Source code of Windows XP (NT5)
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/*++
Copyright (c) 2000 Microsoft Corporation
Module Name:
worker.c
Abstract:
This module defines functions for the worker thread pool.
Author:
Gurdeep Singh Pall (gurdeep) Nov 13, 1997
Revision History:
lokeshs - extended/modified threadpool.
Rob Earhart (earhart) September 29, 2000
Split off from threads.c
Environment:
These routines are statically linked in the caller's executable
and are callable only from user mode. They make use of Nt system
services.
--*/
#include <ntos.h>
#include <ntrtl.h>
#include "ntrtlp.h"
#include "threads.h"
// Worker Thread Pool
// ------------------
// Clients can submit functions to be executed by a worker thread. Threads are
// created if the work queue exceeds a threshold. Clients can request that the
// function be invoked in the context of a I/O thread. I/O worker threads
// can be used for initiating asynchronous I/O requests. They are not terminated if
// there are pending IO requests. Worker threads terminate if inactivity exceeds a
// threshold.
// Clients can also associate IO completion requests with the IO completion port
// waited upon by the non I/O worker threads. One should not post overlapped IO requests
// in worker threads.
ULONG StartedWorkerInitialization ; // Used for Worker thread startup synchronization
ULONG CompletedWorkerInitialization ; // Used to check if Worker thread pool is initialized
ULONG NumFutureWorkItems = 0 ; // Future work items (timers, waits, &c to exec in workers)
ULONG NumFutureIOWorkItems = 0 ; // Future IO work items (timers, waits, &c to exec in IO workers)
ULONG NumIOWorkerThreads ; // Count of IO Worker Threads alive
ULONG NumWorkerThreads ; // Count of Worker Threads alive
ULONG NumMinWorkerThreads ; // Min worker threads should be alive: 1 if ioCompletion used, else 0
ULONG NumIOWorkRequests ; // Count of IO Work Requests pending
ULONG NumLongIOWorkRequests ; // IO Worker threads executing long worker functions
ULONG NumWorkRequests ; // Count of Work Requests pending.
ULONG NumQueuedWorkRequests; // Count of work requests pending on IO completion
ULONG NumLongWorkRequests ; // Worker threads executing long worker functions
ULONG NumExecutingWorkerThreads ; // Worker threads currently executing worker functions
ULONG TotalExecutedWorkRequests ; // Total worker requests that were picked up
ULONG OldTotalExecutedWorkRequests ; // Total worker requests since last timeout.
HANDLE WorkerThreadTimerQueue = NULL ; // Timer queue used by worker threads
HANDLE WorkerThreadTimer = NULL ; // Timer used by worker threads
RTL_CRITICAL_SECTION WorkerTimerCriticalSection; // Synchronizes access to the worker timer
ULONG LastThreadCreationTickCount ; // Tick count at which the last thread was created
LIST_ENTRY IOWorkerThreads ; // List of IOWorkerThreads
PRTLP_IOWORKER_TCB PersistentIOTCB ; // ptr to TCB of persistest IO worker thread
HANDLE WorkerCompletionPort ; // Completion port used for queuing tasks to Worker threads
RTL_CRITICAL_SECTION WorkerCriticalSection ; // Exclusion used by worker threads
NTSTATUS
RtlpStartWorkerThread (
VOID
);
VOID
RtlpWorkerThreadCancelTimer(
VOID
)
{
if (! RtlTryEnterCriticalSection(&WorkerTimerCriticalSection)) {
//
// Either another thread is setting a timer, or clearing it.
// Either way, there's no reason for us to clear the timer --
// return immediately.
//
return;
}
__try {
if (WorkerThreadTimer) {
ASSERT(WorkerThreadTimerQueue);
RtlDeleteTimer(WorkerThreadTimerQueue,
WorkerThreadTimer,
NULL);
}
} __finally {
WorkerThreadTimer = NULL;
RtlLeaveCriticalSection(&WorkerTimerCriticalSection);
}
}
VOID
RtlpWorkerThreadTimerCallback(
PVOID Context,
BOOLEAN NotUsed
)
/*++
Routine Description:
This routine checks if new worker thread has to be created
Arguments:
None
Return Value:
None
--*/
{
IO_COMPLETION_BASIC_INFORMATION Info ;
BOOLEAN bCreateThread = FALSE ;
NTSTATUS Status ;
ULONG QueueLength, Threshold, ShortWorkRequests ;
Status = NtQueryIoCompletion(
WorkerCompletionPort,
IoCompletionBasicInformation,
&Info,
sizeof(Info),
NULL
) ;
if (!NT_SUCCESS(Status))
return ;
QueueLength = Info.Depth ;
if (!QueueLength) {
OldTotalExecutedWorkRequests = TotalExecutedWorkRequests ;
return ;
}
RtlEnterCriticalSection (&WorkerCriticalSection) ;
// if there are queued work items and no new work items have been scheduled
// in the last 30 seconds then create a new thread.
// this will take care of deadlocks.
