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Diffstat (limited to 'lib/frr_pthread.h')
| -rw-r--r-- | lib/frr_pthread.h | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/lib/frr_pthread.h b/lib/frr_pthread.h new file mode 100644 index 0000000..89519ab --- /dev/null +++ b/lib/frr_pthread.h @@ -0,0 +1,270 @@ +/* + * Utilities and interfaces for managing POSIX threads within FRR. + * Copyright (C) 2017 Cumulus Networks, Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; see the file COPYING; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef _FRR_PTHREAD_H +#define _FRR_PTHREAD_H + +#include <pthread.h> +#include "frratomic.h" +#include "memory.h" +#include "frrcu.h" +#include "thread.h" + +#ifdef __cplusplus +extern "C" { +#endif + +#define OS_THREAD_NAMELEN 16 + +struct frr_pthread; +struct frr_pthread_attr; + +struct frr_pthread_attr { + void *(*start)(void *); + int (*stop)(struct frr_pthread *, void **); +}; + +struct frr_pthread { + + /* + * Mutex protecting this structure. Must be taken for reading some + * fields, denoted by a 'Requires: mtx'. + */ + pthread_mutex_t mtx; + + /* pthread id */ + pthread_t thread; + + struct rcu_thread *rcu_thread; + + /* thread master for this pthread's thread.c event loop */ + struct thread_master *master; + + /* caller-specified data; start & stop funcs, name, id */ + struct frr_pthread_attr attr; + + /* + * Notification mechanism for allowing pthreads to notify their parents + * when they are ready to do work. This mechanism has two associated + * functions: + * + * - frr_pthread_wait_running() + * This function should be called by the spawning thread after + * frr_pthread_run(). It safely waits until the spawned thread + * indicates that is ready to do work by posting to the condition + * variable. + * + * - frr_pthread_notify_running() + * This function should be called by the spawned thread when it is + * ready to do work. It will wake up any threads waiting on the + * previously described condition. + */ + pthread_cond_t *running_cond; + pthread_mutex_t *running_cond_mtx; + atomic_bool running; + + /* + * Fake thread-specific storage. No constraints on usage. Helpful when + * creating reentrant pthread implementations. Can be used to pass + * argument to pthread entry function. + * + * Requires: mtx + */ + void *data; + + /* + * Human-readable thread name. + * + * Requires: mtx + */ + char *name; + + /* Used in pthread_set_name max 16 characters */ + char os_name[OS_THREAD_NAMELEN]; +}; + +extern const struct frr_pthread_attr frr_pthread_attr_default; + +/* + * Initializes this module. + * + * Must be called before using any of the other functions. + */ +void frr_pthread_init(void); + +/* + * Uninitializes this module. + * + * Destroys all registered frr_pthread's and internal data structures. + * + * It is safe to call frr_pthread_init() after this function to reinitialize + * the module. + */ +void frr_pthread_finish(void); + +/* + * Creates a new frr_pthread with the given attributes. + * + * The 'attr' argument should be filled out with the desired attributes, + * including ID, start and stop functions and the desired name. Alternatively, + * if attr is NULL, the default attributes will be used. The pthread will be + * set up to run a basic threadmaster loop and the name will be "Anonymous". + * Scheduling tasks onto the threadmaster in the 'master' field of the returned + * frr_pthread will cause them to run on that pthread. + * + * @param attr - the thread attributes + * @param name - Human-readable name + * @param os_name - 16 characters (including '\0') thread name to set in os, + * @return the created frr_pthread upon success, or NULL upon failure + */ +struct frr_pthread *frr_pthread_new(const struct frr_pthread_attr *attr, + const char *name, const char *os_name); + +/* + * Changes the name of the