src/backend/port/win32/signal.c - hawq - Git at Google

 /*-------------------------------------------------------------------------
  *
  * signal.c
  *	  Microsoft Windows Win32 Signal Emulation Functions
  *
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
  *	  $PostgreSQL: pgsql/src/backend/port/win32/signal.c,v 1.22 2009/01/01 17:23:46 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */

 #include "postgres.h"

 #include <libpq/pqsignal.h>

 /*
  * These are exported for use by the UNBLOCKED_SIGNAL_QUEUE() macro.
  * pg_signal_queue must be volatile since it is changed by the signal
  * handling thread and inspected without any lock by the main thread.
  * pg_signal_mask is only changed by main thread so shouldn't need it.
  */
 volatile int pg_signal_queue;
 int			pg_signal_mask;

 HANDLE		pgwin32_signal_event;
 HANDLE		pgwin32_initial_signal_pipe = INVALID_HANDLE_VALUE;

 /*
  * pg_signal_crit_sec is used to protect only pg_signal_queue. That is the only
  * variable that can be accessed from the signal sending threads!
  */
 static CRITICAL_SECTION pg_signal_crit_sec;

 static pqsigfunc pg_signal_array[PG_SIGNAL_COUNT];
 static pqsigfunc pg_signal_defaults[PG_SIGNAL_COUNT];


 /* Signal handling thread function */
 static DWORD WINAPI pg_signal_thread(LPVOID param);
 static BOOL WINAPI pg_console_handler(DWORD dwCtrlType);


 /*
  * pg_usleep --- delay the specified number of microseconds, but
  * stop waiting if a signal arrives.
  *
  * This replaces the non-signal-aware version provided by src/port/pgsleep.c.
  */
 void
 pg_usleep(long microsec)
 {
 	if (WaitForSingleObject(pgwin32_signal_event,
 							(microsec < 500 ? 1 : (microsec + 500) / 1000))
 		== WAIT_OBJECT_0)
 	{
 		pgwin32_dispatch_queued_signals();
 		errno = EINTR;
 		return;
 	}
 }


 /* Initialization */
 void
 pgwin32_signal_initialize(void)
 {
 	int			i;
 	HANDLE		signal_thread_handle;

 	InitializeCriticalSection(&pg_signal_crit_sec);

 	for (i = 0; i < PG_SIGNAL_COUNT; i++)
 	{
 		pg_signal_array[i] = SIG_DFL;
 		pg_signal_defaults[i] = SIG_IGN;
 	}
 	pg_signal_mask = 0;
 	pg_signal_queue = 0;

 	/* Create the global event handle used to flag signals */
 	pgwin32_signal_event = CreateEvent(NULL, TRUE, FALSE, NULL);
 	if (pgwin32_signal_event == NULL)
 		ereport(FATAL,
 				(errmsg_internal("failed to create signal event: %d", (int) GetLastError())));

 	/* Create thread for handling signals */
 	signal_thread_handle = CreateThread(NULL, 0, pg_signal_thread, NULL, 0, NULL);
 	if (signal_thread_handle == NULL)
 		ereport(FATAL,
 				(errmsg_internal("failed to create signal handler thread")));

 	/* Create console control handle to pick up Ctrl-C etc */
 	if (!SetConsoleCtrlHandler(pg_console_handler, TRUE))
 		ereport(FATAL,
 				(errmsg_internal("failed to set console control handler")));
 }

 /*
  * Dispatch all signals currently queued and not blocked
  * Blocked signals are ignored, and will be fired at the time of
  * the sigsetmask() call.
  */
 void
 pgwin32_dispatch_queued_signals(void)
 {
 	int			i;