// this will create a problem only if some thread is running for a long time
if (TotalExecutedWorkRequests == OldTotalExecutedWorkRequests) {
bCreateThread = TRUE ;
}
// if there are a lot of queued work items, then create a new thread
{
ULONG NumEffWorkerThreads = NumWorkerThreads > NumLongWorkRequests
? NumWorkerThreads - NumLongWorkRequests
: 0;
ULONG ShortWorkRequests ;
ULONG CapturedNumExecutingWorkerThreads;
ULONG ThreadCreationDampingTime = NumWorkerThreads < NEW_THREAD_THRESHOLD
? THREAD_CREATION_DAMPING_TIME1
: (NumWorkerThreads < 30
? THREAD_CREATION_DAMPING_TIME2
: (NumWorkerThreads << 13)); // *100ms
Threshold = (NumWorkerThreads < MAX_WORKER_THREADS
? (NumEffWorkerThreads < 7
? NumEffWorkerThreads*NumEffWorkerThreads
: ((NumEffWorkerThreads<40)
? NEW_THREAD_THRESHOLD * NumEffWorkerThreads
: NEW_THREAD_THRESHOLD2 * NumEffWorkerThreads))
: 0xffffffff) ;
CapturedNumExecutingWorkerThreads = NumExecutingWorkerThreads;
ShortWorkRequests = QueueLength + CapturedNumExecutingWorkerThreads > NumLongWorkRequests
? QueueLength + CapturedNumExecutingWorkerThreads - NumLongWorkRequests
: 0;
if (LastThreadCreationTickCount > NtGetTickCount())
LastThreadCreationTickCount = NtGetTickCount() ;
if (ShortWorkRequests > Threshold
&& (LastThreadCreationTickCount + ThreadCreationDampingTime
< NtGetTickCount()))
{
bCreateThread = TRUE ;
}
}
if (bCreateThread && NumWorkerThreads<MaxThreads) {
RtlpStartWorkerThread();
RtlpWorkerThreadCancelTimer();
}
OldTotalExecutedWorkRequests = TotalExecutedWorkRequests ;
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
}
NTSTATUS
RtlpWorkerThreadSetTimer(
VOID
)
{
NTSTATUS Status;
HANDLE NewTimerQueue;
HANDLE NewTimer;
Status = STATUS_SUCCESS;
if (! RtlTryEnterCriticalSection(&WorkerTimerCriticalSection)) {
//
// Either another thread is setting a timer, or clearing it.
// Either way, there's no reason for us to set the timer --
// return immediately.
//
return STATUS_SUCCESS;
}
__try {
if (! WorkerThreadTimerQueue) {
Status = RtlCreateTimerQueue(&NewTimerQueue);
if (! NT_SUCCESS(Status)) {
__leave;
}
WorkerThreadTimerQueue = NewTimerQueue;
}
ASSERT(WorkerThreadTimerQueue != NULL);
if (! WorkerThreadTimer) {
Status = RtlCreateTimer(
WorkerThreadTimerQueue,
&NewTimer,
RtlpWorkerThreadTimerCallback,
NULL,
60000,
60000,
WT_EXECUTEINTIMERTHREAD
) ;
if (! NT_SUCCESS(Status)) {
__leave;
}
WorkerThreadTimer = NewTimer;
}
} __finally {
RtlLeaveCriticalSection(&WorkerTimerCriticalSection);
}
return Status;
}
#if _MSC_FULL_VER >= 13008827
#pragma warning(push)
#pragma warning(disable:4715) // Not all control paths return (due to infinite loop)
#endif
LONG
RtlpWorkerThread (
PVOID Parameter
)
/*++
Routine Description:
All non I/O worker threads execute in this routine. Worker thread will try to
terminate when it has not serviced a request for
STARTING_WORKER_SLEEP_TIME +
STARTING_WORKER_SLEEP_TIME << 1 +
...
STARTING_WORKER_SLEEP_TIME << MAX_WORKER_SLEEP_TIME_EXPONENT
Arguments:
HandlePtr - Pointer to our handle.
N.B. This is closed by RtlpStartWorkerThread, but
we're still responsible for the memory.
Return Value:
--*/
{
NTSTATUS Status ;
PVOID WorkerProc ;
PVOID Context ;
IO_STATUS_BLOCK IoSb ;
ULONG SleepTime ;
LARGE_INTEGER TimeOut ;
ULONG Terminate ;
PVOID Overlapped ;
UNREFERENCED_PARAMETER(Parameter);
#if DBG
DbgPrintEx(DPFLTR_RTLTHREADPOOL_ID,
RTLP_THREADPOOL_TRACE_MASK,
"Starting worker thread\n");
#endif
// Set default sleep time for 40 seconds.
#define WORKER_IDLE_TIMEOUT 40000 // In Milliseconds
SleepTime = WORKER_IDLE_TIMEOUT ;
// Loop servicing I/O completion requests
for ( ; ; ) {
TimeOut.QuadPart = Int32x32To64( SleepTime, -10000 ) ;
Status = NtRemoveIoCompletion(
WorkerCompletionPort,
(PVOID) &WorkerProc,
&Overlapped,
&IoSb,
&TimeOut
) ;
if (Status == STATUS_SUCCESS) {
TotalExecutedWorkRequests ++ ;//interlocked op not req
InterlockedIncrement(&NumExecutingWorkerThreads) ;
InterlockedDecrement(&NumQueuedWorkRequests);
if (NumExecutingWorkerThreads == NumWorkerThreads
&& NumQueuedWorkRequests > 0) {
RtlpWorkerThreadSetTimer();
}
// Call the work item.
// If IO APC, context1 contains number of IO bytes transferred, and context2
// contains the overlapped structure.
// If (IO)WorkerFunction, context1 contains the actual WorkerFunction to be
// executed and context2 contains the actual context
Context = (PVOID) IoSb.Information ;
RtlpApcCallout(WorkerProc,
IoSb.Status,
Context,
Overlapped);
SleepTime = WORKER_IDLE_TIMEOUT ;
InterlockedDecrement(&NumExecutingWorkerThreads) ;
RtlpWorkerThreadCancelTimer();
} else if (Status == STATUS_TIMEOUT) {
// NtRemoveIoCompletion timed out. Check to see if have hit our limit
// on waiting. If so terminate.
