gnu/dist/gdb6/gdb/osf-share/RIOS/cma_thread_io.h

   1 /*
   2  * (c) Copyright 1990-1996 OPEN SOFTWARE FOUNDATION, INC.
   3  * (c) Copyright 1990-1996 HEWLETT-PACKARD COMPANY
   4  * (c) Copyright 1990-1996 DIGITAL EQUIPMENT CORPORATION
   5  * (c) Copyright 1991, 1992 Siemens-Nixdorf Information Systems
   6  * To anyone who acknowledges that this file is provided "AS IS" without
   7  * any express or implied warranty: permission to use, copy, modify, and
   8  * distribute this file for any purpose is hereby granted without fee,
   9  * provided that the above copyright notices and this notice appears in
  10  * all source code copies, and that none of the names listed above be used
  11  * in advertising or publicity pertaining to distribution of the software
  12  * without specific, written prior permission.  None of these organizations
  13  * makes any representations about the suitability of this software for
  14  * any purpose.
  15  */
  16 /*
  17  *      Header file for thread synchrounous I/O
  18  */
  19
  20 #ifndef CMA_THREAD_IO
  21 #define CMA_THREAD_IO
  22
  23 /*
  24  *  INCLUDE FILES
  25  */
  26
  27 #include <cma_config.h>
  28 #include <sys/select.h>
  29 #include <cma.h>
  30 #include <sys/types.h>
  31 #include <sys/time.h>
  32 #include <cma_init.h>
  33 #include <cma_errors.h>
  34
  35 /*
  36  * CONSTANTS
  37  */
  38
  39 /*
  40  * Maximum number of files (ie, max_fd+1)
  41  */
  42 #define cma__c_mx_file  FD_SETSIZE
  43
  44 /*
  45  * Number of bits per file descriptor bit mask (ie number of bytes * bits/byte)
  46  */
  47 #define cma__c_nbpm     NFDBITS
  48
  49 /*
  50  * TYPE DEFINITIONS
  51  */
  52
  53 typedef enum CMA__T_IO_TYPE {
  54     cma__c_io_read   = 0,
  55     cma__c_io_write  = 1,
  56     cma__c_io_except = 2
  57     } cma__t_io_type;
  58 #define cma__c_max_io_type      2
  59
  60 /*
  61  * From our local <sys/types.h>:
  62  *
  63  *  typedef long    fd_mask;
  64  *
  65  *  typedef struct fd_set {
  66  *          fd_mask fds_bits[howmany(FD_SETSIZE, NFDBITS)];
  67  *  } fd_set;
  68  *
  69  */
  70 typedef fd_mask cma__t_mask;
  71 typedef fd_set  cma__t_file_mask;
  72
  73
  74
  75 /*
  76  *  GLOBAL DATA
  77  */
  78
  79 /*
  80  * Maximum number of files (ie, max_fd+1) as determined by getdtablesize().
  81  */
  82 extern int      cma__g_mx_file;
  83
  84 /*
  85  * Number of submasks (ie "int" sized chunks) per file descriptor mask as
  86  * determined by getdtablesize().
  87  */
  88 extern int      cma__g_nspm;
  89
  90 /*
  91  * MACROS
  92  */
  93
  94 /*
  95  * Define a constant for the errno value which indicates that the requested
  96  * operation was not performed because it would block the process.
  97  */
  98 # define cma__is_blocking(s) \
  99     ((s == EAGAIN) || (s == EWOULDBLOCK) || (s == EINPROGRESS) || \
 100      (s == EALREADY) || (s == EDEADLK))
 101
 102 /*
 103 *       It is necessary to issue an I/O function, before calling cma__io_wait()
 104 *       in the following cases:
 105 *
 106 *               *       This file descriptor has been set non-blocking by CMA
 107 *               *       This file descriptor has been set non-blocking by the user.
 108 */
 109
 110 #define cma__issue_io_call(fd)                                  \
 111         ( (cma__g_file[fd]->non_blocking) || \
 112           (cma__g_file[fd]->user_fl.user_non_blocking) )
 113
 114
 115 #define cma__set_user_nonblocking(flags) \
 116
 117 /*
 118  * Determine if the file is open
 119  */
 120 /*
 121  * If the file gets closed while waiting for the mutex cma__g_file[rfd]
 122  * gets set to null. This results in a crash if NDEBUG is set to 0
 123  * since cma__int_lock tries to dereference it to set the mutex ownership
 124  * after it gets the mutex. The following will still set the ownership
 125  * in cma__int_lock so we'll set it back to noone if cma__g_file is null
 126  * when we come back just in case it matters. It shouldn't since its no
 127  * longer in use but.....
