Actual source code: send.c
1: #include <petscsys.h>
3: #if defined(PETSC_NEEDS_UTYPE_TYPEDEFS)
4: /* Some systems have inconsistent include files that use but do not
5: ensure that the following definitions are made */
6: typedef unsigned char u_char;
7: typedef unsigned short u_short;
8: typedef unsigned short ushort;
9: typedef unsigned int u_int;
10: typedef unsigned long u_long;
11: #endif
13: #include <errno.h>
14: #include <ctype.h>
15: #if defined(PETSC_HAVE_MACHINE_ENDIAN_H)
16: #include <machine/endian.h>
17: #endif
18: #if defined(PETSC_HAVE_UNISTD_H)
19: #include <unistd.h>
20: #endif
21: #if defined(PETSC_HAVE_SYS_SOCKET_H)
22: #include <sys/socket.h>
23: #endif
24: #if defined(PETSC_HAVE_SYS_WAIT_H)
25: #include <sys/wait.h>
26: #endif
27: #if defined(PETSC_HAVE_NETINET_IN_H)
28: #include <netinet/in.h>
29: #endif
30: #if defined(PETSC_HAVE_NETDB_H)
31: #include <netdb.h>
32: #endif
33: #if defined(PETSC_HAVE_FCNTL_H)
34: #include <fcntl.h>
35: #endif
36: #if defined(PETSC_HAVE_IO_H)
37: #include <io.h>
38: #endif
39: #if defined(PETSC_HAVE_WINSOCK2_H)
40: #include <Winsock2.h>
41: #endif
42: #include <sys/stat.h>
43: #include <../src/sys/classes/viewer/impls/socket/socket.h>
45: #if defined(PETSC_NEED_CLOSE_PROTO)
46: PETSC_EXTERN int close(int);
47: #endif
48: #if defined(PETSC_NEED_SOCKET_PROTO)
49: PETSC_EXTERN int socket(int, int, int);
50: #endif
51: #if defined(PETSC_NEED_SLEEP_PROTO)
52: PETSC_EXTERN int sleep(unsigned);
53: #endif
54: #if defined(PETSC_NEED_CONNECT_PROTO)
55: PETSC_EXTERN int connect(int, struct sockaddr *, int);
56: #endif
58: static PetscErrorCode PetscViewerDestroy_Socket(PetscViewer viewer)
59: {
60: PetscViewer_Socket *vmatlab = (PetscViewer_Socket *)viewer->data;
62: PetscFunctionBegin;
63: if (vmatlab->port) {
64: int ierr;
66: #if defined(PETSC_HAVE_CLOSESOCKET)
67: ierr = closesocket(vmatlab->port);
68: #else
69: ierr = close(vmatlab->port);
70: #endif
71: PetscCheck(!ierr, PETSC_COMM_SELF, PETSC_ERR_SYS, "System error closing socket");
72: }
73: PetscCall(PetscFree(vmatlab));
74: PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerBinarySetSkipHeader_C", NULL));
75: PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerBinaryGetSkipHeader_C", NULL));
76: PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerBinaryGetFlowControl_C", NULL));
77: PetscFunctionReturn(PETSC_SUCCESS);
78: }
80: /*@
81: PetscOpenSocket - handles connected to an open port where someone is waiting.
