include/lttng/health-internal.h

   1 #ifndef HEALTH_INTERNAL_H
   2 #define HEALTH_INTERNAL_H
   3
   4 /*
   5  * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
   6  * Copyright (C) 2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License, version 2 only, as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  15  * more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along with
  18  * this program; if not, write to the Free Software Foundation, Inc., 51
  19  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20  */
  21
  22 #include <assert.h>
  23 #include <time.h>
  24 #include <pthread.h>
  25 #include <urcu/tls-compat.h>
  26 #include <urcu/uatomic.h>
  27 #include <urcu/list.h>
  28
  29 /*
  30  * These are the value added to the current state depending of the position in
  31  * the thread where is either waiting on a poll() or running in the code.
  32  */
  33 #define HEALTH_POLL_VALUE       (1UL << 0)
  34 #define HEALTH_CODE_VALUE       (1UL << 1)
  35
  36 #define HEALTH_IS_IN_POLL(x)    ((x) & HEALTH_POLL_VALUE)
  37
  38 struct health_app;
  39
  40 enum health_flags {
  41         HEALTH_ERROR                     = (1U << 0),
  42 };
  43
  44 struct health_state {
  45         /*
  46          * last counter and last_time are only read and updated by the health_check
  47          * thread (single updater).
  48          */
  49         unsigned long last;
  50         struct timespec last_time;
  51
  52         /*
  53          * current and flags are updated by multiple threads concurrently.
  54          */
  55         unsigned long current;          /* progress counter, updated atomically */
  56         enum health_flags flags;        /* other flags, updated atomically */
  57         int type;                       /* Indicates the nature of the thread. */
  58         /* Node of the global TLS state list. */
  59         struct cds_list_head node;
  60 };
  61
  62 /* Declare TLS health state. */
  63 extern DECLARE_URCU_TLS(struct health_state, health_state);
  64
  65 /*
  66  * Update current counter by 1 to indicate that the thread entered or left a
  67  * blocking state caused by a poll(). If the counter's value is not an even
  68  * number (meaning a code execution flow), an assert() is raised.
  69  */
  70 static inline void health_poll_entry(void)
  71 {
  72         /* Code MUST be in code execution state which is an even number. */
  73         assert(!(uatomic_read(&URCU_TLS(health_state).current)
  74                                 & HEALTH_POLL_VALUE));
  75
  76         uatomic_add(&URCU_TLS(health_state).current, HEALTH_POLL_VALUE);
  77 }
  78
  79 /*
  80  * Update current counter by 1 indicating the exit of a poll or blocking call.
  81  * If the counter's value is not an odd number (a poll execution), an assert()
  82  * is raised.
  83  */
  84 static inline void health_poll_exit(void)
  85 {
  86         /* Code MUST be in poll execution state which is an odd number. */
  87         assert(uatomic_read(&URCU_TLS(health_state).current)
  88                                 & HEALTH_POLL_VALUE);
  89
  90         uatomic_add(&URCU_TLS(health_state).current, HEALTH_POLL_VALUE);
  91 }
  92
  93 /*
  94  * Update current counter by 2 indicates progress in execution of a
  95  * thread.
  96  */
  97 static inline void health_code_update(void)
  98 {
  99         uatomic_add(&URCU_TLS(health_state).current, HEALTH_CODE_VALUE);
 100 }
 101
 102 /*
 103  * Set health "error" flag.
 104  */
 105 static inline void health_error(void)
 106 {
 107         uatomic_or(&URCU_TLS(health_state).flags, HEALTH_ERROR);
 108 }
 109
 110 struct health_app *health_app_create(int nr_types);
 111 void health_app_destroy(struct health_app *ha);
 112 int health_check_state(struct health_app *ha, int type);
 113 void health_register(struct health_app *ha, int type);
 114 void health_unregister(struct health_app *ha);
 115
 116 #endif /* HEALTH_INTERNAL_H */