 128  * Callers of this should recheck cma__g_file after the reservation to
 129  * make sure continueing makes sense.
 130  */
 131 #define cma__fd_reserve(rfd)    \
 132                 { \
 133                 cma__t_int_mutex *__mutex__; \
 134                 __mutex__ = cma__g_file[rfd]->mutex; \
 135                 cma__int_lock (__mutex__); \
 136                 if(cma__g_file[rfd] == (cma__t_file_obj *)cma_c_null_ptr) \
 137                         cma__int_unlock(__mutex__); \
 138                 }
 139
 140
 141 /*
 142  * Unreserve a file descriptor
 143  */
 144 #define cma__fd_unreserve(ufd)  cma__int_unlock (cma__g_file[ufd]->mutex)
 145
 146 /*
 147  * AND together two select file descriptor masks
 148  */
 149 #define cma__fdm_and(target,a,b)                                        \
 150         {                                                               \
 151         int __i__ = cma__g_nspm;                                        \
 152         while (__i__--)                                                 \
 153             (target)->fds_bits[__i__] =                                 \
 154                 (a)->fds_bits[__i__] & (b)->fds_bits[__i__];            \
 155         }
 156
 157 /*
 158  * Clear a bit in a select file descriptor mask
 159  *
 160  * FD_CLR(n, p)  :=  ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
 161  */
 162 #define cma__fdm_clr_bit(n,p)   FD_CLR (n, p)
 163
 164 /*
 165  * Copy the contents of one file descriptor mask into another.  If the
 166  * destination operand is null, do nothing; if the source operand is null,
 167  * simply zero the destination.
 168  */
 169 #define cma__fdm_copy(src,dst,nfds) {                                   \
 170         if (dst)                                                        \
 171             if (src) {                                                  \
 172                 cma__t_mask *__s__ = (cma__t_mask *)(src);              \
 173                 cma__t_mask *__d__ = (cma__t_mask *)(dst);              \
 174                 int __i__;                                              \
 175                 for (__i__ = 0; __i__ < (nfds); __i__ += cma__c_nbpm)   \
 176                     *__d__++ = *__s__++;                                \
 177                 }                                                       \
 178             else                                                        \
 179                 cma__fdm_zero (dst);                                    \
 180             }
 181
 182 /*
 183  * To increment count for each bit set in fd - mask
 184  */
 185 #define cma__fdm_count_bits(map,count)                                  \
 186         {                                                               \
 187         int     __i__ = cma__g_nspm;                                    \
 188         while (__i__--) {                                               \
 189             cma__t_mask    __tm__;                                      \
 190             __tm__ = (map)->fds_bits[__i__];                            \
 191             while(__tm__) {                                             \
 192                 (count)++;                                              \
 193                 __tm__ &= ~(__tm__ & (-__tm__)); /* Assumes 2's comp */ \
 194                 }                                                       \
 195             }                                                           \
 196         }
 197
 198 /*
 199  * Test if a bit is set in a select file descriptor mask
 200  *
 201  * FD_ISSET(n,p)  :=  ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
 202  */
 203 #define cma__fdm_is_set(n,p)    FD_ISSET (n, p)
 204
 205 /*
 206  * OR together two select file descriptor masks
 207  */
 208 #define cma__fdm_or(target,a,b)                                         \
 209         {                                                               \
 210         int __i__ = cma__g_nspm;                                        \
 211         while (__i__--)                                                 \
 212             (target)->fds_bits[__i__] =                                 \
 213                 (a)->fds_bits[__i__] | (b)->fds_bits[__i__];            \
 214         }
 215
 216 /*
 217  * Set a bit in a select file descriptor mask
 218  *
 219  * FD_SET(n,p)  :=  ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
 220  */
 221 #define cma__fdm_set_bit(n,p)   FD_SET (n, p)
 222
 223 /*
 224  * Clear a select file descriptor mask.
 225  */
 226 #define cma__fdm_zero(n)                                                \
 227         cma__memset ((char *) n, 0, cma__g_nspm * sizeof(cma__t_mask))
 228
 229
 230
 231
 232 \f
 233 /*
 234  * CMA "thread-synchronous" I/O read/write operations
 235  */
 236
 237     /*
 238      * Since all CMA "thread-synchronous" I/O (read or write) operations on
 239      * U*ix follow the exact same structure, the wrapper routines have been
 240      * condensed into a macro.