83: Input Parameters:
84: + hostname - for example www.mcs.anl.gov
85: - portnum - for example 80
87: Output Parameter:
88: . t - the socket number
90: Notes:
91: Use close() to close the socket connection
93: Use read() or `PetscHTTPRequest()` to read from the socket
95: Level: advanced
97: .seealso: `PetscSocketListen()`, `PetscSocketEstablish()`, `PetscHTTPRequest()`, `PetscHTTPSConnect()`
98: @*/
99: PetscErrorCode PetscOpenSocket(const char hostname[], int portnum, int *t)
100: {
101: struct sockaddr_in sa;
102: struct hostent *hp;
103: int s = 0;
104: PetscBool flg = PETSC_TRUE;
105: static int refcnt = 0;
107: PetscFunctionBegin;
108: if (!(hp = gethostbyname(hostname))) {
109: perror("SEND: error gethostbyname: ");
110: SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SYS, "system error open connection to %s", hostname);
111: }
112: PetscCall(PetscMemzero(&sa, sizeof(sa)));
113: PetscCall(PetscMemcpy(&sa.sin_addr, hp->h_addr_list[0], hp->h_length));
115: sa.sin_family = (unsigned char)hp->h_addrtype;
116: sa.sin_port = htons((u_short)portnum);
117: while (flg) {
118: if ((s = socket(hp->h_addrtype, SOCK_STREAM, 0)) < 0) {
119: perror("SEND: error socket");
120: SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SYS, "system error");
121: }
122: if (connect(s, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
123: #if defined(PETSC_HAVE_WSAGETLASTERROR)
124: ierr = WSAGetLastError();
125: if (ierr == WSAEADDRINUSE) (*PetscErrorPrintf)("SEND: address is in use\n");
126: else if (ierr == WSAEALREADY) (*PetscErrorPrintf)("SEND: socket is non-blocking \n");
127: else if (ierr == WSAEISCONN) {
128: (*PetscErrorPrintf)("SEND: socket already connected\n");
129: Sleep((unsigned)1);
130: } else if (ierr == WSAECONNREFUSED) {
131: /* (*PetscErrorPrintf)("SEND: forcefully rejected\n"); */
132: Sleep((unsigned)1);
133: } else {
134: perror(NULL);
135: SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SYS, "system error");
136: }
137: #else
138: if (errno == EADDRINUSE) {
139: PetscErrorCode ierr = (*PetscErrorPrintf)("SEND: address is in use\n");
140: (void)ierr;
141: } else if (errno == EALREADY) {
142: PetscErrorCode ierr = (*PetscErrorPrintf)("SEND: socket is non-blocking \n");
143: (void)ierr;
144: } else if (errno == EISCONN) {
145: PetscErrorCode ierr = (*PetscErrorPrintf)("SEND: socket already connected\n");
146: (void)ierr;
147: sleep((unsigned)1);
148: } else if (errno == ECONNREFUSED) {
149: refcnt++;
150: PetscCheck(refcnt <= 5, PETSC_COMM_SELF, PETSC_ERR_SYS, "Connection refused by remote host %s port %d", hostname, portnum);
151: PetscCall(PetscInfo(NULL, "Connection refused in attaching socket, trying again\n"));
152: sleep((unsigned)1);
153: } else {
154: perror(NULL);
155: SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SYS, "system error");
156: }
157: #endif
158: flg = PETSC_TRUE;
159: #if defined(PETSC_HAVE_CLOSESOCKET)
160: closesocket(s);
161: #else
162: close(s);
163: #endif
164: } else flg = PETSC_FALSE;
165: }
166: *t = s;
167: PetscFunctionReturn(PETSC_SUCCESS);
168: }
170: /*
171: PetscSocketEstablish - starts a listener on a socket
173: Input Parameter:
174: . portnumber - the port to wait at
176: Output Parameter:
177: . ss - the socket to be used with `PetscSocketListen()`
179: Level: advanced
181: .seealso: `PetscSocketListen()`, `PetscOpenSocket()`
182: */
183: static PetscErrorCode PetscSocketEstablish(int portnum, int *ss)
184: {
185: char myname[PETSC_MAX_OPTION_NAME];
186: int s;
187: struct sockaddr_in sa;
188: struct hostent *hp;
190: PetscFunctionBegin;
191: PetscCall(PetscGetHostName(myname, sizeof(myname)));
193: PetscCall(PetscMemzero(&sa, sizeof(struct sockaddr_in)));
195: hp = gethostbyname(myname);
196: PetscCheck(hp, PETSC_COMM_SELF, PETSC_ERR_SYS, "Unable to get hostent information from system");
