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Merge branch 'lukas/erts/win32_flush_console_io/OTP-10325' into maint

* lukas/erts/win32_flush_console_io/OTP-10325:
  Make sure io is flushed when driver is closed
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commit 7e200a6e6e182f37f9ab6f0a74056b2936bc27a1 2 parents b974565 + 2a400b8
@garazdawi garazdawi authored
Showing with 74 additions and 3 deletions.
  1. +74 −3 erts/emulator/sys/win32/sys.c
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77 erts/emulator/sys/win32/sys.c
@@ -420,6 +420,8 @@ typedef struct async_io {
HANDLE ioAllowed; /* The thread will wait for this event
* before starting a new read or write.
*/
+ HANDLE flushEvent; /* Used to signal that a flush should be done. */
+ HANDLE flushReplyEvent; /* Used to signal that a flush has been done. */
DWORD pendingError; /* Used to delay presentating an error to Erlang
* until the check_io function is entered.
*/
@@ -878,6 +880,8 @@ init_async_io(AsyncIo* aio, int use_threads)
aio->ov.Offset = 0L;
aio->ov.OffsetHigh = 0L;
aio->ioAllowed = NULL;
+ aio->flushEvent = NULL;
+ aio->flushReplyEvent = NULL;
aio->pendingError = 0;
aio->bytesTransferred = 0;
#ifdef ERTS_SMP
@@ -890,6 +894,12 @@ init_async_io(AsyncIo* aio, int use_threads)
aio->ioAllowed = CreateAutoEvent(FALSE);
if (aio->ioAllowed == NULL)
return -1;
+ aio->flushEvent = CreateAutoEvent(FALSE);
+ if (aio->flushEvent == NULL)
+ return -1;
+ aio->flushReplyEvent = CreateAutoEvent(FALSE);
+ if (aio->flushReplyEvent == NULL)
+ return -1;
}
return 0;
}
@@ -923,6 +933,14 @@ release_async_io(AsyncIo* aio, ErlDrvPort port_num)
if (aio->ioAllowed != NULL)
CloseHandle(aio->ioAllowed);
aio->ioAllowed = NULL;
+
+ if (aio->flushEvent != NULL)
+ CloseHandle(aio->flushEvent);
+ aio->flushEvent = NULL;
+
+ if (aio->flushReplyEvent != NULL)
+ CloseHandle(aio->flushReplyEvent);
+ aio->flushReplyEvent = NULL;
}
/* ----------------------------------------------------------------------
@@ -2083,16 +2101,26 @@ threaded_writer(LPVOID param)
AsyncIo* aio = (AsyncIo *) param;
HANDLE thread = GetCurrentThread();
char* buf;
- DWORD numToWrite;
+ DWORD numToWrite, handle;
int ok;
+ HANDLE handles[2];
+ handles[0] = aio->ioAllowed;
+ handles[1] = aio->flushEvent;
for (;;) {
- WaitForSingleObject(aio->ioAllowed, INFINITE);
+ handle = WaitForMultipleObjects(2, handles, FALSE, INFINITE);
if (aio->flags & DF_EXIT_THREAD)
break;
+
buf = OV_BUFFER_PTR(aio);
numToWrite = OV_NUM_TO_READ(aio);
aio->pendingError = 0;
+
+ if (handle == (WAIT_OBJECT_0 + 1) && numToWrite == 0) {
+ SetEvent(aio->flushReplyEvent);
+ continue;
+ }
+
ok = WriteFile(aio->fd, buf, numToWrite, &aio->bytesTransferred, NULL);
if (!ok) {
aio->pendingError = GetLastError();
@@ -2127,7 +2155,11 @@ threaded_writer(LPVOID param)
}
}
}
- SetEvent(aio->ov.hEvent);
+ OV_NUM_TO_READ(aio) = 0;
+ if (handle == (WAIT_OBJECT_0 + 1))
+ SetEvent(aio->flushReplyEvent);
+ else
+ SetEvent(aio->ov.hEvent);
if (aio->pendingError != NO_ERROR || aio->bytesTransferred == 0)
break;
if (aio->flags & DF_EXIT_THREAD)
@@ -2193,6 +2225,43 @@ fd_start(ErlDrvPort port_num, char* name, SysDriverOpts* opts)
if ((dp = new_driver_data(port_num, opts->packet_bytes, 2, TRUE)) == NULL)
return ERL_DRV_ERROR_GENERAL;
+ /**
+ * Here is a brief description about how the fd driver works on windows.
+ *
+ * fd_init:
+ * For each in/out fd pair a threaded_reader and threaded_writer thread is
+ * created. Within the DriverData struct each of the threads have an AsyncIO
+ * sctruct associated with it. Within AsyncIO there are two important HANDLEs,
+ * ioAllowed and ov.hEvent. ioAllowed is used to signal the threaded_* threads
+ * should read/write some data, and ov.hEvent is driver_select'ed to be used to
+ * signal that the thread is done reading/writing.
+ *
+ * The reason for the driver being threaded like this is because once the FD is open
+ * on windows, it is not possible to set the it in overlapped mode. So we have to
+ * simulate this using threads.
+ *
+ * output:
+ * When an output occurs the data to be outputted is copied to AsyncIO.ov. Then
+ * the ioAllowed HANDLE is set, ov.hEvent is cleared and the port is marked as busy.
+ * The threaded_writer thread is lying in WaitForMultipleObjects on ioAllowed, and
+ * when signalled it writes all data in AsyncIO.ov and then sets ov.hEvent so that
+ * ready_output gets triggered and (potentially) sends the reply to the port and
+ * marks the port an non-busy.
+ *
+ * input:
+ * The threaded_reader is lying waiting in ReadFile on the in fd and when a new
+ * line is written it sets ov.hEvent that new data is available and then goes
+ * and waits for ioAllowed to be set. ready_input is run when ov.hEvent is set and
+ * delivers the data to the port. Then ioAllowed is signalled again and threaded_reader
+ * goes back to ReadFile.
+ *
+ * shutdown:
+ * In order to guarantee that all io is outputted before the driver is stopped,
+ * fd_stop uses flushEvent and flushReplyEvent to make sure that there is no data
+ * in ov which needs writing before returning from fd_stop.
+ *
+ **/
+
if (!create_file_thread(&dp->in, DO_READ)) {
dp->port_num = PORT_FREE;
return ERL_DRV_ERROR_GENERAL;
@@ -2241,6 +2310,8 @@ static void fd_stop(ErlDrvData d)
(void) driver_select(dp->port_num,
(ErlDrvEvent)dp->out.ov.hEvent,
ERL_DRV_WRITE, 0);
+ SetEvent(dp->out.flushEvent);
+ WaitForSingleObject(dp->out.flushReplyEvent, INFINITE);
}
}
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