server:
request=newtls
ident=string
The anvil(8) server answers with the number of new TLS session requests per unit time for the (service, client) combination specified with ident:
status=0
rate=number
To retrieve new TLS session request rate information without updating the counter information, send:
request=newtls_report
ident=string
The anvil(8) server answers with the number of new TLS session requests per unit time for the (service, client) combination specified with ident:
status=0
rate=number
The anvil(8) server maintains an in-memory table with information about recent clients requests. No persistent state is kept because standard system library routines are not sufficiently robust for update-intensive applications.
Although the in-memory state is kept only temporarily, this may require a lot of memory on systems that handle connections from many remote clients. To reduce memory usage, reduce the time unit over which state is kept.
Upon exit, and every anvil_status_update_time seconds, the server logs the maximal count and rate values measured, together with (service, client) information and the time of day associated with those events. In order to avoid unnecessary overhead, no measurements are done for activity that isn't concurrency limited or rate limited.
In this preliminary implementation, a count (or rate) limited server process can have only one remote client at a time. If a server process reports multiple simultaneous clients, state is kept only for the last reported client.
The anvil(8) server automatically discards client request information after it expires. To prevent the anvil(8) server from discarding client request rate information too early or too late, a rate limited service should always register connect/disconnect events even when it does not explicitly limit them.
The text below provides only a parameter summary. See postconf(5) for more details including examples.