{- |
Copyright  : Will Thompson, Iñaki García Etxebarria and Jonas Platte
License    : LGPL-2.1
Maintainer : Iñaki García Etxebarria (garetxe@gmail.com)

The #GCond struct is an opaque data structure that represents a
condition. Threads can block on a #GCond if they find a certain
condition to be false. If other threads change the state of this
condition they signal the #GCond, and that causes the waiting
threads to be woken up.

Consider the following example of a shared variable.  One or more
threads can wait for data to be published to the variable and when
another thread publishes the data, it can signal one of the waiting
threads to wake up to collect the data.

Here is an example for using GCond to block a thread until a condition
is satisfied:
|[<!-- language="C" -->
  gpointer current_data = NULL;
  GMutex data_mutex;
  GCond data_cond;

  void
  push_data (gpointer data)
  {
    g_mutex_lock (&data_mutex);
    current_data = data;
    g_cond_signal (&data_cond);
    g_mutex_unlock (&data_mutex);
  }

  gpointer
  pop_data (void)
  {
    gpointer data;

    g_mutex_lock (&data_mutex);
    while (!current_data)
      g_cond_wait (&data_cond, &data_mutex);
    data = current_data;
    current_data = NULL;
    g_mutex_unlock (&data_mutex);

    return data;
  }
]|
Whenever a thread calls pop_data() now, it will wait until
current_data is non-%NULL, i.e. until some other thread
has called push_data().

The example shows that use of a condition variable must always be
paired with a mutex.  Without the use of a mutex, there would be a
race between the check of @current_data by the while loop in
pop_data() and waiting. Specifically, another thread could set
@current_data after the check, and signal the cond (with nobody
waiting on it) before the first thread goes to sleep. #GCond is
specifically useful for its ability to release the mutex and go
to sleep atomically.

It is also important to use the g_cond_wait() and g_cond_wait_until()
functions only inside a loop which checks for the condition to be
true.  See g_cond_wait() for an explanation of why the condition may
not be true even after it returns.

If a #GCond is allocated in static storage then it can be used
without initialisation.  Otherwise, you should call g_cond_init()
on it and g_cond_clear() when done.

A #GCond should only be accessed via the g_cond_ functions.
-}

module GI.GLib.Structs.Cond
    ( 

-- * Exported types
    Cond(..)                                ,
    noCond                                  ,


 -- * Methods
-- ** condBroadcast
    condBroadcast                           ,


-- ** condClear
    condClear                               ,


-- ** condInit
    condInit                                ,


-- ** condSignal
    condSignal                              ,


-- ** condWait
    condWait                                ,


-- ** condWaitUntil
    condWaitUntil                           ,




    ) where

import Prelude ()
import Data.GI.Base.ShortPrelude

import qualified Data.Text as T
import qualified Data.ByteString.Char8 as B
import qualified Data.Map as Map

import GI.GLib.Types
import GI.GLib.Callbacks

newtype Cond = Cond (ForeignPtr Cond)
noCond :: Maybe Cond
noCond = Nothing

-- method Cond::broadcast
-- method type : OrdinaryMethod
-- Args : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- Lengths : []
-- hInArgs : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- returnType : TBasicType TVoid
-- throws : False
-- Skip return : False

foreign import ccall "g_cond_broadcast" g_cond_broadcast :: 
    Ptr Cond ->                             -- _obj : TInterface "GLib" "Cond"
    IO ()


condBroadcast ::
    (MonadIO m) =>
    Cond ->                                 -- _obj
    m ()
condBroadcast _obj = liftIO $ do
    let _obj' = unsafeManagedPtrGetPtr _obj
    g_cond_broadcast _obj'
    touchManagedPtr _obj
    return ()

-- method Cond::clear
-- method type : OrdinaryMethod
-- Args : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- Lengths : []
-- hInArgs : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- returnType : TBasicType TVoid
-- throws : False
-- Skip return : False

foreign import ccall "g_cond_clear" g_cond_clear :: 
    Ptr Cond ->                             -- _obj : TInterface "GLib" "Cond"
    IO ()


condClear ::
    (MonadIO m) =>
    Cond ->                                 -- _obj
    m ()
condClear _obj = liftIO $ do
    let _obj' = unsafeManagedPtrGetPtr _obj
    g_cond_clear _obj'
    touchManagedPtr _obj
    return ()