frr_pthread as reported by the operating + * system. + * + * @param fpt - the frr_pthread to operate on + * @return - on success returns 0 otherwise nonzero error number. + */ +int frr_pthread_set_name(struct frr_pthread *fpt); + +/* + * Destroys an frr_pthread. + * + * Assumes that the associated pthread, if any, has already terminated. + * + * @param fpt - the frr_pthread to destroy + */ +void frr_pthread_destroy(struct frr_pthread *fpt); + +/* + * Creates a new pthread and binds it to a frr_pthread. + * + * This function is a wrapper for pthread_create. The first parameter is the + * frr_pthread to bind the created pthread to. All subsequent arguments are + * passed unmodified to pthread_create(). The frr_pthread * provided will be + * used as the argument to the pthread entry function. If it is necessary to + * pass additional data, the 'data' field in the frr_pthread may be used. + * + * This function returns the same code as pthread_create(). If the value is + * zero, the provided frr_pthread is bound to a running POSIX thread. If the + * value is less than zero, the provided frr_pthread is guaranteed to be a + * clean instance that may be susbsequently passed to frr_pthread_run(). + * + * @param fpt - frr_pthread * to run + * @param attr - see pthread_create(3) + * + * @return see pthread_create(3) + */ +int frr_pthread_run(struct frr_pthread *fpt, const pthread_attr_t *attr); + +/* + * Waits until the specified pthread has finished setting up and is ready to + * begin work. + * + * If the pthread's code makes use of the startup synchronization mechanism, + * this function should be called before attempting to use the functionality + * exposed by the pthread. It waits until the 'running' condition is satisfied + * (see struct definition of frr_pthread). + * + * @param fpt - the frr_pthread * to wait on + */ +void frr_pthread_wait_running(struct frr_pthread *fpt); + +/* + * Notifies other pthreads that the calling thread has finished setting up and + * is ready to begin work. + * + * This will allow any other pthreads waiting in 'frr_pthread_wait_running' to + * proceed. + * + * @param fpt - the frr_pthread * that has finished setting up + */ +void frr_pthread_notify_running(struct frr_pthread *fpt); + +/* + * Stops a frr_pthread with a result. + * + * @param fpt - frr_pthread * to stop + * @param result - where to store the thread's result, if any. May be NULL if a + * result is not needed. + */ +int frr_pthread_stop(struct frr_pthread *fpt, void **result); + +/* Stops all frr_pthread's. */ +void frr_pthread_stop_all(void); + +#ifndef HAVE_PTHREAD_CONDATTR_SETCLOCK +#define pthread_condattr_setclock(A, B) +#endif + +/* mutex auto-lock/unlock */ + +/* variant 1: + * (for short blocks, multiple mutexes supported) + * break & return can be used for aborting the block + * + * frr_with_mutex(&mtx, &mtx2) { + * if (error) + * break; + * ... + * } + */ +#define _frr_with_mutex(mutex) \ + *NAMECTR(_mtx_) __attribute__(( \ + unused, cleanup(_frr_mtx_unlock))) = _frr_mtx_lock(mutex), \ + /* end */ + +#define frr_with_mutex(...) \ + for (pthread_mutex_t MACRO_REPEAT(_frr_with_mutex, ##__VA_ARGS__) \ + *_once = NULL; _once == NULL; _once = (void *)1) \ + /* end */ + +/* variant 2: + * (more suitable for long blocks, no extra indentation) + * + * frr_mutex_lock_autounlock(&mtx); + * ... + */ +#define frr_mutex_lock_autounlock(mutex) \ + pthread_mutex_t *NAMECTR(_mtx_) \ + __attribute__((unused, cleanup(_frr_mtx_unlock))) = \ + _frr_mtx_lock(mutex) \ + /* end */ + +static inline pthread_mutex_t *_frr_mtx_lock(pthread_mutex_t *mutex) +{ + pthread_mutex_lock(mutex); + return mutex; +} + +static inline void _frr_mtx_unlock(pthread_mutex_t **mutex) +{ + if (!*mutex) + return; + pthread_mutex_unlock(*mutex); + *mutex = NULL; +} + +#ifdef __cplusplus +} +#endif + +#endif /* _FRR_PTHREAD_H */ |