src/thread.h

   1 /* Thread definitions
   2 Copyright (C) 2012-2018 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   6 GNU Emacs is free software: you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation, either version 3 of the License, or
   9 (at your option) any later version.
  10
  11 GNU Emacs is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef THREAD_H
  20 #define THREAD_H
  21
  22 #include "regex.h"
  23
  24 #ifdef WINDOWSNT
  25 #include <sys/socket.h>
  26 #endif
  27
  28 #ifdef MSDOS
  29 #include <signal.h>             /* sigset_t */
  30 #endif
  31
  32 #include "sysselect.h"          /* FIXME */
  33 #include "systime.h"            /* FIXME */
  34 #include "systhread.h"
  35
  36 struct thread_state
  37 {
  38   union vectorlike_header header;
  39
  40   /* The buffer in which the last search was performed, or
  41      Qt if the last search was done in a string;
  42      Qnil if no searching has been done yet.  */
  43   Lisp_Object m_last_thing_searched;
  44 #define last_thing_searched (current_thread->m_last_thing_searched)
  45
  46   Lisp_Object m_saved_last_thing_searched;
  47 #define saved_last_thing_searched (current_thread->m_saved_last_thing_searched)
  48
  49   /* The thread's name.  */
  50   Lisp_Object name;
  51
  52   /* The thread's function.  */
  53   Lisp_Object function;
  54
  55   /* If non-nil, this thread has been signaled.  */
  56   Lisp_Object error_symbol;
  57   Lisp_Object error_data;
  58
  59   /* If we are waiting for some event, this holds the object we are
  60      waiting on.  */
  61   Lisp_Object event_object;
  62
  63   /* m_stack_bottom must be the first non-Lisp field.  */
  64   /* An address near the bottom of the stack.
  65      Tells GC how to save a copy of the stack.  */
  66   char *m_stack_bottom;
  67 #define stack_bottom (current_thread->m_stack_bottom)
  68
  69   /* The address of an object near the C stack top, used to determine
  70      which words need to be scanned by the garbage collector.  This is
  71      also used to detect heuristically whether segmentation violation
  72      address indicates stack overflow, as opposed to some internal
  73      error in Emacs.  If the C function F calls G which calls H which
  74      calls ... F, then at least one of the functions in the chain
  75      should set this to the address of a local variable.  */
  76   void *stack_top;
  77
  78   struct catchtag *m_catchlist;
  79 #define catchlist (current_thread->m_catchlist)
  80
  81   /* Chain of condition handlers currently in effect.
  82      The elements of this chain are contained in the stack frames
  83      of Fcondition_case and internal_condition_case.
  84      When an error is signaled (by calling Fsignal),
  85      this chain is searched for an element that applies.  */
  86   struct handler *m_handlerlist;
  87 #define handlerlist (current_thread->m_handlerlist)
  88
  89   struct handler *m_handlerlist_sentinel;
  90 #define handlerlist_sentinel (current_thread->m_handlerlist_sentinel)
  91
  92   /* Current number of specbindings allocated in specpdl.  */
  93   ptrdiff_t m_specpdl_size;
  94 #define specpdl_size (current_thread->m_specpdl_size)
  95
  96   /* Pointer to beginning of specpdl.  */
  97   union specbinding *m_specpdl;
  98 #define specpdl (current_thread->m_specpdl)
  99
 100   /* Pointer to first unused element in specpdl.  */
 101   union specbinding *m_specpdl_ptr;
 102 #define specpdl_ptr (current_thread->m_specpdl_ptr)
 103
 104   /* Depth in Lisp evaluations and function calls.  */
 105   EMACS_INT m_lisp_eval_depth;
 106 #define lisp_eval_depth (current_thread->m_lisp_eval_depth)
 107
 108   /* This points to the current buffer.  */
 109   struct buffer *m_current_buffer;
 110 #define current_buffer (current_thread->m_current_buffer)
 111
 112   /* Every call to re_match, etc., must pass &search_regs as the regs
 113      argument unless you can show it is unnecessary (i.e., if re_match
 114      is certainly going to be called again before region-around-match
 115      can be called).