Terminate = FALSE ;
RtlEnterCriticalSection (&WorkerCriticalSection) ;
// The thread terminates if there are > 1 threads and the queue is small
// OR if there is only 1 thread and there is no request pending
if (NumWorkerThreads > 1) {
ULONG NumEffWorkerThreads = NumWorkerThreads > NumLongWorkRequests
? NumWorkerThreads - NumLongWorkRequests
: 0;
if (NumEffWorkerThreads<=NumMinWorkerThreads) {
Terminate = FALSE ;
} else {
//
// have been idle for very long time. terminate irrespective of number of
// work items. (This is useful when the set of runnable threads is taking
// care of all the work items being queued). dont terminate if
// (NumEffWorkerThreads == 1)
//
if (NumEffWorkerThreads > 1) {
Terminate = TRUE ;
} else {
Terminate = FALSE ;
}
}
} else {
if ( NumMinWorkerThreads == 0
&& NumWorkRequests == 0
&& NumFutureWorkItems == 0) {
Terminate = TRUE ;
} else {
Terminate = FALSE ;
}
}
if (Terminate) {
THREAD_BASIC_INFORMATION ThreadInfo;
ULONG IsIoPending ;
Terminate = FALSE ;
Status = NtQueryInformationThread( NtCurrentThread(),
ThreadIsIoPending,
&IsIoPending,
sizeof( IsIoPending ),
NULL
);
if (NT_SUCCESS( Status )) {
if (! IsIoPending )
Terminate = TRUE ;
}
}
if (Terminate) {
ASSERT(NumWorkerThreads > 0);
NumWorkerThreads--;
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
RtlpExitThreadFunc( 0 );
} else {
// This is the condition where a request was queued *after* the
// thread woke up - ready to terminate because of inactivity. In
// this case dont terminate - service the completion port.
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
}
} else {
ASSERTMSG ("NtRemoveIoCompletion failed",
(Status != STATUS_SUCCESS) && (Status != STATUS_TIMEOUT)) ;
}
}
return 1 ;
}
#if _MSC_FULL_VER >= 13008827
#pragma warning(pop)
#endif
NTSTATUS
RtlpStartWorkerThread (
VOID
)
/*++
Routine Description:
This routine starts a regular worker thread
Arguments:
Return Value:
NTSTATUS error codes resulting from attempts to create a thread
STATUS_SUCCESS
--*/
{
HANDLE ThreadHandle;
ULONG CurrentTickCount;
NTSTATUS Status;
// Create worker thread
Status = RtlpStartThreadpoolThread (RtlpWorkerThread,
NULL,
&ThreadHandle);
if (NT_SUCCESS(Status)) {
#if DBG
DbgPrintEx(DPFLTR_RTLTHREADPOOL_ID,
RTLP_THREADPOOL_TRACE_MASK,
"Created worker thread; handle %d (closing)\n",
ThreadHandle);
#endif
// We don't care about worker threads' handles.
NtClose(ThreadHandle);
// Update the time at which the current thread was created
LastThreadCreationTickCount = NtGetTickCount() ;
// Increment the count of the thread type created
NumWorkerThreads++;
} else {
#if DBG
DbgPrintEx(DPFLTR_RTLTHREADPOOL_ID,
RTLP_THREADPOOL_TRACE_MASK,
"Failed to create worker thread; status %p\n",
Status);
#endif
// Thread creation failed. If there is even one thread present do not return
// failure - else queue the request anyway.
if (NumWorkerThreads <= NumLongWorkRequests) {
return Status ;
}
}
return STATUS_SUCCESS ;
}
NTSTATUS
RtlpInitializeWorkerThreadPool (
)
/*++
Routine Description:
This routine initializes all aspects of the thread pool.
Arguments:
None
Return Value:
None
--*/
{
NTSTATUS Status = STATUS_SUCCESS ;
LARGE_INTEGER TimeOut ;
SYSTEM_BASIC_INFORMATION BasicInfo;
// Initialize the timer component if it hasnt been done already
if (CompletedTimerInitialization != 1) {
Status = RtlpInitializeTimerThreadPool () ;
if ( !NT_SUCCESS(Status) )
return Status ;
}
// In order to avoid an explicit RtlInitialize() function to initialize the thread pool
// we use StartedInitialization and CompletedInitialization to provide us the necessary
// synchronization to avoid multiple threads from initializing the thread pool.
// This scheme does not work if RtlInitializeCriticalSection() fails - but in this case the
// caller has no choices left.
