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Diffstat (limited to 'rts/win32/AsyncIO.c')
| -rw-r--r-- | rts/win32/AsyncIO.c | 345 |
1 files changed, 345 insertions, 0 deletions
diff --git a/rts/win32/AsyncIO.c b/rts/win32/AsyncIO.c new file mode 100644 index 0000000000..7bcf571cf8 --- /dev/null +++ b/rts/win32/AsyncIO.c @@ -0,0 +1,345 @@ +/* AsyncIO.c + * + * Integrating Win32 asynchronous I/O with the GHC RTS. + * + * (c) sof, 2002-2003. + */ +#include "Rts.h" +#include "RtsUtils.h" +#include <windows.h> +#include <stdio.h> +#include "Schedule.h" +#include "RtsFlags.h" +#include "Capability.h" +#include "win32/AsyncIO.h" +#include "win32/IOManager.h" + +/* + * Overview: + * + * Haskell code issue asynchronous I/O requests via the + * async{Read,Write,DoOp}# primops. These cause addIORequest() + * to be invoked, which forwards the request to the underlying + * asynchronous I/O subsystem. Each request is tagged with a unique + * ID. + * + * addIORequest() returns this ID, so that when the blocked CH + * thread is added onto blocked_queue, its TSO is annotated with + * it. Upon completion of an I/O request, the async I/O handling + * code makes a back-call to signal its completion; the local + * onIOComplete() routine. It adds the IO request ID (along with + * its result data) to a queue of completed requests before returning. + * + * The queue of completed IO request is read by the thread operating + * the RTS scheduler. It de-queues the CH threads corresponding + * to the request IDs, making them runnable again. + * + */ + +typedef struct CompletedReq { + unsigned int reqID; + int len; + int errCode; +} CompletedReq; + +#define MAX_REQUESTS 200 + +static CRITICAL_SECTION queue_lock; +static HANDLE completed_req_event; +static HANDLE abandon_req_wait; +static HANDLE wait_handles[2]; +static CompletedReq completedTable[MAX_REQUESTS]; +static int completed_hw; +static HANDLE completed_table_sema; +static int issued_reqs; + +static void +onIOComplete(unsigned int reqID, + int fd STG_UNUSED, + int len, + void* buf STG_UNUSED, + int errCode) +{ + DWORD dwRes; + /* Deposit result of request in queue/table..when there's room. */ + dwRes = WaitForSingleObject(completed_table_sema, INFINITE); + switch (dwRes) { + case WAIT_OBJECT_0: + break; + default: + /* Not likely */ + fprintf(stderr, "onIOComplete: failed to grab table semaphore, dropping request 0x%x\n", reqID); + fflush(stderr); + return; + } + EnterCriticalSection(&queue_lock); + if (completed_hw == MAX_REQUESTS) { + /* Shouldn't happen */ + fprintf(stderr, "onIOComplete: ERROR -- Request table overflow (%d); dropping.\n", reqID); + fflush(stderr); + } else { +#if 0 + fprintf(stderr, "onCompl: %d %d %d %d %d\n", + reqID, len, errCode, issued_reqs, completed_hw); + fflush(stderr); +#endif + completedTable[completed_hw].reqID = reqID; + completedTable[completed_hw].len = len; + completedTable[completed_hw].errCode = errCode; + completed_hw++; + issued_reqs--; + if (completed_hw == 1) { + /* The event is used to wake up the scheduler thread should it + * be blocked waiting for requests to complete. The event resets once + * that thread has cleared out the request queue/table. + */ + SetEvent(completed_req_event); + } + } + LeaveCriticalSection(&queue_lock); +} + +unsigned int +addIORequest(int fd, + int forWriting, + int isSock, + int len, + char* buf) +{ + EnterCriticalSection(&queue_lock); + issued_reqs++; + LeaveCriticalSection(&queue_lock); +#if 0 + fprintf(stderr, "addIOReq: %d %d %d\n", fd, forWriting, len); fflush(stderr); +#endif + return AddIORequest(fd,forWriting,isSock,len,buf,onIOComplete); +} + +unsigned int +addDelayRequest(int msecs) +{ + EnterCriticalSection(&queue_lock); + issued_reqs++; + LeaveCriticalSection(&queue_lock); +#if 0 + fprintf(stderr, "addDelayReq: %d\n", msecs); fflush(stderr); +#endif + return AddDelayRequest(msecs,onIOComplete); +} + +unsigned int +addDoProcRequest(void* proc, void* param) +{ + EnterCriticalSection(&queue_lock); + issued_reqs++; + LeaveCriticalSection(&queue_lock); +#if 0 + fprintf(stderr, "addProcReq: %p %p\n", proc, param); fflush(stderr); +#endif + return AddProcRequest(proc,param,onIOComplete); +} + + +int +startupAsyncIO() +{ + if (!StartIOManager()) { + return 0; + } + InitializeCriticalSection(&queue_lock); + /* Create a pair of events: + * + * - completed_req_event -- signals the deposit of request result; manual reset. + * - abandon_req_wait -- external OS thread tells current RTS/Scheduler + * thread to abandon wait for IO request completion. + * Auto reset. + */ + completed_req_event = CreateEvent (NULL, TRUE, FALSE, NULL); + abandon_req_wait = CreateEvent (NULL, FALSE, FALSE, NULL); + wait_handles[0] = completed_req_event; + wait_handles[1] = abandon_req_wait; + completed_hw = 0; + if ( !