 	EnterCriticalSection(&pg_signal_crit_sec);
 	while (UNBLOCKED_SIGNAL_QUEUE())
 	{
 		/* One or more unblocked signals queued for execution */
 		int			exec_mask = UNBLOCKED_SIGNAL_QUEUE();

 		for (i = 0; i < PG_SIGNAL_COUNT; i++)
 		{
 			if (exec_mask & sigmask(i))
 			{
 				/* Execute this signal */
 				pqsigfunc	sig = pg_signal_array[i];

 				if (sig == SIG_DFL)
 					sig = pg_signal_defaults[i];
 				pg_signal_queue &= ~sigmask(i);
 				if (sig != SIG_ERR && sig != SIG_IGN && sig != SIG_DFL)
 				{
 					LeaveCriticalSection(&pg_signal_crit_sec);
 					sig(i);
 					EnterCriticalSection(&pg_signal_crit_sec);
 					break;		/* Restart outer loop, in case signal mask or
 								 * queue has been modified inside signal
 								 * handler */
 				}
 			}
 		}
 	}
 	ResetEvent(pgwin32_signal_event);
 	LeaveCriticalSection(&pg_signal_crit_sec);
 }

 /* signal masking. Only called on main thread, no sync required */
 int
 pqsigsetmask(int mask)
 {
 	int			prevmask;

 	prevmask = pg_signal_mask;
 	pg_signal_mask = mask;

 	/*
 	 * Dispatch any signals queued up right away, in case we have unblocked
 	 * one or more signals previously queued
 	 */
 	pgwin32_dispatch_queued_signals();

 	return prevmask;
 }


 /* signal manipulation. Only called on main thread, no sync required */
 pqsigfunc
 pqsignal(int signum, pqsigfunc handler)
 {
 	pqsigfunc	prevfunc;

 	if (signum >= PG_SIGNAL_COUNT || signum < 0)
 		return SIG_ERR;
 	prevfunc = pg_signal_array[signum];
 	pg_signal_array[signum] = handler;
 	return prevfunc;
 }

 /* Create the signal listener pipe for specified pid */
 HANDLE
 pgwin32_create_signal_listener(pid_t pid)
 {
 	char		pipename[128];
 	HANDLE		pipe;

 	snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%u", (int) pid);

 	pipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
 					   PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
 						   PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);

 	if (pipe == INVALID_HANDLE_VALUE)
 		ereport(ERROR,
 				(errmsg("could not create signal listener pipe for pid %d: error code %d",
 						(int) pid, (int) GetLastError())));

 	return pipe;
 }


 /*
  * All functions below execute on the signal handler thread
  * and must be synchronized as such!
  * NOTE! The only global variable that can be used is
  * pg_signal_queue!
  */


 void
 pg_queue_signal(int signum)
 {
 	if (signum >= PG_SIGNAL_COUNT || signum <= 0)
 		return;

 	EnterCriticalSection(&pg_signal_crit_sec);
 	pg_signal_queue |= sigmask(signum);
 	LeaveCriticalSection(&pg_signal_crit_sec);

 	SetEvent(pgwin32_signal_event);
 }

 /* Signal dispatching thread */
 static DWORD WINAPI
 pg_signal_dispatch_thread(LPVOID param)
 {
 	HANDLE		pipe = (HANDLE) param;
 	BYTE		sigNum;
 	DWORD		bytes;

 	if (!ReadFile(pipe, &sigNum, 1, &bytes, NULL))
 	{
 		/* Client died before sending */
 		CloseHandle(pipe);
 		return 0;
 	}
 	if (bytes != 1)
 	{
 		/* Received <bytes> bytes over signal pipe (should be 1) */
 		CloseHandle(pipe);
 		return 0;
 	}
 	WriteFile(pipe, &sigNum, 1, &bytes, NULL);	/* Don't care if it works or
 												 * not.. */
 	FlushFileBuffers(pipe);
 	DisconnectNamedPipe(pipe);
 	CloseHandle(pipe);

 	pg_queue_signal(sigNum);
 	return 0;
 }

 /* Signal handling thread */
 static DWORD WINAPI
 pg_signal_thread(LPVOID param)
 {
 	char		pipename[128];
 	HANDLE		pipe = pgwin32_initial_signal_pipe;

