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/* -----------------------------------------------------------------------------
*
* (c) The GHC Team, 1998-2006
*
* The IO manager thread in THREADED_RTS.
* See also libraries/base/GHC/Conc.hs.
*
* NOTE: This is used by both MIO and WINIO
* ---------------------------------------------------------------------------*/
#include "Rts.h"
#include "ThrIOManager.h"
#include "MIOManager.h"
#include "rts/OSThreads.h"
#include "Prelude.h"
#include <windows.h>
// Here's the Event that we use to wake up the IO manager thread
static HANDLE io_manager_event = INVALID_HANDLE_VALUE;
#define EVENT_BUFSIZ 256
// We lock using OS_ACQUIRE_LOCK the ensure the non-threaded WINIO
// C thread does not race with the scheduler code which can also
// access the event queue via FFI.
Mutex event_buf_mutex;
StgWord32 event_buf[EVENT_BUFSIZ];
uint32_t next_event;
/*Creates the IO Managers event object.
Idempotent after first call.
*/
HANDLE
getIOManagerEvent (void)
{
HANDLE hRes;
OS_ACQUIRE_LOCK(&event_buf_mutex);
if (io_manager_event == INVALID_HANDLE_VALUE) {
hRes = CreateEvent ( NULL, // no security attrs
true, // manual reset
false, // initial state,
NULL ); // event name: NULL for private events
if (hRes == NULL) {
sysErrorBelch("getIOManagerEvent");
stg_exit(EXIT_FAILURE);
}
io_manager_event = hRes;
} else {
hRes = io_manager_event;
}
OS_RELEASE_LOCK(&event_buf_mutex);
return hRes;
}
HsWord32
readIOManagerEvent (void)
{
HsWord32 res;
OS_ACQUIRE_LOCK(&event_buf_mutex);
if (io_manager_event != INVALID_HANDLE_VALUE) {
if (next_event == 0) {
res = 0; // no event to return
} else {
do {
// Dequeue as many wakeup events as possible.
res = (HsWord32)(event_buf[--next_event]);
} while (res == IO_MANAGER_WAKEUP && next_event);
if (next_event == 0) {
if (!ResetEvent(io_manager_event)) {
sysErrorBelch("readIOManagerEvent");
stg_exit(EXIT_FAILURE);
}
}
}
} else {
res = 0;
}
OS_RELEASE_LOCK(&event_buf_mutex);
//debugBelch("readIOManagerEvent: %d\n", res);
return res;
}
void
sendIOManagerEvent (HsWord32 event)
{
OS_ACQUIRE_LOCK(&event_buf_mutex);
//debugBelch("sendIOManagerEvent: %d to %p\n", event, io_manager_event);
if (io_manager_event != INVALID_HANDLE_VALUE) {
if (next_event == EVENT_BUFSIZ) {
errorBelch("event buffer overflowed; event dropped");
} else {
event_buf[next_event++] = (StgWord32)event;
if (!SetEvent(io_manager_event)) {
sysErrorBelch("sendIOManagerEvent: SetEvent");
stg_exit(EXIT_FAILURE);
}
}
}
OS_RELEASE_LOCK(&event_buf_mutex);
}
void
interruptIOManagerEvent (void)
{
if (is_io_mng_native_p ()) {
OS_ACQUIRE_LOCK(&event_buf_mutex);
/* How expensive is this??. */
Capability *cap;
cap = rts_lock();
rts_evalIO(&cap, interruptIOManager_closure, NULL);
rts_unlock(cap);
OS_RELEASE_LOCK(&event_buf_mutex);
}
}
void
ioManagerWakeup (void)
{
sendIOManagerEvent(IO_MANAGER_WAKEUP);
}
void
ioManagerDie (void)
{
sendIOManagerEvent(IO_MANAGER_DIE);
// IO_MANAGER_DIE must be idempotent, as it is called
// repeatedly by shutdownCapability(). Try conc059(threaded1) to
// illustrate the problem.
OS_ACQUIRE_LOCK(&event_buf_mutex);
io_manager_event = INVALID_HANDLE_VALUE;
OS_RELEASE_LOCK(&event_buf_mutex);
// ToDo: wait for the IO manager to pick up the event, and
// then release the Event and Mutex objects we've allocated.
}
void
ioManagerStart (void)
{
#if defined(THREADED_RTS)
initMutex(&event_buf_mutex);
#endif
next_event = 0;
// Make sure the IO manager thread is running
Capability *cap;
if (io_manager_event == INVALID_HANDLE_VALUE) {
cap = rts_lock();
rts_evalIO(&cap, ensureIOManagerIsRunning_closure, NULL);
rts_unlock(cap);
}
}
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