WaitForMultipleObjectsEx

Description

Waits until one or all of the specified objects are in the signaled state, an I/O completion routine or asynchronous procedure call (APC) is queued to the thread, or the time-out interval elapses.

Syntax

DWORD WINAPI WaitForMultipleObjectsEx(
  _In_  DWORD nCount,
  _In_  const HANDLE *lpHandles,
  _In_  BOOL bWaitAll,
  _In_  DWORD dwMilliseconds,
  _In_  BOOL bAlertable
);

Parameters

nCount [in]

The number of object handles to wait for in the array pointed to by lpHandles. The maximum number of object handles is MAXIMUM_WAIT_OBJECTS. This parameter cannot be zero.

lpHandles [in]

An array of object handles. The array can contain handles of objects of different types. It may not contain multiple copies of the same handle.

If one of these handles is closed while the wait is still pending, the function's behavior is undefined.

The handles must have the SYNCHRONIZE access right.

bWaitAll [in]

If this parameter is TRUE, the function returns when the state of all objects in the lpHandles array is set to signaled. If FALSE, the function returns when the state of any one of the objects is set to signaled. In the latter case, the return value indicates the object whose state caused the function to return.

dwMilliseconds [in]

The time-out interval, in milliseconds. If a nonzero value is specified, the function waits until the specified objects are signaled, an I/O completion routine or APC is queued, or the interval elapses. If dwMilliseconds is zero, the function does not enter a wait state if the criteria is not met; it always returns immediately. If dwMilliseconds is INFINITE, the function will return only when the specified objects are signaled or an I/O completion routine or APC is queued.

bAlertable [in]

If this parameter is TRUE and the thread is in the waiting state, the function returns when the system queues an I/O completion routine or APC, and the thread runs the routine or function. Otherwise, the function does not return and the completion routine or APC function is not executed.

A completion routine is queued when the ReadFileEx or WriteFileEx function in which it was specified has completed. The wait function returns and the completion routine is called only if bAlertable is TRUE and the calling thread is the thread that initiated the read or write operation. An APC is queued when you call QueueUserAPC.

Return value

If the function succeeds, the return value indicates the event that caused the function to return. It can be one of the following values. (Note that WAIT_OBJECT_0 is defined as 0 and WAIT_ABANDONED_0 is defined as 0x00000080L.)

Return code/value	Description
WAIT_OBJECT_0 to (WAIT_OBJECT_0 + nCount– 1)	If bWaitAll is TRUE, a return value in this range indicates that the state of all specified objects is signaled. If bWaitAll is FALSE, the return value minus WAIT_OBJECT_0 indicates the lpHandles array index of the object that satisfied the wait. If more than one object became signaled during the call, this is the array index of the signaled object with the smallest index value of all the signaled objects.
WAIT_ABANDONED_0 to (WAIT_ABANDONED_0 + nCount– 1)	If bWaitAll is TRUE, a return value in this range indicates that the state of all specified objects is signaled, and at least one of the objects is an abandoned mutex object. If bWaitAll is FALSE, the return value minus WAIT_ABANDONED_0 indicates the lpHandles array index of an abandoned mutex object that satisfied the wait. Ownership of the mutex object is granted to the calling thread, and the mutex is set to nonsignaled. If a mutex was protecting persistent state information, you should check it for consistency.
WAIT_IO_COMPLETION 0x000000C0L	The wait was ended by one or more user-mode asynchronous procedure calls (APC) queued to the thread.
WAIT_TIMEOUT 0x00000102L	The time-out interval elapsed, the conditions specified by the bWaitAll parameter were not satisfied, and no completion routines are queued.
WAIT_FAILED (DWORD)0xFFFFFFFF	The function has failed. To get extended error information, call GetLastError.