From fbb049b3024409811aaad51bc573446f548da564 Mon Sep 17 00:00:00 2001
From: Johan Tibell <johan.tibell@gmail.com>
Date: Wed, 12 Jan 2011 12:54:30 +0000
Subject: [PATCH] Document System.Event

---
 System/Event.hs         |    4 ++++
 System/Event/Manager.hs |   12 ++++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/System/Event.hs b/System/Event.hs
index 126107a..9fd836d 100644
--- a/System/Event.hs
+++ b/System/Event.hs
@@ -1,3 +1,7 @@
+-- | This module provides scalable event notification for file
+-- descriptors and timeouts.
+--
+-- This module should be considered GHC internal.
 module System.Event
     ( -- * Types
       EventManager
diff --git a/System/Event/Manager.hs b/System/Event/Manager.hs
index 1206d66..c47b6c6 100644
--- a/System/Event/Manager.hs
+++ b/System/Event/Manager.hs
@@ -96,6 +96,7 @@ type IOCallback = FdKey -> Event -> IO ()
 instance Show IOCallback where
     show _ = "IOCallback"
 
+-- | A timeout registration cookie.
 newtype TimeoutKey   = TK Unique
     deriving (Eq)
 
@@ -217,7 +218,8 @@ cleanup EventManager{..} = do
 ------------------------------------------------------------------------
 -- Event loop
 
--- | Start handling events.  This function loops until told to stop.
+-- | Start handling events.  This function loops until told to stop,
+-- using 'shutdown'.
 --
 -- /Note/: This loop can only be run once per 'EventManager', as it
 -- closes all of its control resources when it finishes.
@@ -346,7 +348,10 @@ closeFd mgr close fd = do
 ------------------------------------------------------------------------
 -- Registering interest in timeout events
 
--- | Register a timeout in the given number of microseconds.
+-- | Register a timeout in the given number of microseconds.  The
+-- returned 'TimeoutKey' can be used to later unregister or update the
+-- timeout.  The timeout is automatically unregistered after the given
+-- time has passed.
 registerTimeout :: EventManager -> Int -> TimeoutCallback -> IO TimeoutKey
 registerTimeout mgr us cb = do
   !key <- newUnique (emUniqueSource mgr)
@@ -365,12 +370,15 @@ registerTimeout mgr us cb = do
       wakeManager mgr
   return $ TK key
 
+-- | Unregister an active timeout.
 unregisterTimeout :: EventManager -> TimeoutKey -> IO ()
 unregisterTimeout mgr (TK key) = do
   atomicModifyIORef (emTimeouts mgr) $ \f ->
       let f' = (Q.delete key) . f in (f', ())
   wakeManager mgr
 
+-- | Update an active timeout to fire in the given number of
+-- microseconds.
 updateTimeout :: EventManager -> TimeoutKey -> Int -> IO ()
 updateTimeout mgr (TK key) us = do
   now <- getCurrentTime
-- 
1.7.10.4