-- method Cond::init
-- method type : OrdinaryMethod
-- Args : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- Lengths : []
-- hInArgs : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- returnType : TBasicType TVoid
-- throws : False
-- Skip return : False

foreign import ccall "g_cond_init" g_cond_init :: 
    Ptr Cond ->                             -- _obj : TInterface "GLib" "Cond"
    IO ()


condInit ::
    (MonadIO m) =>
    Cond ->                                 -- _obj
    m ()
condInit _obj = liftIO $ do
    let _obj' = unsafeManagedPtrGetPtr _obj
    g_cond_init _obj'
    touchManagedPtr _obj
    return ()

-- method Cond::signal
-- method type : OrdinaryMethod
-- Args : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- Lengths : []
-- hInArgs : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- returnType : TBasicType TVoid
-- throws : False
-- Skip return : False

foreign import ccall "g_cond_signal" g_cond_signal :: 
    Ptr Cond ->                             -- _obj : TInterface "GLib" "Cond"
    IO ()


condSignal ::
    (MonadIO m) =>
    Cond ->                                 -- _obj
    m ()
condSignal _obj = liftIO $ do
    let _obj' = unsafeManagedPtrGetPtr _obj
    g_cond_signal _obj'
    touchManagedPtr _obj
    return ()

-- method Cond::wait
-- method type : OrdinaryMethod
-- Args : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing},Arg {argName = "mutex", argType = TInterface "GLib" "Mutex", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- Lengths : []
-- hInArgs : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing},Arg {argName = "mutex", argType = TInterface "GLib" "Mutex", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- returnType : TBasicType TVoid
-- throws : False
-- Skip return : False

foreign import ccall "g_cond_wait" g_cond_wait :: 
    Ptr Cond ->                             -- _obj : TInterface "GLib" "Cond"
    Ptr Mutex ->                            -- mutex : TInterface "GLib" "Mutex"
    IO ()


condWait ::
    (MonadIO m) =>
    Cond ->                                 -- _obj
    Mutex ->                                -- mutex
    m ()
condWait _obj mutex = liftIO $ do
    let _obj' = unsafeManagedPtrGetPtr _obj
    let mutex' = unsafeManagedPtrGetPtr mutex
    g_cond_wait _obj' mutex'
    touchManagedPtr _obj
    touchManagedPtr mutex
    return ()

-- method Cond::wait_until
-- method type : OrdinaryMethod
-- Args : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing},Arg {argName = "mutex", argType = TInterface "GLib" "Mutex", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing},Arg {argName = "end_time", argType = TBasicType TInt64, direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- Lengths : []
-- hInArgs : [Arg {argName = "_obj", argType = TInterface "GLib" "Cond", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing},Arg {argName = "mutex", argType = TInterface "GLib" "Mutex", direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing},Arg {argName = "end_time", argType = TBasicType TInt64, direction = DirectionIn, mayBeNull = False, argScope = ScopeTypeInvalid, argClosure = -1, argDestroy = -1, transfer = TransferNothing}]
-- returnType : TBasicType TBoolean
-- throws : False
-- Skip return : False

foreign import ccall "g_cond_wait_until" g_cond_wait_until :: 
    Ptr Cond ->                             -- _obj : TInterface "GLib" "Cond"
    Ptr Mutex ->                            -- mutex : TInterface "GLib" "Mutex"
    Int64 ->                                -- end_time : TBasicType TInt64
    IO CInt


condWaitUntil ::
    (MonadIO m) =>
    Cond ->                                 -- _obj
    Mutex ->                                -- mutex
    Int64 ->                                -- end_time
    m Bool
condWaitUntil _obj mutex end_time = liftIO $ do
    let _obj' = unsafeManagedPtrGetPtr _obj
    let mutex' = unsafeManagedPtrGetPtr mutex
    result <- g_cond_wait_until _obj' mutex' end_time
    let result' = (/= 0) result
    touchManagedPtr _obj
    touchManagedPtr mutex
    return result'