| Safe Haskell | None |
|---|---|
| Language | Haskell98 |
System.Daemon
Description
An RPC-like interface for daemons is provided by
ensureDaemonRunning and runClient.
A more versatile interface that lets you supply your own Handler
is provided by ensureDaemonWithHandlerRunning and
runClientWithHandler. These are useful if, for instance, you
need streaming requests or replies, or if you need to change your
event handler at runtime.
The event handling loop is provided by runInForeground. You may
want to use this for debugging purposes or if you want to handle
daemonization manually.
Synopsis
- ensureDaemonRunning :: (Serialize a, Serialize b) => String -> DaemonOptions -> (a -> IO b) -> IO ()
- ensureDaemonWithHandlerRunning :: String -> DaemonOptions -> Handler () -> IO ()
- runClient :: (Serialize a, Serialize b) => HostName -> Port -> a -> IO (Maybe b)
- runClientWithHandler :: HostName -> Port -> Handler a -> IO a
- data DaemonOptions = DaemonOptions {}
- data PidFile
- type HostName = String
- type Port = Int
- runInForeground :: Port -> Handler () -> IO ()
- bindPort :: Port -> IO Socket
- getSocket :: HostName -> Port -> IO Socket
Daemons
Arguments
| :: (Serialize a, Serialize b) | |
| => String | name |
| -> DaemonOptions | options |
| -> (a -> IO b) | handler |
| -> IO () |
Simple wrapper around ensureDaemonWithHandlerRunning which uses
a simple function to respond to commands and doesn't deal with
pipes.
The handler is just a function that takes a command and returns a
response.
ensureDaemonWithHandlerRunning Source #
Arguments
| :: String | name |
| -> DaemonOptions | options |
| -> Handler () | handler |
| -> IO () |
Start a daemon running on the given port, using the given handler to respond to events. If the daemon is already running, don't do anything. Returns immediately.
The pidfile PidFile options will be created and locked. This
function checks the pidfile to see if the daemon is already
running.
The daemon will listen for incoming connections on all interfaces
on daemonPort options.
The handler is a function that takes the reader and writer
ByteString pipes and does something with them. See
commandReceiver for an example handler.
Clients,
Send a command to the daemon running at the given network address and wait for a response.
This is a simple wrapper around runClientWithHandler that sends a
single command and waits for a single response.
If the connection is closed before receiving a response, return
Nothing.
Connect to the given network address and run the handler on the reader and wrier pipes for the socket.
The handler is a function that takes the reader and writer
ByteString pipes and does something with them. For an example
handler, see commandSender, which sends a command and waits for a
response.
Types
data DaemonOptions Source #
The configuration options of a daemon. See ensureDaemonRunning
for a description of each.
Constructors
| DaemonOptions | |
Fields | |
Instances
| Show DaemonOptions Source # | |
Defined in System.Daemon Methods showsPrec :: Int -> DaemonOptions -> ShowS # show :: DaemonOptions -> String # showList :: [DaemonOptions] -> ShowS # | |
| Default DaemonOptions Source # | |
Defined in System.Daemon Methods def :: DaemonOptions # | |
The location of the daemon's pidfile.
Helpers
runInForeground :: Port -> Handler () -> IO () Source #
Start the given handler in the foreground. It will listen and respond to events on the given port.
This is the function that ensureDaemonWithHandlerRunning runs on
the daemon thread.