 241      *
 242      * The steps performed are as follows:
 243      *  1. Check that the file descriptor is a legitimate value.
 244      *  2. Check that the entry in the CMA file "database" which corresponds to
 245      *      the file descriptor indicates that the "file" was "opened" by CMA.
 246      *  3. Reserve the file, to serialized access to files.  This not only
 247      *      simplifies things, but also defends against non-reentrancy.
 248      *  4. If the "file" is "set" for non-blocking I/O, check if we
 249      *      have actually set the file non-blocking yet, and if not do so.
 250      *      Then, issue the I/O operantion.
 251      *      Success or failure is returned immediately, after unreserving the
 252      *      file.  If the error indicates that the operation would have caused
 253      *      the process to block, continue to the next step.
 254      *  5. The I/O prolog adds this "file" to the global bit mask, which
 255      *      represents all "files" which have threads waiting to perform I/O on
 256      *      them, and causes the thread to block on the condition variable for
 257      *      this "file".  Periodically, a select is done on this global bit
 258      *      mask, and the condition variables corresponding to "files" which
 259      *      are ready for I/O are signaled, releasing those waiting threads to
 260      *      perform their I/O.
 261      *  6. When the thread returns from the I/O prolog, it can (hopefully)
 262      *      perform its operation without blocking the process.
 263      *  7. The I/O epilog clears the bit in the global mask and/or signals the
 264      *      the next thread waiting for this "file", as appropriate.
 265      *  8. If the I/O failed, continue to loop.
 266      *  9. Finally, the "file" is unreserved, as we're done with it, and the
 267      *      result of the operation is returned.
 268      *
 269      *
 270      * Note:  currently, we believe that timeslicing which is based on the
 271      *      virtual-time timer does not cause system calls to return EINTR.
 272      *      Threfore, any EINTR returns are relayed directly to the caller.
 273      *      On platforms which do not support a virtual-time timer, the code
 274      *      should probably catch EINTR returns and restart the system call.
 275      */
 276
 277 /*
 278  * This macro is used for both read-type and write-type functions.
 279  *
 280  * Note:  the second call to "func" may require being bracketed in a
 281  *        cma__interrupt_disable/cma__interrupt_enable pair, but we'll
 282  *        wait and see if this is necessary.
 283  */
 284 #define cma__ts_func(func,fd,arglist,type,post_process) { \
 285     cma_t_integer   __res__; \
 286     cma_t_boolean   __done__ = cma_c_false; \
 287     if ((fd < 0) || (fd >= cma__g_mx_file)) return (cma__set_errno (EBADF), -1); \
 288     if (!cma__is_open(fd)) return (cma__set_errno (EBADF), -1); \
 289     cma__fd_reserve (fd); \
 290     if (!cma__is_open(fd)) return (cma__set_errno (EBADF), -1); \
 291     if (cma__issue_io_call(fd)) {\
 292         if ((!cma__g_file[fd]->set_non_blocking) && \
 293                 (cma__g_file[fd]->non_blocking == cma_c_true)) \
 294             cma__set_nonblocking(fd); \
 295         cma__interrupt_disable (0); \
 296         TRY { \
 297             __res__ = func arglist; \
 298             } \
 299         CATCH_ALL { \
 300             cma__interrupt_enable (0); \
 301             cma__fd_unreserve (fd); \
 302             RERAISE; \
 303             } \
 304         ENDTRY \
 305         cma__interrupt_enable (0); \
 306         if ((__res__ != -1) \
 307                 || (!cma__is_blocking (errno)) \
 308                 || (cma__g_file[fd]->user_fl.user_non_blocking)) \
 309             __done__ = cma_c_true; \
 310         } \
 311     if (__done__) { \
 312         cma__fd_unreserve (fd); \
 313         } \
 314     else { \
 315         TRY { \
 316             cma__io_prolog (type, fd); \
 317             while (!__done__) { \
 318                 cma__io_wait (type, fd); \
 319                 __res__ = func arglist; \
 320                 if ((__res__ != -1) \
 321                         || (!cma__is_blocking (errno)) \
 322                         || (cma__g_file[fd]->user_fl.user_non_blocking)) \
 323                     __done__ = cma_c_true; \
 324                 } \
 325             } \
 326         FINALLY { \
 327             cma__io_epilog (type, fd); \
 328             cma__fd_unreserve (fd); \
 329             } \
 330         ENDTRY \
 331         } \
 332     if (__res__ != -1)  post_process; \
 333     return __res__;  \
 334     }
 335
 336     /*
 337      * Since most CMA "thread-synchronous" I/O ("open"-type) operations on
 338      * U*ix follow the exact same structure, the wrapper routines have been
 339      * condensed into a macro.