198: sa.sin_family = (unsigned char)hp->h_addrtype;
199: sa.sin_port = htons((u_short)portnum);
201: PetscCheck((s = socket(AF_INET, SOCK_STREAM, 0)) >= 0, PETSC_COMM_SELF, PETSC_ERR_SYS, "Error running socket() command");
202: #if defined(PETSC_HAVE_SO_REUSEADDR)
203: {
204: int optval = 1; /* Turn on the option */
205: int ret = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&optval, sizeof(optval));
206: PetscCheck(!ret, PETSC_COMM_SELF, PETSC_ERR_LIB, "setsockopt() failed with error code %d", ret);
207: }
208: #endif
210: while (bind(s, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
211: #if defined(PETSC_HAVE_WSAGETLASTERROR)
212: ierr = WSAGetLastError();
213: if (ierr != WSAEADDRINUSE) {
214: #else
215: if (errno != EADDRINUSE) {
216: #endif
217: close(s);
218: SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SYS, "Error from bind()");
219: }
220: }
221: listen(s, 0);
222: *ss = s;
223: PetscFunctionReturn(PETSC_SUCCESS);
224: }
226: /*
227: PetscSocketListen - Listens at a socket created with `PetscSocketEstablish()`
229: Input Parameter:
230: . listenport - obtained with `PetscSocketEstablish()`
232: Output Parameter:
233: . t - pass this to read() to read what is passed to this connection
235: Level: advanced
237: .seealso: `PetscSocketEstablish()`
238: */
239: static PetscErrorCode PetscSocketListen(int listenport, int *t)
240: {
241: struct sockaddr_in isa;
242: #if defined(PETSC_HAVE_ACCEPT_SIZE_T)
243: size_t i;
244: #else
245: int i;
246: #endif
248: PetscFunctionBegin;
249: /* wait for someone to try to connect */
250: i = sizeof(struct sockaddr_in);
251: PetscCheck((*t = accept(listenport, (struct sockaddr *)&isa, (socklen_t *)&i)) >= 0, PETSC_COMM_SELF, PETSC_ERR_SYS, "error from accept()");
252: PetscFunctionReturn(PETSC_SUCCESS);
253: }
255: // "Unknown section 'Environmental Variables'"
256: // PetscClangLinter pragma disable: -fdoc-section-header-unknown
257: /*@
258: PetscViewerSocketOpen - Opens a connection to a MATLAB or other socket based server.
260: Collective
262: Input Parameters:
263: + comm - the MPI communicator
264: . machine - the machine the server is running on, use `NULL` for the local machine, use "server" to passively wait for
265: a connection from elsewhere
266: - port - the port to connect to, use `PETSC_DEFAULT` for the default
268: Output Parameter:
269: . lab - a context to use when communicating with the server
271: Options Database Keys:
272: For use with `PETSC_VIEWER_SOCKET_WORLD`, `PETSC_VIEWER_SOCKET_SELF`,
273: `PETSC_VIEWER_SOCKET_()` or if
274: `NULL` is passed for machine or PETSC_DEFAULT is passed for port
275: + -viewer_socket_machine <machine> - the machine where the socket is available
276: - -viewer_socket_port <port> - the socket to connect to
278: Environmental variables:
279: + `PETSC_VIEWER_SOCKET_MACHINE` - machine name
280: - `PETSC_VIEWER_SOCKET_PORT` - portnumber
282: Level: intermediate
284: Notes:
285: Most users should employ the following commands to access the
286: MATLAB `PetscViewer`
287: .vb
289: PetscViewerSocketOpen(MPI_Comm comm, char *machine,int port,PetscViewer &viewer)
290: MatView(Mat matrix,PetscViewer viewer)
291: .ve
292: or
293: .vb
294: PetscViewerSocketOpen(MPI_Comm comm,char *machine,int port,PetscViewer &viewer)
295: VecView(Vec vector,PetscViewer viewer)
296: .ve
298: Currently the only socket client available is MATLAB, PETSc must be configured with --with-matlab for this client. See
299: src/dm/tests/ex12.c and ex12.m for an example of usage.
301: The socket viewer is in some sense a subclass of the binary viewer, to read and write to the socket
302: use `PetscViewerBinaryRead()`, `PetscViewerBinaryWrite()`, `PetscViewerBinarWriteStringArray()`, `PetscViewerBinaryGetDescriptor()`.
