lib/frr_pthread.h

   1 /*
   2  * Utilities and interfaces for managing POSIX threads within FRR.
   3  * Copyright (C) 2017  Cumulus Networks, Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; see the file COPYING; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  */
  19
  20 #ifndef _FRR_PTHREAD_H
  21 #define _FRR_PTHREAD_H
  22
  23 #include <pthread.h>
  24 #include "frratomic.h"
  25 #include "memory.h"
  26 #include "thread.h"
  27
  28 DECLARE_MTYPE(FRR_PTHREAD);
  29 DECLARE_MTYPE(PTHREAD_PRIM);
  30
  31 #define OS_THREAD_NAMELEN 16
  32
  33 struct frr_pthread;
  34 struct frr_pthread_attr;
  35
  36 struct frr_pthread_attr {
  37         void *(*start)(void *);
  38         int (*stop)(struct frr_pthread *, void **);
  39 };
  40
  41 struct frr_pthread {
  42
  43         /*
  44          * Mutex protecting this structure. Must be taken for reading some
  45          * fields, denoted by a 'Requires: mtx'.
  46          */
  47         pthread_mutex_t mtx;
  48
  49         /* pthread id */
  50         pthread_t thread;
  51
  52         /* thread master for this pthread's thread.c event loop */
  53         struct thread_master *master;
  54
  55         /* caller-specified data; start & stop funcs, name, id */
  56         struct frr_pthread_attr attr;
  57
  58         /*
  59          * Notification mechanism for allowing pthreads to notify their parents
  60          * when they are ready to do work. This mechanism has two associated
  61          * functions:
  62          *
  63          * - frr_pthread_wait_running()
  64          *   This function should be called by the spawning thread after
  65          *   frr_pthread_run(). It safely waits until the spawned thread
  66          *   indicates that is ready to do work by posting to the condition
  67          *   variable.
  68          *
  69          * - frr_pthread_notify_running()
  70          *   This function should be called by the spawned thread when it is
  71          *   ready to do work. It will wake up any threads waiting on the
  72          *   previously described condition.
  73          */
  74         pthread_cond_t *running_cond;
  75         pthread_mutex_t *running_cond_mtx;
  76         _Atomic bool running;
  77
  78         /*
  79          * Fake thread-specific storage. No constraints on usage. Helpful when
  80          * creating reentrant pthread implementations. Can be used to pass
  81          * argument to pthread entry function.
  82          *
  83          * Requires: mtx
  84          */
  85         void *data;
  86
  87         /*
  88          * Human-readable thread name.
  89          *
  90          * Requires: mtx
  91          */
  92         char *name;
  93
  94         /* Used in pthread_set_name max 16 characters */
  95         char os_name[OS_THREAD_NAMELEN];
  96 };
  97
  98 extern struct frr_pthread_attr frr_pthread_attr_default;
  99
 100 /*
 101  * Initializes this module.
 102  *
 103  * Must be called before using any of the other functions.
 104  */
 105 void frr_pthread_init(void);
 106
 107 /*
 108  * Uninitializes this module.
 109  *
 110  * Destroys all registered frr_pthread's and internal data structures.
 111  *
 112  * It is safe to call frr_pthread_init() after this function to reinitialize
 113  * the module.
 114  */
 115 void frr_pthread_finish(void);
 116
 117 /*
 118  * Creates a new frr_pthread with the given attributes.
 119  *
 120  * The 'attr' argument should be filled out with the desired attributes,
 121  * including ID, start and stop functions and the desired name. Alternatively,
 122  * if attr is NULL, the default attributes will be used. The pthread will be
 123  * set up to run a basic threadmaster loop and the name will be "Anonymous".
 124  * Scheduling tasks onto the threadmaster in the 'master' field of the returned
 125  * frr_pthread will cause them to run on that pthread.
 126  *
 127  * @param attr - the thread attributes
 128  * @param name - Human-readable name
 129  * @param os_name - 16 characters (including '\0') thread name to set in os,
 130  * @return the created frr_pthread upon success, or NULL upon failure
 131  */
 132 struct frr_pthread *frr_pthread_new(struct frr_pthread_attr *attr,
 133                                     const char *name, const char *os_name);
 134
 135 /*
 136  * Changes the name of the frr_pthread.
 137  *
 138  * @param fpt - the frr_pthread to operate on
 139  * @param name - Human-readable name
 140  * @param os_name - 16 characters thread name , including the null
 141  * terminator ('\0') to set in os.
 142  * @return -  on success returns 0 otherwise nonzero error number.
 143  */
 144 int frr_pthread_set_name(struct frr_pthread *fpt, const char *name,
 145                          const char *os_name);
 146
 147 /*
 148  * Destroys an frr_pthread.
 149  *
 150  * Assumes that the associated pthread, if any, has already terminated.
 151  *
 152  * @param fpt - the frr_pthread to destroy
 153  */
 154 void frr_pthread_destroy(struct frr_pthread *fpt);
 155
 156 /*
 157  * Creates a new pthread and binds it to a frr_pthread.
 158  *
 159  * This function is a wrapper for pthread_create. The first parameter is the
 160  * frr_pthread to bind the created pthread to. All subsequent arguments are
 161  * passed unmodified to pthread_create(). The frr_pthread * provided will be
 162  * used as the argument to the pthread entry function. If it is necessary to
 163  * pass additional data, the 'data' field in the frr_pthread may be used.
 164  *
 165  * This function returns the same code as pthread_create(). If the value is
 166  * zero, the provided frr_pthread is bound to a running POSIX thread. If the
 167  * value is less than zero, the provided frr_pthread is guaranteed to be a
 168  * clean instance that may be susbsequently passed to frr_pthread_run().
 169  *
 170  * @param fpt - frr_pthread * to run
 171  * @param attr - see pthread_create(3)
 172  *
 173  * @return see pthread_create(3)
 174  */
 175 int frr_pthread_run(struct frr_pthread *fpt, const pthread_attr_t *attr);
 176
 177 /*
 178  * Waits until the specified pthread has finished setting up and is ready to
 179  * begin work.
 180  *
 181  * If the pthread's code makes use of the startup synchronization mechanism,
 182  * this function should be called before attempting to use the functionality
 183  * exposed by the pthread. It waits until the 'running' condition is satisfied
 184  * (see struct definition of frr_pthread).
 185  *
 186  * @param fpt - the frr_pthread * to wait on
 187  */
 188 void frr_pthread_wait_running(struct frr_pthread *fpt);
 189
 190 /*
 191  * Notifies other pthreads that the calling thread has finished setting up and
 192  * is ready to begin work.
 193  *
 194  * This will allow any other pthreads waiting in 'frr_pthread_wait_running' to
 195  * proceed.
 196  *
 197  * @param fpt - the frr_pthread * that has finished setting up
 198  */
 199 void frr_pthread_notify_running(struct frr_pthread *fpt);
 200
 201 /*
 202  * Stops a frr_pthread with a result.
 203  *
 204  * @param fpt - frr_pthread * to stop
 205  * @param result - where to store the thread's result, if any. May be NULL if a
 206  * result is not needed.
 207  */
 208 int frr_pthread_stop(struct frr_pthread *fpt, void **result);
 209
 210 /* Stops all frr_pthread's. */
 211 void frr_pthread_stop_all(void);
 212
 213 #ifndef HAVE_PTHREAD_CONDATTR_SETCLOCK
 214 #define pthread_condattr_setclock(A, B)
 215 #endif
 216
 217 #endif /* _FRR_PTHREAD_H */