 	snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%lu", GetCurrentProcessId());

 	for (;;)
 	{
 		BOOL		fConnected;
 		HANDLE		hThread;

 		if (pipe == INVALID_HANDLE_VALUE)
 		{
 			pipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
 					   PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
 							   PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);

 			if (pipe == INVALID_HANDLE_VALUE)
 			{
 				write_stderr("could not create signal listener pipe: error code %d; retrying\n", (int) GetLastError());
 				SleepEx(500, FALSE);
 				continue;
 			}
 		}

 		fConnected = ConnectNamedPipe(pipe, NULL) ? TRUE : (GetLastError() == ERROR_PIPE_CONNECTED);
 		if (fConnected)
 		{
 			hThread = CreateThread(NULL, 0,
 						  (LPTHREAD_START_ROUTINE) pg_signal_dispatch_thread,
 								   (LPVOID) pipe, 0, NULL);
 			if (hThread == INVALID_HANDLE_VALUE)
 				write_stderr("could not create signal dispatch thread: error code %d\n",
 							 (int) GetLastError());
 			else
 				CloseHandle(hThread);
 		}
 		else
 			/* Connection failed. Cleanup and try again */
 			CloseHandle(pipe);

 		/* Set up so we create a new pipe on next loop */
 		pipe = INVALID_HANDLE_VALUE;
 	}
 	return 0;
 }


 /* Console control handler will execute on a thread created
    by the OS at the time of invocation */
 static BOOL WINAPI
 pg_console_handler(DWORD dwCtrlType)
 {
 	if (dwCtrlType == CTRL_C_EVENT ||
 		dwCtrlType == CTRL_BREAK_EVENT ||
 		dwCtrlType == CTRL_CLOSE_EVENT ||
 		dwCtrlType == CTRL_SHUTDOWN_EVENT)
 	{
 		pg_queue_signal(SIGINT);
 		return TRUE;
 	}
 	return FALSE;
 }
	/*-------------------------------------------------------------------------
	*
	* signal.c
	* Microsoft Windows Win32 Signal Emulation Functions
	*
	* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
	*
	* IDENTIFICATION
	* $PostgreSQL: pgsql/src/backend/port/win32/signal.c,v 1.22 2009/01/01 17:23:46 momjian Exp $
	*
	*-------------------------------------------------------------------------
	*/

	#include "postgres.h"

	#include <libpq/pqsignal.h>

	/*
	* These are exported for use by the UNBLOCKED_SIGNAL_QUEUE() macro.
	* pg_signal_queue must be volatile since it is changed by the signal
	* handling thread and inspected without any lock by the main thread.
	* pg_signal_mask is only changed by main thread so shouldn't need it.
	*/
	volatile int pg_signal_queue;
	int pg_signal_mask;

	HANDLE pgwin32_signal_event;
	HANDLE pgwin32_initial_signal_pipe = INVALID_HANDLE_VALUE;

	/*
	* pg_signal_crit_sec is used to protect only pg_signal_queue. That is the only
	* variable that can be accessed from the signal sending threads!
	*/
	static CRITICAL_SECTION pg_signal_crit_sec;

	static pqsigfunc pg_signal_array[PG_SIGNAL_COUNT];
	static pqsigfunc pg_signal_defaults[PG_SIGNAL_COUNT];


	/* Signal handling thread function */
	static DWORD WINAPI pg_signal_thread(LPVOID param);
	static BOOL WINAPI pg_console_handler(DWORD dwCtrlType);


	/*
	* pg_usleep --- delay the specified number of microseconds, but
	* stop waiting if a signal arrives.
	*
	* This replaces the non-signal-aware version provided by src/port/pgsleep.c.
	*/
	void
	pg_usleep(long microsec)
	{
	if (WaitForSingleObject(pgwin32_signal_event,
	(microsec < 500 ? 1 : (microsec + 500) / 1000))
	== WAIT_OBJECT_0)
	{
	pgwin32_dispatch_queued_signals();
	errno = EINTR;
	return;
	}
	}