304: Use this for communicating with an interactive MATLAB session, see `PETSC_VIEWER_MATLAB_()` for writing output to a
305: .mat file. Use `PetscMatlabEngineCreate()` or `PETSC_MATLAB_ENGINE_()`, `PETSC_MATLAB_ENGINE_SELF`, or `PETSC_MATLAB_ENGINE_WORLD`
306: for communicating with a MATLAB Engine
308: .seealso: [](sec_viewers), `PETSCVIEWERBINARY`, `PETSCVIEWERSOCKET`, `MatView()`, `VecView()`, `PetscViewerDestroy()`, `PetscViewerCreate()`, `PetscViewerSetType()`,
309: `PetscViewerSocketSetConnection()`, `PETSC_VIEWER_SOCKET_`, `PETSC_VIEWER_SOCKET_WORLD`,
310: `PETSC_VIEWER_SOCKET_SELF`, `PetscViewerBinaryWrite()`, `PetscViewerBinaryRead()`, `PetscViewerBinaryWriteStringArray()`,
311: `PetscBinaryViewerGetDescriptor()`, `PetscMatlabEngineCreate()`
312: @*/
313: PetscErrorCode PetscViewerSocketOpen(MPI_Comm comm, const char machine[], int port, PetscViewer *lab)
314: {
315: PetscFunctionBegin;
316: PetscCall(PetscViewerCreate(comm, lab));
317: PetscCall(PetscViewerSetType(*lab, PETSCVIEWERSOCKET));
318: PetscCall(PetscViewerSocketSetConnection(*lab, machine, port));
319: PetscFunctionReturn(PETSC_SUCCESS);
320: }
322: static PetscErrorCode PetscViewerSetFromOptions_Socket(PetscViewer v, PetscOptionItems *PetscOptionsObject)
323: {
324: PetscInt def = -1;
325: char sdef[256];
326: PetscBool tflg;
328: PetscFunctionBegin;
329: /*
330: These options are not processed here, they are processed in PetscViewerSocketSetConnection(), they
331: are listed here for the GUI to display
332: */
333: PetscOptionsHeadBegin(PetscOptionsObject, "Socket PetscViewer Options");
334: PetscCall(PetscOptionsGetenv(PetscObjectComm((PetscObject)v), "PETSC_VIEWER_SOCKET_PORT", sdef, 16, &tflg));
335: if (tflg) {
336: PetscCall(PetscOptionsStringToInt(sdef, &def));
337: } else def = PETSCSOCKETDEFAULTPORT;
338: PetscCall(PetscOptionsInt("-viewer_socket_port", "Port number to use for socket", "PetscViewerSocketSetConnection", def, NULL, NULL));
340: PetscCall(PetscOptionsString("-viewer_socket_machine", "Machine to use for socket", "PetscViewerSocketSetConnection", sdef, NULL, sizeof(sdef), NULL));
341: PetscCall(PetscOptionsGetenv(PetscObjectComm((PetscObject)v), "PETSC_VIEWER_SOCKET_MACHINE", sdef, sizeof(sdef), &tflg));
342: if (!tflg) PetscCall(PetscGetHostName(sdef, sizeof(sdef)));
343: PetscOptionsHeadEnd();
344: PetscFunctionReturn(PETSC_SUCCESS);
345: }
347: static PetscErrorCode PetscViewerBinaryGetSkipHeader_Socket(PetscViewer viewer, PetscBool *skip)
348: {
349: PetscViewer_Socket *vsocket = (PetscViewer_Socket *)viewer->data;
351: PetscFunctionBegin;
352: *skip = vsocket->skipheader;
353: PetscFunctionReturn(PETSC_SUCCESS);
354: }
356: static PetscErrorCode PetscViewerBinarySetSkipHeader_Socket(PetscViewer viewer, PetscBool skip)
357: {
358: PetscViewer_Socket *vsocket = (PetscViewer_Socket *)viewer->data;
360: PetscFunctionBegin;
361: vsocket->skipheader = skip;
362: PetscFunctionReturn(PETSC_SUCCESS);
363: }
365: PETSC_INTERN PetscErrorCode PetscViewerBinaryGetFlowControl_Binary(PetscViewer, PetscInt *);
367: /*MC
368: PETSCVIEWERSOCKET - A viewer that writes to a Unix socket
370: Level: beginner
372: .seealso: [](sec_viewers), `PETSC_VIEWERBINARY`, `PetscViewerSocketOpen()`, `PetscViewerDrawOpen()`, `PETSC_VIEWER_DRAW_()`, `PETSC_VIEWER_DRAW_SELF`, `PETSC_VIEWER_DRAW_WORLD`,
373: `PetscViewerCreate()`, `PetscViewerASCIIOpen()`, `PetscViewerBinaryOpen()`, `PETSCVIEWERBINARY`, `PETSCVIEWERDRAW`,
374: `PetscViewerMatlabOpen()`, `VecView()`, `DMView()`, `PetscViewerMatlabPutArray()`, `PETSCVIEWERASCII`, `PETSCVIEWERMATLAB`,