(completed_table_sema = CreateSemaphore (NULL, MAX_REQUESTS, MAX_REQUESTS, NULL)) ) { + DWORD rc = GetLastError(); + fprintf(stderr, "startupAsyncIO: CreateSemaphore failed 0x%x\n", rc); + fflush(stderr); + } + + return ( completed_req_event != INVALID_HANDLE_VALUE && + abandon_req_wait != INVALID_HANDLE_VALUE && + completed_table_sema != NULL ); +} + +void +shutdownAsyncIO() +{ + CloseHandle(completed_req_event); + ShutdownIOManager(); +} + +/* + * Function: awaitRequests(wait) + * + * Check for the completion of external IO work requests. Worker + * threads signal completion of IO requests by depositing them + * in a table (completedTable). awaitRequests() matches up + * requests in that table with threads on the blocked_queue, + * making the threads whose IO requests have completed runnable + * again. + * + * awaitRequests() is called by the scheduler periodically _or_ if + * it is out of work, and need to wait for the completion of IO + * requests to make further progress. In the latter scenario, + * awaitRequests() will simply block waiting for worker threads + * to complete if the 'completedTable' is empty. + */ +int +awaitRequests(rtsBool wait) +{ +#ifndef THREADED_RTS + // none of this is actually used in the threaded RTS + +start: +#if 0 + fprintf(stderr, "awaitRequests(): %d %d %d\n", issued_reqs, completed_hw, wait); + fflush(stderr); +#endif + EnterCriticalSection(&queue_lock); + /* Nothing immediately available & we won't wait */ + if ((!wait && completed_hw == 0) +#if 0 + // If we just return when wait==rtsFalse, we'll go into a busy + // wait loop, so I disabled this condition --SDM 18/12/2003 + (issued_reqs == 0 && completed_hw == 0) +#endif + ) { + LeaveCriticalSection(&queue_lock); + return 0; + } + if (completed_hw == 0) { + /* empty table, drop lock and wait */ + LeaveCriticalSection(&queue_lock); + if ( wait && sched_state == SCHED_RUNNING ) { + DWORD dwRes = WaitForMultipleObjects(2, wait_handles, FALSE, INFINITE); + switch (dwRes) { + case WAIT_OBJECT_0: + /* a request was completed */ + break; + case WAIT_OBJECT_0 + 1: + case WAIT_TIMEOUT: + /* timeout (unlikely) or told to abandon waiting */ + return 0; + case WAIT_FAILED: { + DWORD dw = GetLastError(); + fprintf(stderr, "awaitRequests: wait failed -- error code: %lu\n", dw); fflush(stderr); + return 0; + } + default: + fprintf(stderr, "awaitRequests: unexpected wait return code %lu\n", dwRes); fflush(stderr); + return 0; + } + } else { + return 0; + } + goto start; + } else { + int i; + StgTSO *tso, *prev; + + for (i=0; i < completed_hw; i++) { + /* For each of the completed requests, match up their Ids + * with those of the threads on the blocked_queue. If the + * thread that made the IO request has been subsequently + * killed (and removed from blocked_queue), no match will + * be found for that request Id. + * + * i.e., killing a Haskell thread doesn't attempt to cancel + * the IO request it is blocked on. + * + */ + unsigned int rID = completedTable[i].reqID; + + prev = NULL; + for(tso = blocked_queue_hd ; tso != END_TSO_QUEUE; prev = tso, tso = tso->link) { + + switch(tso->why_blocked) { + case BlockedOnRead: + case BlockedOnWrite: + case BlockedOnDoProc: + if (tso->block_info.async_result->reqID == rID) { + /* Found the thread blocked waiting on request; stodgily fill + * in its result block. + */ + tso->block_info.async_result->len = completedTable[i].len; + tso->block_info.async_result->errCode = completedTable[i].errCode; + + /* Drop the matched TSO from blocked_queue */ + if (prev) { + prev->link = tso->link; + } else { + blocked_queue_hd = tso->link; + } + if (blocked_queue_tl == tso) { + blocked_queue_tl = prev ? prev : END_TSO_QUEUE; + } + + /* Terminates the run queue + this inner for-loop. */ + tso->link = END_TSO_QUEUE; + tso->why_blocked = NotBlocked; + pushOnRunQueue(&MainCapability, tso); + break; + } + break; + default: + if (tso->why_blocked != NotBlocked) { + barf("awaitRequests: odd thread state"); + } + break; + } + } + /* Signal that there's completed table slots available */ + if ( !ReleaseSemaphore(completed_table_sema, 1, NULL) ) { + DWORD dw = GetLastError(); + fprintf(stderr, "awaitRequests: failed to signal semaphore (error code=0x%x)\n", dw); + fflush(stderr); + } + } + completed_hw = 0; + ResetEvent(completed_req_event); + LeaveCriticalSection(&queue_lock); + return 1; + } +#endif /* !THREADED_RTS */ +} + +/* + * Function: abandonRequestWait() + * + * Wake up a thread that's blocked waiting for new IO requests + * to complete (via awaitRequests().) + */ +void +abandonRequestWait( void ) +{ + /* the event is auto-reset, but in case there's no thread + * already waiting on the event, we want to return it to + * a non-signalled state. + * + * Careful! There is no synchronisation between + * abandonRequestWait and awaitRequest, which means that + * abandonRequestWait might be called just before a thread + * goes into a wait, and we miss the abandon signal. So we + * must SetEvent() here rather than PulseEvent() to ensure + * that the event isn't lost. We can re-optimise by resetting + * the event somewhere safe if we know the event has been + * properly serviced (see resetAbandon() below). --SDM 18/12/2003 + */ + SetEvent(abandon_req_wait); +} + +void +resetAbandonRequestWait( void ) +{ + ResetEvent(abandon_req_wait); +} + |