if (!InterlockedExchange(&StartedWorkerInitialization, 1L)) {
if (CompletedWorkerInitialization)
InterlockedExchange( &CompletedWorkerInitialization, 0 ) ;
do {
// Initialize Critical Sections
Status = RtlInitializeCriticalSection( &WorkerCriticalSection );
if (!NT_SUCCESS(Status))
break ;
Status = RtlInitializeCriticalSection( &WorkerTimerCriticalSection );
if (! NT_SUCCESS(Status)) {
RtlDeleteCriticalSection( &WorkerCriticalSection );
break;
}
InitializeListHead (&IOWorkerThreads) ;
// get number of processors
Status = NtQuerySystemInformation (
SystemBasicInformation,
&BasicInfo,
sizeof(BasicInfo),
NULL
) ;
if ( !NT_SUCCESS(Status) ) {
BasicInfo.NumberOfProcessors = 1 ;
}
// Create completion port used by worker threads
Status = NtCreateIoCompletion (
&WorkerCompletionPort,
IO_COMPLETION_ALL_ACCESS,
NULL,
BasicInfo.NumberOfProcessors
);
if (!NT_SUCCESS(Status)) {
RtlDeleteCriticalSection( &WorkerCriticalSection );
RtlDeleteCriticalSection( &WorkerTimerCriticalSection );
break;
}
} while ( FALSE ) ;
if (!NT_SUCCESS(Status) ) {
StartedWorkerInitialization = 0 ;
InterlockedExchange( &CompletedWorkerInitialization, ~0 ) ;
return Status ;
}
// Signal that initialization has completed
InterlockedExchange (&CompletedWorkerInitialization, 1L) ;
} else {
LARGE_INTEGER Timeout ;
// Sleep 1 ms and see if the other thread has completed initialization
ONE_MILLISECOND_TIMEOUT(TimeOut) ;
while (!*((ULONG volatile *)&CompletedWorkerInitialization)) {
NtDelayExecution (FALSE, &TimeOut) ;
}
if (CompletedWorkerInitialization != 1)
return STATUS_NO_MEMORY ;
}
return NT_SUCCESS(Status) ? STATUS_SUCCESS : Status ;
}
LONG
RtlpIOWorkerThread (
PVOID Parameter
)
/*++
Routine Description:
All I/O worker threads execute in this routine. All the work requests execute as APCs
in this thread.
Arguments:
HandlePtr - Pointer to our handle.
Return Value:
--*/
{
#define IOWORKER_IDLE_TIMEOUT 40000 // In Milliseconds
LARGE_INTEGER TimeOut ;
ULONG SleepTime = IOWORKER_IDLE_TIMEOUT ;
PRTLP_IOWORKER_TCB ThreadCB ; // Control Block allocated on the
// heap by the parent thread
NTSTATUS Status ;
BOOLEAN Terminate ;
ASSERT(Parameter != NULL);
ThreadCB = (PRTLP_IOWORKER_TCB) Parameter;
#if DBG
DbgPrintEx(DPFLTR_RTLTHREADPOOL_ID,
RTLP_THREADPOOL_TRACE_MASK,
"Starting IO worker thread\n");
#endif
// Sleep alertably so that all the activity can take place
// in APCs
for ( ; ; ) {
// Set timeout for IdleTimeout
TimeOut.QuadPart = Int32x32To64( SleepTime, -10000 ) ;
Status = NtDelayExecution (TRUE, &TimeOut) ;
// Status is STATUS_SUCCESS only when it has timed out
if (Status != STATUS_SUCCESS) {
continue ;
}
//
// idle timeout. check if you can terminate the thread
//
Terminate = FALSE ;
RtlEnterCriticalSection (&WorkerCriticalSection) ;
// dont terminate if it is a persistent thread
if (ThreadCB->Flags & WT_EXECUTEINPERSISTENTIOTHREAD) {
TimeOut.LowPart = 0x0;
TimeOut.HighPart = 0x80000000;
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
continue ;
}
// The thread terminates if there are > 1 threads and the queue is small
// OR if there is only 1 thread and there is no request pending
if (NumIOWorkerThreads > 1) {
ULONG NumEffIOWorkerThreads = NumIOWorkerThreads > NumLongIOWorkRequests
? NumIOWorkerThreads - NumLongIOWorkRequests
: 0;
ULONG Threshold;
if (NumEffIOWorkerThreads == 0) {
Terminate = FALSE ;
} else {
// Check if we need to shrink worker thread pool
Threshold = NEW_THREAD_THRESHOLD * (NumEffIOWorkerThreads-1);
if (NumIOWorkRequests-NumLongIOWorkRequests < Threshold) {
Terminate = TRUE ;
} else {
Terminate = FALSE ;
SleepTime <<= 1 ;
}
}
} else {
if (NumIOWorkRequests == 0
&& NumFutureIOWorkItems == 0) {
// delay termination of last thread
if (SleepTime < 4*IOWORKER_IDLE_TIMEOUT) {
SleepTime <<= 1 ;
Terminate = FALSE ;
} else {
Terminate = TRUE ;
}
} else {
Terminate = FALSE ;
}
}
//
// terminate only if no io is pending
//
if (Terminate) {
NTSTATUS Status;
THREAD_BASIC_INFORMATION ThreadInfo;
ULONG IsIoPending ;
Terminate = FALSE ;
Status = NtQueryInformationThread( ThreadCB->ThreadHandle,
ThreadIsIoPending,
&IsIoPending,
sizeof( IsIoPending ),
NULL
);
if (NT_SUCCESS( Status )) {
if (! IsIoPending )
Terminate = TRUE ;
}
}
if (Terminate) {
ASSERT(NumIOWorkerThreads > 0);
NumIOWorkerThreads--;
RemoveEntryList (&ThreadCB->List) ;
NtClose( ThreadCB->ThreadHandle ) ;
RtlpFreeTPHeap( ThreadCB );
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
RtlpExitThreadFunc( 0 );
} else {
// This is the condition where a request was queued *after* the
// thread woke up - ready to terminate because of inactivity. In
// this case dont terminate - service the completion port.
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
}
}
return 0 ; // Keep compiler happy
}
NTSTATUS
RtlpStartIOWorkerThread (
)
/*++
Routine Description:
This routine starts an I/O worker thread
N.B. Callers MUST hold the WorkerCriticalSection.