	/* Initialization */
	void
	pgwin32_signal_initialize(void)
	{
	int i;
	HANDLE signal_thread_handle;

	InitializeCriticalSection(&pg_signal_crit_sec);

	for (i = 0; i < PG_SIGNAL_COUNT; i++)
	{
	pg_signal_array[i] = SIG_DFL;
	pg_signal_defaults[i] = SIG_IGN;
	}
	pg_signal_mask = 0;
	pg_signal_queue = 0;

	/* Create the global event handle used to flag signals */
	pgwin32_signal_event = CreateEvent(NULL, TRUE, FALSE, NULL);
	if (pgwin32_signal_event == NULL)
	ereport(FATAL,
	(errmsg_internal("failed to create signal event: %d", (int) GetLastError())));

	/* Create thread for handling signals */
	signal_thread_handle = CreateThread(NULL, 0, pg_signal_thread, NULL, 0, NULL);
	if (signal_thread_handle == NULL)
	ereport(FATAL,
	(errmsg_internal("failed to create signal handler thread")));

	/* Create console control handle to pick up Ctrl-C etc */
	if (!SetConsoleCtrlHandler(pg_console_handler, TRUE))
	ereport(FATAL,
	(errmsg_internal("failed to set console control handler")));
	}

	/*
	* Dispatch all signals currently queued and not blocked
	* Blocked signals are ignored, and will be fired at the time of
	* the sigsetmask() call.
	*/
	void
	pgwin32_dispatch_queued_signals(void)
	{
	int i;

	EnterCriticalSection(&pg_signal_crit_sec);
	while (UNBLOCKED_SIGNAL_QUEUE())
	{
	/* One or more unblocked signals queued for execution */
	int exec_mask = UNBLOCKED_SIGNAL_QUEUE();

	for (i = 0; i < PG_SIGNAL_COUNT; i++)
	{
	if (exec_mask & sigmask(i))
	{
	/* Execute this signal */
	pqsigfunc sig = pg_signal_array[i];

	if (sig == SIG_DFL)
	sig = pg_signal_defaults[i];
	pg_signal_queue &= ~sigmask(i);
	if (sig != SIG_ERR && sig != SIG_IGN && sig != SIG_DFL)
	{
	LeaveCriticalSection(&pg_signal_crit_sec);
	sig(i);
	EnterCriticalSection(&pg_signal_crit_sec);
	break; /* Restart outer loop, in case signal mask or
	* queue has been modified inside signal
	* handler */
	}
	}
	}
	}
	ResetEvent(pgwin32_signal_event);
	LeaveCriticalSection(&pg_signal_crit_sec);
	}

	/* signal masking. Only called on main thread, no sync required */
	int
	pqsigsetmask(int mask)
	{
	int prevmask;

	prevmask = pg_signal_mask;
	pg_signal_mask = mask;

	/*
	* Dispatch any signals queued up right away, in case we have unblocked
	* one or more signals previously queued
	*/
	pgwin32_dispatch_queued_signals();

	return prevmask;
	}


	/* signal manipulation. Only called on main thread, no sync required */
	pqsigfunc
	pqsignal(int signum, pqsigfunc handler)
	{
	pqsigfunc prevfunc;

	if (signum >= PG_SIGNAL_COUNT \|\| signum < 0)
	return SIG_ERR;
	prevfunc = pg_signal_array[signum];
	pg_signal_array[signum] = handler;
	return prevfunc;
	}

