lib/coverage.h

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef COVERAGE_H
  18 #define COVERAGE_H 1
  19
  20 /* This file implements a simple form of coverage instrumentation.  Points in
  21  * source code that are of interest must be explicitly annotated with
  22  * COVERAGE_INC.  The coverage counters may be logged at any time with
  23  * coverage_log().
  24  *
  25  * This form of coverage instrumentation is intended to be so lightweight that
  26  * it can be enabled in production builds.  It is obviously not a substitute
  27  * for traditional coverage instrumentation with e.g. "gcov", but it is still
  28  * a useful debugging tool. */
  29
  30 #include "ovs-thread.h"
  31 #include "compiler.h"
  32
  33 /* Makes coverage_run run every 5000 ms (5 seconds).
  34  * If this value is redefined, the new value must
  35  * divide 60000 (1 minute). */
  36 #define COVERAGE_RUN_INTERVAL    5000
  37 BUILD_ASSERT_DECL(60000 % COVERAGE_RUN_INTERVAL == 0);
  38
  39 #define COVERAGE_CLEAR_INTERVAL  1000
  40 BUILD_ASSERT_DECL(COVERAGE_RUN_INTERVAL % COVERAGE_CLEAR_INTERVAL == 0);
  41
  42 /* Defines the moving average array length. */
  43 #define MIN_AVG_LEN (60000/COVERAGE_RUN_INTERVAL)
  44 #define HR_AVG_LEN  60
  45
  46 /* A coverage counter. */
  47 struct coverage_counter {
  48     const char *const name;            /* Textual name. */
  49     unsigned int (*const count)(void); /* Gets, zeros this thread's count. */
  50     unsigned long long int total;      /* Total count. */
  51     unsigned long long int last_total;
  52     /* The moving average arrays. */
  53     unsigned int min[MIN_AVG_LEN];
  54     unsigned int hr[HR_AVG_LEN];
  55 };
  56
  57 void coverage_counter_register(struct coverage_counter*);
  58
  59 /* Defines COUNTER.  There must be exactly one such definition at file scope
  60  * within a program. */
  61 #define COVERAGE_DEFINE(COUNTER)                                        \
  62         DEFINE_STATIC_PER_THREAD_DATA(unsigned int,                     \
  63                                       counter_##COUNTER, 0);            \
  64         static unsigned int COUNTER##_count(void)                       \
  65         {                                                               \
  66             unsigned int *countp = counter_##COUNTER##_get();           \
  67             unsigned int count = *countp;                               \
  68             *countp = 0;                                                \
  69             return count;                                               \
  70         }                                                               \
  71         static inline void COUNTER##_add(unsigned int n)                \
  72         {                                                               \
  73             *counter_##COUNTER##_get() += n;                            \
  74         }                                                               \
  75         extern struct coverage_counter counter_##COUNTER;               \
  76         struct coverage_counter counter_##COUNTER                       \
  77             = { #COUNTER, COUNTER##_count, 0, 0, {0}, {0} };            \
  78         OVS_CONSTRUCTOR(COUNTER##_init) {                               \
  79             coverage_counter_register(&counter_##COUNTER);              \
  80         }
  81
  82 /* Adds 1 to COUNTER. */
  83 #define COVERAGE_INC(COUNTER) COVERAGE_ADD(COUNTER, 1)
  84
  85 /* Adds AMOUNT to COUNTER. */
  86 #define COVERAGE_ADD(COUNTER, AMOUNT) COUNTER##_add(AMOUNT)
  87
  88 void coverage_init(void);
  89 void coverage_log(void);
  90 void coverage_clear(void);
  91 void coverage_try_clear(void);
  92 void coverage_run(void);
  93
  94 #endif /* coverage.h */