Arguments:
Return Value:
NTSTATUS error codes resulting from attempts to create a thread
STATUS_SUCCESS
--*/
{
ULONG CurrentTickCount ;
NTSTATUS Status ;
PRTLP_IOWORKER_TCB ThreadCB;
// Create the worker's control block
ThreadCB = (PRTLP_IOWORKER_TCB) RtlpAllocateTPHeap(sizeof(RTLP_IOWORKER_TCB), 0);
if (! ThreadCB) {
return STATUS_NO_MEMORY;
}
// Fill in the control block
ThreadCB->Flags = 0;
ThreadCB->LongFunctionFlag = FALSE;
// Create worker thread
Status = RtlpStartThreadpoolThread (RtlpIOWorkerThread,
ThreadCB,
&ThreadCB->ThreadHandle);
if (NT_SUCCESS(Status)) {
// Update the time at which the current thread was created,
// and insert the ThreadCB into the IO worker thread list.
LastThreadCreationTickCount = NtGetTickCount() ;
NumIOWorkerThreads++;
InsertHeadList(&IOWorkerThreads, &ThreadCB->List);
} else {
// Thread creation failed.
RtlpFreeTPHeap(ThreadCB);
// If there is even one thread present do not return
// failure since we can still service the work request.
if (NumIOWorkerThreads <= NumLongIOWorkRequests) {
return Status ;
}
}
return STATUS_SUCCESS ;
}
VOID
RtlpExecuteLongIOWorkItem (
PVOID Function,
PVOID Context,
PVOID ThreadCB
)
/*++
Routine Description:
Executes an IO Work function. RUNs in a APC in the IO Worker thread.
Arguments:
Function - Worker function to call
Context - Argument for the worker function.
NotUsed - Argument is not used in this function.
Return Value:
--*/
{
RtlpWorkerCallout(Function,
Context,
NULL,
NULL);
((PRTLP_IOWORKER_TCB)ThreadCB)->LongFunctionFlag = FALSE ;
RtlEnterCriticalSection(&WorkerCriticalSection);
// Decrement pending IO requests count
NumIOWorkRequests--;
// decrement pending long funcitons
NumLongIOWorkRequests--;
RtlLeaveCriticalSection(&WorkerCriticalSection);
}
VOID
RtlpExecuteIOWorkItem (
PVOID Function,
PVOID Context,
PVOID NotUsed
)
/*++
Routine Description:
Executes an IO Work function. RUNs in a APC in the IO Worker thread.
Arguments:
Function - Worker function to call
Context - Argument for the worker function.
NotUsed - Argument is not used in this function.
Return Value:
--*/
{
RtlpWorkerCallout(Function,
Context,
NULL,
NULL);
RtlEnterCriticalSection(&WorkerCriticalSection);
// Decrement pending IO requests count
NumIOWorkRequests--;
RtlLeaveCriticalSection(&WorkerCriticalSection);
}
NTSTATUS
RtlpQueueIOWorkerRequest (
WORKERCALLBACKFUNC Function,
PVOID Context,
ULONG Flags
)
/*++
Routine Description:
This routine queues up the request to be executed in an IO worker thread.
Arguments:
Function - Routine that is called by the worker thread
Context - Opaque pointer passed in as an argument to WorkerProc
Return Value:
--*/
{
NTSTATUS Status ;
PRTLP_IOWORKER_TCB TCB ;
BOOLEAN LongFunction = (Flags & WT_EXECUTELONGFUNCTION) ? TRUE : FALSE ;
PLIST_ENTRY ple ;
if (Flags & WT_EXECUTEINPERSISTENTIOTHREAD) {
if (!PersistentIOTCB) {
for (ple=IOWorkerThreads.Flink; ple!=&IOWorkerThreads; ple=ple->Flink) {
TCB = CONTAINING_RECORD (ple, RTLP_IOWORKER_TCB, List) ;
if (! TCB->LongFunctionFlag)
break;
}
if (ple == &IOWorkerThreads) {
return STATUS_NO_MEMORY;
}
PersistentIOTCB = TCB ;
TCB->Flags |= WT_EXECUTEINPERSISTENTIOTHREAD ;
} else {
TCB = PersistentIOTCB ;
}
} else {
for (ple=IOWorkerThreads.Flink; ple!=&IOWorkerThreads; ple=ple->Flink) {
TCB = CONTAINING_RECORD (ple, RTLP_IOWORKER_TCB, List) ;
// do not queue to the thread if it is executing a long function, or
// if you are queueing a long function and the thread is a persistent thread
if (! TCB->LongFunctionFlag
&& (! ((TCB->Flags&WT_EXECUTEINPERSISTENTIOTHREAD)
&& (Flags&WT_EXECUTELONGFUNCTION)))) {
break ;
}
}
if ((ple == &IOWorkerThreads) && (NumIOWorkerThreads<1)) {
#if DBG
DbgPrintEx(DPFLTR_RTLTHREADPOOL_ID,
RTLP_THREADPOOL_WARNING_MASK,
"Out of memory. "
"Could not execute IOWorkItem(%x)\n", (ULONG_PTR)Function);
#endif
return STATUS_NO_MEMORY;
}
else {
ple = IOWorkerThreads.Flink;
TCB = CONTAINING_RECORD (ple, RTLP_IOWORKER_TCB, List) ;
// treat it as a short function so that counters work fine.
LongFunction = FALSE;
}
// In order to implement "fair" assignment of work items between IO worker threads
// each time remove the entry and reinsert at back.