 116
 117      Since the registers are now dynamically allocated, we need to make
 118      sure not to refer to the Nth register before checking that it has
 119      been allocated by checking search_regs.num_regs.
 120
 121      The regex code keeps track of whether it has allocated the search
 122      buffer using bits in the re_pattern_buffer.  This means that whenever
 123      you compile a new pattern, it completely forgets whether it has
 124      allocated any registers, and will allocate new registers the next
 125      time you call a searching or matching function.  Therefore, we need
 126      to call re_set_registers after compiling a new pattern or after
 127      setting the match registers, so that the regex functions will be
 128      able to free or re-allocate it properly.  */
 129   struct re_registers m_search_regs;
 130 #define search_regs (current_thread->m_search_regs)
 131
 132   /* If non-zero the match data have been saved in saved_search_regs
 133      during the execution of a sentinel or filter. */
 134   bool m_search_regs_saved;
 135 #define search_regs_saved (current_thread->m_search_regs_saved)
 136
 137   struct re_registers m_saved_search_regs;
 138 #define saved_search_regs (current_thread->m_saved_search_regs)
 139
 140   /* This is the string or buffer in which we
 141      are matching.  It is used for looking up syntax properties.
 142
 143      If the value is a Lisp string object, we are matching text in that
 144      string; if it's nil, we are matching text in the current buffer; if
 145      it's t, we are matching text in a C string.  */
 146   Lisp_Object m_re_match_object;
 147 #define re_match_object (current_thread->m_re_match_object)
 148
 149   /* This member is different from waiting_for_input.
 150      It is used to communicate to a lisp process-filter/sentinel (via the
 151      function Fwaiting_for_user_input_p) whether Emacs was waiting
 152      for user-input when that process-filter was called.
 153      waiting_for_input cannot be used as that is by definition 0 when
 154      lisp code is being evalled.
 155      This is also used in record_asynch_buffer_change.
 156      For that purpose, this must be 0
 157      when not inside wait_reading_process_output.  */
 158   int m_waiting_for_user_input_p;
 159 #define waiting_for_user_input_p (current_thread->m_waiting_for_user_input_p)
 160
 161   /* True while doing kbd input.  */
 162   bool m_waiting_for_input;
 163 #define waiting_for_input (current_thread->m_waiting_for_input)
 164
 165   /* For longjmp to where kbd input is being done.  This is per-thread
 166      so that if more than one thread calls read_char, they don't
 167      clobber each other's getcjmp, which will cause
 168      quit_throw_to_read_char crash due to using a wrong stack.  */
 169   sys_jmp_buf m_getcjmp;
 170 #define getcjmp (current_thread->m_getcjmp)
 171
 172   /* The OS identifier for this thread.  */
 173   sys_thread_t thread_id;
 174
 175   /* The condition variable for this thread.  This is associated with
 176      the global lock.  This thread broadcasts to it when it exits.  */
 177   sys_cond_t thread_condvar;
 178
 179   /* This thread might be waiting for some condition.  If so, this
 180      points to the condition.  If the thread is interrupted, the
 181      interrupter should broadcast to this condition.  */
 182   sys_cond_t *wait_condvar;
 183
 184   /* This thread might have released the global lock.  If so, this is
 185      non-zero.  When a thread runs outside thread_select with this
 186      flag non-zero, it means it has been interrupted by SIGINT while
 187      in thread_select, and didn't have a chance of acquiring the lock.
