1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
|
/*
*
* Copyright 2015, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/* RPC-internal Census API's. These are designed to be generic enough that
* they can (ultimately) be used in many different RPC systems (with differing
* implementations). */
#ifndef CENSUS_CENSUS_H
#define CENSUS_CENSUS_H
#include <grpc/grpc.h>
#ifdef __cplusplus
extern "C" {
#endif
/* Identify census features that can be enabled via census_initialize(). */
enum census_features {
CENSUS_FEATURE_NONE = 0, /* Do not enable census. */
CENSUS_FEATURE_TRACING = 1, /* Enable census tracing. */
CENSUS_FEATURE_STATS = 2, /* Enable Census stats collection. */
CENSUS_FEATURE_CPU = 4, /* Enable Census CPU usage collection. */
CENSUS_FEATURE_ALL =
CENSUS_FEATURE_TRACING | CENSUS_FEATURE_STATS | CENSUS_FEATURE_CPU
};
/** Shutdown and startup census subsystem. The 'features' argument should be
* the OR (|) of census_features values. If census fails to initialize, then
* census_initialize() will return a non-zero value. It is an error to call
* census_initialize() more than once (without an intervening
* census_shutdown()). */
int census_initialize(int features);
void census_shutdown(void);
/** Return the features supported by the current census implementation (not all
* features will be available on all platforms). */
int census_supported(void);
/** Return the census features currently enabled. */
int census_enabled(void);
/* Internally, Census relies on a context, which should be propagated across
* RPC's. From the RPC subsystems viewpoint, this is an opaque data structure.
* A context must be used as the first argument to all other census
* functions. Conceptually, contexts should be thought of as specific to
* single RPC/thread. The context can be serialized for passing across the
* wire. */
typedef struct census_context census_context;
/* This function is called by the RPC subsystem whenever it needs to get a
* serialized form of the current census context (presumably to pass across
* the wire). Arguments:
* 'buffer': pointer to memory into which serialized context will be placed
* 'buf_size': size of 'buffer'
*
* Returns: the number of bytes used in buffer if successful, or 0 if the
* buffer is of insufficient size.
*
* TODO(aveitch): determine how best to communicate required/max buffer size
* so caller doesn't have to guess. */
size_t census_context_serialize(const census_context *context, char *buffer,
size_t buf_size);
/* Create a new census context, possibly from a serialized buffer. If 'buffer'
* is non-NULL, it is assumed that it is a buffer encoded by
* census_context_serialize(). If `buffer` is NULL, a new, empty context is
* created. The decoded/new contest is returned in 'context'.
*
* Returns 0 if no errors, non-zero if buffer is incorrectly formatted, in
* which case a new empty context will be returned. */
int census_context_deserialize(const char *buffer, census_context **context);
/* The given context is destroyed. Once destroyed, using the context in
* future census calls will result in undefined behavior. */
void census_context_destroy(census_context *context);
/* Max number of characters in tag key */
#define CENSUS_MAX_TAG_KEY_LENGTH 20
/* Max number of tag value characters */
#define CENSUS_MAX_TAG_VALUE_LENGTH 50
/* A Census tag set is a collection of key:value string pairs; these form the
basis against which Census metrics will be recorded. Keys are unique within
a tag set. All contexts have an associated tag set. */
typedef struct census_tag_set census_tag_set;
/* Returns a pointer to a newly created, empty tag set. If size_hint > 0,
indicates that the tag set is intended to hold approximately that number
of tags. */
census_tag_set *census_tag_set_create(size_t size_hint);
/* Add a new tag key/value to an existing tag set; if the tag key already exists
in the tag set, then its value is overwritten with the new one. Can also be
used to delete a tag, by specifying a NULL value. If key is NULL, returns
the number of tags in the tag set.
Return values:
-1: invalid length key or value
non-negative value: the number of tags in the tag set. */
int census_tag_set_add(census_tag_set *tags, const char *key,
const char *value);
/* Destroys a tag set. This function must be called to prevent memory leaks.
Once called, the tag set cannot be used again. */
void census_tag_set_destroy(census_tag_set *tags);
/* Get a contexts tag set. */
census_tag_set *census_context_tag_set(census_context *context);
/* A read-only representation of a tag for use by census clients. */
typedef struct {
size_t key_len; /* Number of bytes in tag key. */
const char *key; /* A pointer to the tag key. May not be null-terminated. */
size_t value_len; /* Number of bytes in tag value. */
const char *value; /* Pointer to the tag value. May not be null-terminated. */
} census_tag_const;
/* Used to iterate through a tag sets contents. */
typedef struct census_tag_set_iterator census_tag_set_iterator;
/* Open a tag set for iteration. The tag set must not be modified while
iteration is ongoing. Returns an iterator for use in following functions. */
census_tag_set_iterator *census_tag_set_open(census_tag_set *tags);
/* Get the next tag in the tag set, by writing into the 'tag' argument. Returns
1 if there is a "next" tag, 0 if there are no more tags. */
int census_tag_set_next(census_tag_set_iterator *it, census_tag_const *tag);
/* Close an iterator opened by census_tag_set_open(). The iterator will be
invalidated, and should not be used once close is called. */
void census_tag_set_close(census_tag_set_iterator *it);
/* A census statistic to be recorded comprises two parts: an ID for the
* particular statistic and the value to be recorded against it. */
typedef struct {
int id;
double value;
} census_stat;
/* Record new stats against the given context. */
void census_record_stat(census_context *context, census_stat *stats,
size_t nstats);
#ifdef __cplusplus
}
#endif
#endif /* CENSUS_CENSUS_H */
|