RemoveEntryList (&TCB->List) ;
InsertTailList (&IOWorkerThreads, &TCB->List) ;
}
// Increment the outstanding work request counter
NumIOWorkRequests++;
if (LongFunction) {
NumLongIOWorkRequests++;
TCB->LongFunctionFlag = TRUE ;
}
// Queue an APC to the IoWorker Thread
Status = NtQueueApcThread(
TCB->ThreadHandle,
LongFunction? (PPS_APC_ROUTINE)RtlpExecuteLongIOWorkItem:
(PPS_APC_ROUTINE)RtlpExecuteIOWorkItem,
(PVOID)Function,
Context,
TCB
);
if (! NT_SUCCESS( Status ) ) {
NumIOWorkRequests--;
if (LongFunction)
NumLongIOWorkRequests--;
}
return Status ;
}
NTSTATUS
RtlSetIoCompletionCallback (
IN HANDLE FileHandle,
IN APC_CALLBACK_FUNCTION CompletionProc,
IN ULONG Flags
)
/*++
Routine Description:
This routine binds an Handle and an associated callback function to the
IoCompletionPort which queues work items to worker threads.
Arguments:
Handle - handle to be bound to the IO completion port
CompletionProc - callback function to be executed when an IO request
pending on the IO handle completes.
Flags - Reserved. pass 0.
--*/
{
IO_STATUS_BLOCK IoSb ;
FILE_COMPLETION_INFORMATION CompletionInfo ;
NTSTATUS Status;
if (LdrpShutdownInProgress) {
return STATUS_UNSUCCESSFUL;
}
// Make sure that the worker thread pool is initialized as the file handle
// is bound to IO completion port.
if (CompletedWorkerInitialization != 1) {
Status = RtlpInitializeWorkerThreadPool () ;
if (! NT_SUCCESS(Status) )
return Status ;
}
//
// from now on NumMinWorkerThreads should be 1. If there is only 1 worker thread
// create a new one.
//
if ( NumMinWorkerThreads == 0 ) {
// Take lock for the global worker thread pool
RtlEnterCriticalSection (&WorkerCriticalSection) ;
if ((NumWorkerThreads-NumLongWorkRequests) == 0) {
Status = RtlpStartWorkerThread () ;
if ( ! NT_SUCCESS(Status) ) {
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
return Status ;
}
}
// from now on, there will be at least 1 worker thread
NumMinWorkerThreads = 1 ;
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
}
// bind to IoCompletionPort, which queues work items to worker threads
CompletionInfo.Port = WorkerCompletionPort ;
CompletionInfo.Key = (PVOID) CompletionProc ;
Status = NtSetInformationFile (
FileHandle,
&IoSb, //not initialized
&CompletionInfo,
sizeof(CompletionInfo),
FileCompletionInformation //enum flag
) ;
return Status ;
}
VOID
RtlpExecuteWorkerRequest (
NTSTATUS StatusIn, //not used
PVOID Context,
PVOID WorkContext
)
/*++
Routine Description:
This routine executes a work item.
Arguments:
Context - contains context to be passed to the callback function.
WorkContext - contains callback function ptr and flags
Return Value:
Notes:
This function executes in a worker thread or a timer thread if
WT_EXECUTEINTIMERTHREAD flag is set.
--*/
{
PRTLP_WORK WorkEntry = (PRTLP_WORK) WorkContext;
NTSTATUS Status;
RtlpWorkerCallout(WorkEntry->Function,
Context,
WorkEntry->ActivationContext,
WorkEntry->ImpersonationToken);
RtlEnterCriticalSection(&WorkerCriticalSection);
NumWorkRequests--;
if (WorkEntry->Flags & WT_EXECUTELONGFUNCTION) {
NumLongWorkRequests--;
}
RtlLeaveCriticalSection(&WorkerCriticalSection);
if (WorkEntry->ActivationContext != INVALID_ACTIVATION_CONTEXT)
RtlReleaseActivationContext(WorkEntry->ActivationContext);
if (WorkEntry->ImpersonationToken) {
NtClose(WorkEntry->ImpersonationToken);
}
RtlpFreeTPHeap( WorkEntry ) ;
}
NTSTATUS
RtlpQueueWorkerRequest (
WORKERCALLBACKFUNC Function,
PVOID Context,
ULONG Flags
)
/*++
Routine Description:
This routine queues up the request to be executed in a worker thread.