375: `PetscViewerFileSetName()`, `PetscViewerFileSetMode()`, `PetscViewerFormat`, `PetscViewerType`, `PetscViewerSetType()`
376: M*/
378: PETSC_EXTERN PetscErrorCode PetscViewerCreate_Socket(PetscViewer v)
379: {
380: PetscViewer_Socket *vmatlab;
382: PetscFunctionBegin;
383: PetscCall(PetscNew(&vmatlab));
384: vmatlab->port = 0;
385: vmatlab->flowcontrol = 256; /* same default as in PetscViewerCreate_Binary() */
386: v->data = (void *)vmatlab;
387: v->ops->destroy = PetscViewerDestroy_Socket;
388: v->ops->flush = NULL;
389: v->ops->setfromoptions = PetscViewerSetFromOptions_Socket;
391: /* lie and say this is a binary viewer; then all the XXXView_Binary() methods will work correctly on it */
392: PetscCall(PetscObjectChangeTypeName((PetscObject)v, PETSCVIEWERBINARY));
393: PetscCall(PetscObjectComposeFunction((PetscObject)v, "PetscViewerBinarySetSkipHeader_C", PetscViewerBinarySetSkipHeader_Socket));
394: PetscCall(PetscObjectComposeFunction((PetscObject)v, "PetscViewerBinaryGetSkipHeader_C", PetscViewerBinaryGetSkipHeader_Socket));
395: PetscCall(PetscObjectComposeFunction((PetscObject)v, "PetscViewerBinaryGetFlowControl_C", PetscViewerBinaryGetFlowControl_Binary));
396: PetscFunctionReturn(PETSC_SUCCESS);
397: }
399: /*@
400: PetscViewerSocketSetConnection - Sets the machine and port that a PETSc socket
401: viewer is to use
403: Logically Collective
405: Input Parameters:
406: + v - viewer to connect
407: . machine - host to connect to, use `NULL` for the local machine,use "server" to passively wait for
408: a connection from elsewhere
409: - port - the port on the machine one is connecting to, use `PETSC_DEFAULT` for default
411: Level: advanced
413: .seealso: [](sec_viewers), `PETSCVIEWERMATLAB`, `PETSCVIEWERSOCKET`, `PetscViewerSocketOpen()`
414: @*/
415: PetscErrorCode PetscViewerSocketSetConnection(PetscViewer v, const char machine[], int port)
416: {
417: PetscMPIInt rank;
418: char mach[256];
419: PetscBool tflg;
420: PetscViewer_Socket *vmatlab;
422: PetscFunctionBegin;
424: if (machine) PetscAssertPointer(machine, 2);
425: vmatlab = (PetscViewer_Socket *)v->data;
427: if (port <= 0) {
428: char portn[16];
429: PetscCall(PetscOptionsGetenv(PetscObjectComm((PetscObject)v), "PETSC_VIEWER_SOCKET_PORT", portn, 16, &tflg));
430: if (tflg) {
431: PetscInt pport;
432: PetscCall(PetscOptionsStringToInt(portn, &pport));
433: PetscCall(PetscMPIIntCast(pport, &port));
434: } else port = PETSCSOCKETDEFAULTPORT;
435: }
436: if (!machine) {
437: PetscCall(PetscOptionsGetenv(PetscObjectComm((PetscObject)v), "PETSC_VIEWER_SOCKET_MACHINE", mach, sizeof(mach), &tflg));
438: if (!tflg) PetscCall(PetscGetHostName(mach, sizeof(mach)));
439: } else {
440: PetscCall(PetscStrncpy(mach, machine, sizeof(mach)));
441: }
443: PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)v), &rank));
444: if (rank == 0) {
445: PetscCall(PetscStrcmp(mach, "server", &tflg));
446: if (tflg) {
447: int listenport = 0;
449: PetscCall(PetscInfo(v, "Waiting for connection from socket process on port %d\n", port));
450: PetscCall(PetscSocketEstablish(port, &listenport));
451: PetscCall(PetscSocketListen(listenport, &vmatlab->port));
452: close(listenport);
453: } else {
454: PetscCall(PetscInfo(v, "Connecting to socket process on port %d machine %s\n", port, mach));
455: PetscCall(PetscOpenSocket(mach, port, &vmatlab->port));
456: }
457: }
458: PetscFunctionReturn(PETSC_SUCCESS);
459: }
461: /*
462: The variable Petsc_Viewer_Socket_keyval is used to indicate an MPI attribute that
463: is attached to a communicator, in this case the attribute is a PetscViewer.