	/* Create the signal listener pipe for specified pid */
	HANDLE
	pgwin32_create_signal_listener(pid_t pid)
	{
	char pipename[128];
	HANDLE pipe;

	snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%u", (int) pid);

	pipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
	PIPE_TYPE_MESSAGE \| PIPE_READMODE_MESSAGE \| PIPE_WAIT,
	PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);

	if (pipe == INVALID_HANDLE_VALUE)
	ereport(ERROR,
	(errmsg("could not create signal listener pipe for pid %d: error code %d",
	(int) pid, (int) GetLastError())));

	return pipe;
	}


	/*
	* All functions below execute on the signal handler thread
	* and must be synchronized as such!
	* NOTE! The only global variable that can be used is
	* pg_signal_queue!
	*/


	void
	pg_queue_signal(int signum)
	{
	if (signum >= PG_SIGNAL_COUNT \|\| signum <= 0)
	return;

	EnterCriticalSection(&pg_signal_crit_sec);
	pg_signal_queue \|= sigmask(signum);
	LeaveCriticalSection(&pg_signal_crit_sec);

	SetEvent(pgwin32_signal_event);
	}

	/* Signal dispatching thread */
	static DWORD WINAPI
	pg_signal_dispatch_thread(LPVOID param)
	{
	HANDLE pipe = (HANDLE) param;
	BYTE sigNum;
	DWORD bytes;

	if (!ReadFile(pipe, &sigNum, 1, &bytes, NULL))
	{
	/* Client died before sending */
	CloseHandle(pipe);
	return 0;
	}
	if (bytes != 1)
	{
	/* Received <bytes> bytes over signal pipe (should be 1) */
	CloseHandle(pipe);
	return 0;
	}
	WriteFile(pipe, &sigNum, 1, &bytes, NULL); /* Don't care if it works or
	* not.. */
	FlushFileBuffers(pipe);
	DisconnectNamedPipe(pipe);
	CloseHandle(pipe);

	pg_queue_signal(sigNum);
	return 0;
	}

	/* Signal handling thread */
	static DWORD WINAPI
	pg_signal_thread(LPVOID param)
	{
	char pipename[128];
	HANDLE pipe = pgwin32_initial_signal_pipe;

	snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%lu", GetCurrentProcessId());

	for (;;)
	{
	BOOL fConnected;
	HANDLE hThread;

	if (pipe == INVALID_HANDLE_VALUE)
	{
	pipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
	PIPE_TYPE_MESSAGE \| PIPE_READMODE_MESSAGE \| PIPE_WAIT,
	PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);

	if (pipe == INVALID_HANDLE_VALUE)
	{
	write_stderr("could not create signal listener pipe: error code %d; retrying\n", (int) GetLastError());
	SleepEx(500, FALSE);
	continue;
	}
	}

	fConnected = ConnectNamedPipe(pipe, NULL) ? TRUE : (GetLastError() == ERROR_PIPE_CONNECTED);
	if (fConnected)
	{
	hThread = CreateThread(NULL, 0,
	(LPTHREAD_START_ROUTINE) pg_signal_dispatch_thread,
	(LPVOID) pipe, 0, NULL);
	if (hThread == INVALID_HANDLE_VALUE)
	write_stderr("could not create signal dispatch thread: error code %d\n",
	(int) GetLastError());
	else
	CloseHandle(hThread);
	}
	else
	/* Connection failed. Cleanup and try again */
	CloseHandle(pipe);

	/* Set up so we create a new pipe on next loop */
	pipe = INVALID_HANDLE_VALUE;
	}
	return 0;
	}


	/* Console control handler will execute on a thread created
	by the OS at the time of invocation */
	static BOOL WINAPI
	pg_console_handler(DWORD dwCtrlType)
	{
	if (dwCtrlType == CTRL_C_EVENT \|\|
	dwCtrlType == CTRL_BREAK_EVENT \|\|
	dwCtrlType == CTRL_CLOSE_EVENT \|\|
	dwCtrlType == CTRL_SHUTDOWN_EVENT)
	{
	pg_queue_signal(SIGINT);
	return TRUE;
	}
	return FALSE;
	}