Arguments:
Function - Routine that is called by the worker thread
Context - Opaque pointer passed in as an argument to WorkerProc
Flags - flags passed to RtlQueueWorkItem
Return Value:
--*/
{
NTSTATUS Status ;
PRTLP_WORK WorkEntry ;
WorkEntry = (PRTLP_WORK) RtlpAllocateTPHeap ( sizeof (RTLP_WORK),
HEAP_ZERO_MEMORY) ;
if (! WorkEntry) {
return STATUS_NO_MEMORY;
}
if (NtCurrentTeb()->IsImpersonating) {
Status = NtOpenThreadToken(NtCurrentThread(),
MAXIMUM_ALLOWED,
TRUE,
&WorkEntry->ImpersonationToken);
if (! NT_SUCCESS(Status)) {
RtlpFreeTPHeap(WorkEntry);
return Status;
}
} else {
WorkEntry->ImpersonationToken = NULL;
}
Status = RtlpThreadPoolGetActiveActivationContext(&WorkEntry->ActivationContext);
if (!NT_SUCCESS(Status)) {
if (Status == STATUS_SXS_THREAD_QUERIES_DISABLED) {
WorkEntry->ActivationContext = INVALID_ACTIVATION_CONTEXT;
Status = STATUS_SUCCESS;
} else {
if (WorkEntry->ImpersonationToken) {
NtClose(WorkEntry->ImpersonationToken);
}
RtlpFreeTPHeap(WorkEntry);
return Status;
}
}
// Increment the outstanding work request counter
NumWorkRequests++;
if (Flags & WT_EXECUTELONGFUNCTION) {
NumLongWorkRequests++;
}
WorkEntry->Function = Function ;
WorkEntry->Flags = Flags ;
if (Flags & WT_EXECUTEINPERSISTENTTHREAD) {
// Queue APC to timer thread
Status = NtQueueApcThread(
TimerThreadHandle,
(PPS_APC_ROUTINE)RtlpExecuteWorkerRequest,
(PVOID) STATUS_SUCCESS,
(PVOID) Context,
(PVOID) WorkEntry
) ;
} else {
InterlockedIncrement(&NumQueuedWorkRequests);
Status = NtSetIoCompletion (
WorkerCompletionPort,
RtlpExecuteWorkerRequest,
(PVOID) WorkEntry,
STATUS_SUCCESS,
(ULONG_PTR)Context
);
if (! NT_SUCCESS(Status)) {
InterlockedDecrement(&NumQueuedWorkRequests);
}
}
if ( ! NT_SUCCESS(Status) ) {
NumWorkRequests--;
if (Flags & WT_EXECUTELONGFUNCTION) {
NumLongWorkRequests--;
}
if (WorkEntry->ActivationContext != INVALID_ACTIVATION_CONTEXT)
RtlReleaseActivationContext(WorkEntry->ActivationContext);
if (WorkEntry->ImpersonationToken) {
NtClose(WorkEntry->ImpersonationToken);
}
RtlpFreeTPHeap( WorkEntry ) ;
}
return Status ;
}
NTSTATUS
RtlQueueWorkItem(
IN WORKERCALLBACKFUNC Function,
IN PVOID Context,
IN ULONG Flags
)
/*++
Routine Description:
This routine queues up the request to be executed in a worker thread.
Arguments:
Function - Routine that is called by the worker thread
Context - Opaque pointer passed in as an argument to WorkerProc
Flags - Can be:
WT_EXECUTEINIOTHREAD - Specifies that the WorkerProc should be invoked
by a thread that is never destroyed when there are pending IO requests.
This can be used by threads that invoke I/O and/or schedule APCs.
The below flag can also be set:
WT_EXECUTELONGFUNCTION - Specifies that the function might block for a
long duration.
Return Value:
STATUS_SUCCESS - Queued successfully.
STATUS_NO_MEMORY - There was not sufficient heap to perform the
requested operation.
--*/
{
ULONG Threshold ;
ULONG CurrentTickCount ;
NTSTATUS Status = STATUS_SUCCESS ;
if (LdrpShutdownInProgress) {
return STATUS_UNSUCCESSFUL;
}
// Make sure the worker thread pool is initialized
if (CompletedWorkerInitialization != 1) {
Status = RtlpInitializeWorkerThreadPool () ;
if (! NT_SUCCESS(Status) )
return Status ;
}
// Take lock for the global worker thread pool
RtlEnterCriticalSection (&WorkerCriticalSection) ;
if (Flags&0xffff0000) {
MaxThreads = (Flags & 0xffff0000)>>16;
}
if (NEEDS_IO_THREAD(Flags)) {
//
// execute in IO Worker thread
//
ULONG NumEffIOWorkerThreads = NumIOWorkerThreads > NumLongIOWorkRequests
? NumIOWorkerThreads - NumLongIOWorkRequests
: 0;
ULONG ThreadCreationDampingTime = NumIOWorkerThreads < NEW_THREAD_THRESHOLD
? THREAD_CREATION_DAMPING_TIME1
: THREAD_CREATION_DAMPING_TIME2 ;
if (NumEffIOWorkerThreads && PersistentIOTCB && (Flags&WT_EXECUTELONGFUNCTION))
NumEffIOWorkerThreads -- ;
// Check if we need to grow I/O worker thread pool
Threshold = (NumEffIOWorkerThreads < MAX_WORKER_THREADS
? NEW_THREAD_THRESHOLD * NumEffIOWorkerThreads
: 0xffffffff) ;
if (LastThreadCreationTickCount > NtGetTickCount())
LastThreadCreationTickCount = NtGetTickCount() ;
if (NumEffIOWorkerThreads == 0
|| ((NumIOWorkRequests - NumLongIOWorkRequests > Threshold)
&& (LastThreadCreationTickCount + ThreadCreationDampingTime
< NtGetTickCount()))) {
// Grow the IO worker thread pool
Status = RtlpStartIOWorkerThread () ;
}
if (NT_SUCCESS(Status)) {
// Queue the work request