464: */
465: PetscMPIInt Petsc_Viewer_Socket_keyval = MPI_KEYVAL_INVALID;
467: /*@C
468: PETSC_VIEWER_SOCKET_ - Creates a socket viewer shared by all processors in a communicator.
470: Collective
472: Input Parameter:
473: . comm - the MPI communicator to share the `PETSCVIEWERSOCKET` `PetscViewer`
475: Level: intermediate
477: Options Database Keys:
478: For use with the default `PETSC_VIEWER_SOCKET_WORLD` or if
479: `NULL` is passed for machine or `PETSC_DEFAULT` is passed for port
480: + -viewer_socket_machine <machine> - machine to connect to
481: - -viewer_socket_port <port> - port to connect to
483: Environmental variables:
484: + `PETSC_VIEWER_SOCKET_PORT` - portnumber
485: - `PETSC_VIEWER_SOCKET_MACHINE` - machine name
487: Notes:
488: This object is destroyed in `PetscFinalize()`, `PetscViewerDestroy()` should never be called on it
490: Unlike almost all other PETSc routines, `PETSC_VIEWER_SOCKET_()` does not return
491: an error code, it returns `NULL` if it fails. The `PETSCVIEWERSOCKET` `PetscViewer` is usually used in the form `XXXView(XXX object, PETSC_VIEWER_SOCKET_(comm))`
493: Currently the only socket client available is MATLAB. See
494: src/dm/tests/ex12.c and ex12.m for an example of usage.
496: Connects to a waiting socket and stays connected until `PetscViewerDestroy()` is called.
498: Use this for communicating with an interactive MATLAB session, see `PETSC_VIEWER_MATLAB_()` for writing output to a
499: .mat file. Use `PetscMatlabEngineCreate()` or `PETSC_MATLAB_ENGINE_()`, `PETSC_MATLAB_ENGINE_SELF`, or `PETSC_MATLAB_ENGINE_WORLD`
500: for communicating with a MATLAB Engine
502: .seealso: [](sec_viewers), `PETSCVIEWERMATLAB`, `PETSCVIEWERSOCKET`, `PETSC_VIEWER_SOCKET_WORLD`, `PETSC_VIEWER_SOCKET_SELF`, `PetscViewerSocketOpen()`, `PetscViewerCreate()`,
503: `PetscViewerSocketSetConnection()`, `PetscViewerDestroy()`, `PETSC_VIEWER_SOCKET_()`, `PetscViewerBinaryWrite()`, `PetscViewerBinaryRead()`,
504: `PetscViewerBinaryWriteStringArray()`, `PetscViewerBinaryGetDescriptor()`, `PETSC_VIEWER_MATLAB_()`
505: @*/
506: PetscViewer PETSC_VIEWER_SOCKET_(MPI_Comm comm)
507: {
508: PetscBool flg;
509: PetscViewer viewer;
510: MPI_Comm ncomm;
512: PetscFunctionBegin;
513: PetscCallNull(PetscCommDuplicate(comm, &ncomm, NULL));
514: if (Petsc_Viewer_Socket_keyval == MPI_KEYVAL_INVALID) PetscCallMPINull(MPI_Comm_create_keyval(MPI_COMM_NULL_COPY_FN, MPI_COMM_NULL_DELETE_FN, &Petsc_Viewer_Socket_keyval, NULL));
515: PetscCallMPINull(MPI_Comm_get_attr(ncomm, Petsc_Viewer_Socket_keyval, (void **)&viewer, (int *)&flg));
516: if (!flg) { /* PetscViewer not yet created */
517: PetscCallNull(PetscViewerSocketOpen(ncomm, NULL, 0, &viewer));
518: PetscCallNull(PetscObjectRegisterDestroy((PetscObject)viewer));
519: PetscCallMPINull(MPI_Comm_set_attr(ncomm, Petsc_Viewer_Socket_keyval, (void *)viewer));
520: }
521: PetscCallNull(PetscCommDestroy(&ncomm));
522: PetscFunctionReturn(viewer);
523: }