 188      It must do so ASAP.  */
 189   int not_holding_lock;
 190
 191   /* Threads are kept on a linked list.  */
 192   struct thread_state *next_thread;
 193 };
 194
 195 INLINE bool
 196 THREADP (Lisp_Object a)
 197 {
 198   return PSEUDOVECTORP (a, PVEC_THREAD);
 199 }
 200
 201 INLINE void
 202 CHECK_THREAD (Lisp_Object x)
 203 {
 204   CHECK_TYPE (THREADP (x), Qthreadp, x);
 205 }
 206
 207 INLINE struct thread_state *
 208 XTHREAD (Lisp_Object a)
 209 {
 210   eassert (THREADP (a));
 211   return XUNTAG (a, Lisp_Vectorlike);
 212 }
 213
 214 /* A mutex in lisp is represented by a system condition variable.
 215    The system mutex associated with this condition variable is the
 216    global lock.
 217
 218    Using a condition variable lets us implement interruptibility for
 219    lisp mutexes.  */
 220 typedef struct
 221 {
 222   /* The owning thread, or NULL if unlocked.  */
 223   struct thread_state *owner;
 224   /* The lock count.  */
 225   unsigned int count;
 226   /* The underlying system condition variable.  */
 227   sys_cond_t condition;
 228 } lisp_mutex_t;
 229
 230 /* A mutex as a lisp object.  */
 231 struct Lisp_Mutex
 232 {
 233   union vectorlike_header header;
 234
 235   /* The name of the mutex, or nil.  */
 236   Lisp_Object name;
 237
 238   /* The lower-level mutex object.  */
 239   lisp_mutex_t mutex;
 240 };
 241
 242 INLINE bool
 243 MUTEXP (Lisp_Object a)
 244 {
 245   return PSEUDOVECTORP (a, PVEC_MUTEX);
 246 }
 247
 248 INLINE void
 249 CHECK_MUTEX (Lisp_Object x)
 250 {
 251   CHECK_TYPE (MUTEXP (x), Qmutexp, x);
 252 }
 253
 254 INLINE struct Lisp_Mutex *
 255 XMUTEX (Lisp_Object a)
 256 {
 257   eassert (MUTEXP (a));
 258   return XUNTAG (a, Lisp_Vectorlike);
 259 }
 260
 261 /* A condition variable as a lisp object.  */
 262 struct Lisp_CondVar
 263 {
 264   union vectorlike_header header;
 265
 266   /* The associated mutex.  */
 267   Lisp_Object mutex;
 268
 269   /* The name of the condition variable, or nil.  */
 270   Lisp_Object name;
 271
 272   /* The lower-level condition variable object.  */
 273   sys_cond_t cond;
 274 };
 275
 276 INLINE bool
 277 CONDVARP (Lisp_Object a)
 278 {
 279   return PSEUDOVECTORP (a, PVEC_CONDVAR);
 280 }
 281
 282 INLINE void
 283 CHECK_CONDVAR (Lisp_Object x)
 284 {
 285   CHECK_TYPE (CONDVARP (x), Qcondition_variable_p, x);
 286 }
 287
 288 INLINE struct Lisp_CondVar *
 289 XCONDVAR (Lisp_Object a)
 290 {
 291   eassert (CONDVARP (a));
 292   return XUNTAG (a, Lisp_Vectorlike);
 293 }
 294
 295 extern struct thread_state *current_thread;
 296
 297 extern void finalize_one_thread (struct thread_state *state);
 298 extern void finalize_one_mutex (struct Lisp_Mutex *);
 299 extern void finalize_one_condvar (struct Lisp_CondVar *);
 300 extern void maybe_reacquire_global_lock (void);
 301
 302 extern void init_threads_once (void);
 303 extern void init_threads (void);
 304 extern void syms_of_threads (void);
 305 extern bool main_thread_p (void *);
 306 extern bool in_current_thread (void);
 307
 308 typedef int select_func (int, fd_set *, fd_set *, fd_set *,
 309                          const struct timespec *, const sigset_t *);
 310
 311 int thread_select  (select_func *func, int max_fds, fd_set *rfds,
 312                     fd_set *wfds, fd_set *efds, struct timespec *timeout,
 313                     sigset_t *sigmask);
 314
 315 bool thread_check_current_buffer (struct buffer *);
 316
 317 #endif /* THREAD_H */