Status = RtlpQueueIOWorkerRequest (Function, Context, Flags) ;
}
} else {
//
// execute in regular worker thread
//
ULONG NumEffWorkerThreads = NumWorkerThreads > NumLongWorkRequests
? NumWorkerThreads - NumLongWorkRequests
: 0;
ULONG ThreadCreationDampingTime = NumWorkerThreads < NEW_THREAD_THRESHOLD
? THREAD_CREATION_DAMPING_TIME1
: (NumWorkerThreads < 30
? THREAD_CREATION_DAMPING_TIME2
: NumWorkerThreads << 13);
// if io completion set, then have 1 more thread
if (NumMinWorkerThreads && NumEffWorkerThreads)
NumEffWorkerThreads -- ;
// Check if we need to grow worker thread pool
Threshold = (NumWorkerThreads < MAX_WORKER_THREADS
? (NumEffWorkerThreads < 7
? NumEffWorkerThreads*NumEffWorkerThreads
: ((NumEffWorkerThreads<40)
? NEW_THREAD_THRESHOLD * NumEffWorkerThreads
: NEW_THREAD_THRESHOLD2 * NumEffWorkerThreads))
: 0xffffffff) ;
if (LastThreadCreationTickCount > NtGetTickCount())
LastThreadCreationTickCount = NtGetTickCount() ;
if (NumEffWorkerThreads == 0 ||
( (NumWorkRequests - NumLongWorkRequests >= Threshold)
&& (LastThreadCreationTickCount + ThreadCreationDampingTime
< NtGetTickCount())))
{
// Grow the worker thread pool
if (NumWorkerThreads<MaxThreads) {
Status = RtlpStartWorkerThread () ;
}
}
// Queue the work request
if (NT_SUCCESS(Status)) {
Status = RtlpQueueWorkerRequest (Function, Context, Flags) ;
}
}
// Release lock on the worker thread pool
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
return Status ;
}
NTSTATUS
RtlpWorkerCleanup(
VOID
)
{
PLIST_ENTRY Node;
ULONG i;
HANDLE TmpHandle;
BOOLEAN Cleanup;
IS_COMPONENT_INITIALIZED( StartedWorkerInitialization,
CompletedWorkerInitialization,
Cleanup ) ;
if ( Cleanup ) {
RtlEnterCriticalSection (&WorkerCriticalSection) ;
if ( (NumWorkRequests != 0) || (NumIOWorkRequests != 0) ) {
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
return STATUS_UNSUCCESSFUL ;
}
// queue a cleanup for each worker thread
for (i = 0 ; i < NumWorkerThreads ; i ++ ) {
NtSetIoCompletion (
WorkerCompletionPort,
RtlpThreadCleanup,
NULL,
STATUS_SUCCESS,
0
);
}
// queue an apc to cleanup all IO worker threads
for (Node = IOWorkerThreads.Flink ; Node != &IOWorkerThreads ;
Node = Node->Flink )
{
PRTLP_IOWORKER_TCB ThreadCB ;
ThreadCB = CONTAINING_RECORD (Node, RTLP_IOWORKER_TCB, List) ;
RemoveEntryList( &ThreadCB->List) ;
TmpHandle = ThreadCB->ThreadHandle ;
NtQueueApcThread(
ThreadCB->ThreadHandle,
(PPS_APC_ROUTINE)RtlpThreadCleanup,
NULL,
NULL,
NULL
);
NtClose( TmpHandle ) ;
}
NumWorkerThreads = NumIOWorkerThreads = 0 ;
RtlLeaveCriticalSection (&WorkerCriticalSection) ;
}
return STATUS_SUCCESS;
}
NTSTATUS
RtlpThreadPoolGetActiveActivationContext(
PACTIVATION_CONTEXT* ActivationContext
)
{
ACTIVATION_CONTEXT_BASIC_INFORMATION ActivationContextInfo = {0};
NTSTATUS Status = STATUS_SUCCESS;
ASSERT(ActivationContext != NULL);
*ActivationContext = NULL;
Status =
RtlQueryInformationActivationContext(
RTL_QUERY_INFORMATION_ACTIVATION_CONTEXT_FLAG_USE_ACTIVE_ACTIVATION_CONTEXT,
NULL,
0,
ActivationContextBasicInformation,
&ActivationContextInfo,
sizeof(ActivationContextInfo),
NULL);
if (!NT_SUCCESS(Status)) {
goto Exit;
}
if ((ActivationContextInfo.Flags & ACTIVATION_CONTEXT_FLAG_NO_INHERIT) != 0) {
RtlReleaseActivationContext(ActivationContextInfo.ActivationContext);
ActivationContextInfo.ActivationContext = NULL;
// fall through
}
*ActivationContext = ActivationContextInfo.ActivationContext;
Status = STATUS_SUCCESS;
Exit:
return Status;
}
NTSTATUS
RtlpAcquireWorker(ULONG Flags)
{
NTSTATUS Status = STATUS_SUCCESS;
if (CompletedWorkerInitialization != 1) {
Status = RtlpInitializeWorkerThreadPool () ;
if (! NT_SUCCESS(Status) )
return Status ;
}
if (NEEDS_IO_THREAD(Flags)) {
RtlEnterCriticalSection(&WorkerCriticalSection);
InterlockedIncrement(&NumFutureIOWorkItems);
if (NumIOWorkerThreads == 0) {
Status = RtlpStartIOWorkerThread();
}
RtlLeaveCriticalSection(&WorkerCriticalSection);
} else {
RtlEnterCriticalSection(&WorkerCriticalSection);
InterlockedIncrement(&NumFutureWorkItems);
if (NumWorkerThreads == 0) {
Status = RtlpStartWorkerThread();
}
RtlLeaveCriticalSection(&WorkerCriticalSection);
}
return Status;
}
VOID
RtlpReleaseWorker(ULONG Flags)
{
if (NEEDS_IO_THREAD(Flags)) {
ASSERT(NumFutureIOWorkItems > 0);
InterlockedDecrement(&NumFutureIOWorkItems);
} else {
ASSERT(NumFutureWorkItems > 0);
InterlockedDecrement(&NumFutureWorkItems);
}
}