 340      *
 341      * The steps performed are as follows:
 342      *  1. Issue the open function.
 343      *  2. If the value returned indicates an error, return it to the caller.
 344      *  3. If the file descriptor returned is larger than what we think is the
 345      *      maximum value (ie if it is too big for our database) then bugcheck.
 346      *  4. "Open" the "file" in the CMA file database.
 347      *  5. Return the file descriptor value to the caller.
 348      *
 349      * FIX-ME: for the time being, if the I/O operation returns EINTR, we
 350      *      simply return it to the caller; eventually, we should catch this
 351      *      and "do the right thing" (if we can figure out what that is).
 352      */
 353
 354 /*
 355  * This macro is used for all "open"-type functions which return a single file
 356  * desciptor by immediate value.
 357  */
 358 #define cma__ts_open(func,arglist,post_process)  {              \
 359     int __fd__;                                                 \
 360     TRY {                                                       \
 361         cma__int_init ();                                       \
 362         cma__int_lock (cma__g_io_data_mutex);                   \
 363         __fd__ = func arglist;                                  \
 364         cma__int_unlock (cma__g_io_data_mutex);                 \
 365         if (__fd__ >= 0 && __fd__ < cma__g_mx_file)             \
 366             post_process;                                       \
 367         }                                                       \
 368     CATCH_ALL                                                   \
 369         {                                                       \
 370         cma__set_errno (EBADF);                                 \
 371         __fd__ = -1;                                            \
 372         }                                                       \
 373     ENDTRY                                                      \
 374     if (__fd__ >= cma__g_mx_file)                               \
 375         cma__bugcheck ("cma__ts_open:  fd is too large");       \
 376     return __fd__;                                              \
 377     }
 378 /*
 379  * This macro is used for all "open"-type functions which return a pair of file
 380  * desciptors by reference parameter.
 381  */
 382 #define cma__ts_open2(func,fdpair,arglist,post_process)  {              \
 383     int     __res__;                                                    \
 384     TRY {                                                               \
 385         cma__int_init ();                                               \
 386         cma__int_lock (cma__g_io_data_mutex);                           \
 387         __res__ = func arglist;                                         \
 388         cma__int_unlock (cma__g_io_data_mutex);                         \
 389         if (__res__ >= 0 && fdpair[0] < cma__g_mx_file                  \
 390                 && fdpair[1] < cma__g_mx_file)                          \
 391             post_process;                                               \
 392         }                                                               \
 393     CATCH_ALL                                                           \
 394         {                                                               \
 395         cma__set_errno (EBADF);                                         \
 396         __res__ = -1;                                                   \
 397         }                                                               \
 398     ENDTRY                                                              \
 399     if ((fdpair[0] >= cma__g_mx_file) || (fdpair[1] >= cma__g_mx_file)) \
 400         cma__bugcheck ("cma__ts_open2:  one of fd's is too large"); \
 401     return __res__;                                                     \
 402     }
 403
 404 /*
 405  * INTERNAL INTERFACES
 406  */
 407 extern void cma__close_general (int);
 408
 409 extern void
 410 cma__init_thread_io (void);
 411
 412 extern cma_t_boolean cma__io_available  (cma__t_io_type,int,struct timeval *);
 413
 414 extern void cma__io_epilog  (cma__t_io_type,int);
 415
 416 extern void cma__io_prolog  (cma__t_io_type,int);
 417
 418 extern void cma__io_wait  (cma__t_io_type,int);
 419
 420 extern void cma__open_general  (int);
 421
 422 extern void cma__reinit_thread_io  (int);
 423
 424 extern void cma__set_nonblocking  (int);
 425
 426 extern void cma__set_user_nonblock_flags  (int,int);
 427
 428 extern cma_t_boolean
 429 cma__is_open (int fd);
 430
 431
 432 #endif
 433
 434